Advances Against Cushing’s Disease

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Horse with Cushing's
With advances in veterinary medicine, we have an increased understanding of diseases that strike our horses. Equine Cushing’s disease has been recognized for more than 70 years, but has often been misunderstood. Today, however, with our improved diagnostic and treatment options, Cushing’s horses are living longer and enjoying a better quality of life. Here’s what we currently know about this disease:

What is Equine Cushing’s Disease?

Over the years, the disease has had a few name changes, with equine Cushing’s disease the most commonly accepted. But labels such as “equine ‘Cushing’s-like’ disease,” “equine Cushing’s syndrome,” “equine pituitary pars intermedia adenoma,” and the most currently accepted name in the veterinary community, “equine pars intermedia dysfunction,” have all been used to describe the condition.

Equine Cushing’s disease is a primary problem of the pituitary gland, located inside the brain. This gland is like a dispatch center, where hormones and other chemical mediators called “proopiomelanocortin peptides” (POMC) are produced and then released into the body to control body functions. Horses with Cushing’s disease have a breakdown of the control of the pituitary gland—it literally doesn’t shut down and continues to produce POMC.

The overactive pituitary gland of a Cushing’s horse can grow in size and even develop benign pre-tumor and tumor cells that press against the brain. In the advanced stages of the disease, this compression can be severe and cause neurological problems if the gland becomes big enough. Cushing’s disease has often been described as a benign tumor of the brain, but there is still debate whether it’s a tumor or hypertrophy, which is tissue enlargement as a result of increased work (similar to the way that muscles enlarge from exercise). Indeed, the pituitary gland can develop cells that grow to become a tumor, but it’s unknown which comes first, hypertrophy or the tumor.

An overactive pituitary gland also affects the horse’s adrenal glands (located near the kidneys). Stimulated by increased POMC production, the adrenal glands overproduce cortisol, which contributes to a host of health problems. Increased cortisol levels have been the traditional marker for detecting and diagnosing equine Cushing’s disease.

New research is leading to a lot of answered questions and development of new questions for this disease. It’s now known that specific nerve cells in the brain secrete dopamine. In normal horses these cells inhibit an overactive pituitary gland and are present in large numbers. Horses with Cushing’s disease have dopamine-producing cells with decreased antioxidation capacity that are more susceptible to dying. But the question remains as to why. What is known is that fewer dopamine-producing cells means pituitary gland activity goes unchecked.

Clinical Signs

The classic Cushing’s case is an old, skinny, hairy horse that grows a long, wavy hair coat year-round. Many people unwittingly believe that their horses are just getting older. In reality these horses are often sick. Along with being very hairy, Cushing’s horses are generally lethargic, sweat easily, tend to run high temperatures, drink and urinate excessively, and have fertility problems. Horses with this disease are also at increased risk of developing laminitis. The high cortisol levels in the body lower the immune system, making the horse more susceptible to infections, such as delayed healing, reoccurring hoof or tooth abscesses, sinus infections and chronic fungal, bacterial or parasite infections. Pneumonia is even possible.

As Cushing’s disease progresses, more and more body changes occur, and symptoms become more obvious. This can take years to happen and it’s really a snowball effect. Cushing’s horses metabolize protein at a higher rate that causes muscle breakdown and wasting, which can be very noticeable along the topline and haunches as the disease progresses. Weakened abdominal muscles become stretched from the weight of the intestines,creating a “pot belly” appearance. Intermittent front limb stiffness can also be seen.

In the advanced stages of the disease, severe neurological problems can occur if the pituitary gland becomes big enough and causes compression in the brain. Symptoms of compression include ataxia (uncoordinated movement of the limbs), fever, hyperventilation and possibly recumbency leading to death. If treatment is not provided—and sometimes even if it is—the pituitary gland gets larger, the immune system weaker and the body condition worsens to the point of real debilitation for the horse. These horses look and act very old. Their hair coats are extremely long, sometimes several inches long, and very wavy. They breathe heavily and sweat in their stalls and seem extremely lethargic. They might start to sway when walking, and in the most extreme cases get to the point where they can’t get up.

Disease Diagnosis

There are several ways to diagnose equine Cushing’s disease. The classic method is to measure body cortisol levels in response to an outside stimulus, most notably dexamethasone (a corticosteroid). Dexamethasone, when administered to a healthy horse, tells the pituitary gland to shut down. Horses with Cushing’s disease don’t respond to dexamethasone stimulus—their pituitary glands continue to produce POMC, and their adrenal glands continue to produce high levels of cortisol. This dexamethasone testing procedure is known as the “dexamethasone suppression test.” The higher the dose of dexamethasone used, the more the pituitary gland should be suppressed.

There are actually two types of “dex” suppression tests: high-dose dex suppression and low-dose dex suppression. It may seem obvious that the high dose is more accurate and should be the test of choice, but it’s not without its complications: The biggest risk is increased chance of developing laminitis. For this reason researchers and clinicians alike are trying to find alternative ways to test for equine Cushing’s disease. And they have found a few.

