What Is Cushing’s Disease In Horses & How To Treat It
Cushing’s disease, otherwise known as Pituitary Pars Intermedia Dysfunction (PPID), is a hormonal disorder affecting horses, especially senior horses. When left untreated, it may trigger severe health problems and can even be fatal.
In this article, we discuss the causes of Cushing’s, the signs and symptoms horse owners should look for, and how to treat it with medications, nutrition, exercise, and other therapies.
We also answer some frequently asked questions about Cushing’s disease in horses.
Signs and Symptoms of Cushing’s Disease in Horses
One of the most common signs of Cushing’s in horses is a long, thick coat that doesn’t shed properly in the spring.
The horse may also have a pot-bellied appearance and may develop laminitis, an inflammatory condition of the laminae in the hoof.
The laminae are the soft, sensitive tissues that attach the hoof wall to the coffin bone. When they become inflamed, they can separate from the coffin bone, causing pain and lameness.
Many things can cause laminitis, but in horses with Cushing’s disease, it is thought to be caused by the excess production of cortisol.
Other potential signs of Cushing’s include:
- Excessive drinking and urination
- Increased body fat
- Weight loss
- Displaced fat
- Muscle wasting
- Recurrent infections
- Insulin resistance
- Reproductive problems
Horses with Cushing’s disease may either lose or gain weight due to the disorder. However, weight gain is much more common.
Since horse owners are much less likely to notice excessive hair growth during the winter season, weight changes and shifting fat that causes a pot-bellied appearance are often the first signs that something is wrong during the winter season. It’s often apparent that the horse is drinking and urinating more frequently as well.
If you detect any of the clinical signs of Cushing’s in your horse, it’s crucial to contact your veterinarian right away. They can determine if your horse has this hormonal disorder with a series of tests and discuss treatment options with you.
Why Do Affected Horses Develop Cushing’s Disease?
Cushing’s disease in horses is caused by a growth or small tumour (most often benign) in the pituitary gland.
In basic terms, the tumour on the pituitary gland causes the gland to produce too much of the hormone ACTH, which in turn leads to an overproduction of cortisol in the horse’s body.
We offer a deeper explanation below.
The Working of the Endocrine System
In order to understand Cushing’s, it is necessary to understand how the endocrine system works. The endocrine system is a network of glands that produce hormones.
Hormones are chemical messenger molecules that are released into the bloodstream by the glands and travel to various parts of the body, where they bind to specific receptors.
This binding triggers a response in the target cells, which can be anything from increasing metabolism to stimulating growth.
The Pituitary Gland
Located near the brain’s base, the pituitary gland is one of the glands in the endocrine system.
The pituitary gland receives signals from the hypothalamus. It acts on them to regulate the production of hormones by other glands in the endocrine system, which is crucial to the horse’s health.
For example, the pituitary gland itself produces ACTH, which stimulates the adrenal glands to produce cortisol. During times of illness or stress, the hypothalamus will instruct the pituitary gland to increase ACTH secretion, triggering the adrenal glands to raise cortisol levels.
The Adrenal Glands
When the pituitary gland malfunctions or has a tumour, it sends excess amounts of ACTH to the adrenal glands. In response to the overabundance of ACTH, the adrenal glands release more cortisol than the horse’s body needs.
Cortisol is a stress hormone that aids the horse in dealing with physical and emotional stress, including injuries, exercise, and disease. When meted out appropriately, cortisol is necessary and even beneficial.
However, too much cortisol leads to a hormonal imbalance, which can cause various health problems, including weight difficulties, a weakened immune system, and Cushing’s disease.
Diagnosing Equine Cushing’s Disease
If your horse is showing any signs of Cushing’s disease, it is vital to consult the vet for a diagnosis. Even with a vet’s expertise, a diagnosis is sometimes challenging.
Several tests can diagnose Cushing’s disease, but urine and blood tests are the most common.
A go-to test to diagnose Cushing’s is called the dexamethasone suppression test. The dexamethasone suppression test involves taking a baseline blood sample. The vet tests the blood sample to measure cortisol production.
Then, the vet administers dexamethasone and tests a second blood sample around 20 hours later. A normal horse will show a decrease in cortisol levels after the dexamethasone dose. However, horses with Cushing’s will maintain the same cortisol levels after a dexamethasone dose.
Alternatively, the vet may opt to perform a urinalysis to look for high levels of ketones or glucose.
Additional tests may follow to confirm findings.
Cushings in Horses: Treatment and Care
There are several treatment options available for horses with Cushing’s disease. Your vet can work with you to develop a customized treatment plan for your horse.
Treatments and care instructions may include:
The most common treatment is medication, typically given orally or by injection. The goal of most medications is to reduce hormone production.
If you can successfully decrease ACTH secretion and cortisol levels with medication, you can better control the clinical signs of Cushing’s. In most cases, medications are needed to lower cortisol levels for the remainder of the horse’s life
In addition to managing cortisol levels, medicines may be prescribed to help with insulin resistance.
Diet and Exercise
Good nutrition and exercise such as lunging are critical for horses with Cushing’s.
Weight loss and sugar reduction are typically key strategies in the management of equine Cushing’s disease. This is because a poor diet and obesity can worsen the symptoms of the disorder, heightening risks for problems like laminitis and insulin resistance.
A healthy, low-starch diet and a suitable exercise program can help control insulin resistance and prevent laminitis by reducing the animal’s weight.
Adequate nutrition and exercise also improve muscle tone and the performance of the equine immune system, enhancing the horse’s overall health.
