The Influence of Infestation by Aelurostrongylus Abstrusus on the Pulmonary Vasculature of the Cat

Abstract

SUMMARY Hypertrophy and hyperplasia of pulmonary arterial muscle is a common condition in the cat. In an attempt to assess the influence of infection by Aelurostrongylus abstrusus on pulmonary vasculature, 122 kittens experimentally infected with the latter parasite after various periods of time, twenty-five spontaneously-affected cats and seventy-two cats with pulmonary arteriopathy but without apparent presence of the parasite were examined and the pulmonary pathological changes compared in each group of animals. First evidence of arterial hypertrophic change was noted 9 days after infestation and increased in extent over the next 3 weeks. From approximately the fourth to the eighteenth week, host reaction to the presence of the parasite was at a peak, and the media of many pulmonary vessels achieved a thickness of from three to twelve times that of normality. From the fourth to the ninth month, most of the signs of parasitic pneumonia regressed but the arterial lesions remained and, although there may have been some reduction in the number of vessels affected, marked hypertrophic change persisted in the arteries for 2 years. There was little difference between the spontaneously-occurring and experimentally-induced lesions. It was considered, on the basis of comparative pathological change, that the seventy-two cats that had suffered from pulmonary arterial disease without immediate evidence of the presence of lungworms were animals that had been infested earlier in life with Aelurostrongylus abstrusus. It was concluded that the condition of feline pulmonary hypertrophy and hyperplasia was a result of infestation with the lungworm, Aelurostrongylus abstrusus , and that such a lesion was present for 2 years and may easily persist for the lifetime of the animal.