Pain Medications for Dogs

Analgesics are drugs used to relieve pain. There are many classes of painkillers. Demerol, morphine, codeine, and other narcotics are subject to federal regulation and cannot be purchased without a prescription.

Buffered or enteric-coated aspirin (acetylsalicylic acid) is an over-the-counter analgesic that is reasonably safe for a short time for home veterinary care in the recommended dosage for dogs. (Aspirin has a very low margin of safety for cats and should not be used.) Buffered or enteric-coated aspirin is much safer than regular aspirin because it is less likely to cause stomach and duodenal ulcers.

Aspirin remains effective as a short-term analgesic to control the pain associated with musculoskeletal injuries. It is no longer recommended for long-term control of osteoarthritis, because of its destructive effects on joint cartilage. There are better analgesics available that do not have this disadvantage. Aspirin should not be given to dogs with any bleeding or clotting disorders. Aspirin should be stopped at least one week before any surgery and should not be used during pregnancy, due to its effects on clotting mechanisms.

Note that individual dogs metabolize aspirin at very different rates. This inconsistency can lead to an unexpected accumulation of dangerous breakdown products in the animal's body. As few as two regular-strength aspirin tablets can produce severe organ damage in some medium-size (30 pounds, 13.6kg) dogs. Follow the exact dosage given in the table on page 571 to avoid this complication.

Aspirin belongs to the general class of drugs collectively known as nonsteroidal anti-inflammatory drugs (NSAIDs). To treat arthritis and other inflammations, newer NSAIDs have been tested extensively in dogs. (See the chart Osteoarthritis Medications, page 404, for more about NSAIDs.) These are generally less upsetting to the stomach than buffered aspirin and appear to be more effective for long-term treatment.

However, all NSAIDs irritate the stomach and are capable of causing stomach and duodenal ulcers. Your veterinarian may prescribe a gastric mucosal protectant, such as misoprostol (Cytotec) or sucralfate (Carafate), to prevent this complication. Remember, never use more than one NSAID (including aspirin) at the same time. Also, do not combine NSAIDs with any corticoteroids, such as prednisone.

Any dog who is going on one of the NSAIDs should have bloodwork done before the drug is administered. The bloodwork should be repeated every three to six months if the dog will be on one of these medications long term. Liver problems have been seen in some dogs, and Labrador Retrievers may have an idiosyncratic reaction to carprofen. If liver or kidney problems develop, even if they are not due to the drug itself, the dosage may need to be adjusted or the dog may be switched to another pain medication.

Many NSAIDs that can be purchased over the counter have unpredictable absorption rates and low margins of safety. None of these should be used without specific instructions from your veterinarian.

Naproxen and ibuprofen (Motrin) are powerful analgesics, but both have a high incidence of gastrointestinal side effects. This makes them unsuitable for long-term administration. Ibuprofen, in particular, is not recommended for dogs.

Phenylbutazone (Butazolidin) is an analgesic that is widely used in horses. In dogs it appears to have harmful effects on joint cartilage. Its other main drawback is that it can cause bone marrow suppression, especially when given in high doses for long periods. It is no longer recommended now that safer analgesics are available.

Flunixin meglumine (Banamine) is a potent analgesic and anti-inflammatory that is also useful in fighting the toxins produced by bacteria. This makes it useful in treating septic shock. Gastrointestinal toxicity limits its use in dogs for routine care. There are also other options available, and new pain medications are being developed all the time.

When pain relievers are used for treating sprains and acute injuries of muscles, tendons, and joints, the dog should be confined or restricted from exercising. Pain relief may cause the dog to overuse the limb, which can delay recovery.

This article is excerpted from “Dog Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc.