Should Veterinarians Use Azathioprine?

Andrew Mackin, BVMS, MVS, DVSC, DACVIM, professor and department head at Mississippi State University College of Veterinary Medicine, explains that although azathioprine is a drug that's been around for a very long time it is not without side effects.

"Azathioprine is a drug that's been around for a very long time and so those of us who have been internists for a long time have used it for a long time, and we're quite attached to the drug. We use it for a lot of things. I think it's a good standard immunosuppressive drug that is cheap and effective against a lot of diseases.

It is a drug with side effects and a lot of veterinarians have become familiar with those side effects because they've used it for 10 or 20 or 30 years and so they've seen a bad case. And what I try and teach veterinarians is azathioprine is still a good, solid immunosuppressive drug, you've just got to know enough about the drug to manage the side effects—expect them, anticipate them, and react to them. No drug is entirely benign, none of the drugs I talk about are entirely benign.

Azathioprine I don't believe is any more dangerous than other drugs but it's no more safe—it's one of the good drugs in your armamentarium and if I was to say 1 thing about azathioprine, it's cheap. And for a lot of owners that matters. I come from Mississippi, and if it isn't cheap people aren't going to be using it. And when you get to big dogs azathioprine often becomes the drug of choice and for a wide range of immune diseases."