Last Updated on December 8, 2022
Cushing’s disease in horses, words a horse owner never wants to hear their veterinarian say. In my 29 years as a horse owner, I have lost two of my favorite horses to Cushing’s, the first being my very first pony, Pepper, and 15 years later my show horse, Samantha.
So that being said, what then is Cushing’s in horses? What are the symptoms? Can this devastating disease be prevented? Unfortunately, there are no easy answers to those questions. However, being able to recognize the early signs and symptoms of a horse with Cushing’s will help you and your horse.
What Is Cushing’s in Horses?
Cushing’s Disease also known as Pars Intermedia Dysfunction (PPID) occurs not only in horses but also in dogs and humans as well. Across all species, the same brain structure, the pituitary gland, is effected.
However, unlike dogs and humans where a tumor affects the pars distalis (the posterior part of the pituitary), Cushing’s Disease in horses targets the pars intermedia (or the middle part) of the pituitary gland. And due to the difference in the targeted areas, the pituitary secretes different hormones based on the location of the tumor. Therefore, Cushing’s Disease in horses secretes different hormones than Cushing’s that are found in dogs and humans.
As a result of the tumor and its location, in horses, the pars intermedia over secretes pro-opiomelanocortin (POMC), adrenocorticotropic hormone (ACTH), and several other hormones like them. In a healthy horse, the function of the pars intermedia is regulated by the hypothalamus which is responsible for a lot of your horse’s bodily functions, like thirst, hunger, body temperature, and blood pressure.
The POMC then creates cortisol, a hormone that regulates your horse’s blood sugar, stress, and inflammation, while the adrenocorticotropic hormone (ACTH) is charged with the regulation of the levels of cortisol that are released into your horse’s body. You can read more about equine endocrinology, the brain structures affected by Cushing’s Disease, and the hormones secreted here.
Signs & Causes of Cushing’s Disease in Horses
Unless you can control the internal workings of your horse’s body, there is no way to prevent Cushing’s Disease since it is caused by a tumor, that grows on your horse’s pituitary gland. However, it is important to know that some steroids used over a long period to treat other conditions your horse may have, can increase their risk of Cushing’s Disease. Thus, before deciding to use steroids long-term, it is very important to talk with your veterinarian, to know how long the steroids will be prescribed and if you’ll have any other treatment options for your four-legged friend.
So how do you know whether or not your horse is living with Cushing’s Disease? Simple. You will notice some changes to their behavior that can be linked back to the bodily regulatory functions of the pars intermedia and the hypothalamus, increased thirst, subsequent increased urination, increased hunger, excessive sweating, and fatigue.
You may also notice some changes in your horse’s body, such as a wavy coat. It is a coat that does not shed when seasonally appropriate, muscle atrophy and chronic laminitis, or founder. You can read more about the clinical signs of Cushing’s Disease here.
Treatment of Cushing’s in Horses
If you notice any sign of Cushing’s Disease in your horse, you have to promptly contact your veterinarian. They will evaluate your horse’s condition and may request a blood test to check the sugar and fat levels in your horse’s blood. This, in combination with the physical evaluation, will help your vet distinguish between Cushing’s Disease and Equine Metabolic Syndrome, which often presents similarly to Cushing’s with a few distinguishing factors.
Once Cushing’s has been diagnosed, there will be many therapies available to you in addition to “supportive care” which will include monitoring your horse and treating any symptoms that may arise as a result of Cushing’s such as laminitis.
Your vet may prescribe your horse a couple of medications based on their evaluation of your horse. The first is Pergolide, a dopamine receptor that will help your horse’s body manage its overactive pituitary gland.
The second is Cyproheptadine, an anti-inflammatory that will block histamine production. The inability to regulate inflammation is a direct result of the tumor on your horse’s pituitary. Thus, this drug will assist your horse in combating unnecessary inflammation.
Always discuss pharmaceutical options with your vet to ensure that the drugs prescribed by your veterinarian are quality drugs, that contain the active ingredients needed to treat Cushing’s. Beware, even though you may find cheaper versions of these drugs from pharmacies on the internet, however, the effect will succinctly tell on your horse, who without quality medication, will suffer in the long run.
Thus, always be sure to use a reputable pharmacy.
One of the most important treatment options for Cushing’s disease in horses is Supportive Care. The purpose of supportive care is to increase your horse’s quality of life. It is extremely important for the longevity of your horse, that you ensure that you are feeding your horse a diet that is right for them. The University of Florida suggests limiting carbohydrates because your horse cannot properly metabolize glucose that is created from these foods by their bodies, as a result of Cushing’s Disease.