One alternative is the low-dose dex suppression test. This test has become the standard and is theoretically safer, due to the lower dose of dexamethasone, especially for the horse that has already had an episode of laminitis. Some researchers suggest avoiding the test during autumn months, as hormone levels in horses can vary seasonally. During fall, researchers are pointing to a higher possibility of false-positive results.

Taking it to the next level, a new test is being developed that combines thyrotropin-releasing hormone and dexamethasone, referred to by some veterinarians and researchers as the “DST/TRH” test. This test allows for increased accuracy in testing in the early stages of the disease.

Other testing methods have also been developed, mostly in an effort to avoid administering dexamethasone to horses that have laminitis or are at greater risk of developing it. One such method is to evaluate the levels of ACTH (adrenocorticotropic hormone) in the body, which has been shown to be higher in Cushing’s horses. Unfortunately, this test can have false negatives, meaning even though the ACTH levels are low, the horse can still have Cushing’s—the disease is just not advanced enough for the test to pick up on it.

There are researchers who suggest that high insulin levels in the horse are an indicator of this disease, and some research is being devoted to testing cortisol levels in saliva.

Another test monitors and measures the day and night levels of cortisol. In normal animals it’s been shown that morning levels of cortisol are high, and in the evening levels drop off. The difference between morning and night should be more than 30 percent; if not, it’s theorized that the cortisol remains at a constant level as a result of the pituitary gland not shutting down.

One final method used quite often in the field is response to treatment. Instead of testing what appears to be an obvious case of Cushing’s, a veterinarian treats the horse with medication and watches for clinical signs to resolve. This has its drawbacks, especially if we are mistaking the disease for something else that should have a completely different treatment.

Treating the Cushing’s Horse

A few drugs have emerged for treating equine Cushing’s disease that are better than others. Today, the most commonly used drug for treating the disease is pergolide. This drug, also used to treat Parkinson’s disease in humans, stimulates dopamine release, which in turn tells the pituitary gland to shut down. There are good anecdotal results and very limited side effects with this drug, as well as a lot of research available that has shown its effectiveness. In some of my patients, owners report that their horses act 10 years younger after starting treatment.

Cyproheptadine was the original drug of choice for treating equine Cushing’s disease, but many studies are now showing that its effectiveness is not nearly as good as pergolide. Some reports indicate that cyproheptadine used with pergolide can be more effective, however.

A human drug called trilostane offers promise for treating equine Cushing’s disease. This drug works at the level of the adrenal gland to slow down cortisol production. Current research has shown that this drug has reversed some of the symptoms of equine Cushing’s disease.

More research is on the way to reproduce these findings and prove the drug’s safety in horses. Trilostane is available in the United Kingdom, and also to veterinarians here through special arrangement with drug compounding companies. At this time trilostane is very expensive, but hopefully, as has been the case with pergolide, when demand grows and efficacy and safety are established, this drug will become more available and affordable.

Diet is gaining significance in the management of Cushing’s disease. Antioxidants, such as vitamins E and C, could play a role in helping to support Cushing’s horses. Chasteberry (Vitex agnus castus) is emerging as an organic source of dopamine stimulation; while it hasn’t completely stood up to the rigors of scientific testing, many researchers are still looking into it as a source of treatment for equine Cushing’s disease.

Feeding a Cushing’s horse can be very challenging, and unfortunately there are no set rules. However, it is safe to say that horses with Cushing’s disease do well on the same type of low-sugar, low-starch diet that horses prone to laminitis do. This type of feeding plan usually rules out alfalfa and grain, and leaves us with grass hay and grass hay pellets. If the disease symptoms aren’t too severe, then extruded feeds utilizing soy and beet pulp can help keep weight on. Generally I try to keep Cushing’s horses on mostly timothy and orchard hays, along with pelleted feeds, like those mentioned above, to keep weight on, and I minimize sugar as much as possible. Since Cushing’s horses are difficult to keep weight on, dedication has to be put into balancing diet with exercise.

Insulin Resistance

One real misconception about Cushing’s disease is that affected horses are hypothyroid and fat. They’re not. We don’t know enough about the thyroid gland and its hormones, but currently it’s believed that the thyroid does not play a direct role in equine Cushing’s disease. In the past, many older horses that were “easy keepers” were diagnosed with Cushing’s disease and put on thyroid medication. Thyroid supplementation hasn’t been proven to help horses with Cushing’s disease. In fact, many horses that are true hypothyroid are not fat at all and can often be thin.

