The good news is that there are answers, and the more knowledge you have, the more power you have to make the right decisions for your horse.

We sat down to chat with Ann Andrews, DVM, CVA, of Park Equine Hospital in Lexington, Ky., to answer your most-asked questions.

Photo by Christiane Slawik

Q: Does my horse need vaccinations?

As modern-day horse owners, it’s easy for us to take for granted the health advantages that vaccines now offer our equines. Not too many years ago, horses died from tetanus, rabies, Eastern and Western encephalomyelitis, and other diseases.

Nowadays, horses can be protected from these diseases with vaccinations; if not completely, at least with the resulting illness being less severe. The key is developing a program alongside your veterinarian that meets the individual needs of your horse.

Q: Is there a safe and essential minimum of vaccinations required?

Like many equine veterinarians, Andrews follows the guidelines of the American Association of Equine Practitioners (AAEP), which recommends a few core vaccines for all horses.

“The AAEP is a great resource for horse owners, and not just for vaccinations, but many health issues,” she says.

There are five diseases the AAEP’s core vaccines protect against: EEE, WEE, rabies, tetanus, and West Nile virus. Photo by peopleimages.com/Adobe Stock

Here’s a brief description of the diseases core vaccines protect against, and their recommended frequency.

◆ Eastern and Western equine encephalomyelitis (EEE/WEE) are viral diseases spread by mosquitoes that cause neurological damage or death. Vaccine frequency is annual in spring prior to the rise in vector season.

◆ Rabies is a fatal neurological disease that affects all mammals; it can be transmitted by raccoons, bats, skunks and foxes. Vaccine frequency is annual.

◆ Tetanus is a bacterial disease that is often fatal; it can be contracted through wounds or punctures. Vaccine frequency is annual.

◆ West Nile virus (WNV) is a neurological disease transmitted by mosquitoes; it can be fatal, and recovered horses may have abnormalities in behavior and gait. Vaccine frequency is annual in spring prior to vector season.

“Depending on your geographic location, regional prevalence, exposure risk, stabling environment and other factors, your vet may also recommend certain additional risk-based vaccinations,” says Andrews.

Commonly recommended risk-based vaccines include:

◆ Equine herpesvirus (rhinopneumonitis/EHV): EHV-1 and EHV-4 are viral diseases that can cause abortions in broodmares, neurological issues, and respiratory illness. Horses that travel, compete, or are kept in high-density environments are particularly susceptible.

u◆Equine influenza (flu) is a highly contagious viral disease that causes respiratory illness and impacts performance. Horses involved in activities that involve contact with other horses are at highest risk.

◆ Potomac horse fever (PHF) is a disease caused by the bacteria Neorickettsia risticii and transmitted to horses drinking from water sources where parasitic worms have infected aquatic insects. Vaccination is recommended in areas where the disease is prevalent, as well as for horses traveling to or through those areas. 

◆ Strangles (Streptococcus equi) is a highly contagious bacterial infection that causes swollen lymph nodes and respiratory issues. Horses in high-risk environments (for example, where new horses arrive frequently) are most susceptible.

Flu/rhino and strangles vaccines are a good idea to add to the list for horses that travel to competitions. Photo by Janet/Adobe Stock

Other risk-based vaccines include:

◆ Anthrax

◆ Botulism

◆ Equine viral arteritis

◆ Leptospirosis

◆ Rotaviral diarrhea

◆ Snake bite

◆ Venezuelan equine encephalomyelitis (VEE)

Q: Do vaccinations differ for horses that compete or are stabled in a large boarding facility versus a small herd or retirees that never travel?

“Even for older horses and those that live in a closed environment with no interaction with outside horses, the four core vaccines are always advised,” says Andrews. These provide protection from common diseases and illnesses, especially those that are spread by mosquitoes or chance encounters with wildlife.

“For horses that travel to competitions and/or live in large barns where lots of horses come and go, I’d also recommend additional vaccines to cover their exposure, including flu/rhino at least annually and perhaps a booster every six months, and strangles,” she adds.

Q: If my horse has reactions to vaccines, what can help minimize them?

Common reactions include swelling at the injection site, lethargy, going off feed, and sometimes colic and laminitis. The best solution might seem to be spreading out vaccinations over several days or weeks to avoid bombarding the horse’s system with multiple antibodies at the same time.

“The problem with this approach is that each vaccine can cause a reaction, even if it’s minimal,” says Andrews. “Then the horse’s system has to process, and potentially react to, each vaccine spread over many days instead of one episode with multiple vaccines.”

However, there are ways to work with your vet to help minimize reactions:

◆ Vary the injection sites for each vaccine, such as different locations on the neck and hip. “This also helps identify reactions to certain vaccines if there’s swelling at the injection site,” says Andrews.

◆ Allow the horse free movement after vaccinations to help his system process the antibodies.

◆ Devise a proactive approach, such as treating with Dexamethasone or Banamine the day before the injections, the day of, and a couple days after.

◆ Another benefit of having a client/vet relationship is the ability to dig deeper to find solution (see more below).

“One client’s horse had severe reactions to vaccines,” she recalls, despite trying the ideas above. “I decided to switch the brand of vaccines, and for whatever reason, that worked for him. Now we have an established protocol that we follow every time, and it’s helping keep his side effects as minimal as possible.”

If your horse has severe reactions to vaccinations, you might consider asking your vet about checking titers—the level of antibodies in the horse’s blood that are specific to a particular pathogen.

Q: Are there any differences for vaccines based on geography, weather, et cetera?

Certain diseases or illnesses can be more prevalent in some areas of the country than others, and your vet’s vaccination recommendations will reflect that.

For example, Potomac horse fever was first discovered in Maryland near the Potomac River. It’s since been reported in numerous states (including California), and it seems to peak in summer and fall in areas with bodies of water, like lakes, creeks, rivers, and ponds.

Botulism, a potentially fatal neurologic disease, is not a regional disease per se, but it’s more commonly found in horses that eat from large round hay bales as well as fermented haylage and silage feeds. If these forage types are common in your area and consumed by your horse, your vet may recommend this vaccination. 

Botulism is more commonly a threat for horses that eat from large round bales. Photo by pimmimemom/Adobe Stock

Horses in Florida and other areas with higher mosquito populations or longer mosquito seasons may be recommended to have boosters for Eastern/Western equine encephalomyelitis and West Nile virus.

Quarantine and Biosecurity Imagine this. After years of searching, your dream horse had finally arrived. You smile as he steps off the trailer and into his stall in the big barn.  A couple days later, he’s lethargic and has stopped eating. When you go to halter him, you notice the area under his jaw was swollen. You call the vet, sure that he has an abscessed tooth. The vet arrives and peeks over the stall door. “Your horse doesn’t have an abscessed tooth. He has strangles.” Within days, every horse in the barn is sick. The following weeks of treatment, mess, stress, and expense could have been avoided with a simple quarantine and biosecurity program. “I believe every horse owner should quarantine any new horse that comes to their property,” says Andrews. “At the client barns where we have a quarantine protocol, I’ve seen numerous times how it prevented huge outbreaks of illness and confined it to one horse.” Setting up a quarantine system is simple and well worth the time. Here’s how: ◆ Use portable panels to set up a corral that’s away from the barn and pasture fence lines. ◆ Keep the new horse in this area for a minimum of two weeks, and up to three. Monitor daily for elevated temperature and other signs of illness. ◆ Avoid cross-contamination with feed and water buckets, grooming tools, et cetera, and be sure all handlers wash their hands after contact with the quarantined horse. ◆ If the quarantined horse gets sick, use biosecurity measures when treating the horse, including separate (or disposable) clothing/gowns, gloves, hats, boots, and masks. ◆ When the horse is released from quarantine, thoroughly clean the area with a 5-10 percent bleach solution and allow to dry. If you don’t already have a separate area, use portable panels to set up a corral away from other horses during the quarantine period. Use brushes and water buckets that aren’t shared with any other equines. Photo by Christiane Slawik

For more on recommended vaccines, visit the American Association of Equine Practitioners.

