Chemotherapy: metronomic

Metronomic chemotherapy involves giving small regular doses of chemotherapy. This can be administered at home.

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Traditional chemotherapy involves giving a large dose of the chemotherapy drug and then giving the body time to recover. Metronomic chemotherapy is different as it is given at a low dose at regular intervals, usually daily or every second day. The chemotherapy drugs are given orally at home. This treatment suppresses blood vessel growth (angiogenesis) and stimulates the immune response against cancer rather than directly killing the cancer cells. If cancer cells lose their blood vessel supply, they are starved of oxygen and nutrients, and will die.

Metronomic chemotherapy can be used to treat a range of tumors and may be used after traditional chemotherapy or on its own. It may be used to slow tumor growth or to try and prevent recurrence.

Metronomic therapy typically consists of a combination of three drugs: cyclophosphamide, a non-steroidal anti-inflammatory drug such as piroxicam or meloxicam, and frusemide. Frusemide is a diuretic and is used to increase urination and decrease the risk of sterile hemorrhagic cystitis that is sometimes seen in dogs on cyclophosphamide.

Other chemotherapy drugs may be given in metronomic protocols but do not require frusemide to be administered.

The low dose of drug used in metronomic chemotherapy means that the risk of side-effects is much lower. The dose used is usually less than 1/10th of that used in traditional chemotherapy protocols. However, it can take a longer time for the drugs to be effective and so this may not be the best treatment in patients with fast growing tumours

• Always follow the instructions provided by your veterinarian and make sure that the drugs are stored correctly and securely.
• Always wear disposable gloves when handling the drug, and wash your hands immediately afterwards.
• Pregnant women or young children must not handle cytotoxic drugs such as cyclophosphamide (and the drug must not be given to another person or another pet).
• Contact your veterinarian immediately if you have given a double dose.

Your dog will excrete products from the chemotherapy drug for a number of days after it has been given. This period is referred to as a the “chemo barrier” period. As there is a small risk of you absorbing these toxic products, there are some sensible precautions you should take to reduce your exposure during this time.

• Wear gloves when  handling any urine, feces, vomit or saliva from your dog. 
• Always 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 the 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.