The effects of chronic chloroquine administration in growing chicks

The effects of chronic administration of graded doses of chloroquine diphosphate, given by daily intraperitoneal injections for up to 52 days, have been examined using chicks. Some of the factors contributing to the observed effects were investigated. Chloroquine depressed the increase in body weight of growing chicks in a dose-related fashion and reduced the body weight of adult fowl, possibly as a result of reducing food and water intakes. Stunting (as assessed from femur length and circumferential growth) following chronic chloroquine administration was found to be dose-dependent. Chloroquine reduced the dry mass and water content of most muscle types and organs examined especially skeletal muscle, smooth muscle and the spleen. However, there was an increase in the wet and dry mass of the adrenal glands, but only with the lowest dose regimen (30 mg/kg daily for 52 days). Chronic chloroquine treatment reduced the size and the number of smooth muscle cells per bundle in the expansor secundariorum. It also caused bleaching of black feathers and reddening of white feathers.