Testing and monitoring for PPID
There is currently no perfect commercially available test to diagnose your horse for PPID, but your horse's age and the signs it is displaying are used to determine the best test for each individual horse.
Your veterinarian will use available guidelines set out by endocrinology conferences, researchers and special interest groups to formulate plans to diagnose and monitor PPID.
As PPID is a progressive neurodegenerative condition there is a clear distinction between what is normal and abnormal for the condition but there is a grey- zone in the middle.
In your horse's early stages of PPID, the results of basic tests may be uncertain or ambiguous. As a result, more sensitive tests are required to determine if abnormal pituitary function is contributing to vague clinical signs such as your horse's:
- decreased athletic performance
- loss of muscle mass
- lethargy
- weight loss or
- elevated liver enzymes.
Older horses can be tested for endogenous ACTH concentration which is equally sensitive to the dexamethasone suppression test, but simpler and safer to perform. To be tested, these horses need to display at least one characteristic clinical sign of PPID including:
- retained long hair coat (hirsutism/hypertrichosis)
- loss of muscle mass
- laminitis
- lethargy
- polyuria/polydipsia
- recurrent infections
- infertility, and either abnormal fat distribution in the earlier stages and weight loss in the later stages
can be tested for endogenous ACTH concentration which is equally sensitive to the dexamethasone suppression test, but simpler and safer to perform.
However, based on post mortem studies of horses, both of these tests may miss early or subclinical cases of PPID.1
Read the full article in the Clinical Review.