PPID Risk Factors in Horses Studied

Veterinarians and scientists have made great strides in understanding, diagnosing, and treating pituitary pars intermedia dysfunction (PPID, often referred to as equine Cushing's disease)—a neuro-degenerative disorder of aged horses, in which dopamine production of the pituitary gland decreases. However, questions about the disease still abound. Researchers from Australia and the United Kingdom recently completed a two-part study in an effort to shed more light on PPID prevalence and risk factors.

“I think (PPID) goes unrecognized as people for years have thought of weight loss, sway back, and even long hair coat as simply signs of aging; it is not until something like laminitis happens that they are triggered into seeing the vet,” reported Cathy McGowan, BVSc, DipVetClinStud, MACVSc, PhD, DEIM, Dipl. ECEIM, FHEA, MRCVS, Head of Equine Internal Medicine and Director of Veterinary Continuing Professional Development at the Institute of Aging and Chronic Disease at University of Liverpool, England.

To better understand PPID prevalence and risk factors, the researchers gathered information on a large group of aged horses in Queensland, Australia, by mailing questionnaires to area horse owners. The team asked owners to complete the survey for any horses aged 15 or older. They hoped to collect data on horse details and history, observed signs of PPID, management practices, and welfare concerns through the survey. The team narrowed down the 974 questionnaire responses returned and then worked with a subgroup of 325 horses whose owners agreed to have the animals evaluated by a veterinarian.

A study veterinarian examined each horse and collected blood samples. Horses were diagnosed with PPID if increases in adrenocorticotropic hormone (ACTH) concentrations were found to be above the seasonally-adjusted reference ranges.

Key findings from the veterinary evaluations in the study included:

  • 21% of horses examined were diagnosed with PPID;
  • Horses diagnosed with PPID were significantly older (an average age of 24 years) than non-diagnosed horses;
  • No associations were found between PPID diagnosis, gender, body mass index, or breed;
  • For each year above age 15, there was an increased risk of PPID diagnosis; and
  • Aged horses with PPID were more likely to have had a history of laminitis than non-diagnosed horses.

From its study findings the team concluded that “PPID is a degenerative disease associated with aging rather than a spontaneously occurring disease.”

For owners who observe signs associated with PPID in their horse, McGowan noted, “It is always important to test to provide baseline values for monitoring progress as well as to confirm the disease and treat.”

The study, “Prevalence, risk factors, and clinical signs predictive for equine pituitary pars intermedia dysfunction in aged horses,” was published in January in the Equine Veterinary Journal.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.