WORMS Worms can infest your pet without you realising it. Very young or very old animals, or animals with heavy worm burdens, may be unwell. These animals have a poor coat, lose weight, become lethargic and have bloated abdomens. They may suffer diarrhoea and vomiting, pneumonia and even life threatening intestinal obstructions. Young, otherwise healthy animals with just a few worms may not show any outward ill effects. However, these animals are reservoirs of infection allowing worms to continue their life cycle and pass eggs, contaminating the environment, infecting other animals and posing a public health risk. There are 2 main classes of worms that infect dogs and cats. ROUNDWORMS INCLUDING HOOKWORMS AND WHIPWORMS The adult worm lives in the gut of the host animal and its eggs are shed into the environment in the animal's faeces. Your pet can then swallow these eggs when they are sniffing about where other cats and dogs have been. They can also swallow eggs if they eat earthworms, birds or mice that are harbouring the larvae. Once the egg is swallowed it will hatch into a larva which burrows through the wall of the gut and migrates around the body of the host. In pregnant animals these migrating larvae will cross the placenta and infect their unborn, hence the reason why it is said that all kittens and puppies are "born with worms". The matured larvae eventually end up back in the gut as adult worms which will lay yet more eggs - and the whole cycle starts again. This can take only 3 weeks to complete so it is possible for many eggs to build up in the environment very quickly. Nursing bitches and queens will pass the larvae to puppies and kittens by their milk and also will be re-infected themselves when they are licking their puppies and kittens to clean them. It is these migrating larvae of the dog roundworm (Toxocara Canis) that pose a public health risk. If children ingest the eggs then they can hatch and start migrating around the body as they would in a dog. In most cases this wouldn't cause a problem and the human immune system can easily deal with them, but occasionally the larvae can migrate to the eye and cause blindness. This is why it is very important to worm dogs regularly to stop them from passing worm eggs and also to clear up dog faeces especially from public places. Roundworm eggs are very tough and can survive in the environment for several years. TAPEWORMS Tapeworms are the other main class of worms affecting cats and dogs. Their lifecycle is different to the roundworms. Tapeworms cannot be passed directly from one animal to another but have to develop in another 'intermediate' host. The flea tapeworm, as its name suggests, develops in the fleas which live on dogs and cats. The adult worm lives in the dog or cat's small intestine and can grow up to five metres long. This adult worm passes small egg packets that look like grains of rice. These can be seen moving and are found around the fur on a pet's bottom, in the litter tray or where they sleep. These egg packets dry out and release hundreds of microscopic eggs which are eaten by flea larvae in the environment. When infected flea larvae hatch into adult fleas it is infected with an immature tapeworm. Dogs and cats, whilst they are grooming themselves, will swallow some of the fleas and then the tapeworm will be released from the flea and grow to adult size in the animals gut. Within 3 weeks it can be shedding egg packets of its own. Other species of tapeworm will develop inside mice and rabbits and so cats that hunt are particularly susceptible to tapeworm infections.