This Q&A about vaccines for horses appeared in the March/April 2025 issue of Horse Illustrated magazine. Click here to subscribe!

The post Horse Vaccines Q&A appeared first on Horse Illustrated Magazine.

Photo by Hedgehog94/Adobe Stock

Visualize the Triangle

Although horses are quite muscular, there are limits to the locations where we can safely give intramuscular injections. These injections should be administered deep into a large muscle to ensure that the entire contents of the syringe are adequately absorbed and metabolized.

In horses, one of the most common and preferred sites for IM injections is the side of the neck. Chances are you’ve probably seen your veterinarian use this site. But the neck of a horse is a wide, flat structure—how do you know exactly where to stick the needle?

An easy way to know for sure is to find the “triangle” formed by three structures in the neck. The nuchal ligament forms the first border; this is the thick ligament that runs from the poll to the withers and holds up the mane. The injection should be below the nuchal ligament.

The second border is made up of the cervical vertebrae (neck bones). This is a little trickier; many people actually mistake the nuchal ligament for the horse’s spine. However, the spinal column in the neck drops almost straight down from the poll and curves at the bottom to meet the thoracic vertebrae at the point of the shoulder.

Finally, the injection should be in front of the shoulder blade, which you can feel if not see. Within these three borders you’ll have a space roughly the size of your open hand. This is where you should give the injection.

Think of a triangle about the size of your open hand bounded by the shoulder blade, nuchal ligament at the top and neck vertebrae at the bottom. Photo by Olga Itina/Adobe Stock

The neck is the most frequently used site for IM injections due to its accessibility, but there are other locations you can consider. The pectoral muscles in the chest are another convenient location. If used, make sure to stand to the side of the horse, not directly in front, and aim for the center of one of the pecs.

The pectoral muscles are a good alternative to giving an IM injection in the neck. Photo by Anita Zander/Adobe Stock

The hamstrings are also an option, but serious consideration to your safety must be made: As you might imagine, injections near the hindquarters put you in danger of being kicked. Rarely are the gluteal muscles used. Although the tops of the haunches are a nice large muscle mass, if infection occurs and an abscess needs to be lanced, this area provides poor drainage.

The Technique for an Intramuscular Injection

When giving any medication to your horse, first start by confirming the following three things:

◆ Is it the correct drug?
◆ Is it the correct dose?
◆ Is it the correct delivery method?

Once you’ve confirmed all three, pick your injection location. Make sure the horse’s skin is dry and free of dirt and grime. Next, with your horse wearing a halter, have a handler hold the lead rope and stand on the same side as you.

Always use a new needle for every injection. Never share needles between horses to prevent the spread of disease and dulling of the needle.

Deliberately insert the needle perpendicular to the skin and all the way to the hub. Do this in a firm and quick movement. Some people like to desensitize the horse first with a pinch of the skin or a few taps of your hand prior to the stick. Using these tricks will depend on the horse and the location you choose.

Some people like to desensitize the skin with a pinch or a tap of the hand before fully inserting the needle. Photo by Eds30129/Adobe Stock

Once the needle is fully inserted, pull back on the plunger slightly; this is a good habit to ensure you’re not in a small blood vessel. If there is blood in the hub, pull out the needle and slightly redirect. Once you confirm there is no blood, depress the plunger steadily until empty, then pull the syringe out. There should be minimal if any blood on the skin.

Once you’ve given the injection, be sure to safely dispose of the used needle. Although you can purchase a specific container for sharps disposal at a pharmacy (like those red tubs you see at hospitals), any hard plastic tub with a secure lid will do. Laundry detergent bottles or coffee canisters with fitted lids work very well. Mark the container with a label, like “Sharps,” so that everyone is aware of its contents.

Possible Complications

Troubleshooting injection site reactions and infections are the two biggest risks when giving an IM injection. Reactions tend to occur despite good aseptic technique; this is the immune system’s reaction to the drug and can range from a small lump and temporary muscle soreness to hives or anaphylactic shock.

If your horse is known to be sensitive to certain types of medications, talk with your veterinarian before giving him an IM injection on your own.

Some medications are known to be more irritating to muscle than others; for this reason, always contact your veterinarian before giving a drug IM that you don’t have experience giving.

NOTE: Not all drugs can be given in the muscle; phenylbutazone (bute) is a prime example. Injectable bute should only be given intravenously (IV) by a person experienced in giving IV injections. Bute should never be given IM, as it causes severe tissue damage.

Some medications, such as injectible bute, should only be given intravenously (IV) by a person experienced with IV injections. Photo by Charlymorlock/Adobe Stock

An infection, usually evidenced by an abscess at the injection site, can be avoided by using clean, sterile needles and syringes and injecting with the correct technique through clean, dry skin.

If an infection does occur, the site will swell and become hot and painful to the touch. The horse may have a fever and go off feed. Abscess formation requires draining for complete healing and a veterinarian should be called to do this. Antibiotics and pain medications are typically prescribed.

One rare but serious complication from IM injections is the risk of Clostridial myositis. This is a deadly bacterial infection from Clostridium bacteria. These bacteria and their spores are ubiquitous in the environment and are also in the horse’s intestinal tract.

Sometimes a deep intramuscular injection can create the perfect anaerobic environment that triggers these spores to activate, resulting in a severe systemic infection in the horse that can quickly progress to septic shock. Being knowledgeable of the drug you are administering is helpful in preventing these cases. When in doubt or unsure, always check with your veterinarian first.

For any medication you have never given IM or are unsure of, always call your veterinarian prior to administration. Photo by Vchalup/Adobe Stock

When To Administer an Intramuscular Injection

Although some of the risks involved with giving a horse an intramuscular injection are serious, be assured that some common medications can be safely administered in the muscle of horses. These include certain antibiotics, such as penicillin and gentamicin, as well as sedatives and tranquilizers like xylazine and acepromazine, and vaccines.

Although the non-steroidal anti-inflammatory drug (NSAID) flunixin meglumine, also known as Banamine, is approved for IM injection in horses, it has been associated with Clostridial myositis. For this reason, Banamine is safer when given IV or orally.

For any medication you have never given IM or are unsure of, always call your veterinarian prior to administration.

IM injections are a useful basic medical skill to have as a horse owner. With knowledge, practice, and someone to help hold your horse, you can confidently add this to your horsemanship toolkit.

This article about giving a horse an intramuscular injection appeared in the March 2023 issue of Horse Illustrated magazine. Click here to subscribe!

The post Intramuscular Injections for the Horse appeared first on Horse Illustrated Magazine.

The 2023 ASPCA Right Horse Summit in Lexington, Kentucky kicked off with a conversation about the importance of intake exams.

Charlotte Kin, DVM, is the primary veterinarian for the Equine Transition and Adoption Center, an Oklahoma-based program with the goal of finding homes for at-risk horses. She said that a good physical exam is at the top of her list for all horses coming into the program.

Kin said that while adoption center staff does their best to catch problems, there are some things that are necessary to diagnose. Her intake exams are similar to a pre-purchase exam. This gives the rescue a solid baseline on the horse and also provides potential adopters with a thorough report.

