Horse Illustrated Magazine

There has been a surge in reported cases of Pigeon Fever in Texas during the past year. With summer and fly season in full swing, now is the perfect time for horse owners to become aware and educated about Pigeon Fever.

There is no vaccine for the disease, so prevention and recognition of its symptoms are of the utmost importance. The disease is named after the symptomatic intramuscular abscesses and swelling of the chest and pectoral regions of infected horses, causing a “pigeon like” appearance. The infection is confirmed with a bacterial culture in reported cases.

Pigeon Fever, also known as Dryland Distemper, is common in drier regions like the western United States. The bacterium that causes Pigeon Fever, Corynebacterium pseudotuberculosis, lives and multiplies in dry soil and manure. While Pigeon Fever is not new to Texas, the past year has seen a rapid increase in reported cases, most likely as a result of the severe drought.

Dr. Keith Chaffin, professor at the CVM, commented on the disease and the increase in incidence.

“We now we see about three or four cases a day in the clinic,” Chaffin said. “And many more veterinarians are reporting cases across the state.”

Horses contract the disease through an open wound or fly bite, with bacteria entering through these abrasions or wounds. Chaffin recommends a good fly control program for your horses (sprays, sheets and repellents), basic sanitation, and recognizing the symptoms quickly for prompt treatment. While most of the cases present with external swelling, some cases can result in internal abscesses that could develop pneumonia, colic, weight loss, fever, lethargy, blood in the urine, and other systemic symptoms.

“Most cases of Pigeon Fever involve external abscesses in the pectoral region and under the belly, back to the mammary or sheath area,” Chaffin said. “About less than ten per cent of cases reported involve internal abscesses, which are most common in the abdomen or thorax. The internal cases are the most dangerous, some can be fatal.”

Treating external Pigeon Fever typically consists of surgically opening the abscesses to allow drainage.

“Timing and ultrasound are so critical to managing this disease,” Chaffin said. “Ultrasound allows the veterinarian to determine if the swelling has reached mature abscess stage. Also, ultrasound allows the veterinarian to see what critical structures are nearby, which helps prevent complications. I don’t know how you would ever treat this disease without ultrasonographic imaging. Because a recently drained abscess is potentially contagious it is important to lavage the abscess cavity with antiseptic solutions and I often prefer to place antimicrobials locally into the abscess cavity.”

Also, it is important to completely disinfect any of the pus that drains from the abscesses. This will help minimize spread of the disease, via flies, to other horses. Once the abscesses have been drained, treated, and healed, the horses are generally no longer contagious.

If you recognize any of the symptoms of Pigeon Fever, you should contact your veterinarian immediately to begin treatment.