Deworming adult cats and dogs is a rather controversial area at the moment. Balancing concerns about animal health, zoonotic disease transmission, drug resistance, compliance and cost is difficult. Risks vary between different regions/climates and there are no clear answers. One area that is much less controversial is deworming of kittens and puppies (less than 6 months of age), as there is general consensus that aggressive deworming is needed in these animals.This is because young animals are much more likely to harbour parasites. They are also more likely to contaminate the household environment during the litter/house training process and tend to have very close contact with people. The greatest concern tends to be about roundworms, since they are very common in dogs and cats (especially young ones) and zoonotic infections  can occur (i.e. visceral and ocular larval migrans, similar to that caused by the raccoon roundworm, Baylisascaris procyonis).

Standard deworming guidelines are:

  • Puppies should be dewormed at 2, 4, 6 and 8 weeks of age, then monthly until 6 months.
  • Kittens should be dewormed at 3, 5, 7 and 9 weeks of age, then monthly until 6 months.

Further treatments depend on various factors, including the animal’s lifestyle (risk of exposure), how common different parasites are in the region and perhaps whether there are high-risk people in the household. Your veterinarian can provide the best advice for your individual pet.

Another thing to remember is that not all parasites are killed by all dewormers. Specific deworming programs need to be set up to address different parasite risks.

More information about roundworms (and other parasites) in dogs and cats can be found on the website of the Companion Animal Parasite Council, an industry-funded organization.

Photo: A large mass of roundworms from the intestine of a heavily infected animal.