Kin likes to perform basic blood work to help catch issues early. To catch and treat cases of pituitary pars intermedia dysfunction (PPID) — often referred to as Cushing’s Disease — early, horses over 12 typically have a Adrenocorticotropic Hormone (ACTH) test. Depending on the results of the ACTH test and time of year, Kin might perform a thyrotropin-releasing hormone (TRH) stimulation test to better confirm a diagnosis. 

During intake, Kin makes a neurological exam a priority. While a hands-on approach is ideal, she keeps neurological concerns in mind when evaluating horses in the field, too. In Oklahoma, her saying is, “Equine Protozoal Myeloencephalitis (EPM) until proven otherwise.”

Most of the horses she sees have been exposed to EPM, but catching symptomatic horses and providing treatment early is critical to ensuring their quality of life and adoptability. She begins with a blood test and if the results are positive and the horse is displaying signs, she starts treatment. If the blood test results come back inconclusive or negative but the horse is showing typical signs of EPM, she performs a spinal tap to either confirm or debunk the potential diagnosis. 

Kin also said that staying ahead of and on top of possible gastric ulcers can make horses more comfortable in their transition.

Kaycie McCarthy, the Equine and Farm Animal Rescue and Outreach Manager for the Massachusetts Society for the Prevention of Cruelty to Animals (MSPCA)-Angell in Boston, said that her rescue has started streamlining their intake process. They used to wait until horses were at a good weight and health to perform a soundness exam, but they started running into situations where they would have a horse for an extensive amount of time, spend time and resources to get them heathy, and then find out that they had major soundness concerns when they began working more with them. By making soundness exams a priority early on, they are able to create better programs with better outcomes.

Last year, McCarthy had 18 horses come into the rescue in one group. They did not have proper paperwork and the entire facility had to be quarantined. They had the 18 horses housed in their indoor arena in round pens. While the situation was far from ideal, they used their quarantine to perform thorough evaluations of all of the horses. The local media got involved and when the horses were ready to be adopted, the coverage they had gained through the local media and their own social media outreach helped find homes for 17 of the horses quickly. She said that the situation “forced us to be creative” and while it resulted in some atypical procedures, it aided in getting the MSPCA in the public eye.

She added that when euthanasia is on the table, a full staff meeting is called (with the vet present when possible). She said that the open communication and discussion about what might be best for the horse (or cat, dog, and guinea pig) can make everyone more comfortable with the hard decisions.

Bonnie McRae, founder and director of After the Races — a racehorse rehoming program in Elkton, Md. — said that a thorough intake exam can help save costs long term. Additionally, knowing more about the possible rehabilitation a horse might need helps them find homes more quickly. When they began doing more thorough intake exams, their horses began staying less than half of the time than they did before, cutting the average time from 170 days down to 42 days.

To help with organization, a veterinarian fills out an intake form for After the Races. Having thorough documentation that can be sent out to potential adopters keeps everyone on the same page and keeps the horses’ wellbeing a priority.

New Vocations Racehorse Adoption Program Thoroughbred Director Anna Ford agreed that more diagnostics means more adoptions. She added that radiographs and ultrasounds becoming digital was a big change. It became easier to store and share records and the began making a dropbox for each horse to increase organization.

Ford reminded attendees that they can do your own basic physicals, flexion tests, and baseline exams even before a vet is able to see the horse. Doing your own basic exam can save time (and resources) when the vet is present to pinpoint more specific concerns.

Investing in a thorough intake evaluation sets horses and their potential adopters up for success. The more the rescues know about the health and history of the horses, and the more they are therefore able to inform their adopters, the better the outcome.

ASPCA Right Horse

ASPCA Right Horse is the online adoption platform of The Right Horse Initiative, a collection of equine industry and welfare professionals and advocates working together to improve the lives of horses in transition. A program of the ASPCA, their goal is to massively increase horse adoption in the United States. To find more adoptable horses and foster horses, visit www.myrighthorse.org. To learn more about The Right Horse, a program of the ASPCA, visit www.aspcarighthorse.org.

The post ASPCA Right Horse Summit: Rescue Intake Exams appeared first on Horse Illustrated Magazine.

Photo by Clix/Shawn Hamilton

Horse owners often find it challenging to keep up with the latest vaccination recommendations, and some may not grasp their importance in keeping horses healthy and strong. Your horse needs certain “core” vaccines, and may also need non-core vaccines based on his usual activities, geographic location, and other considerations.

Although you might be hesitant to get your horse poked, it’s for his protection, and vaccines are generally safe. They have been well-tested, and many have been used for decades. Vaccination should be routine, so read on for current recommendations, potential side effects, and the overall importance of having your horse vaccinated.

Core Vaccines

One of the best measures to protect your horse’s health is a vaccination program. Core vaccines are often administered in an initial series of two to three shots, and then once or twice a year after that. Skipping core vaccinations could mean sickness or even death among your equine family.

The American Association of Equine Practitioners (AAEP) has established vaccination guidelines for horses. Core vaccinations are those recommended for all horses, regardless of age, sex or region where they live. These include any vaccines required by law and those that protect animals from diseases that are highly infectious, pose a risk of severe illness, are of potential public health significance, or are endemic to a region.

Kris Hiney, Ph.D., is an assistant professor and equine extension specialist for the Oklahoma State University Department of Animal and Food Sciences. She says the five core vaccines are Eastern and Western equine encephalomyelitis, West Nile virus, tetanus and rabies.

“We consider these ‘core’ due to the risk of fatality associated with these diseases,” she says. “And the human health risk with rabies, of course.”

5 Core Vaccines

The following are recommendations for core vaccines based on the guidelines provided by the American Association of Equine Practitioners. Always work with your veterinarian to develop the ideal vaccination schedule for your horse.

◆ Eastern & Western Equine Encephalomyelitis: EEE and WEE are primarily transmitted by mosquitoes, but they’re also infrequently transmitted by ticks, other insects, or nasal secretions. While EEE has been reported throughout North and South America, WEE is more common in the western United States. Both have a high mortality rate, and vaccinations are recommended for all horses in North America.

Combo shots include multiple core vaccines with one poke, like this one for EEE, WEE and tetanus. Photo by Clix/Shawn Hamilton

◆ Rabies: Rabies is transmitted through the bite of an infected animal, typically wildlife, and is endemic in every state but Hawaii. Although the incidence of rabies in horses is low, it presents a considerable public health risk, and it’s almost always fatal among horses, making it a core annual vaccination to all equines.

◆ Tetanus: Tetanus presents a risk to all horses and is often fatal. Although it isn’t contagious, horses can develop tetanus through a Clostridium tetani infection resulting from its entrance into a wound or from environmental exposure to the toxin—which resides in the soil—if a horse eats contaminated soil or droppings. The vaccines currently available are recommended for all horses.

◆ West Nile Virus: WNV is nearly always transmitted by mosquitoes that have fed on infected birds. It’s been identified throughout the continental United States, Mexico, and most of Canada, and is the leading cause of arbovirus encephalitis in horses. However, it’s not directly contagious from horse to horse or equine to human.

Non-Core Vaccines

One or more non-core vaccines also may be recommended following a risk-benefit analysis. Recommendations of non-core vaccines vary based on region and specific horse populations
within an area.

The risks of horses contracting non-standard diseases aren’t always easy to identify, which is one of the many reasons it’s important to consult a veterinarian. Equine vets understand what’s endemic in an area and which horses may be at higher risk for certain diseases, so they can recommend the appropriate non-core vaccines to add.

“Non-core—flu/rhino, strangles, Potomac—are considered risk-based more on the lifestyle of the horse and if they are endemic,” Hiney explains.

