Polyarteritis in a beagle

A 13-month-old Beagle became anorectic and had fever, stiff gait, and tenderness in the inguinal region. Clinical signs of disease were associated with neutrophilia and a decrease in the albumin-to-globulin ratio. The dog became clinically normal for 5 days after 3 days of treatment with penicillin G and dihydrostreptomycin. Clinical signs of disease recurred, and the dog was euthanatized after failing to respond to administration of a trimethoprim-sulfamethoxazole combination for 9 days. Disseminated arteritis was seen in the testes, epididymides, mesentery, coronary arteries, aorta, and thyroid gland. Lesions were seen in large and medium-sized arteries and varied from acute necrotizing arteries to a chronic lesion with organization and recanalization of thrombi. The clinical signs of disease resembled those of Beagle pain syndrome, described in laboratory Beagles.     

Polyarteritis nodosa and rheumatic heart disease in a dog

A 12-year-old spayed Corgi-type dog developed an acute febrile illness about 2 weeks after excision of a subcutaneous arteriovenous fistula. The dog was moribund after 1 week of illness and was euthanatized. Necropsy disclosed uncommon lesions comparable to those of polyarteritis nodosa and rheumatic heart disease of human beings. The pathogenesis of the arterial and cardiac lesions was not established, but was consistent with that of an immune-mediated mechanism.     

Polyarteritis nodosa in a cynomolgus macaque (Macaca fascicularis)

Polyarteritis nodosa (PAN) is an idiopathic necrotizing vasculitis affecting small- to medium-sized arteries. The disease is well recognized in humans, and PAN-like syndromes have been described in a number of other species. This report describes a case of PAN in a 6-year-old male cynomolgus macaque. The animal had necrotizing arteritis affecting vessels in the kidney, small intestine, colon, heart, spleen, mesentery, urinary bladder, and pancreas. The lesions were segmental in distribution and of varying severity and stage of development. A transmural mixed inflammatory cell infiltrate was present, often accompanied by fibrinoid necrosis of the tunica media and loss of the internal elastic lamina. Immunohistochemical staining showed that many of the infiltrating cells were T lymphocytes and histiocytes, suggesting a cell-mediated component to the pathogenesis.     

Within-flock transmission of sheep scab in naive sheep housed with single infested sheep.

The within flock transmission of sheep scab was studied in two trials, which lasted 14 and 12 weeks, respectively. A total of 40 non-infested, scab-naive sheep were divided into six groups of between 6 and 20 individuals. Each group was subsequently housed with a single infested index case, carrying scab lesions of different ages. The groups of sheep in both trials were video recorded continuously and all the sheep were individually examined on a weekly basis. The occurrence of transmission was measured in two ways: first, by the detection of early scab lesions during clinical examination and, second, by an increase in the rubbing of individual sheep as noted from the analysis of the video recordings. These two methods complemented each other in predicting the week on which transmission occurred. Overall, transmission was detected in 34 of the 40 scab-naive sheep. Transmission was shown to occur at about the time when the population of adult mites in lesions on index cases reached their peak numbers. The highest number of mites at this time, however, differed markedly between index sheep. There was no obvious relationship between the incidence of transmission and the time index sheep spent rubbing each day or other index sheep variables, including the age of the lesion or the time since the introduction to the scab free sheep.