Equine Cushing's Syndrome

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The Equine Cushing syndrome (ECS) is a by a tumor of the anterior pituitary (secondary Cushing) or the adrenal cortex (primary Cushing, rare in the horse) induced overactive adrenal cortex ( hyperadrenocorticism ) in horses . The disease is a hormonal disorder that corresponds to Cushing's syndrome in humans. It is now called Pituitary Pars Intermedia Dysfunction (PPID).


An adenoma of the adenohypophysis (part of the pituitary gland ) is suspected to be the cause of an ECS . This regulates the production of cortisol in the adrenal cortex, which increases the cortisol level in the blood.

Due to the very different symptoms of the disease, other options such as age-related dopamine insensitivity are also possible. Dopamine plays a role in controlling that part of the pituitary gland which in turn controls the adrenal cortex, as mentioned above.

It is noticeable that very predominantly easy-to-feed horses - mostly members of so-called robust breeds - are to be found among the sick horses. This suggests that the ECS is a "disease of affluence" that affects largely overweight, underemployed horses of advanced age. It is not always easy to distinguish it from Equine Metabolic Syndrome (EMS), a metabolic disease affecting fat horses. ECS and EMS are similar in terms of symptoms, while EMS more often affects younger horses, from around the age of 15 it is more likely to be an ECS.

The hormone cortisol influences numerous metabolic functions , the cardiovascular system and the immune system . As a result, a number of the most varied, sometimes life-threatening health disorders gradually arise. Cortisol disrupts protein metabolism, insulin production is throttled, blood sugar levels rise.


The symptoms of ECS are often very unspecific. They are often mistaken for signs of old age. ECS should be considered when 2-3 symptoms occur and other diseases are excluded.

  • Changes in the coat
    • thick, long winter coat , delayed, overlapping coat change , old hair often remains
    • long fur in summer, often curls, long, fluffy droppings
  • excessive thirst accompanied with frequent urination
  • Emaciation even with good eating behavior and high feedings
  • Muscle regression, especially on the back (sagging back), sometimes accompanied by fat pads on the stomach (hanging stomach) and mane crest
  • Hoof problems (hoof abscesses, dermis, laminitis with an atypical appearance and also at very atypical times of the year. This deer can lead to coffin bone rotation or subsidence, but is possibly almost painless for the horse at times and therefore does not show the typical deer posture.)
  • Tendinitis
  • Cardiovascular problems up to the occasional falling over
  • seldom massive metabolic imbalances with symptoms similar to those of the crate
  • frequent and persistent infections, untreatable diarrhea / faecal water
  • Bone problems, osteoporosis
  • lethargy
  • Refusal to feed, with a decreasing protective layer of the gastric mucosa and increased gastric acid production, risk of gastric ulcers
  • strange sweating for no apparent reason
  • Mauke , fungal attack
  • Chewing the lap, saliva, general eating problems, as horses are more prone to periodontal diseases.
  • Edema over the eyes
  • Affected horses often hang their heads when standing
  • Horses appear depressed and absent


The dexamethasone suppression test is the most informative . Alternatively, the endogenous ACTH level can be measured on a stress-free and pain-free horse .


There is no cure for the disease, but with treatment, most Cushing patients can still have many years of symptom-free life. The earlier therapy is started, the sooner the symptoms will subside. The animal's condition can improve dramatically within a few weeks to months of starting treatment.

Pergolide in low dosage is considered the drug of choice. Prascend is approved for horses. The second agent is trilostane , a hydroxysteroid dehydrogenase inhibitor that has proven itself in dogs.

If laminitis was triggered by the ECS as one of many possible symptoms, it is often lengthy and difficult to process the hooves. With patience and, above all, short treatment intervals, dramatic successes are possible here too.

Preparations made from monk's pepper ( Vitex agnus castes ) are an alternative medical alternative to pergolide.

Problems and risks with hoof care or shoeing

Farriers or farriers can be misled by the lack of typical symptoms of the presence of deer. This is especially true for "easy-to-feed" breeds such as Icelandic horses . So it is possible that a horse does not adopt the typical deer posture and can also move relatively well at stride at times if it feels no or only little pain. The cause for this is likely to be too much endogenous cortisol in the bloodstream, which fatally also reduces the sensation of pain. Nevertheless, within the horny capsule of the hoof, the typical damage such as coffin bone rotation or coffin bone subsidence occurs . From the outside, in addition to a misalignment (fetlock axis broken backwards), disturbances in the sequence of movements can be observed: a deer-typical traditional costume footing and an unclear gait when the horse is driven to a trot. If at the same time the general appearance of the animal speaks for the risk of the presence of the ECS (e.g. changes in coat), cutting out or shoeing would be risky for the horse: If the sole of the hoof is cut out too much, penetration (hoof bone breakthrough) could occur. This would then possibly be charged to the farrier or farrier - completely wrongly - as their own fault if the real cause of the ECS remains undetected.

Sources and individual references

  1. N. Schräder, G. Alber: The monk's pepper (Vitex agnus-castus L.) - alternative treatment for equine Cushing's syndrome? In: Journal for Holistic Veterinary Medicine. 26 (4), 2012, pp. 128-132. doi: 10.1055 / s-0032-1327846

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