Some non-core vaccinations that may be recommended due to risk-based assessments include:
◆ Anthrax
◆ Botulism
◆ Equine herpesvirus (also called equine rhinopneumonitis, or “rhino”)
◆ Equine influenza (aka “flu”)
◆ Equine viral arteritis
◆ Leptospirosis
◆ Potomac Horse Fever
◆ Rotavirus
◆ Snake bite
◆ Strangles
◆ Venezuelan equine encephalomyelitis

Don’t Forget Boosters

Once your horse receives the initial series of a core vaccine, he’ll still require boosters. Many vaccines require an annual booster to maintain immunity, but some diseases may require more frequent action.

“Booster frequency depends on how endemic the disease is and your horse’s level of exposure,” Hiney explains. She says there isn’t a lot of research on how long vaccines last in horses, which is why they recommend annual boosters for all, and even more frequent ones in certain circumstances. She says they have a better idea of the duration of immunity in companion animals.

“To some degree, we’re probably over-vaccinating horses for tetanus,” says Garrett Metcalf, DVM, an equine veterinarian at Pine Ridge Equine Hospital in Glenpool, Okla. “However, horses are rather sensitive to the neurotoxin produced from Clostridium tetani that leads to the clinical signs of tetanus. Infected horses can be treated and saved, but up to 75 percent of them still die. It’s better to just over-vaccinate them, which won’t hurt them.”

Boosters help maintain a good protective level of antibodies, so if you forgo boosters, your horse may no longer be protected when exposed to a disease. If you allow his annual vaccinations to lapse longer than a couple of years, your vet may recommend that the primary series be administered again before recommencing annual boosters.

Injection Site

The best injection site for vaccinations is another area where a veterinarian’s extensive knowledge plays a key role. You must consider the possibility of adverse reactions when choosing injection sites.

For example, it’s not recommended to inject vaccines into the gluteal muscles or hip region of a horse because considerable tissue damage can occur should an abscess develop. If lesions erupt, they could require a long healing time.

“The neck is the usual site, in the ‘triangle,’” says Hiney. “But if a horse has an adverse reaction and his neck is stiff and sore, he may be more reluctant to move.”

The ideal vaccination site is the “triangle” of muscle in front of the shoulder above the neck vertebrae and below the fat and nuchal ligament of the neck crest. Photo by Clix/Shawn Hamilton

Metcalf says that some people still vaccinate their own horses, and some vaccines can be purchased at feed stores. He emphasizes that it’s always better to let your vet administer vaccines, but if he has a client who insists on doing it themselves, he always shows them at least once where to give the shot.

“The ideal spot is [the triangle-shaped area] about the size of your hand right in front of the shoulder blade, in the middle of the neck,” says Metcalf. “Too low and it’s too near the cervical spine. Too high and it’s in the fat within the nuchal ligament instead of the muscle.

“When it’s in the fat, the horse won’t have an immune response,” he continues. “Horses can also get really sore when vaccinated in this spot. They can’t lower their head to eat and can’t move their neck well. Be educated.”

Having a vet administer your horse’s vaccines will ensure they are stored and administered correctly to minimize the chance of any adverse reaction. Photo by Clix/Shawn Hamilton

While administering your horse’s vaccines yourself isn’t advisable, working with your vet also has the benefit of ensuring serious side effects can be quickly identified and handled properly. If you insist on administering vaccines yourself, realize that some manufacturers will not reimburse for adverse outcomes.

“The vaccine makers want a vet to administer vaccinations,” Hiney says. “Usually, they only guarantee vaccines administered by a vet and not purchased online or through a feed store.”

Adverse Reactions

Adverse reactions are an inherent risk of vaccination. Horses commonly experience local muscle swelling and soreness at the vaccination site. Transient, self-limiting clinical signs, which last only a short time and resolve without treatment, may include fever, lethargy, and lack of appetite.

Severe reactions at injection sites may require prolonged treatment and convalescence. Allergic-type reactions, such as hives, purpura hemorrhagica colic, or anaphylaxis can also occur and are particularly dangerous. Although unlikely to occur if proper procedure is followed, the potential for severe adverse reactions is one major reason why vaccines should be administered by a veterinarian.

“Some horses will react to the adjuvant, which is the ‘extra’ part that stimulates the horses’ general immune system,” Hiney says. “If that is the case, you may want to switch brands; it can make a difference.”

Metcalf advises horse owners who are concerned about adverse reactions to research the vaccine manufacturer, because the reactions can vary. However, he says usually less than 1% of horses have a severe reaction.

Administering multiple vaccines of both multiple antigens and adjuvants simultaneously may increase a horse’s risk of a reaction. When multiple products are needed, ask if your vet recommends staggering administration by three to four weeks between shots.

“If your horse has reactions, I would not give multiple [vaccines] at once,” Hiney says. “But many manufacturers now bundle vaccines together, sort of a ‘one and done.’”

If your horse has had a reaction in the past, you may need to avoid combo vaccines and stagger his shots.

“But then you have to worry about them developing a fever and other bad responses from having too many injections,” warns Metcalf. “Most companies mix vaccines with five, six or seven types all together to keep injection sites from getting sore. There are actually fewer problems with the mix of vaccines, which we use.”

Best Vaccination Practices

It’s important to develop a comprehensive vaccination program, but a one-size-fits-all version for all horses doesn’t exist.

“Talk to your vet,” Hiney stresses. “Remember biosecurity! Even if you take a vaccinated horse to a show and have others at home, you may be dragging pathogens back with you, so always think about good biosecurity protocols—don’t just rely on vaccines alone.”

This article about horse vaccinations appeared in the March 2022 issue of Horse Illustrated magazine. Click here to subscribe!

The post Horse Vaccinations 101 appeared first on Horse Illustrated Magazine.

Be careful with commingling your horse with unfamiliar ones during travel season. Photo courtesy acceptphoto/Shutterstock.

Two potential dangers for your horse are strangles and equine herpes virus (EHV), both of which are highly contagious and can easily infect a horse at any barn, arena, or other facility. As cases increase during show and rodeo seasons, Kelli Beavers, DVM, clinical assistant professor of equine veterinary education at the Texas A&M College of Veterinary Medicine & Biomedical Sciences’ Veterinary Education, Research, and Outreach (VERO) program, housed at West Texas A&M University, gives advice on how to prevent illnesses like strangles and EHV.

Preventing Exposure

Preventing exposure to strangles or EHV starts by taking simple precautions when you travel with your horse to new facilities around other horses.

“Both of these illnesses can be transmitted by horses and by people. Most disease transmission occurs from horses that do not yet show signs of illness.” Beavers says. “Be very careful about traveling with your horse. Make sure to clean the stall you will be using before you unload everything, including your horse. Washing with soapy water is good and using a hand-held disinfectant sprayer on the walls of the stall as well. One example of a disinfectant is Virkon-S. As far as avoiding exposure, just make sure that you don’t comingle your horses with others that you are unfamiliar with.”

It is also important to ensure your horse is healthy prior to any travel. It is best to avoid any travel if your horse has signs of illness.

Beavers explains that having a quarantine barn is important for coming back home from an event.

“It’s a really great practice to protect your home farm by having a quarantine barn,” Beavers says. “If you come back from a show and realize that your horse has been at risk or exposed, you can make sure to keep other horses safe, whether it be your own horses or others sharing a boarding facility.”

Using Public Utilities

Wash racks and other areas at public facilities can be helpful but should also be approached with caution. Beavers explains how to use these amenities properly to keep your horse from becoming ill.

When using public utilities, be sure to wash down walls and place fresh bedding for your horse to prevent illness. Photo courtesy Chen’s Photos/Shutterstock.

