Pathology of glanders in horses in Iraq.

Abstract

Glanders is an age-old respiratory disease of the horse. It occasionally is found in other animals, especially members of the cat family including lions that have fed on infected horse meat [8, 101. Numerous infections have occurred in persons caring for glanderous animals, especially stablemen and veterinarians [11, 121. The disease in man usually is fatal in 2 to 4 weeks. A few cases of glanders in man occurred in Russia during World War I [2], and chronic glanders in man has been described [6, 71 in reports of a British veterinarian who contracted the disease in India. The disease is now rare in the United States and has been practically eliminated from western Europe but still occurs in the Balkan States and in Russia and is even common in some parts of Asia [l, 9, 13-17]. The disease was common in horses in Europe during the first world war and reintroduced to Germany after World War TI. As early as the 17th Century it was recognized as contagious. The infectious nature was proved by inoculation tests long before the causative agent was found. The organism (Malleomyces mallei, now Actinobacillus mallei), was isolated and shown to be the cause [3]. Three serological groups of A. mallei used to be recognized [4, 51 but now five groups are recognized [9]. Until recently, glanders has been the scourge of Army horses. From ancient to modern times, wars have caused the disease to flourish [18]. During the early part of the present century, after an excellent diagnostic test had been developed, the disease was rapidly brought under control, especially with the advent of motor cars and trucks and less use of horses in armies. Three horses with advanced glanders were presented at our clinic from a stable of 315 horses. They were examined and killed. There were deep ulcerations of the mucosa of upper air passages, particularly over the septum. The lesions in the nasal passages began as submucosal nodules, which quickly ruptured, forming shallow crateriform ulcers that exuded a thick, sticky purulent material mixed with blood. Most of the pulmonary lesions were discrete firm miliary granulomatous nodules but there were some areas of diffuse pneumonia. Many alveoli had fibrinous exudate. The granulomatous nodules had a caseonecrotic centre with karyorrhectic neutrophils, surrounded by epithelioid cells, a few giant cells and some lymphocytes. This structure is unlike that of a tubercle. The submaxillary lymph nodes were enlarged but not ulcerated. The skin lesions were persistent ulcers connected by tortuous, indurated, thick-walled lymphatics. Nodules were also under the skin, particularly of the hind legs, along the costal arch (abdominal ridge) and on the face along the zygomatic ridge and facial crest. They were along lymph channels and formed chains of nodules connected by indurated cords. This form of glanders is known as farcy. No lesions were seen in the mesenteric lymph glands, liver, spleen or other viscera. The glanders bacillus and other organisms were isolated from the sticky viscous exudative discharge from the nasal or skin ulcers, mixed with other suppurative organisms. A. mallei was isolated in pure culture from unopened glanderous lung nodules. Corynebacterium pyogenes was also isolated from two horses with glanderous suppurative bronchopneumonia. The mode of infection of glanders is disputed. It may be by ingestion but if this be so one would expect to find lesions in mesenteric lymph nodes, intestine or liver. No such lesions