The roundworm dilemma

There are several varieties of worm that live inside our pets - hookworms, whipworms, heartworms, lungworms, tapeworms - all unpleasant, some potentially dangerous - but in this country , the main contender for public enemy number 1 is the roundworm.

Toxacara canis - the dog roundworm and the commonest worm by far, will transmit to people. Toxocari cati - the cat roundworm MAY transmit - we're not sure yet. The larval form of these worms cause visceral larval migrans, and opthalmic larval migrans which can cause, among other disorders, liver disease, epilepsy and blindness in children and adults.

It is safe to assume that from puppyhood, the rate of worm infestation in dogs is close to 100%. One needs to understand a little of the worm's life cycle to realize why this happens.

When the worm eggs are eaten by a dog , they hatch in the intestines. The minute larvai burrow through the intestinal wall into tiny blood vessels. They are initially carried to the liver. From there they enter larger blood vessels and proceed to the lungs. By now, they are quite large and their presence causes the dog to cough, releasing the larvae into the throat where they are swallowed back down into the intestines. Here they grow into large worms, lay more eggs....and so it goes....

BUT - not all the larvae complete the cycle. Some lie low in the bitch's muscle tissue where they can lie dormant for months if not years protected from most drugs and wormers. When the bitch becomes pregnant and approaches labour - the larvae wake up. They pass via the umbilicus into the unborn pup. That is why all pups are born with worms.

Thorough pup worming is therefore essential. The wormer needs to be chosen with care - not everything you buy is 100% effective. Worming the bitch during pregnancy will reduce puppy infestation, but they will not all be killed; some will survive to pass into the pups.

So far so good and logical. But the story does not end there. In the countryside are foxes which carry the same worms and which cannot be wormed. It is thought that cats can pick up dog worms and pass them on. There are numerous rodents which as as transport hosts, carry larvae in the bodies. In the town and villages are dogs and cats which are not regularly wormed. Everywhere a dog or cat defaecates is a potential source of infection, especially as faeces are a magnet to all animals.

Be vigilant. Be a responsible pet owner. Think worm!