New diagnostic protocols for wasting disease in horses

Dec 05, 2013 by Rushmie Nofsinger

Equine pituitary pars intermedia dysfunction (PPID) can be detected earlier and more reliably with a new set of guidelines developed by the Equine Endocrinology Group (EEG), a body of leading veterinarians and researchers in the field of equine endocrinology.

Similar to Cushing's disease in humans but affecting a different area of the , PPID is associated with elevated levels of hormones in the blood. Horses with the condition often have a wide range of clinical signs depending on the stage of the disease, from loss of energy to muscle wasting, and the condition is more common in older horses.

The EEG created a set of recommendations in 2011 to help practitioners identify early versus advanced stages of PPID, and their new recommendations adjust and refine testing procedures for a more thorough and accurate approach to diagnosis. Recommendations are based upon published research on PPID.

"Our collective research has shown that horses can often develop this disease earlier in life, yet earlier clinical signs don't always translate into positive test results," said Nicholas Frank, D.V.M, DACVIM, professor and chair of the Department of Clinical Sciences at the Cummings School of Veterinary Medicine at Tufts University and group coordinator for the Equine Endocrinology Group. "As research on PPID advances, we are identifying practical ways to improve early detection and diagnosis."

In addition to Dr. Frank, the Equine Endocrinology Group includes Drs. Frank Andrews (Louisiana State University); Andy Durham (Liphook Equine Hospital); Dianne McFarlane (Oklahoma State University); and Hal Schott (Michigan State University).

While the clinical signs of PPID are the same, the recommendations address changes to the diagnostic process. Previously, horses showing any signs of this disease were recommended to a undergo one of two tests. One test measures levels of resting adrenocorticotropin hormone (ACTH) which is produced and secreted by the pituitary gland. The other is an overnight dexamethasone suppression test (DST) that causes the production of cortisol to decrease in healthy horses, but not those with PPID.

The newly established guidelines retain the recommendation to measure resting ACTH concentrations, but the group has lowered the recommendation for using the DST. Recent research shows that the DST is no better at detecting PPID than other tests, and horse owners have concerns about dexamethasone inducing laminitis, a painful condition affecting the feet that can lead to death.

Instead, the EEG group recommends a thyrotropin-releasing hormone (TRH) stimulation test, which is particularly useful when horses with early PPID have normal resting ACTH concentrations. TRH causes the pituitary gland to release more hormones and ACTH concentrations increase to a higher level in horses with PPID. This test is easily performed on the farm by taking a baseline blood sample, injecting TRH intravenously, and collecting a second blood sample 10 minutes later. At present, the TRH stimulation test should only be used between December and June, which is the only period in which cut-off values have been established. Cut-off values allow veterinarians to interpret results and determine whether the horse suffers from PPID.

Explore further: Are you carrying adrenal Cushing's syndrome without knowing it?

More information: For more information on the PPID diagnostic guidelines visit sites.tufts.edu/equineendogroup/

add to favorites email to friend print save as pdf

Related Stories

Protecting competition horses from the flu

Nov 05, 2013

A deep hacking cough, a runny nose and fever—just like humans, horses can suffer badly when struck down by the flu. Although equine influenza is rarely fatal, it is highly contagious and can seriously disrupt ...

Study shines light on mules, their blood chemistry

May 16, 2013

Offspring of female horses and male donkeys, mules are often associated with caution and hard work. While they'll never be mistaken for thoroughbreds, mules play important roles in modern society – performing ...

Transforming the diagnosis of equine colic

Dec 12, 2012

Colic is the number one killer of horses. But one of the difficulties faced by vets is differentiating between a mild case and a potentially life threatening case that is in its early stages.

Researchers identify virus that causes horse hepatitis

Mar 19, 2013

(Phys.org) —Theiler's Disease is one of the most common causes of equine hepatitis. Death rates in horses that develop symptoms range between 50 and 90 percent. Although veterinarians have known about ...

Recommended for you

Dogs hear our words and how we say them

16 hours ago

When people hear another person talking to them, they respond not only to what is being said—those consonants and vowels strung together into words and sentences—but also to other features of that speech—the ...

Amazonian shrimps: An underwater world still unknown

18 hours ago

A study reveals how little we know about the Amazonian diversity. Aiming to resolve a scientific debate about the validity of two species of freshwater shrimp described in the first half of the last century, ...

Factors that drive sexual traits

19 hours ago

Many male animals have multiple displays and behaviours to attract females; and often the larger or greater the better.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.