It is the horse with insulin resistance that is fat. Insulin resistance is fast becoming a buzzword as the culprit behind easy keepers. The pituitary gland has nothing to do with this disease. Instead, as its name suggests, cells become resistant to insulin. When this happens, sugar (carbohydrates) circulating in the bloodstream is no longer drawn into the cells by insulin. This leaves excess sugar in the blood that gets converted to fat. In horses this often causes a cresty neck and large fat pads in abnormal places. Mustangs are genetically engineered for this condition so that they can put on fat stores in times of plenty to rely on when food is sparse. This leads us to believe that genetics play a large role in insulin resistance.

The trouble with modern horsekeeping is that we often provide plenty of food all the time for our beloved equines, so they just keep making fat stores—some better than others. Insulin resistance can create dire health problems, especially in the hoof, where laminitis can occur.

In the End

Cushing’s is an easily recognized and treatable disease, but unfortunately it can’t be cured yet. It is a slow-progressing disease that often goes unrecognized in the early stages. Sadly, Cushing’s disease usually gets diagnosed once the clinical signs are more advanced. When caught early, treatment is very successful in reducing clinical signs and allowing affected horses to live almost normal lives. For those horses in advanced stages of the disease, treatment still offers improved quality of life and longevity.

This disease hits close to home for me since my own horse Prophecy was diagnosed with it at the age of 9 using the morning and night cortisol levels testing method. I have had him on pergolide since that time, which was about four years ago. His symptoms at the time of diagnosis were for the most part very mild and very subtle. He had many episodes of “ain’t doing right,” laziness in the arena and a mild case of laminitis. His owner at that time, having had a dog with Cushing’s disease, asked me to test him. I’m happy to report that he is symptom free today. However, to be on the safe side, I’m starting Prophecy on higher dose vitamin E supplements and will test him using low-dose dexamethasone suppression combined with TRH stimulation. If he tests positive with that method, I will seriously consider trilostane for him.

In my practice area, horses with Cushing’s disease do very well and can lead an active lifestyle. Those undergoing treatment do much better for a longer period with fewer problems; I rarely have to deal with laminitis in these horses. I have one 18-year-old Grand Prix dressage horse with Cushing’s disease that is still competing and doing well. She has been on pergolide for three years, but we are starting to see a few more symptoms, so we are increasing her dosage and are considering trilostane for her.

Overall, horse owners shouldn’t fear this disease, but we must all have a healthy respect for it.

Further Reading

Optimal Diet for Cushing’s Disease

What is safe to feed a horse with Cushing’s?

Author Janice Posnikoff, DVM, heads up Orange County Equine Veterinary Services in Southern California.


This article originally appeared in the November 2005 issue of Horse Illustrated. Click here to subscribe.

89 COMMENTS

  1. Well written article, but it left me a bit confused. I have a horse that was diagnosed with Cushings three years ago. He was also labeled “insulin resistant” as well. He is typical of Dr. Posnikoff desciption of the body type; extra fat stores, chronic laminitis, etc.. But, I got the impression from the article that she does not consider the two diseases to be related. Is there anyway I can get more information about the differences and/or similarities? My guy is currently on Pergolide and Metaboleze and we were considering trying the Chasteberry.

  2. I have a mare that was diagnosed with Cushings when she was only 9 years old. She is now 14.
    I had her on perolite for about a year. Then my farrier recommended that we try diet changes. I now feed her Stratagy (in the white bag – has no sugars of any kind in it), stabelized rice bran, grass hay and corn oil. She has been on this diet for over 2 years and off of pergolite. She has shed out the past 2 summers, has no problem in movement. In fact she has races with the other mare running to the front of my property to the back. Kicks her heals up with the best of them. Also, she is very inquisitive (nick name is Nosey Rosie). She is doing fantastic.
    Thought you would be interested.

  3. This is by far the most pro-active article on Equine Cushings I have read. My horse developed Cushings about 9 years ago at age 17 (the first year or so we were treating him for hypothyroidism, however after more testing, Cushings was determined.) One other useful note even with Pergolide (Permax)treatment you may find your horse’s teeth more delicate. My horse has had a couple of broken teeth and it should also be noted that some horse cookies and forms of pellets can be very hard. I make sure that any treats are not going to put him at risk for any more breaks and check his teeth daily to remove hay that has accumulated between his front teeth so it won’t rot there. Please keep up the good work, I look forward to any updates!

  4. This really helped me understand this disease. My horse was thought to have this by many people in my barn but after reading this it is not something I need to worry about. Thanks for all the great info.

  5. Thank you for the informative article on Equine Cushings. I have a 19 and a 27 year old horse that I want to keep a close eye on for health problems. I now know what to look for to catch Cushings at an earlier stage.

  6. THANK YOU AUTHOR OF THIS ARTICLE! It really cleared some things up for me. I have an insanely adorable old gelding who is the biggest sweetheart in the world. He has “Cushing’s Syndrome” and pretty much all I knew about it was that if he didn’t get his pergolide, he’d die! With it, he shows almost no sign of being a “cushing’s horse” and is still happily eventing. Articles like this help me understand what he’s going through, which makes it a lot less scary for me.

