Cushings In Horses

Cushings In Horses Horse Supplements and Horse Feeds Supporting Cushings

Cushing's disease in horses, also known as Pituitary Pars Intermedia Dysfunction (PPID), is a common endocrine disorder that affects the horse’s pituitary gland, leading to hormonal imbalances. It's most often diagnosed in older horses (usually over 15 years of age), but younger horses can be affected as well. PPID can lead to a variety of symptoms and health issues, some of which can severely impact a horse's quality of life if not managed properly.

What Causes Cushing’s Disease in Horses?

Cushing’s disease is caused by dysfunction of the pituitary gland, specifically the pars intermedia region. Normally, this part of the pituitary helps regulate hormone production in response to signals from the hypothalamus. However, in horses with PPID, the regulatory control is lost, resulting in the overproduction of certain hormones, particularly adrenocorticotropic hormone (ACTH). This hormonal imbalance leads to the wide range of symptoms seen in horses with PPID.

Symptoms of Cushing’s Disease:

The symptoms of PPID can be quite varied, and horses may show one or several signs of the disease. The most common signs include:

1. Long, Curly Coat (Hirsutism) or Delayed Shedding:

• One of the hallmark signs of Cushing’s disease is an abnormally long, often curly coat that doesn’t shed out properly in the spring and summer. This is the most obvious symptom of PPID and is unique to horses with the condition.

2. Excessive Sweating:

• Horses with PPID may sweat excessively, even in cool weather. This is thought to be related to the abnormal coat and the body’s struggle to regulate temperature.

3. Laminitis:

• Laminitis is a painful and serious inflammation of the sensitive structures in the hoof, and it is one of the most significant complications of PPID. Horses with PPID are at an increased risk of developing chronic laminitis, even in the absence of other typical risk factors, like overfeeding or metabolic syndrome.

4. Increased Thirst and Urination:

• Horses with PPID often drink more water than usual (polydipsia) and urinate more frequently (polyuria). This is a common sign of hormonal imbalance.

5. Muscle Wasting and Loss of Topline:

• Muscle loss, particularly along the topline, is common in horses with Cushing’s. This can result in a pot-bellied appearance and general loss of condition, even if the horse has a normal or increased appetite.

6. Lethargy or Lack of Energy:

• Affected horses may seem dull, tired, or reluctant to exercise. This lethargy is related to the overall hormonal imbalances caused by PPID.

7. Recurrent Infections:

• PPID can weaken the immune system, making horses more susceptible to infections such as abscesses, sinus infections, and skin conditions. Non-healing skin wounds and poor coat condition may also occur.

8. Increased Susceptibility to Parasites:

• Horses with PPID may be more prone to internal parasites because their immune systems are compromised.

9. Abnormal Fat Deposits:

• Horses with Cushing’s may develop abnormal fat deposits, particularly around the eyes (supraorbital hollows) and on the crest of the neck or above the tail.

Diagnosing Cushing's Disease:

If a horse is showing symptoms consistent with PPID, a veterinarian will typically recommend diagnostic testing. The most common tests include:

1. ACTH Blood Test:

• This test measures the levels of adrenocorticotropic hormone (ACTH) in the horse’s blood. Horses with PPID often have elevated ACTH levels, particularly in the fall when seasonal increases in hormone levels occur naturally.

2. Dexamethasone Suppression Test:

• This test involves giving the horse a dose of dexamethasone (a corticosteroid) and then measuring cortisol levels before and after administration. In a normal horse, dexamethasone suppresses cortisol production, but in a horse with PPID, cortisol levels remain high.

3. TRH Stimulation Test:

• The thyrotropin-releasing hormone (TRH) stimulation test can be used to diagnose early or borderline cases of PPID. This test measures the horse’s response to an injection of TRH, which stimulates the pituitary to release ACTH.

Managing Cushing’s Disease in Horses:

While there is no cure for PPID, it can be managed effectively with medication, dietary adjustments, and careful monitoring. Management aims to reduce symptoms and prevent complications like laminitis.

1. Medication (Pergolide):

• The primary treatment for PPID is pergolide mesylate (commonly sold under the brand name Prascend). Pergolide is a dopamine agonist that helps regulate the overproduction of hormones in the pituitary gland. It’s highly effective at managing symptoms and improving the horse’s quality of life.
• Horses on pergolide must be monitored regularly by a veterinarian, as the dose may need to be adjusted over time. Blood tests are often recommended to track ACTH levels and ensure proper management.

2. Dietary Management:

• Horses with PPID often have insulin resistance, so it’s important to manage their diet carefully. Key recommendations include:
  • Low-Sugar and Low-Starch Diet: Avoid feeds high in non-structural carbohydrates (NSC), such as grains and sweet feeds. Instead, focus on hay and forage that are low in sugar.
  • Forage Analysis: It may be beneficial to test the hay for NSC levels to ensure it’s suitable for a horse with PPID.
  • Supplementation: Horses with PPID may benefit from vitamin E, magnesium, and omega-3 fatty acids to support their overall health, immune function, and muscle condition.

3. Preventing Laminitis:

• Because laminitis is a serious risk for horses with PPID, it’s critical to take preventive measures:
  • Weight Management: Keep the horse at a healthy weight to avoid extra stress on their hooves.
  • Regular Hoof Care: Work closely with a farrier to ensure the horse’s hooves are well-trimmed and supported.
  • Avoid High-Sugar Feeds: As mentioned, avoid feeds that are high in starches or sugars, which can trigger laminitis.

4. Body Clipping and Grooming:

• Horses with PPID often have trouble shedding their winter coat. Regular body clipping can help keep the horse cool and comfortable, especially in the warmer months. Frequent grooming will also help maintain a healthy coat and skin.

5. Managing Infections and Immune Health:

• Due to the compromised immune system in PPID horses, it’s important to stay on top of health care. This includes regular deworming, dental care, and monitoring for infections or wounds.

Long-Term Outlook for Horses with Cushing's Disease:

With proper management, many horses with PPID can live happy, productive lives for many years. Early diagnosis and treatment are key to preventing complications like laminitis and maintaining a good quality of life. Regular veterinary care, along with consistent monitoring and medication, will help manage symptoms and slow the progression of the disease.

Conclusion:

Cushing's disease (PPID) is a serious but manageable condition in horses, especially with early diagnosis and proper treatment. By working closely with a veterinarian and implementing medication, dietary changes, and preventive care, horse owners can help their horses live comfortably and avoid the complications associated with this condition.