Answer: In general the intestinal worms, roundworms, hookworms and tapeworms, cause no harm to adult cats and only large numbers produced signs of infections, usually in kittens. The other parasitic worms may cause more serious problems. Nevertheless regardless of its effect on the cat, most owners find the presence of even single worm aesthetically distasteful.
Strictly speaking all the nematode worm should be referred to as roundworms because they are all circular in cross-section. However, by popular usage this description is often reserved for the commonest member of the group the ascarids.
Ascarid worms produce egg in the intestine of the cat which pas out in the motions. An infective larva develops inside each egg and if this is eaten by a cat the larva develops into an adult worm in its intestine. More usually through the egg is eaten by another spices, often a rodent, and its by eating this animal that the cat in turn becomes infected. In a female cat some larva of Toxocara Cati do not develop to adults about remain dormant in the body tissues. If the cat should happen to give birth to kittens these larvae then pass to the mammary gland and out in the milk consumed by the newborn offspring. Consequently kitten can be, and usually are, infected very soon after they are born. Because these dormant larvae are not in the intestine they cannot be removed by conventional worming drugs, although drugs are currently being developed which are able to destroy larvae in the tissues.
Larger numbers of these worms in kittens can produce persistent diarrhea, a poor coat and a pot belly. At times worms may appear in the motions or vomit and can cause coughing.
The common tapeworms are long, flat worms (like white ribbons), attached to the lining of the intestine with book and suckers, though again the generally cause no signs. Tapeworms are hermaphrodite, segmented worms which grow continuously; the oldest segments containing the eggs, are shed one or more at a time from the end of the worm furthest from its head. To complete their life cycle these eggs, after passing out at the anus, must then be eaten by a particular spices of animal. In the case of Dipylidium caninum (the commonest cat tapeworm) this ‘intermediate host’ must be the flea or louse; in the case of Taenia taeniaeformis, a mouse or rat. An egg will develop into a cyst-like structure in the intermediate host, and if this host is then eaten by a cat the cyst-like structure develops into a new tapeworm in its intestine. But if tapeworm eggs are eaten by a cat they do not develop further.