  7. One of the better articles I have read since starting intensive research several months ago. Many articles are a repeat of common knowledge but this one brought up some new treatment options. I had just read an article touting thyroid medication as beneficial to many cases…this article had a different perspective. Thanks

  8. Thank you for putting such helpful horse articles. Soon I will be getting a horse and I want to learn about everything I can. Each day I read two of your articles and they always help me learn more. Thanks so much!!

  9. The article on Equine Cushings was very good, however, I am still VERY confused if my 26y/o TB really has the disease or is insulin resistant.He’s been on Pergolide, timothy hay only & Seminole Happy Hoof for at least 3-4 yrs now, but I don’t like the looks of his hair. It’a dull & brittle. He also get 1/4 up corn oil every night. I don’t want to put him through any test.

  10. My children’s teenage Shetland pony looks 30 and has all of the symptoms (except excessive thirst/urination) so I suspect Cushing’s. Sadly is sounds as if quite late stages, but thanks for all the info. Will do what I can for her. I do not live in Florida but will select that state as I have a sister living there!

  11. I found the article most interesting..I too, have a horse with Cushing’s. I decided to put her on Cinnamon powder and Chasteberry. Because we are into our 6th month of winter and cold, it’s hard to tell if it is working with the shedding and long hair part of it, but what I have noticed, in fact right after I first started her on the herbs, was that her excessive drinking and urinating had stopped. I have her on a small amount of pelleted low insulin feed just to get her herbs down..(I also give her magnesium and MSM…she is 25 years old. I also see an improvement in her energy….we love her so much and she is so worth the extra care we give her. I can’t wait to see her when she sheds out, if she stays shed out until fall like the other horses or if she regrows back right away. I hope the herbs work in that sense too b/c then I know it’s working full circle for her.

  12. Thankyou for the useful information. I recently acquired a mare that I now believe has cushings!
    I was unaware of this coat being so unusual lookin and the past owner had mentioned that last summer she never shed this long thick coat.
    I’m not sure now what I will do. I have not had her too long and will speak with the previous owner.
    Thanks again.

  13. Interesting article with a lot of good information, a word of caution though…..my horse showed no symptoms apart from slight “filling” of the pockets above his eyes, he was 22 yrs old and excercised every day, it was early winter time and he developed laminitis, worst in his hind feet, one of which sank and he ended up in hospital for a fortnight, it took a very long time to get him comfortable again. He wasn’t on a high starch/sugar diet. His first sign of laminitis was a pottery walk which due to the time of year ( cold and damp) and his age the vet diagnosed as arthritis, this didn’t seem right as he’d never been particularly bad before but I took the vets advice and walked him in hand then all hell broke loose! I suppose what I’m trying to say is be aware that they don’t always show typical signs and if in doubt, check it out…..I wish I’d had the blood tests done sooner.

  14. Read your article with interest. My 18 yr old mare has been on pergolide for 3 years. Did well for a while but worsened this year. New Vet suggested cutting down on pergolide dosage and blending with herbal casteberry tincture,Thyroid treatment, adding metaboleeze, hoof sup. and other supplements. She worsened after 2 weeks. Lost weight very suddenly and severely. Weight had been good before, had the crested neck and lethargic. No lameness. Wish someone would tell me now what to do. I think it obvious the pergolide should be reinstated full strength. My veterinarian only suggested adding weight by increasing rice bran and a neutrogena safe guard to add callories. Her top line shows back bone, hip bone. Only since changing treatment. Can anyone offer a suggestion. Thank you.

  15. I can assure everyone that I followed all recommendations in treating my horse, and she had 3 good years with treatment. Then worsened and was put on additional supplements/herbs along with the pergolide. I don’t know why, but she continued to develop all the late stage symptoms, even with everything given her and updates from her vet. She developed extreme weight loss and the stagering gate. Within 2 days of the staggering gate, she died. I don’t know what more could have been done. All the vet ever told me was that her numbers were extremely off the wall. Nothing really helped much. I’m confused, don’t understand and heartbroken. Not blaming her vet, I just don’t know what happened.

  16. I am curious about the use of Chasteberry Tree powder. My 20 yr old horse has been on Pergolide for about 2 years, plus a lower starch diet and is currently doing quite well. A friend of mine put her Cushing’s horse on Pergolide in June 2008 (3 months ago), plus she’s giving the mare 1 rounded teaspoon of the Chastetree Berry powder morning and evening. She tells me that her mare’s hair coat is shedding.
    Has anyone else had any experience with their Cushing’s horse on Chasteberry Tree powder?

  17. This was an extremely helpful article. I do have a few questions though. I have a 19 year old horse that was diagnosed as borderline for Cushings. She has been treated with Pergolide for the last 2 years. She is now starting to exhibit a few of the signs you mention, intermitten front limb stiffness, pot belly, loss of topline, and failure for wounds to heal in a normal amount of time, just to name a few. Is it possible for these symptoms to be from the Cushings even though we are treating her with 1CC pergolide every day, or could this possibly be another ailment. Does pergolide completely HAULT the symptoms of Cushings, or does it just delay?

