PPID in older horses – is it actually normal?
Cushings Disease is a name commonly given to a disease of horses called Pituitary Pars Intermedia Dysfunction PPID. It is the most common endocrine disease seen in older horses. Its thought to affect around 20 of horses over the age of 15 and 2 9 of the general population. It is rare but not unheard of in horses under the age of 10. However it is worth noting that this may be an underestimate as not all horses will be tested for the disease.
What causes it?
It is a degenerative condition that develops over time leading to an overproduction of hormones especially ACTH by the pituitary gland. The only consistent risk factor for the development of PPID is increasing age. In other words this is not a disease we can prevent as we cannot prevent ageing. Mares and geldings are affected in equal proportion.
The most common clinical signs associated with PPID are hypertrichosis excessive hair coat hair colour changes usually darker hair turning copper in colour bulging of the tissue around the eyes laminitis muscle wastage particularly loss of topline and the development of a pot belly excessive drinking and excessive sweating. Lethargy depression and weight loss are also sometimes seen along with an increased susceptibility to infections.
In the UK many horses will be diagnosed with PPID following an episode of laminitis which often prompts diagnostic testing. One can have a high index of suspicion that a horse may have PPID based on clinical presentation but it is usually confirmed by means of a blood test to measure the levels of ACTH Adrenocorticotropic hormone. This test is often enough to reach a diagnosis. But in rare cases the test may need to be repeated or another test with a hormone known as TRH may be needed.
It is well understood that horses with PPID are at an increased risk of developing laminitis. Laminitis has been demonstrated in 2482 of horses with PPID and can be life limiting or life threatening in some cases. Even mild cases will affect the welfare of the horse and can be costly in terms of vets fees.
Horses with PPID are also susceptible to Equine Metabolic Syndrome EMS and it should be mentioned that these diseases can coexist. So cases of laminitis may need to be tested for both conditions.
PPID is not a
