| Abbreviation | Definition |
|---|---|
| ISGA | International Sugar Glider Association |
| ISGA | Irish Salmon Growers Association |
| ISHAM | International Society for Human and Animal Mycology |
| ISIS | International Species Information System |
| ISITA | Irish Society for Information Technology in Agriculture |
| ISO | International Standards Organization |
| ISOM | International Society for Orthomolecular Medicine |
| ISOT | International Society of Ocular Toxicology |
| ISP | International Society for Pathophysiology |
| ISVC | International Sheep Veterinary Congress |
| ISVM | Indian Society for Veterinary Medicine |
| ISVMA | Illinois State Veterinary Medical Association |
| ISVO | International Society of Veterinary Ophthalmology |
| ISVP | International Society of Veterinary Perinatology |
| ITM | Institute for Traditional Medicine |
| IU | Insulated Underwear |
| IUTOX | International Union of Toxicology |
| IVA | Indian Veterinary Association |
| IVA | Irish Veterinary Association (obsolete, now part of Veterinary Ireland) |
| IVABS | Institute of Veterinary Animal and Biomedical Sciences |