“When using public utilities at shows or rodeos, be sure to give yourself enough time to get done what you need done without being crowded by other horses,” Beavers says. “You can certainly wash down or disinfect any walls or railings. Make sure to keep your distance from unfamiliar horses if you can and use your common sense in those situations. You can’t completely avoid all risks, especially in common use areas. Using your own grooming equipment, and not comingling your equipment with unfamiliar people or horses can reduce the risk of these illnesses.”

Veterinarian Help

Working with your veterinarian when you suspect your horse might have contracted an illness is crucial, especially if it could be strangles or EHV. Beavers explains how veterinarian help is important to give your horse the best chance of recovery.

“When working with your veterinarian, you can make sure to stay up to date on medication and vaccinations for your horses that do travel and your horses that stay at home. With your veterinarian you can also create an individualized plan for you and your horse,” Beavers says.

Some horse shows and facilities require that a horse be vaccinated with EHV and equine influenza vaccines within a certain timeframe before the event. Be sure to check state and local regulations before traveling.

Next Steps After Horse Illness Exposure

Exposure to strangles or EHV can be shocking and even scary, so focus on the steps to a solution if this occurs.

Traveling with horses can be great if done correctly. Stay safe with these tips during times of travel. Photo courtesy Kim Lewis Photography/Shutterstock

“If your horse has been exposed, make sure that you have a plan for quarantine set up where you keep your horse. Make sure to monitor your horse for any signs of fever and take their temperature daily,” Beavers says. “If you’re taking care of sick or exposed horses, be sure and take care of them last. That way you can change clothes and get yourself clean without going back to tend to healthy horses.”

Isolate Horses with These Symptoms

It’s essential to know the early symptoms of illnesses like EHV and strangles. According to the American Association of Equine Practitioners, symptoms to watch for include:

1. Body temperature greater than 101.5°F (38.9°C)
2. Ataxia or recumbency
3. Aggressive behavior or stupor
4. Profuse diarrhea
5. Oral or coronary band vesicular or ulcerative lesions
6. Nasal discharge, coughing, and/or lymphadenopathy

Tell your veterinarian, farrier, trainer, and any other individuals who might come into contact with your horse becomes symptomatic. These professionals work with multiple horses every day, so it is important to notify them of exposure to keep other horses safe.

“It’s important to stay informed, Equine Disease Communication Center is really great because it tracks incidents and when horse illnesses occur so that you know if [strangles or EHV] is in your area,” Beavers says.

Travel with horses can bring excitement and new opportunities for equestrians of all kinds. Keep the excitement going this summer and integrate these tips into your travel routine to keep your horses safe from illness.

The post Preventing Exposure to Illness When Traveling with Horses appeared first on Horse Illustrated Magazine.

Learn how to protect your horse—and his herd mates—from equine rabies. Photo by PK Studio/Shutterstock

Rabies doesn’t always come in the form of a drooling, snarling, biting dog. Sometimes, especially in horses, this deadly disease presents itself quietly and mimics other conditions. Although equine rabies is relatively rare, it’s a silent killer. Not only can it fatally harm your horse, it infect you and others around the barn. Thankfully, rabies is easy to prevent.

Where and How Equine Rabies Starts

According to the Centers for Disease Control and Prevention (CDC), bats were the most frequently reported wildlife with rabies nationwide in 2018. Rabid bats are found in every state except Hawaii. Skunks, raccoons, and foxes also commonly carry the disease.

Anytime there’s an uptick in wildlife around your livestock, there’s an increased risk of your horse encountering an infected animal. This is especially true if an animal is displaying erratic behavior such as a nocturnal animal skulking about during the daytime. As we all know, horses are naturally curious, but that curiosity can be deadly.

Bats are a common carrier of rabies, but it can come from many other sources, too. Photo by Rudmer Zwerver/Shutterstock

According to Kris Hiney, PhD, assistant professor and equine extension specialist at Oklahoma State University, horses most commonly contract rabies simply due to their curious nature.

“We’ve all seen horses that investigate animals, especially those acting abnormally,” she said. “Thankfully, it’s not extremely common, but rabies is endemic in the U.S. The closer your horse is to wildlife (essentially horses in pastures!) it has the potential to be exposed.”

Rabid animals transmit the viral disease through their saliva, most commonly through a bite. However, transmission can also occur when an infected animal’s saliva enters an open wound on your horse’s skin or through any mucous membrane, including the eyes, nose, and mouth.

Signs of Equine Rabies

There are two classic types of rabies your horse can contract—encephalitic and paralytic. These are more commonly referred to as furious or dumb rabies.

“Furious is just as it sounds, aggressive, and the dumb form results in lethargy, depression, etc.,” Hiney explained.

Clinical signs of equine rabies greatly vary, and the disease may progress rapidly or have a long incubation time with symptoms not appearing for two to six weeks, or even longer. Hiney said that commonly reported symptoms include going off feed, depression, and neurological changes. Other symptoms can include sudden behavioral changes, lameness, muscle tremors, head pressing, difficulty urinating, incoordination, teeth grinding, drooling, and facial paralysis among others.

After the onset of symptoms, your horse is highly contagious and usually only has a few days to a week to live. Unfortunately, the clinical signs of rabies in horses are easily confused with other diseases, which can result in exposure of other animals and human caregivers to the rabies virus.

Both humans and other animals around the barn may be susceptible to infection from a horse with rabies. Photo by RisingTimber/Shutterstock

“Rabies symptoms may be mistaken for colic, EEE, WNV, toxicities, etc.,” Hiney said. “Anytime you see neurologic signs in a horse, you need to take it extremely seriously.”

There isn’t a definitive test to diagnose rabies in horses prior to death. Diagnosis can only be made postmortem through an evaluation of the horse’s brain. If rabies is suspected, it’s critical to limit exposure to the infected horse.

Preventing The Silent Killer

Rabies exposure in horses is less common than in other domestic animals. There were only 13 rabid horses/donkeys reported to the CDC in 2018, but a report from the University of Kentucky indicates about 30 to 60 equine rabies cases are confirmed annually.

With those numbers, why take a chance? An annual shot given with other essential vaccinations protects your horse and prevents him from becoming fatally ill.

“Vaccinate! This disease is preventable and more important it’s a human health risk,” Hiney stressed. “It should be considered part of the core vaccines–Tetanus, Rabies, West Nile, and Eastern and Western encephalitis.”

An annual vaccination protects your horse from contracting this deadly virus. Photo by Konstantin Tronin/Shutterstock

The alternative to a low-cost vaccination is grim. There aren’t any successful treatments for equine rabies, so there’s no cure.

“Death is always the outcome,” Hiney warned. “The horse may become depressed, ataxic, or more aggressive, depending on how the disease presents, but it always results in death.”

Routine contact with an infected horse may be all it takes for rabies to spread to the horse’s owner or caretaker, too.

“Rabies is kind of a cool virus strategically,” Hiney explained. “It causes salivation and painful swallowing. A large amount of virus is shed in the saliva so essentially it causes the body to do what will optimize its spread. So, any handling of the horse’s mouth could result in transmission. That’s why I recommend using extreme caution and optimal biosecurity protocols with a horse with neurologic conditions. And notify your vet of what they’re walking into!”

The post Equine Rabies: Preventing the Silent Killer appeared first on Horse Illustrated Magazine.

We’ve all been there. It’s a spring day of good weather, perfect for a ride. As you amble to the barn to saddle up, you hear coughing. Turning the corner, you see the coughing culprit is your horse.

