Many different types of drugs are used to relieve pain. Regardless of the type, always follow your vet’s instructions carefully about how and when to give these drugs.
Opioids: Opioids (like morphine) are strong painkillers used by vets. They work on the nervous system to decrease pain but can cause side effects, like sleepiness, mood changes, or excitement. Different species and even individual pets react differently to these drugs, so doses must be adjusted carefully. For example, a horse might weigh much more than a dog but need a similar dose. Some opioids have a “ceiling effect,” meaning that higher doses don’t always give more pain relief.
Nonsteroidal anti-inflammatory drugs (NSAIDs): NSAIDs decreases inflammation (swelling), which causes pain. They are often used after surgery or for chronic pain, like arthritis. NSAIDs last a long time, are usually affordable, and can be given at home. Vets prescribe NSAIDs only if the animal’s blood-clotting ability is normal and their kidneys, liver, and stomach function properly.
Common NSAIDs for dogs include carprofen, meloxicam, firocoxib, deracoxib, grapiprant, and robenacoxib. For cats, meloxicam and robenacoxib are used carefully, because cats are sensitive to these drugs, and sometimes these drugs can cause kidney failure or death. In the US, NSAIDs are only approved for short-term use in cats.
Corticosteroids: Steroids like prednisone decrease inflammation and pain but are used less often after surgery because they weaken the immune system temporarily and may inhibit healing. Side effects include increased hunger, thirst, and urination. Corticosteroids should not be used with NSAIDs.
Alpha-2 agonists: These drugs are used in large animals like horses to relieve pain and calm, or sedate, them during medical procedures while standing. Sedating animals decreases their nervousness and excitement. Examples of alpha-2 agonists are xylazine, medetomidine, detomidine, and romifidine. Using these drugs with opioids gives stronger pain relief and sedation.
Alpha-2 agonists are also used during surgery but usually not afterward because these drugs can cause side effects like prolonged sedation, loss of coordination, and a slower return to normal activity. In small animals, these drugs cause deep sedation at pain-relieving doses, so if vets prescribe them after surgery, they typically use lower doses.
Neuropathic pain medications: Some drugs relieve nerve pain or change how pain signals are sent to the brain. They may also decrease anxiety or cause sedation. Examples include gabapentin, pregabalin, tramadol, ketamine, and amantadine.
Anti–nerve growth factor antibodies: These special antibodies are used to treat chronic arthritis pain. Examples are bedinvetmab for dogs and frunevetmab for cats.
Local anesthetics: Local anesthetics like lidocaine relieve pain once they are injected by numbing a small area, such as around a wound or surgery site. In large animals, local anesthetics are often used alone or with inhaled gas anesthesia during surgery. This decreases the amount of gas that has to be used, so pets wake up faster. In small animals, local anesthetics are used for minor procedures, like stitching cuts.
Over-the-counter pain relievers: Nonprescription human pain medicines like acetaminophen, aspirin, ibuprofen, and naproxen can be dangerous or even deadly to pets. For example, acetaminophen can cause fatal liver failure in cats. Only give pain medicine prescribed by your vet.
