Worm Awareness

All dogs and cats have worms throughout their lives. This is particularly true during their puppy or kittenhood, and at this time owners should always be on guard and looking for symptoms. However, adult pets are constantly picking up worms, and their treatment, though less frequent, should not be neglected. Whilst worms can cause illness, remember that an apparently healthy pet may also pass or vomit worms, or show no symptoms at all.The worms found in dogs and cats in the UK fall into two main categories – roundworms and tapeworms. The majority live on partly digested food in the intestines. Despite a large amount of superstition and mythology about the effects of worms, unless they are present in large quantities, they are unlikely to produce symptoms of illness (except in the case of young puppies or kittens).

There are several species of roundworm that affect dogs and cats. The main type affecting dogs is Toxocara canis, whereas the main species to affect cats is Toxocara cati.

Roundworms and dogs
Toxocara canis worms can be up to several inches in length, and have round bodies (very similar to a tiny earthworm, but without the segments). They are a whitish or pinkish brown colour due to ingested material. These worms are spread from dog to grass to dog. The eggs are microscopic in size and are passed in the faeces. They stick to muzzles and feet, and are ingested again by licking. Subsequently, they hatch into larvae in the intestines of the dog, travel via the liver into the bloodstream, and so enter the lungs. They are coughed up from the lungs, and are swallowed again, so reaching the intestines, where they mature into adults and start producing eggs, thus completing the cycle. The adult worms are usually noticed in puppies when they are vomited or passed in the faeces. In the adult dog, most larvae remain as harmless ‘cysts’ in the muscles, and only a small number reach egg-laying adulthood. However, in the pregnant and lactating female, the larvae in the cysts can become active again, infecting the puppies via the placenta before birth, and the milk after birth.

Roundworms and cats
Toxocara cati are very similar in appearance to the dog roundworm, Toxocara canis. The adult worm may be passed in the faeces, but because cats tend to bury these, the worms are not easily detected. They may also be vomited, and it is not uncommon for an adult cat to expel a single large worm when regurgitating hair. Worm eggs ingested by the cat hatch out as larvae in the intestines, and, as in dogs, pass through the gut wall and migrate around the body before returning to the intestines. Again, some of the larvae fail to return to the intestines in the adult and become dormant in the tissues. Dormant worm larvae can also be found in other creatures, e.g. mice (that have eaten the eggs). If an infected mouse is eaten by a cat, these larvae then develop into adult worms in the cat’s intestines. Young kittens can be infected either by ingesting eggs or by ingesting larvae that have passed through their mother’s milk. Infection before birth, which occurs in dogs, does not happen in cats.

Tapeworms in dogs and cats
Tapeworms of two different species (Taenia and Dipylidium) are most commonly found in adult dogs and cats. The ‘worm’ consists of a number of segments, which are joined together to form the ‘tape’, which can be up to one metre in length. This terminates at the narrow end in a head, which is attached by minute hooks and suckers to the lining of the intestines. The presence of the worm is usually recognised when the mature segments are shed via the rectum, or with the faeces, or occasionally when the cat or dog vomits a worm. The individual segments can be up to a centimetre in length, some are oval in shape (resembling a grain of rice) and may be moving when they are shed. Others are little, flat rectangles, usually two or three in a chain. Tapeworms are never transmitted from dog to dog, or from cat to cat, but always through an “intermediate host”. These may be birds, mice, rabbits and lice. However, the most common tapeworm affecting both cats and dogs is Dipylidium caninum, the intermediate host of which is the flea. The dog or cat may swallow the flea whilst grooming, and thus become infected by the worm that is parasitising it.

The symptoms can vary in their intensity. In young pups and kittens, roundworms may cause abdominal swelling and pain, loss of weight, vomiting or diarrhoea, and on rare occasions, rupture of the bowel. A post mortem may find that the stomach and intestines contain hundreds of worms. The migrating larvae in the lungs may also cause coughing, which can be an important symptom. These larvae may also travel through the liver, brain or other tissues. A young kitten or puppy that is thin with a ‘pot belly’ is often described as a typically ‘wormy’ puppy or kitten. In adult animals, symptoms are rarely seen, except for an occasional adult worm in faeces or vomit. Nevertheless, it is still very important to treat adults for roundworms, or they will continue to infect other pets, and possibly also children. Tapeworms consume very little food, so it is only when they are present in large quantities that they may interfere with normal digestion. Tapeworms therefore do not usually cause loss of weight. However, the presence of worms almost certainly causes some discomfort or irritation around the anus as a result of shedding segments.

Worming pets has never been easier. It is important to remember to worm regularly. The recommendation for worming is as follows: 2 – 12 weeks = dose every 2 weeks (as puppies and kittens are continually being re-infected by mother’s milk). Mothers should be treated concurrently, until weaning. 3 months + = dose every 3 months (acquired immunity is beginning to interrupt the worms’ life cycle, so less frequent treatment is possible. Continued treatment will remove those worms that will be acquired during daily life). Beaphar’s wide range of worming preparations has been designed for effectiveness and ease of use. Tablets, granules (for mixing with food for animals that are not as willing to take tablets), creams and syrups (for kittens and puppies) are all available.

Although dog & cat roundworms cannot complete their life cycle in humans, ingested eggs, on very rare occasions, can cause serious conditions in children. They hatch into larvae in the gut and then migrate to various organs of the body, including the liver, lungs, eyes and brain where they can become permanently encysted. It is therefore of great importance to see that puppies and kittens which are in contact with children are kept free from worms, and that a good standard of hygiene is maintained. Faeces should be cleared away as soon as possible from gardens, litter trays, etc. Eggs in fresh faeces are not infective (they take about two weeks to develop on the grass), so you are not in danger when “scooping the poop”. Additionally, responsible dog owners always carry “poop bags” when exercising their pet, and clean away any mess, whether this be in towns or the countryside. Allowing dogs to defecate on country footpaths is no more acceptable than on town pavements.

Certain worms are capable of being transmitted from animals to humans; such worms are said to have a ‘zoonotic potential’. The dog roundworm, Toxocara canis, is probably the best known of these and human infection may occur if a person swallows the microscopic worm eggs, having picked them up from contaminated soil.