Flared nostrils, even at rest, are one sign of airway allergies like equine asthma. Photo by Marie Charouzova/shutterstock

In another barn, a rider grabs the grooming kit to brush her horse in preparation for the saddle. As she runs her hand over his neck, she feels, and then sees, numerous bumps, some of which have merged to form large bumps.

What is going on with these horses? Allergies.

A Teeming World of Horse Allergies

Unseen by the naked eye, the world is abundant in proteins and substances that can incite an allergic response. These allergens may be inhaled, ingested, or may affect a horse through topical contact. You’ll be tipped off to signs of trouble when you notice your horse has itching, hives, or breathing problems.

Allergies are common throughout the human and animal world, and horses are no exception. Usually, horses manage in their environment just fine without developing obvious signs that microscopic compounds are affecting them. Horse allergies happen when a horse’s immune system overreacts to a foreign protein, goes on the offense and becomes over-sensitized.

Sometimes it takes months or years of accumulated exposure for a horse to become hypersensitive; sometimes the response is more immediate and acute. Whatever specific protein causes the reaction, it sets up a cascade of inflammatory events that release prostaglandins and histamines to create obvious skin or respiratory allergic signs.

Skin Allergies in Horses

Horse allergies that manifest in the skin may result from topical contact, but also may develop from oral ingestion or inhaled particles. Aerosolized dust, mold, pollen, bedding, and insect bites are just a few of the sources that can cause itching and/or hives.

A major cause of itching starts with the bite of insects called Culicoides, also known as midges or no-see-ums. While the midges tend to feed on the abdomen, a horse displays an allergic response to the midge saliva by aggressively rubbing his tail, hindquarters, neck and mane due to intense itching. Those areas become raw, crusty, and inflamed, with substantial hair loss.

Some breeds and lines of horses tend to be particularly allergic to midges, such as Morgans, Icelandics and Arabians. The solution relies on moving the horse away from areas favorable to midge breeding, like ponds, wetlands and slow-moving streams.

Fly sheets with belly panels provide protection from biting midges, as does keeping horses in during dawn and dusk when these pests are most active. Photo by Ro_Ma_Li/shutterstock

Fly sheets are important, but they should have belly bands of netting material. Bringing a horse inside at dusk and dawn also helps to reduce midge exposure, as that is their preferred feeding time.

In contrast to an itching reaction (pruritus), hives aren’t typically itchy but herald a definite sign of exposure to some kind of allergen. Hives tend to be soft swellings that indent when you push in with your finger, called pitting edema.

They may be variable in size, sometimes coalescing into one big welt when several are close together. Inhaled allergens also can cause hives, referred to as atopic dermatitis.
Contact dermatitis is also not unusual. One example that occurs fairly commonly is hives from contact with pine bedding. If there is a suspicion that bedding is a problem, substitute paper bedding or a different source of pine bedding to see if the hives resolve.

Some shampoos or fly sprays can cause skin irritation and hives, as can laundry detergent residue or dirt on a saddle pad. On rare occasions, a horse with a fungal infection called ringworm may develop hive-like reactions around a fungal lesion.

Hives are bumps on the skin, signalling exposure to some form of allergen. Often it occurs from direct contact with the culprit, such as bedding or a particular shampoo. Photo by Horse Crazy/shutterstock

Hives can develop acutely and disappear just as quickly. Sometimes they persist long after the allergen is removed from the environment. In difficult cases, it may be necessary to medicate the horse with a short course of a corticosteroid like dexamethasone or prednisolone, which are effective anti-inflammatory medications.

Certain feedstuffs can set off a skin reaction, although food allergies are not that common. If it is a food allergy, however, it’s often a challenge to determine the exact food or oral substance that is the culprit.

This may need to be done through a process of elimination: eliminate all food and supplements and start by feeding only grass hay, although diet changes may need to be done slowly. Check with your vet. After a couple of weeks with no signs of hive lesions, add in one more food element and wait a week or two before adding in another. This may help pinpoint the cause.

Supplements tend to be the likeliest culprit, far more than hay or feed materials, although alfalfa has been known to cause allergic reactions.

Respiratory Allergies in Horses

Respiratory allergies can affect horse performance by impacting breathing and comfort, especially during exercise. A horse with a respiratory allergy often has a dry cough or wheezing that amplifies when he is eating or exercising. There may be a chronic or intermittent nasal discharge, as well.

Airborne arena footing is a common respiratory irritant that can cause persistent coughing. Photo by Firefighter Montreal/shutterstock

Respiratory health is at risk when horses are placed inside barns, especially those with poor ventilation, and/or are exercised in indoor arenas. Many toxic compounds are aerosolized to circulate in the air in those environments: endotoxin (part of the cell wall of Gram-negative bacteria) in manure, ammonia vapor from urine-soaked bedding, mold spores from hay, or hay dust filtering down when stored in lofts above the stalls or arena. Arena footing can also contribute to respiratory irritation.

The best solution is to minimize a horse’s time indoors and instead turn him out as much as possible. Better yet, arrange full-time outdoor living with run-in sheds to protect against inclement weather. Soaking or steaming hay before feeding helps tamp down dust and mold.

If barn living is all you have available, then implementing good ventilation is very important. Use appropriately placed fans, open windows, and open barn doors to keep fresh air circulating. Store hay in a building separate from horse housing.

Mold spores from hay and ammonia vapor from soiled stall bedding are two culprits of respiratory irritation. Open doors and windows and use fans to increase fresh air circulation in barns as much as possible. Photo by Heureeka/Shutterstock

Another important strategy for respiratory health is to keep your horse on a regular immunization schedule, especially against respiratory viruses. Equine influenza virus is known for causing long-term respiratory damage, including development of equine asthma. Discuss an appropriate vaccine schedule with your veterinarian.

Once a horse develops equine asthma, a variety of medications, including inhaled and/or oral bronchodilators, can help improve his comfort and ease of breathing. It is much easier and more effective to apply an ounce of preventive strategies for respiratory health than a pound of cure to treat after the fact.

Equine Anaphylaxis

In an instance where a horse’s immune system develops a profound and severe reaction, a horse can experience life-threatening anaphylaxis. With that in mind, it’s important to contact your vet immediately when seeing signs of an allergic response, particularly if your horse is having difficulty breathing and/or there is swelling of his face and muzzle or limbs and belly.

If your horse has a known allergy to a medication, such as penicillin or a non-steroidal anti-inflammatory drug (NSAID) like phenylbutazone or flunixin meglumine, it’s critical to place caution signs on the horse’s stall door and paddock to prevent accidental administration of potentially deadly drugs.

In severe cases, horses with equine asthma may need nebulizer treatments with corticosteroids to reduce inflammation. Photo by Nancy S. Loving, DVM

People with allergies wear neck tags or bracelets to convey this critical information, but for horses, it’s necessary to post signs in obvious places. Advise your barn manager and staff, friends and veterinarians who may deal with your horse.

Allergies can be troublesome to resolve, so observe and monitor every facet of your horse’s environment. With knowledge about potential problems, you can deter allergic problems before they begin.

The post Horse Allergies: Symptoms, Treatment, and Prevention appeared first on Horse Illustrated Magazine.

Photo by Jane Stanley/Shutterstock

Marvin the pony was a rare find, and his owners knew it. When young Lucas went for a ride, Marvin always brought him home safely. You’d never catch Marvin ducking and weaving around an arena as his rider held on for dear life. Marvin would never drop his head and come to a screeching halt, launching the unsuspecting child headfirst into a small cross-rail jump. He would never buck furiously as though demons were pursuing him, and then prick his ears innocently at his unhappy rider sprawled on the ground. In a world full of children terrorized by devil-minded ponies, Marvin was pretty much a saint. Or so he seemed. But this pony held one very bad habit.

