Complications After Intramuscular Injections in Equids

•Intramuscular (IM) injections can be causative for clostridial myonecrosis.•Skin cores produced by cannulas advance bacteria into muscle tissue.•Bacterial skin flora is considered the main cause for injection complications.•Chemical properties of drugs damage muscle tissue, causing necrosis.•Muscle damage after IM injections causes creatinine phosphokinase elevation.

Literature on complications after intramuscular (IM) injections in equids is fairly sparse and consists of a few studies, case series, personal opinions, and surveys. The necessity of injection-site preparation protocols and appropriate localization for IM injections are often discussed, especially when compensation claims arise. The variety of adverse reactions and their symptoms is well known to all practitioners, with some being less frequently observed than others. Especially, the contribution of tissue-irritating capacities of IM administered drugs to abscess formation or even clostridial myonecrosis is discussed. With this review, we aim to summarize the current knowledge, standards and opinions on injection-site preparation protocols, injection techniques, adequacy of injection sites, complications after IM injections, and possible causes of IM injection complications.