Selection of sites for intramuscular injections in the neck of the horse

Abstract

A radio-opaque marker was injected intramuscularly at different levels and with needles of different lengths into the cervical musculature of a series of ponies and horses which were under profound anaesthesia prior to euthanasia. Subsequently the necks were sectioned and radiographed to determine the fate of the injected material. The results indicated that care was necessary in the selection of the level for injection in order to prevent deposition of material on to the periosteal surface of the cervical vertebrae or on to the ligamentum nuchae and fascial sheaths. The muscle mass over the third vertebra was relatively poor but increased in the more caudal cervical regions. The best site for intramuscular injection appeared to be at the level of the fifth cervical vertebra, ventral to the funicular part of the ligamentum nuchae but dorsal to the brachiocephalic muscle. Even at this position injection material sometimes entered intermuscular fascial sheaths.