A Very Good Boy

One day when I was working on the farm, I saw Lucas climbing Marvin like a tree, his coattails flapping as he struggled sideways into the saddle. The gray pony never moved a muscle, but the saddle did, rotating 180 degrees and dumping the child into the dirt under Marvin’s legs. I gasped as the boy struggled to his feet, and his helmeted head thudded into Marvin’s belly, but all Marvin did was nose Lucas’ side and stand patiently while his saddle was fixed.

Another time, Marvin and Lucas were jogging around the arena during a lesson, and an out-of-control horse charged past them, kicking out viciously. Marvin dodged the kick, unseating Lucas, who ended up straddling the back of the pony’s neck.

Marvin came to a stop immediately, and Lucas, who was apparently part monkey, was able to scramble back into his saddle without ever hitting the ground. He straightened his tweed coat, and they trotted off with dignity.

Needle-Shy

The only time Marvin was less than perfect was when I had to give him his shots. Lucas’ mother, Daphne, would take a firm grip on Marvin’s halter, walk him off, and I’d follow, syringes uncapped and ready.

When I first started doing Marvin’s shots, I’d give the pony a chance to behave and would try giving the shots in the usual manner. I’d take hold of the skin on his neck and ease the needle in, but when Marvin felt the first poke, all hell broke loose.

While he usually bolted forward, sometimes he’d rear, and sometimes he’d spin into me. He was powerful and fast and was instantly enraged by the pokes. We had found the bad habit of this pony.

By then, I’d either dropped the syringe into the dirt or bent the needle, and Daphne would be panting, hauling on the halter and scolding the pony. Lucas would hide behind a nearby stall door, chanting, “Come on now, Marvin. Marvin stop that! Marvin, you behave yourself! Marvin, you bad boy!”

Successful Tactics

On one memorable visit, the full syringe was left dangling from Marvin’s neck after he exploded, driving him into a frenzy of charging and rearing until he’d managed to shake it loose and trample it into the ground.

I retrieved the broken pieces of the syringe but never did find the needle. Daphne found it the next day, wedged in the sole of her muck boot. Clearly different tactics were needed to get the shots into this pony, and after some dramatic mishaps with a rope twitch, which I quickly abandoned, I’d discovered an approach that sort of worked.

Daphne would walk Marvin briskly along the gravel path, rattling a feed bucket and distracting him. I’d sidle up to him with my heart pounding and syringes uncapped and tucked between my fingers. I’d rapidly shoot them into the gray neck without any warning, and—if I was lucky—I was in and out before Marvin had a chance to react.

Daphne would swiftly distract him with the grain, and all was well. If I messed up, it was war, so I made a point to get it right.

New On the Black

One spring, there was a new vet sniffing around the barn, and while I normally
welcomed new colleagues, it was clear that this woman had no interest in any sort of a professional relationship with me.

She wanted my clients and was doing everything in her power to lure them, launching direct email campaigns, hanging posters, and offering discounted vaccine and Coggins clinics to all new clients. It was a free country, and horse owners had a right to use whichever vet they wanted, but it still stung a little when I didn’t hear from Daphne and Lucas that season.

I was very busy with my regular barns, so I put Marvin out of my mind and focused on my work. But one day in late spring my phone rang, and Daphne’s number popped up on the screen.

“Dr. Diehl, I’m embarrassed. We decided to use another vet this spring to save money, but things didn’t go so well.”

“I’m sorry to hear that,” I said. “What happened?”

“Well, as you know, Marvin’s a little tricky with shots. He kind of outdid himself this time.”

I hid a grin at the pony’s probable display of his only bad habit..

“Oh?”

“Yes,” Daphne said. “The vet wouldn’t listen when I told her how you do it. They tried giving the shots the usual way, and he knocked the tech down and ran away. Then they tried to twitch him when I said not to, and he struck the twitch off, and it hit the vet in the face and broke her nose. I feel absolutely awful. We’ve arranged for a trainer to work with him, but can you please come vaccinate him?”

Back to Business

I said that I would, and we got Marvin vaccinated, barely. After his experience at the vaccine clinic, he was worse than usual, but my old trick eventually worked, and soon he was munching his handful of grain, and I was shakily capping my empty syringes. Lucas emerged from his hiding place, wideeyed, and marched up to Marvin, shaking a small finger.

“Marvin, you’re naughty, and I’m very, very mad at you.”

Then he produced a carrot from his coat pocket. Marvin crunched the carrot adoringly, and Lucas stroked the lowered gray head. “But you sure showed that other vet, didn’t you!”

This Vet Adventure column about a pony’s very bad habit appeared in the July 2020 issue of Horse Illustrated magazine. Click here to subscribe!

The post Vet Adventures: Angel or Demon? One Pony’s Very Bad Habit appeared first on Horse Illustrated Magazine.

Core vaccines are recommended by the AAEP for all horses; talk to your vet about which risk-based vaccines your horse may benefit from. Photo by Shelley Paulson

Vaccines for horses are a cornerstone of good health and horse owner responsibility. A robust vaccination program can reliably prevent numerous deadly and highly contagious diseases, offering convenient and safe protection for your horse, and in some cases, you as well.

However, deciding what vaccines to give your horse can feel daunting at times, given the numerous options and their relative dependence on your horse’s age, location, and activities. Fortunately, the American Association of Equine Practitioners (AAEP) publishes authoritative guidelines covering what they’ve determined to be the four “core” vaccines for all horses in the U.S. Let’s take a closer look at these guidelines and what they mean for your horse.

First, it helps to understand what is meant by the term “core.” The AAEP refers to the American Veterinary Medical Association for a working definition, which is that core vaccines are those that “protect from diseases that are endemic to a region, those with potential public health significance, required by law, virulent/highly infectious, and/or those posing a risk of severe disease. Core vaccines have clearly demonstrated efficacy and safety, and thus exhibit a high enough level of patient benefit and low enough level of risk to justify their use in the majority of patients.”

Based on this definition, AAEP classifies four horse vaccines to be core in the U.S. Let’s take a closer look at each one.

1. EEE and WEE

Transmitted primarily by mosquitoes, Eastern Equine Encephalitis (EEE) and Western Equine Encephalitis (WEE) are considered endemic to the United States, although WEE tends to occur more commonly, typically west of the Mississippi River as its name suggests.

These viruses are neurotropic, meaning they prefer to localize specifically in brain tissue. In fact, an older layman’s term for these diseases used to be “brain fever.” Sometimes even now they are colloquially referred to as “sleeping sickness.”

Signs of infection include fever and lethargy in addition to neurological signs, such as a wobbly gait, head-pressing, circling, and recumbency. EEE is the more deadly, with a mortality rate of 90 percent. WEE causes death in up to 40 percent of cases.

West Nile virus, WEE and EEE are all transmitted by mosquitoes and target a horse’s brain, resulting in neurologic symptoms. Photo by Kwangmoozaa/Shutterstock

Both diseases are also zoonotic, meaning they can be passed to humans. Although human cases are very rare, when they occur, they are severe to fatal.

Because mosquitoes spread these viruses, there’s little chance of eradication. Additionally, given there is no cure and the possibility of permanent neurological damage or death, vaccines for horses against these two viruses are a simple way to remain worry-free.

While there is a third virus in this family, Venezuelan Equine Encephalitis (VEE), this is considered a risk-based vaccine (see “RiskBased Vaccines,” pg. 44) due to its geographical limitations within Central and South America, with occasional cases in southern states. Discuss with your veterinarian whether your horse is at risk for VEE.

