Azathioprine For Dogs: Uses, Dosage, & Side Effects

Healthcare worker making notes and looking at camera with dog on background

(Picture Credit: Getty Images)

Azathioprine for dogs is a drug that suppresses the immune system, which is useful in treatment for various disorders and autoimmune diseases of the skin, blood, or other areas of the body.

While it is not FDA approved for veterinary use, it can be prescribed by a licensed veterinarian, and it is only available with a prescription. Because it is an immunosuppressant, it does leave dogs more open to infections, so dogs who take azathioprine must be closely monitored for signs of illness.

Steps should be taken to decrease the risk of infection, including keeping dogs who take the drug away from stray or wild animals, as well as any other pets known to be suffering from contagious infections.

Dogs usually take the medication over a long period of time, and it may take up to six weeks before medical conditions show signs of improvement. If your veterinarian prescribes azathioprine for your dog, follow their instructions closely and continue giving your dog the medication until your veterinarian advises you to stop.

Here’s what you should know about the uses, dosage, and side effects of azathioprine for dogs.

Uses Of Azathioprine For Dogs

Lazy dog sleeping

(Picture Credit: Getty Images)

Azathioprine for dogs is used to treat a variety of autoimmune disorders–medical conditions where the immune system attacks the body’s own tissue or organs.

As an immunosuppressant drug, it reduces the immune system response that is causing symptoms, but it also hinders the body’s ability to fight off infection, which is why dogs who take the drug need to be monitored closely.

Here are some of the conditions in dogs that may be treated with azathioprine:

  • Inflammatory bowel disease
  • Immune mediated anemia
  • Thrombocytopenia
  • Colitis
  • Myasthenia gravis
  • Immune mediated skin disease
  • Chronic liver, gastrointestinal, or kidney disease
  • Lupus
  • Rheumatoid arthritis
  • Polyarthritis
  • Polymyositis
  • Eosinophilic enteritis
  • Atrophic gastritis
  • Erythematosus
  • Ocular histiocytoma
  • Chronic active hepatitis

Dosage Of Azathioprine For Dogs

Female nurse writing medicine prescription for dog and explaining to its owner at clinic

(Picture Credit: Getty Images)

The usual dosage of azathioprine for dogs is 0.5 to 1 mg per pound of body weight given orally once a day. It comes in 50 mg tablets, and your veterinarian will give further instructions on how to properly administer them to your dog in the correct dosage. You can also give azathioprine to your dog with or without food.

Additionally, dogs who receive this drug should not stop taking it abruptly. If your dog must discontinue use, then a veterinarian can give instructions on how to wean them off gradually.

A further word of caution: Azathioprine can be absorbed through the skin, so dog owners should wear gloves when giving this medication to their pets and wash their hands thoroughly afterward. However, pregnant dog owners should not handle the drug at all.

Side Effects Of Azathioprine For Dogs

Central Asian Shepherd Dog closeup portrait on a white background

(Picture Credit: Getty Images)

There are some potential side effects of azathioprine use in dogs. The drug is normally safe to use with veterinary supervision, but if you see concerning side effects of the medication in your dog, then contact your veterinarian, as they may wish to adjust the dosage or seek an alternative form of treatment.

Here are some reported side effects seen in dogs who take azathioprine:

  • Diarrhea
  • Vomiting
  • Loss of appetite
  • Fever
  • Lethargy
  • Bruising
  • Blood in urine or stool
  • Infections
  • Rash of red spots on the skin
  • Pale nose or gums
  • Jaundice
  • Pancreatitis

Make sure your veterinarian is aware of any other medical conditions your dog suffers from, particularly liver or pancreatic disease. Inform your veterinarian of any other medications your dog is taking, especially ACE inhibitors and muscle relaxers, as these can interact poorly when mixed with azathioprine.

As with almost all medications, there is also a risk of allergic reaction that can lead to anaphylaxis, a potentially life-threatening condition. If you see the signs of an allergic reaction, including swelling, difficulty breathing, hives, or any other symptoms, then you must consult your veterinarian immediately.

Has your dog ever taken azathioprine? Did it help treat their condition? Then let us know in the comments below!