Jugular venous thrombosis as a risk factor for exercise-induced pulmonary hemorrhage in thoroughbred racehorses

Exercise-induced pulmonary hemorrhage (EIPH) is one of the most commonly diagnosed disorders in racehorses. Many EIPH risk factors such as breed, age, high or low environmental temperature, and distance of the race have been studied in racehorses.

The aim of this study was to study the relationship between EIPH and the presence of jugular vein thrombose in racehorses.

Forty-eight thoroughbred racehorses randomly selected from animals with exercise intolerance due to respiratory disorders were enrolled in the present study. Clinical and tracheobronchoscopy examinations were done for EIPH grading. In addition, both jugular veins were examined using ultrasonography for vein thrombosis.

It was noted during endoscopy that many cases suffered from laryngeal paralysis, and we were not able to assess the degree of laryngeal paralysis under sedation. About 40% of horses with exercise intolerance suffered from EIPH of varying degrees. Most cases of jugular vein thrombosis were of the chronic type, as local heat and pain were not observed. About 42% of the exercise-intolerant horses had jugular vein thrombose with most jugular vein thrombosis on the left side. Combined jugular veins thrombose and EIPH were found in about 25% of exercise intolerance horses, while 17% showed jugular vein thrombose without EIPH, and 41% showed no EIPH with the absence of jugular vein thrombose.

The present study revealed that jugular vein thrombosis may cause disorders-associated damage to the vessels and anatomical structures close to it, such as the trachea causing EIPH.