2. West Nile Virus

It seems over the past 20 years that horse owners are more familiar with West Nile virus (WNV) than EEE and WEE, given WNV’s rapid and dramatic expansion across the U.S. and its greater impact on human health.

West Nile Virus, like EEE and WEE, is spread by mosquitoes and targets the brain, resulting in neurologic signs, such as gait and behavioral changes. With an equine mortality rate of about 35 percent, it’s not as deadly as EEE, but data have shown horses that survive the acute infection can have a roughly 40 percent chance of residual neurological damage.

Because this virus has been identified in all 48 contiguous states, infection remains a seasonal threat to U.S. horses. Mosquito control is only that—control, and not eradication. Vaccination against WNV is the best way to prevent this disease.

3. Rabies

Rabies is perhaps the quintessential vaccine for numerous domestic species for many reasons, from cultural (Old Yeller, anyone?) to epidemiological, making it the one most people are familiar with, and rightly so.

Rabies is fatal. Period. Additionally, the course of the disease is highly unpleasant and extremely dangerous to others, as, unlike with the viral encephalitis diseases, it is spread through contact with an infected animal.

For these reasons alone, it is the only vaccine for horses that is technically required by law and must be administered by a United States Department of Agriculture (USDA)-accredited veterinarian.

4. Tetanus

Like rabies, tetanus also has a presence in our everyday vernacular, likely due to the fact that humans have been contracting (and dying from) tetanus for millennia. Images of rusty nails or the term “lockjaw” come to most minds when discussing this disease.

Photo by Shelley Paulson

Caused by the bacteria Clostridium tetani, which is ubiquitous in soil, this fatal disease causes skeletal muscle paralysis; death occurs due to the eventual paralysis of the muscle in the diaphragm, which is required for breathing.

Any open wound, from a puncture or laceration to a surgical incision or traumatic foaling can be sources of C. tetani infection in horses. An ounce of prevention really is worth a pound of cure—yearly boosters with a tetanus toxoid will help bolster immunity in your horse.

Make a Plan

Horse owners should be aware that different vaccine companies typically market combination horse vaccines. It’s common to find various “three-way” or more combinations, depending on the manufacturer.

For this reason, if you’re not sure what the right vaccines for horses, be sure to talk with your vet. This helps ensure your horse receives the most efficient protection for his health and your pocketbook.

This article about vaccines for horses appeared in the March 2021 issue of Horse Illustrated magazine. Click here to subscribe!

The post Vital Vaccines for Horses appeared first on Horse Illustrated Magazine.

After considering numerous strange signs plaguing a draft-cross gelding, could the cause of the mystery illness be found in the hay? Photo courtesy Shutterstock

I loaded up my tote with a stethoscope, thermometer and a flashlight. To be safe, I put on a pair of heavy-duty exam gloves. I didn’t yet know what was going on with Hans, but horses with chewing and swallowing issues make me nervous. There are a few possible infectious causes, some of which could be dangerous to humans, and I wasn’t taking any chances. I made Cathy glove up, too.

The Mystery Disease Exam

Hans’s vitals were worrying: an elevated heart rate and low body temperature. His mucus membranes were muddy with a very slow capillary refill time, which told me that he was dehydrated and in shock.

The rectal exam revealed rock-hard, mucus-covered manure balls in a flaccid rectum. There was no muscle tone in any of the intestine that I could palpate, and nothing seemed to be moving.

The tail and anal tone were very poor, and Hans’ triceps, chest and hamstring muscles twitched and jumped randomly. Another strange sign, he was also walking as though he were drunk.

We offered Hans some water. The big gelding shoved his muzzle deep into the bucket in frustration, then flipped his head back and forth, sloshing water everywhere. It was clear that he was unable to swallow.

I opened his mouth and gently drew his tongue forward, and Hans made no attempt to withdraw it or even move it. His tongue was limp in my hand and hung from the side of his mouth when I let it go. His jaw tone was also very poor, and drool spilled from his lower lip.

Cathy watched me expectantly, but my mind was racing, trying to come up with a list of diseases that would explain all of Hans’s clinical signs. I’ve learned the hard way to not talk too much until I’ve had a chance to formulate some ideas, otherwise I tend to contradict myself and confuse the owner.

Thinking Through the Mystery

Could this be trauma? He was walking very strangely. Maybe he’d collided with another horse on the ranch, except he showed no signs of a concussion, and I’d seen plenty of those when I was a rodeo vet.

EPM? We didn’t really have many cases high in the Colorado Rockies, and there was no significant travel history. A virus that affected the brain? Supposedly he was fully vaccinated.

While I was thinking through possible differential diagnoses, I clipped Hans’s jugular vein to place an IV catheter, and connect two large bags of fluids. I didn’t know what was going on with this mystery disease, but I could at least treat his dehydration.

I also passed a stomach tube and cautiously delivered a small amount of electrolyte water after I was certain that he wasn’t refluxing. Once he was hydrated, I blasted a high dose of steroids through his catheter.

Then a horrible idea hit me. Could this possibly be rabies? There had been a recent case in a mule in an adjoining county, but he’d been vaccinated, hadn’t he?

“Cathy, he had the rabies vaccine this year, right?”

She frowned. “You know, I don’t think he did. The vet said it wasn’t necessary, because we don’t see rabies up here.”

Hans’ vitals were worrying: an elevated heart rate and low body temperature. His mucus membranes were muddy with a very slow capillary refill time, which told me that he was dehydrated and in shock.

Considering More Causes of a Mystery Disease

My heart pounded. Now I had to put rabies on the list, and the more I thought about it, the more frightened I felt. I pictured the thin trickle of saliva, the inability to drink, the muscle tremors. So many of Hans’ signs of his mystery disease matched.

My hands shook as I added calcium gluconate and dextrose to the fluids, while Hans nuzzled my arm gently. Could a rabies patient be this bright and alert?

Cathy stroked Hans’s neck. “Moldy grain? Something in the water?”

I shook my head.

“No, surely not. And there aren’t any toxic weeds in his paddock. He’s getting grass hay, right?”

She nodded.

“In fact, they put a huge round bale in the feeder last week.”

I frowned. A huge round bale, a horse not walking well, muscle tremors, poor tongue and tail tone. Something was trying to formulate in my brain, and I walked towards my car in frustration, trying to put it all together. What was the connection creating this mystery disease?

Lightbulb Moment Reveals the Mystery Disease

Then it hit me. And it was not an option that I wanted on my list.

Botulism—probably from an animal carcass baled up in the hay. Large round or square bales are the perfect anaerobic environment for Clostridium bacteria to generate botulism spores and their deadly toxin; then the poor, unsuspecting horse eats the contaminated hay.

An icy hand gripped my chest, and I frantically started scrolling through the vet manuals on my phone. Hans had every single sign. I looked back at Hans and Cathy standing together, and my heart sank.

A quick call to the veterinary university confirmed my suspicions, although rabies was also still possible. Soon Cathy and I were ushering Hans onto her trailer, and they headed to the referral hospital.

The news was grim. Botulism was indeed the top suspect of the mystery illness, and the antitoxin was several thousand dollars. Without it, Hans had virtually no chance of recovery, and even with it, his odds of survival were only about 20 percent.

Cathy didn’t hesitate, and soon Hans was receiving the potentially lifesaving treatment. But would it be enough to save him?

Read the conclusion of this story here.

This Vet Adventures column about identifying a mystery disease appeared in the May 2021 issue of Horse Illustrated magazine. Click here to subscribe!

The post Vet Adventures: A Mystery Disease appeared first on Horse Illustrated Magazine.