  18. I loved the article. I have a 33 year old Tennessee Walker mare with Cushings. She was diagnosed about 5 years ago. I retired her from riding at 29 years old. She is still eating well, and enjoying her retirement
    I met you Dr. at our printing company, then in Anaheim, now in Orange. Would like to meet you again.
    Jacqui Tarpley
    Stadium Printing

  19. My Keiger Mustang taken as a yearling wild in 1980, with a history of extensive endurance racing now has an ACTH level of 76.9. I have to wonder where this disease comes from (Cushing’s). I heard it was genetics.

  20. Is there a cause known to this disease? In a very short time 4 horses have been diagnosed in our barn, Ortega Equestrian Center, SJC, age ranging from 10-20. Could the environment, bedding, feed or water cause it?

  21. I think Cushings is being diagnosed more because horses are living longer and we are discovering why ‘old’ horses are the way they are. I hope there will be more research on this and more taught and understood by all vets, as it seems many are not on the same page. My horse has been on pergolide for 3 months and has returned to his ‘normal’ self, I just hopes he sheds out his LONG THICK coat come spring!

  22. A good source of information about the disease, but there is still alot that is unknown. I will be adding this info to my stable as I know some horses who have had the disease and all the information we can get on it will help out.

  23. Your article on Cushings was very informative…I have a 15 year old Paint that was diagnosed 2 years ago….he came up not quite lame but just off…we took him to an equine clinic..had xrays and the whole nine yards…the vet tested him for Cushings using all but the dexamethasone suppression test…we tested using the “rhythm” method and his difference was 27 percent…he was put on pergolide and has been doing well ever since….he is not on pasture but is put on a dry lot during the summer…he has no signs of CUSHINGS..no fat pads..no mouth issues..no excessive sweating or urination…he still has bouts of laminitis and the vet says he may always have that..he is the 3rd horse we have had that has tested positive for the disease…my advice to anyone is to read read read…get all the info you can…my first diagnosed horse was an Appaloosa back in 2000…I had read an article in Equus magazine that pinpointed my mare to a T…our vet was very honest in that he had never treated a horse with Cushings and didn’t know very much about it…we were in constant contact with Cornell and tiptoed thru the process…she ultimately was put down due to a twisted gut but did very well on the pergolide…this is a terrible disease with many ups and just as many downs…very important to keep yourself informed and KNOW YOUR ANIMAL…hopefully there will be a cure in my lifetime…if we all pull together we can make it happen

  24. My old horse Maggie was a Cushings horse. She crossed the Rainbow Bridge a few weeks ago. She had been taking Vitex and had never been put on Pergolide. I suppose if she had lived longer, or been younger, we would have concidered it. But Maggie was 31 years old when she passed.

  25. Excellent article! I have a 28 year old Arab mare that has been on pergolide for 10 years now. In that time we’ve raised her dosage twice. We feed her soaked beet pulp and hay pellets, she has never had a fat pad. She is doing well and we just quit riding her 2 years ago. I also have a 17 year old insulin resistant Arab gelding. We took him 6 years ago after he had suffered chronic laminitis for 7 years. There is nothing similar in these two horses, other than how I feed them. He has ugly fat pads on his croupe, tons of energy and muscle density. I put them both on a supplement with alot of magnesium, vitamin A, D3, E and C among much more. What a difference it made for both. It is important for people to realize there is a difference between these 2 diseases, but that diet is 99% of the answer.

  26. very good article,I have a paso fino, 18 yrs, that has had severe internittent lameness in the rt front for 8 months.there is no swelling or heat in the joint.We tried streoid injections with no response at all.now i understand alot of the peices ofthe puzzel .thankyou .

  27. I have a 3 year old world class halter Quarter Horse who was diagnosed with cushings 2 weeks ago. He lost 600 pounds in a couple months–grew long hair, etc. It was SO QUICK!! He is on some experimental medication along with diet, etc, and is showing tremendous improvement already. Next week he will go on to another experimental treatment that has shown great promise. Maybe there is light at the end of the tunnel. I will keep posting his condition. My vet is fantastic in both equine care and research. My email address is kathy5014@att.net if anyone wants more info on his medications. Also, cushings is caused by possum feces–at least thats one of the ways. Even after the feces have dried and crumbled, parasites are still alive and active.

