Oxytetracycline plasma levels in dogs after intramuscular administration of two formulations. 
Plasma levels of oxytetracycline in dogs were compared in a cross-over study.  A long-acting formulation and a polyvinylpyrrolidone formulation were injected intramuscularly.  Symptoms of histamine release were recorded after the use of polyvinylpyrrolidone formulation.  Higher peak plasma concentrations but shorter maintenance of therapeutic concentrations were recorded in the case of the polyvinylpyrrolidone formulation than with the long-acting formulation.