Category Archives: Medicines & Treatments

Chemotherapy And Cytotoxic Drugs

What is chemotherapy?

Cancer chemotherapy uses cytotoxic drugs to kill cancer cells. Unfortunately they also affects normal rapidly multiplying cells like those that line the gut and bone marrow cells that produce blood cells.

What is cancer?

Cancer is a disease of uncontrolled growth of cells. Cells are the basic structural units of the body. Normally they replicate to replace themselves as they age. In cancer a particular cell line multiplies in an inappropriate and uncontrolled manner.

What are cytotoxic drugs?

Many anti-cancer drugs are cytotoxic. Cytotoxic means “damaging to cells”. These drugs block cell growth and division and thus prevent cancer cells from multiplying. Cytotoxic drugs act only on rapidly dividing cells such as cancer cells but they can also harm normal body cells.

What side effects do cytotoxic drugs have?

Because cytotoxic drugs affect all rapidly dividing cells in the body, normal cells in blood-producing bone marrow, the gut, skin and reproductive organs are also affected.

Many animals on chemotherapy experience no side effects. However, they are more prone to infections, bleeding, vomiting, diarrhoea and loss of appetite.

Animals do not lose all their fur with chemotherapy drugs. Reproductive function is usually not relevant.

Some cytotoxic drugs cause liver, kidney or heart problems. The most serious side effect of chemotherapy is infection. We monitor for these problems with regular blood tests.

Am I at risk of exposure from these drugs?

Cytotoxic drugs are very potent and must be handled with care. We admit animals to hospital to administer most chemotherapy. Some are given by injection while other drugs are given as capsules or tablets.

Do not to handle urine or faeces after any chemotherapy session.

This information is of a general nature only, and must not be used as veterinary advice except where directed by your veterinarian. Hall Veterinary Surgery does not warrant the suitability of this information for specific cases. If your animal is unwell or you want to act on this information, please contact us on 6230 2223.

Cortisone

Cortisone

We often prescribe cortisone for allergies and immune related diseases. Prednisolone, Macrolone or Antihistalone tablets contain a form of cortisone called prednisolone.  Short or long acting cortisone injections contain dexamethasone.

After 5 days of prednisolone tabs every day the adrenal glands start to slow their production of natural cortisol. It is safe to stop after 5 days of daily tablets but if we prescribe a longer course follow our instructions carefully.  Usually we recommend every other day tablets so that the adrenal glands keep functioning.

On a long course of prednisolone do not stop giving the tablets suddenly. Your pet may not be able to step up the production of cortisol fast enough to cope with an emergency, like a dog attack, a new pet or illness, and may collapse.

Side effects of cortisone include:

  • Increased fluid intake
  • Increased urine production
  • Increased appetite

Longer term and more serious side effects of cortisone include:

  • Cushings disease signs like a pot belly, flakey skin, enlarged liver and weak legs
  • Diabetes mellitus

Cortisone and anti-inflammatories given at the same time cause stomach ulcers.  We give anti-inflammatories such as Previcox, Deramax, Rimadyl, Metacam and Meloxicam for postoperative pain relief or arthritis. Please make sure your vet knows that your pet is on anti-inflammatories already.

A short acting dexamethasone injection rarely causes more than a mild increase in fluid and food intake.

We only inject long-acting dexamethasone if your pet is difficult to medicate or if your cat has a chronic condition that is not responsive to other cortisones.  Cats are generally more resistant than dogs to the side-effects of cortisone but very occasionally long-acting dexamethasone tips a weak heart into failure.