How often should I deworm my dog?

Because most are born with worms or catch them in the first days of life. Roundworm larvae rest in the mother's body and can wake up during pregnancy, crossing the placenta to infect the puppies before birth, and more pass through her milk. TroCCAP says treating every 2 weeks stops these infections becoming established before the worms start laying eggs. Merck describes the first signs as poor growth and loss of condition, with a dull coat, a pot belly, and worms in the poo or vomit.

Hookworms are the more dangerous worm in hot, humid places. Their larvae get in through the skin, by mouth or through the mother's milk, and TroCCAP warns that in puppies they cause diarrhoea, often bloody, with anaemia that can kill, sometimes from as early as 10 days of age. Merck calls anaemia in young puppies the characteristic, and often fatal, sign. A pale, weak or listless puppy needs a vet the same day.

TroCCAP's monthly advice is written for tropical conditions like ours: heat and humidity that keep worm eggs and larvae alive in soil, and many dogs sharing the same streets. A review of Indian studies estimated that about 11% of soil samples from public places in India held Toxocara roundworm eggs, the eggs that infect children who play in parks and put their hands in their mouths.

That second point is why deworming is also family health. CDC says children are most at risk of roundworm infection, which can damage the eye, and TroCCAP says all animal hookworms can infect people, usually as itchy skin tracks. And a clean poo test is not the whole story: TroCCAP notes that finding no eggs in a sample does not rule out infection.