  28. Dear HC, I commented on this article in February ’09, but have just re-read it. Now I am VERY confused re: my 26y/o TB. In 2003 he had a severe bout of laminitis and was showing “fat pads” and slightly thick wavy hair coat. On the symptoms alone my then vet diagnosed him with Cushings. He’s been on Pergolide ever since and a specific feed from Seminole to help horses with this disorder. Now I’m thinking he may have misdiagnosed. He’s NEVER been skinny, just recently developed a slight “pot belly” and not shaggy. He is out in the pastures about 8-12 hrs daily and only gets KY timothy hay. Should I get a secong vet opinion? Thanks, OC

  29. Good info, Dr. Posnikoff! So glad to know that you aren’t too far from me!
    RE: Insulin Resitance and feeding. I have learned that there is a fine line btwn feeding too much and feeding too little and that it is possibl to starve a fat horse. My 22yo TWH is “metabolically challenged” — IR. He is overweight [not grossly] and the boarding stable was steadily declining the amount of grass hay he gets 2x/d to roughly 1% of his bodyweight/day. He lost no weight. Through alot of research, we concluded that he was on an overly restricted diet which likely induced [or worsened] IR by throwing him into “starvation mode”. My understanding is that, in this state, the body stores more fat [which increases IR] and burns muscle. I recently began giving him more grass hay [teff/tiffany] and absolutely no treats [he never got grain]. I give his supps in 1 cup of soaked beet pulp. He gets at least 1 hr. of exercise daily. He is slimming down slowly but surely. Most notably, he and his pen-mate are both MUCH calmer having hay in front of them most of the day. My boy is no longer a maniac at feeding time and I frequently work him at dinnertime. They both will walk away from their hay and not bolt thru they used to. I’m now working on a ground-level, slow-feed system that will [hopefully] satisfy the grazing instinct to some degree.
    It *seeems* that modern horsekeeping [living in stalls w/infrequent exercise and being fed 2x/d] may be contributing to the incidence of IR and possibly other diseases.
    A resource that I have found very helpful is http://www.ecirhorse.com

  30. I’ve known a number of horses who have had Cushings disease, and not only old horses. I’m glad that this disease continues to attract researchers and funding.

  31. I will have to re-read this article, I have one rescue pony, that looks like she might have the start of Cushings. At least I will know what the next step is.

  32. Thanks. This has been a huge help to me. My horse has shown a possible sign of early Cushings disease, & this article is a great starting point in learning about the problem.

  33. Thanks Dr. Posnikoff for your article; had a elderly gelding with cushings in my mare’s pasture (for a short while); real sweet guy; just learned he had to be put down due to colic.

  34. My French racehorse, aged 26, Rubes, developed Cushings Disease. He was given the usual medication and became depressed and lethargic. I am studying herbal medicine at UEL London. Through research online, I found out about Vitex Agnus Castus. I put him on two scoops (2 tablespoons each) of this dried herb a day in his feed for two weeks and he showed slow improvement but by two weeks he was enormously improved. His mood was back to normal, his hair growth went back to normal and Rubes returned to his old personality of a grubby kneed schoolkid – full of fun and back to himself again. Vitex Agnus Castus normalises the pituitary gland. He is still on it – only one tablespoon a day now in his feed. He’s fine now. Why not find a herbal shop or herbalist to prescribe it for you and see if it helps. This herb is not toxic. Herbs, unlike drugs, do not suppress illnesses, they heal.

  35. hello..
    i have a grand prix dressage horse on pergolide in great shape.veteran pan am games 1999..can he show in the fei still .do you know?thanks

  36. Hi
    My 5yr old daughters pony has been dignosed with it, the pony was a cruelity job when we got her, battled long & hard with all the other problems before this latest 1 although the pony, Maggie has been in great form. Shes recently got the “skoots” hasn’t had a solid dung in over a week, vet has give me injections says she has an infection in her stomach, can yu tell me is this another side effect? Is the infection infectous to my other horses?
    Thanks & worried

  37. the horse i ride is showing symptoms of Cushing’s and most likely has it. but no one seems to notice. my instructor thinks so as well,but is not sure how to go about telling the barn owner she thinks the horse should be treated. the owner might not even think he needs to be treated. i hate to think a horse might die and i can do something about it,but i don’t know how!

  38. I have A hores his name is Buck he is 31 years old you would never take him for that age the issue I have is that he has hoof abcess. Alot what can I do ?

  39. My 20yr old Thoroughbred was visually diagnosed with Cushing’s in November 2010. I was completely ignorant about Cushing’s. Asked my vet the prognosis and what I could do and was told about diet and that I should prepare myself for the worst. I am not the type to accept a death sentence and research on the internet educated me about Pergolide. Pergolide is not available in Antigua so I tried neighbouring islands as far north as Jamaica and as far south as Trinidad…not available! Tried the UK (could not find a chemist willing to ship overseas). Tried USA and ran into overseas prescription acceptance problems initially and eventually found a compounding pharmacy that was willing to help. My horse very quickly started to respond to the Pergolide and I also had to learn how to deal with the Laminitis which is now under control and relatively mild.
    I have never had access to any blood tests applicable to Cushing’s, so, basically her diet and treatment is regulated by visual, common sense and instinct (and advice from wherever I can get it). I started Chaste Berry powder recently…2tspns every morning and Pergolide in the evening. My horse, in 4 months, now looks absolutely stunning in comparison. No pop belly, no swelling, shiny coat which has naturally almost completely shed. No more gaunt look or protruding backbone (her hind area is round looking again) and most important she is living a quality (spoilt) life. She has gone back to being the dominant female and can gallop with and control the other two as has been her lifestyle in the past. Our location has presented a struggle with some aspects of treatment, but for now all is good and that is very rewarding.

