15/04/2024
Pars pituitary intermedia dysfunction (PPID) is common endocrine disorder in aged horses. PPID is often diagnosed in horses older than 15 years of age, however, it can also occur in younger horses.
Characteristically, horses with PPID present with hypertrichosis (long wavey haircoat), muscle loss, increased thirst, increased urination and abnormal sweating. A spectrum of clinical signs can be seen and may be subtle in cases of mild PPID. Affected horses can also present with reproductive abnormalities, chronic infections (skin, sinus and parasitic), dental disease and laminitis.
Endocrinopathic laminitis secondary to PPID and insulin dysregulation (ID) is a potentially life-threatening condition with considerable implications for the affected animal's welfare. Repeated or severe bouts of laminitis can cause substantial damage to the pedal bone and subsequent rotation which may warrant euthanasia due to chronic lameness and reduced quality of life. Therefore, early diagnosis of PPID is essential to improving the quality of life in aged horses.
Screening testing for PPID is readily available in Australia and includes a blood test measuring adrenocorticotropic hormone (ACTH). At the Veterinary Clinical Centre, we are also able to perform dynamic testing (thyrotropin releasing hormone stimulation test) to increase test sensitivity for those equivocal cases. Screening for insulin dysregulation may also be warranted acknowledging that horses with PPID can concurrently have ID and an increased risk of developing laminitis. If there is a history of laminitis, radiographic examination of the feet may be recommended.
Treatment of PPID involves daily oral administration of pergolide mesylate, in either a liquid or tablet formulation. Following a diagnosis of PPID, this medication will need to be administered for the life of the horse for treatment to be effective. Generally, annual or twice-a-year ACTH testing is recommended to monitor whether any changes in treatment dose are necessary.
As for all horses, regular hoof trimming, good parasite control, annual vaccinations, and regular dental examinations are important in aged horses to ensure overall optimal health. Dietary management of PPID and ID horses needs to be tailored to the individual animal’s needs, however, reduced dietary sugar is generally recommended.
We recommend annual health checks for aged horses to discuss all of the above and assist in developing an individual management plan to help your horse throughout Winter and beyond.
