Tuesday, April 21, 2009

Cushing’s Disease in Horses

How Do I Know if My Horse has Cushing's Disease?
Cushing’s Disease is a slowly progressing disease that has no cure and typically appears in older horses. The most common sign of this disease is a long, wavy hair coat that doesn’t shed out in the spring. Other signs of Cushing's Disease are:

  • excessive drinking and urination,
  • loss of muscle across the top line which results in a potbellied look and swayback,
  • depression and lethargy,
  • recurring laminitis, and
  • susceptibility to infections.

In some horses there are fat deposits at the base of the tail, the crest of the neck, and behind the shoulders due to insulin resistance. At the onset of this disease these signs may be slight and hard to determine, but as the disease progresses, they become more and more obvious.

What causes Cushing’s Disease?
Usually, but not always, Cushing's Disease is caused by a benign tumor of the pituitary gland. The pituitary and hypothalamus, which is next to the pituitary gland, work together to regulate the body’s systems and cause the adrenal gland to produce cortisol. When the tumor grows and obstructs the pituitary gland, it causes the adrenal gland to keep producing cortisol without control. Normally, cortisol maintains the immune system and heart function, regulates nerve tissue, muscle tone and the body’s metabolism, balances insulin, and helps the horse respond to stress. Because of where the pituitary gland is located – at the base of the brain – surgery to remove the tumor is not an option. There are drugs that can help control the disease, the most common being Pergolide, but as time goes on the drug needs to be increased.

Because their immune system is compromised, horses with Cushing’s Disease need to have special care taken to avoid infections and exposure to other diseases. Their diets need to be monitored and they need to be watched for signs of laminitis. One other side effect can be the inability to handle stress so this horse would need to be kept stress-free.

Although there is no cure, with drugs and care horses with Cushing’s Disease are still able to have many years of use.


***Cited Sources***

Advances Against Cushing's Disease by Janice Posnikoff, DVM @ HorseChannel.com
Cushing's Disease @ infovets.com
and articles @ thehorse.com

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