Which abbreviation denotes the administration of medication into a vein?

The abbreviation that denotes the administration of medication into a vein is 'IV,' which stands for intravenous. This method involves delivering medications directly into the bloodstream, allowing for rapid absorption and immediate therapeutic effects. The 'IV' route is commonly used in veterinary medicine for administering fluids, medications, and other treatments when quick action is needed or when patients cannot take medications orally.

In contrast, the other abbreviations refer to different methods of administration: 'IM' stands for intramuscular, which involves injecting medications into a muscle; 'SC' indicates subcutaneous, referring to the administration of medication under the skin; and 'PO' signifies per os or oral administration, where medications are given by mouth. Each route has its particular use based on the immediate needs of the patient, the nature of the medication, and the preferred method of administration.