Although it is very common, PPID (Cushing’s Disease) is somewhat challenging to diagnose. Veterinarians used to rely on the manifestation of equine PPID symptoms to make a diagnosis, most notably abnormal hair coat, or lack of shedding. In recent years, diagnostic tests have become more accurate and can now help lead to a more concrete diagnosis, earlier in the progression of the disease. Early diagnosis and treatment may offer horses suffering from the disease a better quality of life.
A number of diagnostic tests exist for PPID, all of which are designed to evaluate hormonal function.
The Equine Endocrinology Group recommends a blood test to diagnose PPID (Cushing’s Disease) in horses:
Resting ACTH test
One of the hormones produced by the pituitary gland (area of the brain responsible for PPID) is called “ACTH.” In PPID, ACTH levels tend to be higher than normal because the pituitary gland is overactive.
The resting ACTH test measures baseline levels of ACTH in the blood. If a horse’s baseline ACTH levels are above the benchmark, this is considered a positive diagnosis for PPID.
What is the outcome for horses with PPID?
When veterinarians relied on the appearance of clinical signs and symptoms to diagnose PPID, it often meant that the disease was already advanced at the time of diagnosis. Therefore, even with treatment, horses’ life expectancy with PPID was shortened. As PPID is becoming better understood by the equine community, PPID symptoms are being recognized earlier, allowing for earlier treatment and an improved quality of life for horses with PPID.