Cutaneous actinomycosis and nocardiosis in dogs: 48 cases (1980-1990).

Medical records of 48 dogs with cutaneous actinomycosis or nocardiosis were reviewed. Male, large-breed dogs kept outdoors were overrepresented. The mean age at admission was 3.6 years. Cutaneous swelling (68%), abscesses (65%), draining tracts (48%), fever (36%), and signs of pain (13%) were the most common clinical findings. The cervicofacial area was affected in 48% of the dogs. Abdominal and thoracic wall involvement was less common. Leukocytosis, neutrophilia with left shift, monocytosis, and hyperglobulinemia were common. The diagnosis was confirmed by cytologic examination, bacteriologic culture, or histologic examination. Gram-positive filamentous bacteria were seen in 69% of the fine needle aspirates and in 50% of the biopsy specimens. Actinomyces spp were isolated from cutaneous lesions in 27 (60%) dogs. Nocardia asteroides was isolated from 1 dog. Treatment consisted of surgical debridement, drainage, and administration of antibiotics in 29 dogs (group A) and antibiotics alone in 13 dogs (group B). The infection redeveloped in 10 (42%) group-A dogs and 6 (60%) group-B dogs. Of the 10 group-A dogs with recurrent infection, 6 had resolution after a second surgery and 4 were euthanatized. Of the 6 group-B dogs, 1 had resolution after surgery, 4 were euthanatized or died because of persistent disease, and 1 had an unresolved infection. The combination of surgery and antibiotic treatment appeared to be superior to antibiotic treatment alone in resolving cutaneous Actinomyces and Nocardia infections.