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Pill-popping pets

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In this second of our two-part series, we look at more drugs for pets and their side-effects, plus vets who have alternative ways to deal with disease

There are few things that make you feel more powerless than standing over an unwell pet. Your vet’s solution is to reach for his prescription pad, which often-times creates more problems than it solves. Here’s a list of the more commonly used drugs and the dangers to watch out for.

Antiparasitic agents

Typical drugs: Ivermectin, moxi-dectin, milbemycin oxime, salamectin.

Use: To prevent or treat parasite-related problems such as heart-worm, roundworm, hookworm, fleas, ticks and ear mites.

Side-effects: Vomiting, diarrhoea, lack of appetite and lethargy, lack of balance or coordination and seizures. Monthly heartworm drugs may trigger immune-mediated haemolytic anaemia/thrombocytopenia (decreases in red blood cells/ platelets).


Use: For diabetic pets.

Side-effects: Even tiny overdoses can lead to life-threatening low blood sugar, weakness, depress-ion, abnormal behaviour, coma, seizures and death.

Steroids (glucocorticoids, cortisone, corticosteroids)

Typical drugs: Prednisone, prednisolone.

Use: Autoimmune conditions like lupus, immune-mediated skin diseases, allergies, including of the skin, shock and central nervous system disorders.

Side-effects: Weight gain, increase in appetite, increased drinking and urination, constant pant-ing, muscle wasting, loss or dulling of hair coat, thinned skin, increased susceptibility to skin infections, inflammation of internal organs (liver and pancreas), intestinal ulcers and internal infections, particularly of the urinary tract. They also raise blood alkaline phosphatase (linked at high levels to disorders like Cushing’s disease and bone problems).

In cats, steroids can cause pneumonia, poor hair coat and persistent cystitis or abscess due to immune suppression. They also increase the possi-bility of developing diabetes or pancreatitis, and of steroid ‘psychosis’, with psychotic symptoms such as depression and mania. Pets can also become physically dependent on these drugs, so never stop them abruptly.

Special warning: After two weeks of use, the dosage should be tapered to one every other day to keep the body’s adrenal glands healthy.

Psychotherapy medication

Typical drugs: Amitriptyline, acepromazine.

Use: For obsessive behaviours such as biting or scratching one particular area, and for itchy skin conditions and granulo-mas (small nodules of tissue) that the pet constantly licks.

Side-effects: Dry mouth, sedation, vomiting, constipation, diarrhoea, hyperactivity, low blood pressure, seizures and neural heart block. These drugs may also cause the same muscle problems (tics of the face and jaw) in animals as in humans.

Acepromazine can lower the seizure threshold in animals, and is linked to hypotension (too-low blood pressure), breathing problems and an abnormally slow heartbeat.

Special warning: Acepromazine should never be given to Boxers as the side-effects are exaggerated and may even prove fatal.

Immune-system depressants

Typical drugs: Cyclosporin, chlorambucil.

Use: For autoimmune skin disorders like ‘mushy footpads’, with bleeding, pain and lameness, and lupus and inflammatory bowel disease.

Side-effects: Vomiting, diarrhoea, poor hair quality, liver and kidney toxicity, suppression of bone marrow and an increased likelihood of infection.

NSAIDs (non-steroidal anti-inflammatory drugs)

Typical drugs: Ibuprofen, carprofen, meloxicam.

Use: Pain and inflammation relief.

Side-effects: Ulcers after just one or two doses, lethargy, vomiting, lack of appetite; can be fatal. Carprofen can cause toxic liver reactions, so regular liver func-tion tests are needed.

Special warning: Golden Retrievers in particular have adverse reactions to carprofen.


Use: For underactive thyroid.

Side-effects: Increased drinking/ urination, personality changes, excessive excitement, increased panting and nervousness.

Special warning: Use with caution in animals with diabetes, heart problems or Addison’s disease (adrenal gland disorder).

Worming agents

Typical drugs: Fenbendazole, metronidazole.

Use: To get rid of worms.

Side-effects: Anaphylactic shock, neurological signs; can cause death in 1-3 per cent of cases, and may cause birth defects in pregnant animals.

Alternatives to drugs

A growing number of vets are turning to alternative forms of medicine-from homeopathy to acupuncture-and numerous studies have demonstrated that they work just as well on pets as they do on humans.

Lynne McTaggart and Joanna Evans

Stay alert to drug reactions.

If you suspect your dog or cat has reacted to a drug, contact:

.in the UK: The Veterinary Medicines Directorate,

tel: 01932 338 462, or visit the online reporting site at

.in the US: The Food and Drug Administration, tel: 240-276-9300 or 1-888-INFO-FDA (1-888-463-6332), or visit its website at

October 2012 vol 23.7

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