The cushing syndrome

Cushing's syndrome

If the disease is not recognized, agonizing infirmity is the consequence.

Long, curly winter coat and unexplained hoof rotations are only two of the possible symptoms that can be caused by Cushing's syndrome. If diagnosed in time, however, the horse can be helped effectively.

The cushing syndrome

Classic symptoms for Cushing's: curly coat, drooping back and belly, pasterns showing through © Dr. Sandra Ranner – Animal Clinic Schierling

From about their 19. In the second year of her life, the gray mare developed an astonishing winter coat: it became thicker and longer from year to year, and small curls formed on her neck and chest. That such a pelt also takes longer to give way to the summer coat seemed logical, and since the mare was otherwise in good health, little attention was paid to the phenomenon. In April 2001, at the age of 21, the horse developed laminitis for no apparent reason. The mare was treated extensively and recovered well. In April 2003 the next deer flare-up occurred, which could again be treated successfully. In July 2004 the mare suddenly gave milk. Whereas the horse's advancing age had previously been blamed for the multiple illnesses and increasing listlessness, the horse's owner now began to study the specialist literature – until the suspicion of "Cushing's" was in the air, which was confirmed by a simple test at the University of Veterinary Medicine. From then on, the gray horse was given the medication recommended by the clinic, pergolide mesilate, and the symptoms subsided within about two months. Today, the horse is 25 years old, is being fed normally and ridden out moderately, and his gaze is lively and interested again. Unfortunately, Equine Cushing Syndrome (ECS) was not detected earlier in this horse – his history of suffering would have been much shorter.

What is Cushing?

That after the American neurologist Harvey W. Cushing's named Equine Cushing's Syndrome likely results from a tumor of the pituitary gland that leads to an overproduction of cortisol. This overproduction of the important hormone sometimes results in life-threatening metabolic disorders. A fairly common manifestation of these metabolic disorders is laminitis – affecting about 82% of horses with Cushing's disease. Until a few years ago, ECS was considered a rare, but quite recognizable disease, especially in old horses. In the meantime, however, new data show that the syndrome is much more frequent and also occurs in young horses – and is also more difficult to diagnose than previously amed. In 2004, Mark T. Donaldson published results of a study conducted in the U.S. showing that ECS was the cause in 70% of the horses studied that suffered from unexplained laminitis, with the average age of the horses being 15 years old and the youngest being three years old. Donaldson started this study in 1996, after he had recognized and confirmed Cushing's disease in a four-year-old pony (after his death). This case made him doubt that Cushing's is only a disease of old age, as is generally amed. Subsequently, over a period of six years, he tested every horse with laminitis for ECS. Surprisingly, out of a total of 40 animals, 28 were positive, although they did not show any of the other possible Cushing's symptoms.

Possible symptoms

It is typical for ECS that there is no typical because uniform clinical picture, which makes the diagnosis more difficult. The possible symptoms can occur individually or in various combinations, are not necessarily present and are often mistakenly z. B. held for signs of aging. It is therefore recommended to always think of Cushing's disease if there is even one sign and other diseases can be ruled out as the cause. The following symptoms can be observed in Cushing's alone or in association:

– thick, long, in the most obvious case curly winter coat delayed or hardly any coat change – chronic laminitis – excessive thirst – the horses drink up to 80 liters of water per day instead of the usual 20 to 30 liters – excessive urination – fat pads above the eyelids and on the mane crest – muscle regression especially on the back (hanging back), but also on the belly (thus hanging belly) – lethargy, depression – emaciation increased susceptibility to infections due to severely weakened immune system – tendency to chronic diseases that are difficult to treat – groundless, patchy sweating – parasite infestation of the coat – punctures in the pasterns – cardiovascular problems up to the point of falling over – abnormal menstrual cycle, infertility, milk production in non-pregnant mares – poor wound healing, sores on the mucous membrane of the mouth – increased worm infestation – high blood sugar – blindness, head banging, dementia


The cushing syndrome

Mouth on: Ulcers in the mouth are also part of the symptomatology of ECS. © Dr. Sandra Ranner – Veterinary Clinic Schierling

In order to be able to make a reliable diagnosis, specific hormone tests are carried out. The most reliable test is the dexamethasone suppression test, which measures the effect of the cortisol-like dexamethasone on the cortisol concentration in the blood. Dexamethasone blocks the secretion of the hormone ACTH by the healthy pituitary gland. Significantly reduces the level of cortisol in the blood. In the case of Cushing's, dexamethasone is unable to do this. Furthermore, the ACTH concentration in the blood can be determined. If it is above normal, Cushing's can be inferred. Disadvantage for the veterinarian here is that the blood sample taken should be processed immediately after collection to avoid false negative results – which is practically not feasible if the horse is not at a clinic. Another disadvantage is that the test is only conclusive in the case of a positive result, so Cushing's disease cannot be ruled out with certainty with a negative test result. The advantage here is that even horses with highly acute laminitis can be tested safely. Since high cortisol concentrations in the blood often lead to increased insulin levels, (symptom diabetes – excessive drinking, urinating!), the blood glucose level should also be examined if Cushing's disease is suspected. All tests are carried out quickly and inexpensively at the Clinic for Internal Medicine and Epidemiology at the University of Veterinary Medicine.


The currently available drugs cannot eliminate the adenoma, but in most cases they can relieve the often painful symptoms. If ECS is detected early, with a little luck you will have a symptom-free, fully usable horse again in a short time. The medication used must not be discontinued if there is improvement and must be fed for life, usually in the morning. In first place in terms of efficacy is certainly pergolide mesilate (Permax®), a drug used in human medicine for the treatment of Parkinson's disease. However, no exact statement can be made about the exact dosage, it varies from horse to horse and must be determined individually under the supervision of a veterinarian. The mare quoted at the beginning was successfully treated with pergolide mesilate, first successes were seen after about three weeks, after two months the fat pads above the eyelids had disappeared and the change of coat was quite successfully completed. Cyproheptadine (Periactin ®) is also frequently used. This is a serotonin blocker, which is also administered in tablet form. Cyproheptadine is effective in 75-80% of cases. Trilostane, which was previously used to treat Cushing's disease in dogs, is currently seen as a new hope. A British study has shown that trilostane not only reduces symptoms without side effects, but also normalizes blood cortisol levels. Alternatively, monk's pepper preparations (Vitex agnus castus), alfalfa (Medicago sativa) or homeopathic agents have recently been suggested. Since Cushing's disease is a tumor-related massive disturbance of the cortisol metabolism. The efficacy of these forms of therapy has not yet been proven, respectively. has even been disproved, alternative methods should be used in a supportive rather than exclusive way.


ECS can be treated but not cured. How to help the horse additionally is shown in the following compilation:

– Avoid stress at all costs. The general hormone status of many Cushing's horses proves the greatly increased stress these horses are under offer the horse a safe, pleasant and familiar living space in its usual environment (no change of stalls, paddocks or location) – sufficient food and water always in the same place – if necessary, shear off the coat in summer, keep hooves in good condition – have teeth checked regularly – do not expose horse to aggression of other horses – avoid contact with strange horses – deworm regularly (every 45 days) – adjust feeding, d. h. Vitamin supplementation, deer prophylaxis (little concentrated feed, avoid corn and barley in particular, limited grazing, avoid freshly sprouting grass in particular).

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This article first appeared in ie 10/2005 of Pferderevue. Pferderevue subscribers can see it together with more than 40.000 others read for free in our online archive. Simply log on to Service/Online Archive. Browse through all ies from 25 years of Pferderevue for free!

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