Hematological and pathological changes in acute systemic anaphylaxis in calves: effects of pharmacological agents.

Calves were sensitized to horse serum in Freund's complete adjuvant and were subjected to acute systemic anaphylactic shock. Increased packed cell volume and potassium ion concentration together with severe neutropenia were observed to accompany the systemic hypotension. The hemoconcentration and hyperkalemia were not inhibited by antihistaminic or antiserotonin drugs, but were strongly inhibited by pretreatment of the calves with sodium meclofenamate and by disodium cromoglycate (DSCG) given simultaneously with diethylcarbamazine (DECC). In contrast there was no measurable diminution of the leukopenia by any inhibitor drug tested. Pulmonary edema and congestion of the liver, intestine, spleen, and kidney accompanied anaphylaxis. Atelectasis and edema with thickening of alveolar septa, together with polymorphonuclear cell infiltration were recorded histologically in the lungs of calves subjected to anaphylaxis. Calves premedicated with sodium meclofenamate sustained slight pulmonary edema only, with no other obvious pathological changes. Pretreatment with DSGG and DECC reduced the edema, congestion, and histopathological damage, but offered less protection than sodium meclofenamate. Antihistaminic or antiserotonin drugs were ineffective in protecting against anaphylactic changes in calves.