They also suggest that feeding a grain that was formulated for older horses will be most helpful. Because they are much more likely to contain fewer carbohydrates. Carbohydrates can also be found in your horses’ hay. Your vet may suggest that you feed them with low-carb hay, which can be pretty mind-boggling. Here is a great link for understanding what to look for when shopping for low-carb hay.
In addition to diet, you are going to want to treat any symptoms that your horse may display. Doing it quickly as a result of Cushing’s Disease. And this can include abscesses or chronic laminitis. You can also support your horse seasonally by helping him shed his winter coat. Do this in the spring by brushing or blanketing him in the winter months when it’s cold.
Can a Horse With Cushing’s Have Haylage?
When feeding a horse with Cushing’s, the aim is to stick to a diet that is low in non-structural carbohydrates, often referred to as sugars. Some types of haylage are fine for horses with this condition, but it is a good idea to check the feed analysis label first to make sure it is not too high in sugar. Nutritional experts advise that hay or haylage fed to horses withCushing’ss contain no more than 10% non-structural carbohydrates.
One problem with horses withCushing’ss disease is that they are often older and tend to lose weight. This could be due to a reduced ability to metabolize nutrients efficiently, or because of dental problems or other concurrent diseases. In this situation, low-sugar hay or haylage may not provide enough nutrition to keep the horse in good condition.
In this situation, additional nutrients and energy can be provided in the form of a high fiber, high-oil diet. Good supplemental feeds for an underweight horse with Cushing’s disease are alfalfa, canola oil, and sugar beet.
Is Cushing’s Disease in Horses Genetic?
It is not clear whether Cushing’s disease in horses is genetic, and no known hereditary link has yet been identified. This disease can occur in horses of all breeds but seems to be more prevalent in ponies and hardier breeds such as quarter horses. However, this may just be because these types of horses tend to live longer and are therefore more likely to be diagnosed withCushing’ss, rather than any genetic link.
How Much is a Cushings Test For Horses?
The simplest test for Cushing’s in horses is a blood test to measure the levels of a substance called ACTH. In straightforward cases of Cushing’s, regular ACTH testing can be used to assess the severity of the disease and response to treatment.
The cost of an ACTH will be slightly variable according to which laboratory is used but expect to pay around $20-30 for the test itself. There is normally also a fee from your veterinarian for taking the blood sample and processing it to send to the laboratory.
In some regions, the manufacturers of medication for Cushing’s in horses offer free ACTH tests for the diagnosis and monitoring of this condition. This enables them to gather valuable data about this common condition.
In more complex cases of Cushing’s, more specialized testing may be required, which will cost more than the basic ACTH test.
Are Horses With Cushing’s in Pain?
The condition of Cushing’s disease itself is not thought to be painful for horses, but this condition causes hormonal and metabolic changes within the body which can lead the horse to develop painful secondary health problems.
A horse with mild Cushings which is well managed should be able to live a pain-free and comfortable life. Any secondary health problems must be quickly identified and treated to keep the horse as comfortable as possible. Regular ACTH testing will help you and your veterinarian assess whether your horse’s Cushing disease treatment is sufficient to keep symptoms under control.
Can Cushing’s Cause Lameness in Horses?
Cushing’s can cause lameness in horses due to a condition called laminitis. When a horse has Cushing’s disease, the normal metabolic functions are disrupted and levels of certain hormones can become increased or decreased. The link between Cushing’s disease and laminitis in horses is not yet fully understood but is thought to be due to an exaggerated insulin response to the consumption of sugars.
How Does Cushing’s Affect Horses Feet?
Cushing’s disease in horses can affect the feed for a range of reasons. One of the most common secondary complications ofCushing’ss disease in horses is laminitis, which causes structural changes within the hoof. If you suspect that your horse has laminitis, veterinary advice must be sought immediately.
Horses with Cushing’s disease may also suffer from poor-quality hoof growth, as a result of an inability to metabolize nutrients efficiently. It may be necessary to feed a good-quality hoof supplement to correct this problem.
When to Put a Horse Down With Cushing’s Disease?
The decision of when to put a horse down with Cushing’s disease can be a difficult one. Horses with this condition often deteriorate very slowly, and it can be hard to identify when they are no longer happy and comfortable. Secondary health problems are the primary cause of concern, as they commonly cause more pain than Cushing’s disease itself.
The main factor to take into account when deciding on the right time to euthanize a horse is the quality of life. When the horse is no longer able to live a normal life free from pain, it may be time to consider euthanasia. To help you decide when the time is right, it can be a good idea to keep a regular record of how you feel your horse is coping with this condition.
Cushing’s Disease, if gone unnoticed or not properly treated, can be devastating to your horse’s health. Nevertheless, there are still many horses with Cushing’s that livefullyl. And quality lives all thanks to the diligence of their owners.
