Weight Loss in Cushing's Horses

Feb 15, 2023
Eleanor Kellon, VMD

Image from Pixabay by ivabalk

Holding weight can be an issue for any horse but especially those with PPID (Cushing's disease).

Senior Horses

All seniors have a variety of factors that can contribute to weight loss. These include:

Wear of Teeth

· Alteration in the angle of the occlusal surface of the teeth that reduces the forces generated during chewing.
- · Sarcopenia of aging which is a loss of muscle mass accompanying aging, especially in horses no longer being exercised.
  - · Reduced number and diversity of organisms in the large intestine.
    - · Possible reduction in the efficiency of enzymatic digestion in the small intestine.

These Changes Can Be Addressed By

Except for sarcopenia of aging, these changes can be efficiently addressed by feeding the horse a diet of soaked pelleted or cubed feed and hay, possibly with the addition of a supplement with both high digestive enzyme and probiotic ingredients. It is also wise to guarantee an adequate intake of essential amino acids.

PPID

Hormonal Effects

With PPID, there are also hormonal effects. PPID is a very catabolic state, meaning there is a breakdown of protein. This frequently causes unexplained tendon or ligament breakdown/injury and also affects muscles.

Muscle Loss

Muscle loses both bulk and strength when PPID is not controlled. This leads to the loss of topline and slack abdomen so typical of PPID but also contributes to weight loss in general because the horse cannot hold a normal weight when protein metabolism is disrupted.

Solution

The solution here is not dietary, although you do still need to guarantee adequate essential amino acids. The first thing to do is ask your veterinarian to check ACTH to make sure your dose of pergolide is adequate to control the PPID and if not, increase it. Contrary to popular belief, 2 mg is not the maximum dose that can be used.

In a poll conducted on the Equine Cushing's and Insulin Resistance Group, only approximately 1/3 of the members' horses were controlled on 2 mg or less of pergolide.

Horses under borderline control may do well through early Summer and then start to lose weight as Fall approaches. Other changes you may see at this time and into September are increased water consumption and urination. These are strong indicators that the horse needs more pergolide.

- Eleanor Kellon, VMD