The Arabian Horse is known for the beauty of its concave profile, large eyes and broad forehead. But a less obvious characteristic is also common to the breed—an unusual throat structure that may affect the ability to swallow.

Indeed, centuries of breeding to accentuate the beauty and refinement of the Arabian head may have led to increased risk for a rare infection.

A strange spike in infections

When a Middle Eastern Arabian breeding farm reported that 20 to 30 percent of each year’s foal crop was developing respiratory infections that did not respond as expected to antibiotic therapy, researchers and veterinarians at the Equine Veterinary Medical Center (EVMC), a branch of the Qatar Foundation, investigated.

The researchers paired 14 affected foals with 10 healthy youngsters on the property for comparison. After complete physical workups, the foals underwent endoscopic and ultrasound examinations.

In addition, the researchers flushed each youngster’s trachea (main airway) and guttural pouches. They also collected the fluids for analysis to determine the bacteria involved.

In the foals showing signs of respiratory infection, the researchers found evidence that milk had aspirated into the guttural pouches. Two air filled sacs, the guttural pouches connect a horse’s pharynx to the middle ear.

What the reseachers found

Analysis of the youngsters’ guttural pouch fluids revealed high levels of Streptococcus equi ssp. zooepidemicus and other pathogens.

This mixture of bacteria supports the theory that the infection originated with the aspirated milk. Instead of ending up in the stomach, the milk passed through the mouth to the back of the pharynx and entered the guttural pouches.

Milk and bacteria that enter the gutteral pouches become trapped there­—spontaneous drainage is impossible. Infection develops as the bacteria feed on the sugars and protein in the milk.

The researchers flushed the foals’ gutteral pouches with a saline and povidone-iodine solution. All affected foals sunsequently recovered.

Ultimately, the researchers conclude, “show-type Arabian foals presenting with upper respiratory disease with nasal discharge may be aspirating milk into the [guttural pouches].” They call for “familial analysis” of affected foals and evaluation of their dynamic swallowing function. In addition, they say, trace vitamin and mineral status may suggest potential inciting causes for pharyngeal dysfunction and dysphagia (inability to swallow normally).

FInally, these findings may help establish a new strategy for diagnosing and treating respiratory conditions in Arabian foals. Specifically, the researchers call for making endoscopy part of examinations of Arabian youngsters presenting with nasal discharge.

Reference: “A case-control study of atypical guttural pouch empyema in Arabian foals,” Veterinary Medicine and Science, July 2023