Proper treatment will not only restore fertility in the prized broodmares of the horse but will also make it ridable. It’s very rare for a horse to reach full remission from Cushing’s. A horse whose symptoms are well managed can be regularly ridden. But that is a choice that varies by the owner. Also, the ability to be ridden again is a discussion you should explore with your veterinarian.
Even if it is concluded that it is safe to ride your horse, you should be on the lookout for overheating and laminitis. A horse with sore hooves should never be ridden. And the inability to regulate body temperature is a symptom of Cushing’s Disease. If you have any questions or comments regarding Cushing’s Disease, please feel free to comment below.
- Cushing’s Disease is also referred to as Pars Intermedia Dysfunction (PPID) with an average onset of 20 years of age.
- Symptoms of Cushing’s Disease include a wavy coat that does not shed, bulgy eyes, and chronic laminitis. Also, increased thirst increased urination and increased appetite.
- Treatments for Cushing’s Disease include medication therapy and supportive care.
- Low Carbohydrate and Low Sugar diets are recommended.
- Be sure to use a quality, reputable pharmacy for any medications prescribed to treat your horse’s condition.
- A horse with Cushing’s Disease can still live a quality life. While the likelihood of remission is low, proper management of symptoms can help. It can increase the chances that your horse will be rideable again.
What are the first signs of Cushing's disease in horses?
In most cases, Cushing's disease begins as subtle changes in behaviour and appearance. The most obvious sign is the lack of a topline. The hair coat may be thin or coarse, and there may be evidence of delayed shedding. Horses with Cushing's disease are usually lethargic. Their appetite and energy levels decrease. They may become reluctant to work and show signs of decreased athletic performance. Affected horses can also suffer from laminitis and infertility.
What is the most common cause of Cushing's syndrome?
The most common cause of Cushing's syndrome in horses is a noncancerous tumor of the adrenal cortex, called an adrenal adenoma. This type of tumor grows slowly and is usually discovered when the horse has a routine physical examination. In some cases, however, the tumor may be missed completely until the horse is examined for another reason.
Cancerous tumors of the adrenal cortex don't develop that often, but if they do, they can also cause Cushing syndrome. These tumors grow much more quickly and are usually found when the horse has symptoms such as weight loss, weakness, depression, diarrhea, fever and other signs of illness. Sometimes, a cancerous tumor will invade nearby tissues or spread to other organs.
Can a horse recover from Cushing's?
Cushing's syndrome can not be cured but the disease can be quite well managed with medication and changes to the horse's diet.
The outlook for a horse with Cushing's depends on a number of factors. These include: the size and location of the tumor, whether or not the tumor is cancerous, how old the horse is when diagnosed, the general health and condition of the horse before the onset of the disease.
It is important for you to understand the signs and symptoms of Cushing's so you can recognize it early in its development and seek veterinary advice immediately.
Should you ride a horse with Cushings?
Before starting an exercise or riding program, you should always check with your veterinary. If the Cushing's syndrome is well controlled, horses with the condition can be ridden like any other horse. There are some things to consider, though. Delay in shedding winter coat can contribute to overheating. You also need to pay attention to signs of laminitis and blindness that can be caused by Cushing's syndrome. If your horse is experiencing any of the above mentioned issues, you can only ride him in a safe environment and under controlled conditions (in the shade, on the smooth surfaces,...).
What is the difference between Cushing's syndrome and Cushing's disease?
Cushing disease is a specific type of Cushing syndrome, caused by a pituitary tumor. Pituitary tumor affacts the body in a way that it produces too much cortisol. The symptoms can be mild or severe and may include tiredness, weight gain, and diabetes. If left untreated, Cushing disease can lead to serious complications including heart disease, diabetes, osteoporosis, and depression.
Cushing disease is the most common form of endogenous (from the body) Cushing syndrome, and makes up about 70% of Cushing syndrome cases. The other 30% of cases are due to exogenous causes, which includes adrenal tumors (adenomas and carcinomas), pituitary tumors (prolactinomas, somatotropinomas, or growth hormone-secreting adenomas), ectopic adrenocorticotropic hormone (ACTH) secreting tumors, and ACTH-producing tumors of extra-pituitary origin.
Michael Dehaan is a passionate horse owner, horse rider, and lover of all things equine. He has been around horses since he was a child, and has grown to become an expert in the field. He has owned and ridden a variety of horses of different breeds, and has trained many to compete in shows and competitions. He is an experienced horseman, having worked with and competed many horses, including his own. He is an active member of the equestrian community, participating in events and teaching riding lessons.