Deworming Your Cat

There appears to be two central points to make about deworming your cat. The first is that even full-time indoor cats can get gastrointestinal parasites. They can be exposed by a new cat joining the family or by catching a mouse which found its way into the home. Then there are fleas and mosquitos which carry a parasite. The second major point is that deworming drugs are not effective against all parasites so a veterinarian needs to be involved to check if worms are present and if so which type. He can then prescribe an effective dewormer.

Feline round and tapeworms
Feline round and tapeworms
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A third point worth making is that deworming should be administered to an otherwise healthy cat because deworming pills are poisonous to both the worm and the cat. It is just that the pill is more poisonous to the worm and kills it but it may make an ill cat more ill and cause other problems.

Roundworms, tapeworms and hookworms are the most common feline intestinal parasites. Healthy adult cats have some immunity to them. Cats can develop a resistance to these parasites. This is probably inherited from the wild cat ancestor of the domestic cat. You can imagine how prone to getting internal parasites wild cats are.

Kittens have less resistance to these parasites. This can lead to infestations and severe illness, even death. When cats are over 6 months of age they are less likely to show symptoms.

Sometimes dormant worm larvae can be activated by drugs administered to a cat such as cortisone and chemotherapy drugs. Stress caused by trauma, disease and surgery can also activate dormant larvae. Dormant roundworm larvae are activated during lactation. This can cause an infestation in litters of kittens even if the mother has been dewormed because the deworming drugs are less ineffective against larvae encysted in tissue.

As mentioned, a precise diagnoses of the presence and type of worm is required unless the cat is a regular outdoor hunter – “it is reasonable to deworm outdoor cats routinely for ascarids (roundworms) and tapeworms, even without a possible stool sample”1.

Diagnosis is carried out through examining a stool with a microscope. A cat may have an illness which appears to be caused by worms but a diagnosis is required because to administer these drugs to a cat made ill by something other than worms will make him more ill.

Hunting outdoor cats should be checked annually or more frequently for worms. Sometimes you can see tapeworm segments on the cat’s bottom. Tapeworms may need to be treated 4-5 times annually.

Before a mother cat breeds her stool should be checked. The presence of worms indicates that a thorough deworming should take place.

A high proportion of kittens are infested with ascarids and perhaps other worms. A vet will check. Before administering deworming drugs the kitten should not be subject to stressful conditions such as chilling, overfeeding, a sharp change in diet or close confinement. A kitten with diarrhoea or other illness should not be dewormed unless the illness is caused by the parasite.

Kittens with roundworms should be dewormed at 2-3 weeks-of-age and also at 5-6 weeks. They may be a further requirement to deworm and some vets recommend deworming kittens every month until 6 months-of-age with an appropriate, safe drug.

Note 1 – page 58 of Cat Owner’s Home Veterinary Handbook edition 3.


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