  40. I have a 24 yo arabian gelding with Cushings that is currently going through a severe laminitis episode which I have as yet been unable to control. I’m interested in Bethany’s post about using ChasteBerry and Pergolide together. I think I had the best results when I was using both but was nervous about it. Does anyone else combine these two treatments? If so, how much Pergolide with the ChasteBerry and do you also separate them between a.m. and p.m.?

  41. My 21-year old Warmblood has cushings and has been on pergolide for 2 years. He has been bit by something(consensus is a spider)and has a hard knot on his right jaw bone and a soft spongy knot under his chin. Can I give him dexamethasone since he does take 2mg of pergolide every morning? I have been hydroing the knots and giving him 3.5g of bute

  42. good info. i have a 15 yr mare with cushings and have been giving her 1mg pergolide daily but confused on what kind of feed 1 vet says one thing another opposite HELP my horse is not getting better since weather is getting colder she seems to be moving slower!

  43. My horse has just being diagnosed with Cushings, he’s 23 yrs of age,my vet thinks we have caught this early, so I am hopeful we can manage it to the best of our ability. I found your article informative, but my biggest fear is that he could eventually get laminitis, but I am managing his diet and do daily check checks for raised pulses and heat in his feet- the more I can learn about the disease the better for me looking after after my horse – thank you

  44. I’d like to suggest that people check carefully when considering Cushing’s disease. With the widespread use of so-called fluoridated water and many horses drinking this poison, it isn’t enough to merely diagnose this.
    Kathy Justus in Pagosa Springs, Colorado, lost numerous horses and several dogs to this poison and she was instrumental in getting this abhorrent practice stopped after many years of research, testing, and heartache.
    PLEASE, if your horses are drinking this terrible poison, STOP it immediately. Fluoride is a known poison that targets the thyroid gland; mares are affected first. Lot of colic and laminitis is seen in affected horses. Kathy Justus documented this carnage in her video called “Poisoned Horses”. Go to fluoridealert . org (remove the spaces) for more information.

  45. Fluorine, from which fluoride is derived, is the 13th most abundant element and is released naturally into the environment in both water and air. Unless you want to have all your soil removed, you cannot avoid this naturally occuring element.
    That said, I own a mare with Cushings. She had been exposed only to well water and natural spring water all her life(no “artificially fluoridated water”). I foaled her in 1980. After an extensive show career in the eighties and nineties, she was retired to trail riding as of 2000. Although her Cushings was not diagnosed until 2004, I feel that it began earlier. There was a heavy, uneven coat ( in some places, 4 to 6 inches long )that was extremely wavy. She was lethargic and depressed with a poor appetite. She did not shed well. She laid down most of the day, and the rest of the time, she drank and urinated excessively.
    Once the Pergolide was started, she perked up within about 5 days. She moved around a lot more, her head was up, her ears were up, her drinking slowed, and also the urination. She started out with .5mg. When I would see the return of symptoms, we would test ACTH and it would be off. At that point we would increase the dose. The dose rose, over 3 yrs, to 2mg. She’s been at that dose for about 4 yrs. and continues to do well. She looks well, functions well, and enjoys life. Before Pergolide, and her diagnosis, we were going to put her down. Sooo…we’ve had her to love for 8 extra years…worth it???? You betcha!

  46. Excellent article and excellent comments! I have learned a great deal here. I have had 2 mares diagnosed with Cushings and this info would have helped me make the best decisions for them.

  47. VERY useful article! Thank you for helping us understand horses health potential horse risks and a heads up for treatment! It makes me feel more at ease as a horse lover/owner

  48. I greatly appreciate the in-depth analysis of this disease and the recommendation on which foods a horse should eat who shows light or severe symptoms. Very useful for me and my first horse (retired) Pride of Par Annie who is now 27 years old and been very hard to keep weight on over the last couple of years. She’s not lethargic, but I can see the correlation to the description of the muscle break down along her top line and I now understand why all of the typical weight gaining supplements have not worked on her.

