There are two sorts of parasites which affect the cat — those which are found inside, endoparasites, and those which are found outside, ectoparasites. As far as cats are concerned, endoparasties are confined to worms harboured in the intestine. There are really two main types of worm which the owner must be concerned about. These are roundworms which are normally present in young cats, and tapeworms which usually infest older cats. It is not commonly realized that cats as well as other animals can develop immunity to the infestation of worms. Certainly roundworms seem to be less of a problem in adult cats, due it is believed to a form of resistance similar to that built up against infectious diseases.
The young kitten is usually infected with the roundworm while it is still in the mother’s uterus, so it is necessary to break the cycle of worm infestation by treating the pregnant queen. Most breeders are aware of this and will administer appropriate tablets at the correct moment to ensure that as far as possible worms are eliminated. It is also common to worm kittens before they are sold to the new owner and this should prevent you from receiving your new kitten with hidden extras.
It is not easy to guarantee that cats are free from roundworm infestation and it is therefore wise to ensure that treatment has been carried out thoroughly and effectively. If in any doubt about this it is sensible to consult your veterinary surgeon. Equally it is wise to check with the breeder that the kitten has been wormed before you take it and, if not, arrange for this to be done either before the kitten arrives in the home or immediately afterwards.
Worm remedies, known as anthelmintics, when properly administered, are effective and safe to use. They eliminate the worms completely but it is usually-wise to give a second dose about fourteen days after the first one. As kittens are delicate creatures it is very important to stick closely to the dosage recommended according to the weight of the kitten. Again, the veterinary surgeon can if necessary take all this worry off your hands by carrying out treatment for you.
There are two main species of roundworm found in the intestine of cats: toxocara cati (mystax) and toxascaris ieonina. Toxocara cati is by far the most common. The worms live in the small intestine of the cat and when mature lay eggs which pass out in the faeces. When the infective egg is swallowed by a cat it hatches into a tiny larva which migrates to the lungs and liver before returning to the bowel to turn into an adult worm. If a young kitten encounters a massive source of infective larvae this migration can cause severe debility and even death due to the widespread damage it does to the sensitive tissues of the liver and lungs. In normal healthy kittens roundworms may be present without any sign. Kittens with a fat belly, a dry dull coat, a little diarrhoea and pale gums, indicating possible anaemia, are likely to be heavily infested.
It is possible for children playing with kittens which have not been properly wormed to ingest infective eggs which form larvae, as they do in the cat, and begin to migrate through the tissue. They may lodge eventually in any part of the body such as the liver, lungs or muscles. Very rarely, the migrating larvae may lodge in extremely sensitive tissues such as the eye or the nervous system causing severe problems. It should be emphasized that the risk of this occurring is so rare that it can almost be ignored. However, it is wise to ensure that when there are children in the house kittens are wormed before being brought in, and that the worming is repeated under the direction of a veterinarian to ensure that it is thorough and complete.
Cats can be affected with two types of hookworm. Their life cycles are similar to that of roundworms except that the larvae develop from the eggs outside the body and gain entrance to the body by penetrating the intact skin of the animal. Hookworms are particularly likely to cause anaemia because they live by attaching themselves to the inside of the intestine and absorbing blood from the tissues.
Although it is very rare, cats can also be afflicted with a lungworm which is remarkable for its unusual life cycle. The study of the devious routes by which worms find their way into the primary host is fascinating and in this case the worm requires the existence of an intermediate host, in the form of a slug or snail, to complete its life cycle. Infective larvae hatching from the eggs of lung-worms present in the lung tissue of the cat find their way up the breathing passages to the back of the throat where they are coughed up and then swallowed. They pass through the intestine to the outside where they must find a slug or snail and burrow into its tissue. Ultimately a cat must then eat the slug or snail (not a common food preference) and the worm then completes its life cycle and finds its way into its new host’s lungs. Happily lungworm in the cat is very unusual and could not be considered a major parasite problem.
With the tapeworm of the cat, Dipylidium caninum, the interesting feature of the life cycle of this rather unpleasant parasite is that it requires the presence of a flea to act as an intermediate host. The larva of the flea eats the tapeworm egg attaching usually to the fur around the tail of the cat. This flea larva develops into an adult and. During the normal cleaning and grooming process, the cat will swallow the adult flea, its digestive juices absorbing the protective shell around the tapeworm egg inside the flea. The tapeworm begins to develop into the sinister, flat, segmented creature that winds its way through the intestine, shedding segments from its tip. By the time they have reached this stage, they have undergone a remarkable cycle of reproduction to produce a little sack full of eggs which can move after detaching itself from the parent’s body. This sack or segment passes out through the anus of the cat and can sometimes be seen, about the size of a cucumber seed and greyish white in colour, moving towards the tip of the hairs under the tail in order to repeat the life cycle. Elimination of fleas is the first line of defence against the tapeworm and, as in all cases of parasitic infestation, breaking the life cycle in this way is the only effective and final method of control. Treatment of tapeworm is not as simple as with roundworm and it is certainly wise to obtain professional help.
There is one other tapeworm found in cats – Taenia taeniaeformis. This goes through a similar life cycle to Dipylidium caninum but the intermediate host in this case is in fact the mouse. The question must be asked, did nature decide that as cats catch mice, the mouse would be a good intermediate host, or did the worm survive simply because of the hunter and hunted cycle?