Catch may can!

Aspirin inhibits primarly a class of enzymes called Cox-1, and to a lesser degree Cox-2. Both enzymes contribute to the production of Prostaglandins which are directly involved in inflamation. The catch is that the Cox-1 enzyme is also directly involved in the regulation of a specific Prostaglandin called Prostaglandin I2, which in turn regulates the mucus secretions that cover the stomach lining. Without the mucus covering, the stomach acid starts to irritate the lining of the stomach. Thus the mechanism by which Aspirin irritates and can cause stomach ulcers in both humans and dogs.

That is why the Cox-2 inhibitors such as Celebrex, and Vioxx came to the human market. The search was for an inhibitor of the Cox-2 enzyme specifically, leaving the Cox-1 uninhibited. The idea being of course of avoiding possible stomach irritation and possible ulcers. Subsequent work also showed the Cox-2 drugs effective in inhibiting polyp growth in the intestine. Both Pfizer and Merck were happy drug companies earning $billions selling Cox-2 inhibitors, until recently... With the findings that Vioxx can increase heart attacks in humans it has been pulled from the market by Merck. Celebrex is under scrutiny, and the lawyers are having a field day filing class action lawsuits.

The latest recommendations coming from the FDA is for people to use aspirin instead of Cox-2 inhibitors, and to include acid blockers to decrease the stomach acid lowering the possibility of ulcers. In particular the proton pump inhibitors such as Prilosec are recommended. This is nothing new, but more emphasis is being placed on it due to the Cox-2 scare. None the less this is the tie in information for my previous post.

Back to dogs...

First Prilosec is starting to be used in Veterinary medicine, although the hydrogen ion inhibitors such as Cimetidine and Randitine are most commonly used. Rantidine tends to be quicker acting (i.e. approx 4-6 hrs), while Cimetidine takes close to a day before it kicks in.

Second the effect of the Cox-2 inhibitors per cardiac problems is currently unknown in dogs.

Thirdly some dogs can take aspirin without problems if given with food. But for others the irritation to the stomach seems immediate and severe resulting in prompt vomiting after eating food with aspirin mixed in. Such was the case for one of my mom's dogs. Even Bufferin didn't help. But with acid blockers widely available OTC at least in the U.S., why chance an upset tummy for the puppy?

I've given my dogs both Cimetidine and Rantidine. My prior dog was a Lymphoma puppy, and she received Cimetidine whenever she was receiving a Chemo treatment. Between the Cimetidine and Metoclopromide she never had any GI upsets. For the Rantidine, that was given to my current male - Barney. Seems the Panacur deworming medication doesn't quite agree with his tummy. The Rantidine seemed to help prevent nausea, and allow him to complete the deworming treatment.

In general Cimetidine and Rantidine are benign drugs with a very low side effect profile. The use of acid blockers plus aspirin could be a viable alternative to Rimadyl, Duramaxx, and Metacam for long term usage to control pain. Discuss the alternatives with your Vet.