Misoprostol and More: Making NSAIDs easier on your dog's gut

I've written before about alternative pain medications for dogs who cannot tolerate NSAIDs, but there are times when an NSAID really is the best choice for pain control. This might be because other types of pain medication don't fully control the pain, or because the animal is sensitive to other medications as well.

There are things you can do to make NSAIDs easier on the dog's GI tract, although they will not always be enough for every dog. To understand how some of these might work, it's important to understand what NSAIDs are, and how they function to control pain.

NSAIDs are anti-inflammatory drugs that inhibit an enzyme called cyclooxygenase (COX for short). Cyclooxygenase is a substance in the body that causes it to produce prostaglandins, which cause pain and swelling. The problem is, prostaglandins do all sorts of beneficial things in the body, too, like maintain and repair the intestinal lining, control the body's hormonal systems, and regulate kidney function. There are, in fact, few body systems that do not rely, at least in part, on prostaglandins, so inhibiting them clearly has the potential to cause as many problems as it solves, or more.

Most people know that non-steroidal anti-inflammatory drugs (NSAIDs) such as Rimadyl, Metacam, Previcox, Deramaxx, Etogesic, and others can irritate the digestive system and cause ulcers of the GI tract. They do this because COX enzymes and prostaglandins are necessary to repair and maintain the intestinal lining. In fact, while kidney damage and death do occur as a result of these drugs and get most of the hype, the main reason dogs are removed from NSAID therapy is because of the damage to their GI tract, including nausea, vomiting, diarrhea, ulcers, and bloody stool.

There are different kinds of COX, and they serve slightly different functions. It was once believed that COX-2 was the "bad" COX, and COX-1 was the "good" COX, and so the newer generation NSAIDs have been developed to be more and more COX-2 specific, but that is not turning out to be the case. It seems that COX-2 does have a protective effect on the gastrointestinal lining, and older generation NSAIDs like aspirin, which tend to inhibit COX-1 more so, or equally to, COX-2, actually have some GI-protectant benefits that help make up for the damage they cause.

So, if your dog has osteoarthritis or some other form of chronic pain, and really needs to take NSAIDs to maintain quality of life, there are a number of things you can do to prevent gastrointestinal problems.

First, make sure you are using multi-modal pain control. If you aren't relying exclusively on the NSAID for total pain control, you'll be able to use a lower dose, or even skip a day every few days and give the gut a chance to heal. Drugs such as Tramadol, amantadine, gabapentin, and narcotics can be used in combination with NSAIDs, or instead of NSAIDs, to control the pain of cancer or osteoarthritis. If your veterinarian isn't familiar with these drugs or is unsure of how to use them, ask for a referral to, or ask your vet to consult with, a veterinary anesthesiologist, or with the Analgesia/Anesthesia consultants on the Veterinary Information Network if they are a member. There is also a great deal of valuable veterinary information on the website of the Veterinary Anesthesia Support Group.

Second, consider alternatives to be used in combination with, or instead of, NSAIDs. Fish oil capsules, glucosamine-chondroiton, Adequan injections, and acupuncture are among the main available alternative therapies that have shown benefit in many cases of osteoarthritis. (And of course, keep your dog lean!) I'd suggest caution, however, when using herbal formulas that claim to be "natural" COX inhibitors; it is COX inhibition itself that does the damage to the GI lining, and while it's possible that there are components to some herbs that mitigate this damage, this has not been proven and is only a hope at this time. If choosing to go the alternative route, it's best to work with an experienced holistic veterinarian.

Third, ask your veterinarian about misoprostol. Misoprostol is a prostaglandin analog, and by taking it orally along with NSAIDs, you can help mitigate some of the effect of COX inhibition on the intestinal lining. While misoprostol can cause upset stomach and diarrhea on its own in some dogs, if your dog tolerates it, it's well worth considering as an adjunct to NSAIDs.

Another useful drug is sucralfate, which is covered very well by Dr. Wendy Brooks on VeterinaryPartner.com.

How about antacids like Pepcid (famotidine) and acid controllers like Prilosec (omeprazole)? While they might reduce the symptoms of GI ulcers in dogs on NSAIDs, they don't appear to have any benefit at all in actually reducing the ulcers. So despite their widespread use with NSAIDs, they probably aren't useful and may actually mask an ongoing problem. Misoprostol actually has some acid regulating properties itself, but more than that, it acts to restore the intestinal lining naturally, to prevent the formation of ulcers and help heal those that have already formed. In addition, the use of antacids can be contraindicated with both misoprostol and sucralfate.

The herb slippery elm might also be worth considering, although it's not clear if it actually helps heal the gut, simply provides some protection to the intestinal lining, or only serves to make the dog feel better. Slippery elm, the inner bark of ulmus fulva, is a soothing, gelatinous substance that has traditionally been used for the treatment of ulcers. It is also used for sore throats and skin irritations. Slippery elm is an extremely safe herb and is actually used as a food. It is sold in bulk in health food stores, as well as in capsules and as a tincture. It's slightly sweet so most dogs will eat it readily, but it can be given in capsule form or as a tincture if necessary. A veterinary product exists called Phytomucil.

Of course, the side effects of NSAIDs are not limited to the GI tract, so it's important to work with your veterinarian to monitor your pet's kidney and liver function as well.

[Update:] More on NSAIDs and Your Dog's Gut here