According to Steve Kennedy, DVM, where is the most common location for an intramuscular injection (IM) on horses and cattle?

The most common location for an intramuscular injection in horses and cattle is the triangle area in the neck muscle. This preferred site is due to several practical reasons. First, the neck muscles are larger and capable of handling the volume of the vaccine or medication being administered. Injecting in this area also minimizes the risk of injury to vital structures, such as major nerves and blood vessels, which are less concentrated in the neck compared to other areas like the legs or the back. Additionally, the neck is easily accessible for the handler, making it simpler to prepare and administer the injection safely.

Choosing the neck muscle also has implications for the animal’s well-being; it encourages a faster recovery and reduces discomfort, as it avoids more sensitive areas that might be adversely affected by an injection. This is particularly important in veterinary practice, where proper technique and care can significantly impact the animal's health and handling in the future.

Other potential injection sites like the shoulders, legs, or back might be considered for specific situations or types of injections, but the neck muscle remains the most standard and recommended location for intramuscular injections in these species.