Reports
Study on Drug induced Retinopathy in Beagle Dogs
1987 Volume 6 Issue 1-2 Pages 23-33
Details
1987 Volume 6 Issue 1-2 Pages 23-33
As an animal model of drug-induced retinopathy, beagle dogs were orally treated with zinc pyridinethione (ZPT) and subjected to time-lapse ophthalmological, electrophysiological, and histopathological examinations.
Administration of 40mg/kg ZPT 3 days a week for 1 to 3 weeks resulted in typical ocular disorders: abnormal pupillary response to light, edema and hemorrhage in the fundus (tapetum lucidum), and retinal detachment. Histopathological observation revealed degeneration of the tapetum lucidum and pigment epithelium, and intense neutrophil infiltration. Three weeks after the last dosing, the pigment epithelium and tapetum lucidum disappeard, the retina atrophied and the optic fibers degenerated.
Administrition of 20mg/kg ZPT 3 to 5 days a week for 2 months produced decrease in amplitude of ERG and VEP waves and decrease in ocular tension from the 2nd dosing week on. Reflection of light from the tapetum lucidum also became weaker with the progress of successive administration. Histologically, mild disarrangement of laminal structure in the tapetum lucidum was the only detectable morphological change in these mildly involved dogs. In a follow-up study, the dogs recovered in a week after drug withdrawal from the slight functional disorder induced by ZPT.
