The most common intestinal worms that dogs and cats may pick up are Roundworms, Hookworms, Whipworms and Tapeworms. There are about 11 different types of species of intestinal worms that can cause problems in dogs and cat. Infestation mainly occurs when a dog or cat eats worm eggs from poo, contaminated meat or offal, or even from grass. However, worms can also pass through the womb or mother's milk and can also burrow through the skin.
Probably the most common worm in dogs and cats. It is a large white worm up to 10.0cm long. There are four possible modes of infection: via the womb (not in cats), in the milk, through eating small birds and rodents, or from soil and poo. Most puppies are born with roundworm. This is why they should be wormed at 2 weeks of age. A dog or cat that has a heavy burden of roundworm may develop a pot-belly appearance, stunted growth, poor coat, occasional diarrhoea and may vomited or poo out live roundworms. When the worms migrate through the body they can also damage the lung.
Infection can be through the skin, through milk or by eating contaminated soil or poo. Hookworms have sharp teeth that cut into the intestinal lining releasing blood that they feed on. In heavy burdens, dogs and cat can become anaemic and underweight, lose appetite and develop a poor coat. Occasionally bloody diarrhoea is seen. Severe cases will lead to death. Hookworm can also infect people through the skin.
Whipworm is mainly transmitted through ingestion of eggs. Most infestations are light and have no clinical signs. On heavier burders, they can cause inflammation to the large intestinal lining and develop watery mucus diarrhoea and anaemia. Whipworms can live in the enviroment for up to 5 years.
Tapeworms are so called as they are very long and are made up of segments which act as egg sacs. The egg sac segments drop off when ready to be passed out in the poo. Tapeworms require two hosts, the main host (e.g. dog or cat) and a secondary intermediate host (e.g. cow, sheep, rabbits), for their life-cycle. The main host usually does not develop serious health problems but the intermediate host can suffer from an infestation. There are two types of tapeworms which both pose human health risks.
The secondary intermediate host is the cow, sheep or rabbit. The worm larvae develops cysts in the major organs, especially liver, of the cow, sheep or rabbit. Dogs and cats become infected when they eat larval cysts when eating raw organs. The dog or cat then poos out the eggs and the cow, sheep or rabbit eats the eggs and the life-cycle starts again. The tapeworm eggs can be seen in the poo of the dog or cat as white rectangular egg sacs. The dog or cat usually do not have health problems except may not grow to full potential and as they poo out eggs may develop an itchy bottom.
If people accidently eat the tapeworm eggs, cysts can form on the liver and other organs, which if burst can cause a serious peritonitis, respiratory distress or anaphylaxis. Cysts can only be removed through surgery.
The more common tapeworm, the secondary intermediate host is the flea. The dog or cat is infected when it eats an adult flea. The adult worm is not dangerous as several hundred adults can be tolerated without problems. Mostly they cause irritation around the bottom as they crawl out. People can become infected when they accidently eat a flea. However, problems in people are not major like the Hydatids. But is it important that effective flea control is also practiced to stop the tapeworm completing its cycle.