Hoof Care and Dentistry
Cushing’s often causes an overgrowth of hooves and hair. Because the hair and hooves of a horse with Cushing’s grow more readily than normal horses, both can reach uncomfortable lengths quickly.
With that in mind, remember to trim an affected horse’s hooves regularly, employing a good farrier who can assist your horse in maintaining strong hooves.
Routine dentistry is also helpful for horses with Cushing’s. Because of the disorder, these animals are more likely to develop problems like excessive plaque buildup, tartar, and gum disease. As with hooves, regular care can help prevent these problems and keep your horse’s mouth healthy.
Skin and Hair Care
Due to their excessive production of hair, horses with Cushing’s are more prone to skin infections. Unless clipped, their hair coat is often long and thick, creating a warm, moist environment that is ideal for bacteria and fungi to grow.
In addition, the increased cortisol levels in the body can cause the skin to become thin and fragile, making it more susceptible to cuts and scrapes.
Be sure to keep your horse’s skin clean and dry and monitor for any signs of infection. Clipping the hair coat may also be necessary to help prevent infections.
Hair management is especially important during summer months because thick hair can cause the horse to overheat. Remember, a horse with Cushing’s can’t regulate its own body temperature well, so you must support the animal in staying at a satisfactory temperature.
Deworming is necessary for all horses, but it is especially vital for horses with Cushing’s. Some horses with this disorder have lowered immunity to parasite infections.
That means they are more likely to become infected with parasites, and the infection can be more severe.
Ensure your horse is on a regular deworming schedule to reduce the chance of worms and infections.
Other Therapies to Treat Cushing’s Horses
Cushing’s disease is a complex disorder, and there is no one-size-fits-all approach to its management. Just about any therapy that enhances the healing process or helps your horse feel more comfortable can be beneficial in managing Cushing’s disease.
The goal is to keep your horse as healthy and happy as possible, and there are many methods to assist you in achieving that goal.
A range of treatments can be used to manage Cushing’s and its symptoms, including recurrent laminitis and delayed wound healing.
Possible therapies include:
Pulsed Electromagnetic Field Therapy
One therapy that can be used to treat the symptoms of Cushing’s is pulsed electromagnetic field (PEMF) therapy.
PEMF therapy is a non-invasive treatment that uses a pulsed electromagnetic field to stimulate the cells in the animal’s body. The pulsed field is said to help reduce inflammation and promote healing.
PEMF therapy is sometimes used to treat laminitis, as it is thought to help reduce inflammation in the hooves. Hoof boots that direct the treatment at the hooves may be most helpful for horses battling Cushing’s and laminitis.
Light therapy, also known as phototherapy, is the use of light to treat disease. There are several different types of light therapy, but all share the common goal of stimulating the body’s natural healing processes to boost health and vitality.
One type of light therapy, called blue light treatment, involves exposing the horse to “blue light,” simulating daylight.
This type of therapy is used to treat many conditions and, according to some recent studies, may be effective in reducing the clinical signs of Cushing’s disease, particularly hair loss and overgrowth.
Equine hydrotherapy can be an extremely beneficial treatment for horses with laminitis. The buoyancy of the water supports the horse’s weight, which takes the pressure off the laminae and allows them to heal.
The warmth of the water also helps to soothe and relax the muscles, and the massage-like action of the water can stimulate blood flow and promote healing.
Hydrotherapy can be used as a standalone treatment or in conjunction with other therapies, such as medication, hoof care, and diet changes.
Frequently Asked Questions About Cushing’s Disease in Horses
We’ve provided a list of a few frequently asked questions about this hormonal disorder in horses below. Hopefully, these answers aid you in better understanding this complex condition.
Can Cushing’s disease be cured?
No, unfortunately, there is no cure for Cushing’s.
That said, the symptoms can often be successfully controlled with careful management, and the horse can enjoy a good quality of life even with the disorder.
What is the life expectancy of a horse with Cushing’s?
There is no definitive answer to this question. An otherwise healthy horse with Cushing’s disease may live for many years, while others may only survive for a few months.
The prognosis for horses with this hormonal disorder depends on many factors, including the severity of the disease, the age of the horse, and the overall health of the horse.
Keep in mind that most horses diagnosed with Cushing’s are aged horses. Young horses with Cushing’s disease aren’t the norm.
How can I prevent my horse from getting Cushing’s?
There is no sure way to prevent Cushing’s. However, there are some preventative steps owners can take to reduce a horse’s risk of developing the condition.
- Feeding a balanced diet with minimal sugar
- Exercising your horse regularly to maintain a healthy weight
- Keeping your horse stress-free
- Regular vet appointments
Older animals are most likely to develop Cushing’s, so regular appointments with the vet become even more essential for geriatric horses.
Can Cushing’s disease be passed on to other horses?
No. Cushing’s disease is not contagious and cannot be passed on to other horses. It’s also not possible for Cushing’s to pass from a horse to other animals or humans.
A horse with Cushing’s does not need to be quarantined or isolated from its stablemates.
Living with Cushing’s Disease
While pituitary pars intermedia dysfunction (or Cushing’s) is a serious disorder, affected horses can often lead great lives with minimal discomfort when they receive the proper rehabilitation and care.
Management of Cushing’s is ongoing, and your horse will require special care from the time it’s diagnosed. But it’s by no means a death sentence for your equine companion.
If you think your horse may have Cushing’s disease, reach out to your veterinarian as soon as possible to confirm your hunch with an official diagnosis.
Prompt attention and speedy treatment mean less discomfort for your horse and the best chance of a satisfactory outcome.
Also see our article on horse anxiety.