Common signs of aging in horses are often do to hormonal changes caused by structural changes in the brain. These signs include:

• Long hair coats (hirsutism) that do not shed out normally in the spring
• Increased water consumption
• Decreased energy levels that can in time lead into mild to moderate depression
• Weight loss, muscle wasting, and abnormal fat deposits along the topline of the neck and tail head
• A tendency to develop laminitis

The structural changes are hormone secreting tumors of the intermedia portion of the pituitary gland in the brain. And result in abnormal levels of some hormones. Because of its similarity to Cushings Disease in other species the disease has come to be called Equine Cushings (EC) but there are important differences so should not be thought of as the same disease. More appropriate is to label this Pituitary Pars Intermedia Dysfunction (PPID). This disease may affect 70% of all horses by the time they reach 30 and has been documented in horses as young as eight years. However the disease is rare in horses under 13 years of age and most often diagnosed in those over 18.

Hyperinsulinemia, a abnormal increase in the insulin levels in the blood, is one of the secondary hormonal abberations of PPID disease. Hyperinsulinemia is a abnormal increase in the insulin levels in the blood and predisposes to founder. Experimentally in very high concentrations it can cause founder itself. Another condition, Equine Metabolic Syndrome (EMS), also has hyperinsulinemia as a feature but should not be confused with PPID as they have very different causes, symptoms, and treatments. Clinically, horses with PPID look very different than horses with EMS.

PPID Older Horses Long hair coat that does not shed out in spring Increasingly a difficult keeper. There is weight loss but may have a cresty neck and be pot bellied

Equine Metabolic Syndrome Younger to middle age horses (but can be in older horses too) Normal hair coat Tends to be fat and a easy keeper.

For more on EMS.

This article discusses clinical signs, symptoms, diagnosis, and treatments, including recent updates to improvements in diagnostic testing and the importance of hyperinsulinemia and founder as it relates to PPID disease.

Older horses are most commonly affected and females are twice as likely to have the problem as males. There have been reports in horses as young as 13 years old and one case in a 8 year old.

PPID presents with a constellation of clinical signs in older horses although often not all are present especially early in the disease:

• long shaggy coats that are slow and do not shed out (80%)
• excessive thirst and urination (70%)
• decreased energy levels and mild to moderate depression
• weight loss and muscle wasting (type 2 muscle fiber atrophy and loss) along with abnormal fat deposition particularly around the crest of the neck and over the hips.
• chronic founder
• excessive sweating
• recurrent infections

Are easy keeping horses with problems with founder PPID cases? Probably not.