Azathioprine For Dogs: Uses, Dosage, & Side Effects

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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 that take azathioprine must be closely monitored for signs of illness. Steps should be taken to decrease the risk of infection, including keeping dogs that take the drug away from stray or wild animals, as well as any other pets that are known to be suffering from contagious infections. The drug is usually given over a long period of time, and it may take up to six weeks before dogs’ 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 is what you should know about the uses, dosage, and side effects of azathioprine for dogs.

Uses Of Azathioprine For Dogs

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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 that 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

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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 instruct you on how to properly administer them to your dog in the correct dosage. Azathioprine can be given with or without food. Use of the drug should not be stopped abruptly, and dogs that take it need to be weaned off of it gradually if they must discontinue use.

A 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. Pregnant dog owners should not handle the drug at all.

Side Effects Of Azathioprine For Dogs

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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, contact your veterinarian, as they may wish to adjust the dosage or seek an alternative form of treatment. Here are some side effects that have been seen in dogs that 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 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, consult your veterinarian immediately.

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