Medication: Methotrexate

Your dog has been prescribed methotrexate to treat lymphoma or an immune-mediated disease.

Key points: 
• Antimetabolite antineoplastic agent.
• Do not handle methotrexate if you are pregnant, breastfeeding, under 18, immunosuppressed or receiving chemotherapy or immunosuppressive drugs.
• Aways wear gloves to handle the tablets/capsules and wash your hands afterwards.
• Never crush or split tablets.
• Dogs will excrete chemotherapy products for up to 7 days after administration so precautions must be followed to reduce exposure to other people and pets.
• Dosage: the frequency of dosing varies and should be clearly stated on the packaging provided by your veterinarian. 

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

• Methotrexate.

Brand name

• There are no licensed veterinary products containing this drug therefore human licensed products may be used extra-label (eg Rheumatrex®, MTX, Amethopterin).

Class of drug

• Antimetabolite antineoplastic agent.

Storage

• Store at room temperature (20°-25° C (68°-77° F)) in a secure container, protected from light.
• Wear gloves when handling and wash hands thoroughly afterwards.
• Can cause birth defects.

Your veterinarian has prescribed methotrexate to treat lymphoma or immune-mediated disease.

Methotrexate is given orally as tablets or by injection by your veterinarian.

Handling methotrexate

• Do not handle methotrexate if you are pregnant, breastfeeding, under 18, immunosuppressed or receiving chemotherapy or immunosuppressive drugs.
• Aways wear gloves to handle the tablets and wash your hands afterwards.
• Never crush or split tablets as it can result in dust which could be dangerous to those around.
• Keep your dog’s drugs in the container supplied. This should be a child proof container.
• Store them in a safe place and always out of the reach of children and pets.
• Methotrexate tablets can be safely given in a little bit of food but make sure it’s not left behind in the bowl or on the floor! It is also fine to give the tablets directly – they can be washed down with some food or water by syringe afterwards to prevent them getting stuck.
• If you find a tablet on the floor after giving the medication, wear gloves to pick it up and bag it. Do not give another dose until you have spoken to your veterinarian.
• If you are unable to give oral medication to your dog, please contact your veterinarian for advice.

The following adverse reactions have been noted:

• Gastrointestinal symptoms (common): not eating, nausea, vomiting, diarrhea.
• Changes in feces: dark or tarry feces or fresh blood or mucoid material in the feces (mucosal sloughing).
• Low white cell count (leukopenia or neutropenia) – regular blood tests will monitor the white blood cell counts.
• Low platelet counts (thrombocytopenia).
• Low red cell counts (anemia).
• Increased liver parameters (hepatotoxicity).
• Increased kidney parameters (nephrotoxicity).

Drug interactions

Many drugs may interact with methotrexate. If your dog is taking other medications or supplements, please check these with your veterinarian before starting treatment.

The following medications are known to interact with methotrexate:

• Immunosuppressive drugs (eg azathioprine, cyclophosphamide, corticosteroids)
• Ketoconazole
• Phenobarbital
• Loop diuretics
• Cyclosporine
• Other antineoplastics
• Neomycin
• NSAIDs
• Sulfonamides
• Vaccines.

The duration of treatment depends on the dog’s response to the medication.

All unused methotrexate should be returned to your veterinary practice for disposal and must not be placed in household waste.

If you miss a dose, give the dose as soon as possible but do not give a double dose.

Contact your veterinarian immediately if you have given your dog an overdose of methotrexate. It can be highly toxic if an overdose is administered.

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

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

Care must be taken to handle this medication safely:

• Keep in a secure storage area out of reach of children.
• Keep children away from feces, urine, or vomit of treated dogs.
• As methotrexate will be present in feces, urine and vomit of dogs under treatment, protective gloves must be worn when cleaning up after the treated dog and any feces, urine or vomit and any disposable towels used in the clean up should be disposed in a sealed plastic bag.

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

Handling your dog

• Your dog will excrete products for up to 7 days after methotrexate has been given. This period is referred to as the “chemo barrier” period. As there is a small risk of you absorbing these toxic products, there are some sensible precautions that you should take to reduce your exposure during this time.
• Wear gloves when handling any urine, feces, vomit or saliva from your dog.
• Aways wash your hands after handling your dog and before eating or drinking.
• The following people should minimize direct contact with your dog:
  • Pregnant or breastfeeding women
  • Young children who do not understand the need for hand washing after contact
  • Immunosuppressed or receiving chemotherapy or immunosuppressive drugs.
• Dogs should be exercised away from areas where children play or where there are lots of other dogs. However they are fine to remain in contact with other pets in the home.
• Double bag all feces and dispose of them as normal. We do not recommend flushing them down the toilet due to risk of aerosols forming.
• Urine passed on a surface where it can drain away (such as grass or soil) is not a problem. If your dog passes urine on a solid surface (pavements, paths etc) use a bottle of water to rinse away the urine.
• There is no risk to other pets in the home from sharing water bowls or toileting in the garden unless the other pet is likely to ingest any contaminated urine or feces. In any case feces passed in the garden should be double bagged as soon as they have been passed.
• If your dog should have an accident in the house or soil itself, you should wear gloves to clean the area as quickly as possible using copious amounts of soapy water. Use disposable paper towels to dry the area and dispose of these in a plastic bag in an outside bin.
• Your dog’s bedding should be washed regularly as some toxic products may end up on your dog’s coat when they lick themselves.
• We discourage people from allowing their dog to sleep in the family beds because their coat may be contaminated.

Your dog will have regular blood tests and your veterinarian may adjust the frequency of dosing accordingly.

Further information

If you have any concerns, further information on methotrexate can be found on the package insert.

Europe & UK

• There are no licensed veterinary products containing this drug in the UK or Europe. Your veterinarian may prescribe a human medication containing this drug and will explain off-license use of medications to you.

US

• There are no licensed veterinary products containing this drug in the US. Your veterinarian may prescribe a human medication containing this drug and will explain off-license use of medications to you.

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