  49. Article & new research into Cushing much appreciated, thank you for taking the time to share your observations, experience & drug management of this horrible disease. I hope more money will be invested for future research into both Human & Equine Cushings

  50. Thank you for this excellent article. I have learned a lot about this condition reading it. I have been offered a fjord horse that is showing signs of cushings (long hair that doesn’t shed out in the Spring) and is taking Pergolide. I’m still on the fence about adopting her as I’m wondering what the long term situation may be, but feel much better now about the outcome.
    I do have a question about feed, though. I also have another horse that has been diagnosed border-line insulin-resistant but has a difficult time keeping weight on during the winter feeding just grass hay and beet pulp. One of the afforable, healthy hay options we have here in New Mexico is beardless winter wheat and my mare has been eating this now for over a year and we have had amazing results in muscle building, keeping a healthy weight, and having enough energy…but not too much like alfalfa tends to do.
    My question is if you believe that beardless winter wheat hay is a viable option for a cushings disease affected horse.
    I would be very appreciative to have your insight.
    Thank you.
    ~Lisa

  51. I have an 38 year old horse that has cushings and I did not realize it was Cushings untill about 3 years ago and I know he had it several years before . Typical symptoms, extremely long curly coat ( I body clip him twice a year)top line wasting, pot belly. My problem also is all his back teeth are gone. He can’t eat hay. I have done research and talked to people and vets. Iwas told to feed him alfalfa. I soak beet pulp, alfalfa cubes and low carb/low starch feed for about 1 to 1.5 hours twice a day. I also started giveing the Chaste Tree Berry. It helps get rid of 75% of the hair, but I still clip him some. NOw I read you are NOT suspose to feed alflafa!! It’s worked so far for me with no bad side effects. He is 100% sound and looks better than some of my younger horses. I also have a horse that I am sure is IR. He is my problem, Finding hay that is low in sugar besides feeding him straight cubes! I have to find 2 year old hay that is pretty much just ole grass hay. Hopeful to fine some orchard grass mix this year. I learned NO BROME…he founderd on Brome last year. I have been told alfalfa is lower in sugars and starch than Brome or Timothy, but he just does not need to be on that!

  52. I am sampson smith and would like to introduce you to Thrive Feed, why because there are many horses who have been diagnosed with Cushings and are were on prescend and having regular blood tests to monitor their condition. Well when these horses were fed Thrive Feed complete feed there condition is reversed, oh, you say how ridiculous . Same things been said about gastric ulcers and Lamanitis.
    May we invite to view the posts on Facebook page ( Thrive Feed Horsefeed in the UK )
    Please feel free to contact the horse owners because they are the ones who put these posts on there and have had the blood tests for proof and these horses now have a healthy happy life.
    We hope you join the Thrive Feed Family. Welcome to the future.

  53. I am sampson smith and would like to introduce you to Thrive Feed, why because there are many horses who have been diagnosed with Cushings and are were on prescend and having regular blood tests to monitor their condition. Well when these horses were fed Thrive Feed complete feed there condition is reversed, oh, you say how ridiculous . Same things been said about gastric ulcers and Lamanitis.
    May we invite to view the posts on Facebook page ( Thrive Feed Horsefeed in the UK )
    Please feel free to contact the horse owners because they are the ones who put these posts on there and have had the blood tests for proof and these horses now have a healthy happy life.
    We hope you join the Thrive Feed Family. Welcome to the future.

  54. Thank you very much. This was very informative for me. Cooper is a 26yr. old quarter gelding that has very advance signs. His blood work came back good since I’ve started him on the meds. He appetite isn’t the best but he’s still happy and runs like a young colt.

  55. Please advise, horse was diagnosed with Cushings a few years ago, nothing was mentioned about treatment and no blood tests were ran. The horse is now blind and a new vet stated that the horse most likely has a brain tumor and advised to put the horse down. He is eating however his gait is off and he does not want to come out of his stall on his own, however he will come out by being led. This is my mother in laws horse.. she fell and broke her arm Tuesday, we were scheduled to put the horse down today but we are rescheduling for next week… I feel like this is a sign for me to maybe get a second opinion??? Any thoughts or advice is appreciated!

  56. A very in depth article. As horse owners we are now in a far better position in regard to recognising and managing this insidious disease. 20 years ago we lost a 20 year old mare to cushings, looking back I now see that some of the signs were there, but not any great indicators. Sadly with no treatment she deteriorated very quickly in the last 6 months of her life. I now have another 22 year old mare, 4 years ago when she was having her routine vaccinations I asked my vet for a cushings blood test. The mare had no physical signs of the disease but due to her age and my previous experience I felt that it was a prudent measure to take. Many people were suprised when the test indicated that she did indeed have cushings, although I was disappointed I now feel in control. One pergolide a day,limited grazing, low sugar diet regular exercise and my mare is in great condition, she belies her age. Her regular blood test results are all coming back within normal limits. I suppose my thoughts on this are,perhaps we don’t want to hear negative news but maybe all equines would benefit from a routine blood test in their later years.

  57. This the third year that my Rocky Mountain gaited horse has come down with ringworm. A new vet I contacted suggested doing a Cushings test and wouldn’t you know, he is pre-Cushings. This explained so much as my other three horses never got ringworm even though it is in my soil. I’ve started him on Peroglide and Platinum Performance and the ringworm is almost gone.

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