Oral medications are convenient, but some drugs aren't absorbed well from the gut. That's where parenteral (injectable) drugs come in. The US veterinary medicine market forecast shows that parenteral administration is the fastest‑growing route, driven by biologics (monoclonal antibodies) for pets with allergies or arthritis. These drugs are too large to be given orally, so they're injected.

What's new? Long‑acting injectables that last weeks or months. For example, a single injection of a monthly heartworm preventive. Also, owner‑administered injectables — with training, you can give your diabetic dog insulin at home. The US veterinary medicine market analysis notes that the fastest‑growing animal type is companion, because owners are willing to learn how to inject their pets.

But needles scare some owners. That's why auto‑injectors (like EpiPens) are being developed for pets. And some biologics are now available as subcutaneous (under the skin) injections, which are easier than intramuscular.

The bottom line: injectable drugs are often more effective, but they require training and courage. If your vet recommends one, ask for a demo. You can do it.