Toxicity of halogenated oxyquinolines in dogs. A clinical study. V. Pathological findings.

A description is given of the post-mortem findings in 21 cases of acute spontaneous oxyquinoline poisoning in dogs after administration of halogenated oxyquinoline drugs once or over a short period. The findings are in accordance with the results of necropsy of 7 cases of experimentally induced oxyquinoline poisoning. Biopsy specimens of the liver were taken in 18 dogs. The investigation reveals that spontaneous as well as experimental poisonings give rise to severe myocardial and liver injuries. The myocardial lesions consisted of focal necrosis with interstitial cellular reaction. The areas of necrosis were most frequent in the papillary muscles of the left ventricle. The liver-cell damage ranged from cloudy swelling to hydropic degeneration with depositions of lipids. In 3 experimental cases, in which rapid fixation methods were used, it was possible to evaluate the pathological lesions in the neurons of the brain and spinal cord. Degenerative neuronal changes with chromatolysis and vacuolation were observed, especially in the hippocampus and hypothalamus. It was presumed that the injuries and destruction of these structures had caused symptoms that were consistent with the clinical pictures of the dogs. The clinical symptoms and post-mortem changes were believed to be due to a toxic effect on the myocardium, liver, and central nervous system.