Medication: Azathioprine

Your dog has been prescribed azathioprine to help suppress their immune system. This may be to help treat inflammatory diseases (particularly affecting the skin or intestines) or immune system diseases such as immune-mediated anemia.

Key points: 
• Immunosuppressant drug.
• Do not handle this medication unless wearing gloves.
• Dispose of your dog’s feces carefully, do not allow your dog to lick you whilst they are on this medication.
• There are no licensed veterinary products containing azathioprine. Your veterinarian may prescribe a human drug to your pet which contains azathioprine. Your veterinarian will explain off-license prescribing to you. 

This information sheet is designed to help answer commonly asked questions and help you give the medication safely and effectively to your pet. It does not contain all available information for this medication. If you have other questions or need more information, contact your veterinarian or pharmacist. Always follow the dosing instructions provided by your veterinarian.

Name

• Azathioprine (ayz-ah-thy-oh-preen).

Brand name

• There are no licensed veterinary products containing azathioprine. Human products containing azathioprine that may be prescribed for your dog include Imuran.

Class of medication

• Immunosuppressant.

Storage

• Store at room temperature.

Your veterinarian has prescribed azathioprine as part of a regimen to reduce inflammation or an excessive immune response. Azathioprine is often given with corticosteroid drugs and by using both together, a lower dose of each may be used and so side-effects may be minimized.

Azathioprine is given by mouth and may be given with or without food. It is usually administered once daily but the dose will likely be reduced to once every other day after 2 to 3 weeks. Do not split or crush tablets.

The person administering this medication to your pet must wear disposable gloves and avoid touching the medication.

The most concerning side-effect of azathioprine is bone marrow suppression. This can be very serious and may manifest as lethargy, weakness, pale mucous membranes, black tarry feces, nose bleeds, red spots on skin or gums. It can also cause gastrointestinal signs, pancreatitis or liver toxicity. Contact your veterinarian if you have any concerns.

Certain medications must be avoided or used with caution in patients receiving azathioprine. In particular, concurrent use of ACE-inhibitors may cause bone marrow suppression.

Azathioprine should be used with caution is patients with kidney disease, liver disease or a history of pancreatitis.

Azathioprine should not be used in animals that have previously had an allergic reaction to azathioprine.

This medication must be kept away from cats as it may be toxic to this species.  Your pet’s feces, urine and saliva may contain traces of this drug. Ensure that their feces is collected and disposed of safely, do not allow them to urinate in areas where children play and do not allow them to lick you or other people. 

It may take several weeks of treatment before the full beneficial effects of azathioprine are seen and your veterinarian may want your pet to stay on this medication for a long period of time. Azathioprine should be administered according to your veterinarian’s instructions.  

Dispose of any unused azathioprine safely – do not flush down the toilet or sink. Ask your veterinary team if they take back medication for disposal. Do not save azathioprine for future use or give to other pets.

If you miss a dose, give the dose as soon as possible but do not give a double dose. Make sure the dose given does not exceed the total recommended dose in any 24-hour period.

If your pet is unwell, contact your veterinarian promptly for advice.

Azathioprine should only be given to the dog that it has been prescribed for. If accidentally given to other pets, contact your veterinarian for advice.

If accidentally consumed by a human, speak to your primary care physician or poison control center.

Your veterinarian will need to regularly check your pet during treatment to ensure that their dose is correct and that side-effects are minimal. Your veterinarian may wish to perform regular blood tests.

Further information

If you have any concerns, further information on azathioprine can be found on the package inserts.

Europe & UK

• There are no licensed veterinary products containing azathioprine available in the UK and Europe.

US

• There are no licensed veterinary products containing azathioprine available in the US.

Always follow the recommended dosage and contact your veterinary team or pharmacist if you have any questions regarding your dog’s medication.