What type of worms do dogs get?
The most common types of intestinal worms are roundworms and tapeworms. Roundworms resemble white pieces of string and can be up to 5- 15 cm long. They tend to coil up like a spring. Roundworms are rarely seen because they stay in the intestines. If roundworms are passed in faeces or vomited up, it usually means that there are huge numbers of worms present in the intestines. Roundworms can produce 200 000 microscopic eggs per day which are passed in the faeces. The most common dog roundworm is Toxocara canis.
Tapeworms are long flat worms made up of many small segments and grow to a length of 50 cm. Tapeworms constantly shed segments filled with eggs that can often be seen in faeces or in the fur around the anus resembling small grains of rice. The most common dog tapeworms are Taenia spp, Dipylidium caninum and Echinococcus spp.
Hookworm, whipworm, heartworm and lungworm can also occur in dogs.
Heartworm is more of a concern for those pets travelling overseas.
Hookworms are very small, thin worms that attach to the wall of the intestine and suck blood. Whipworms resemble tiny pieces of thread, with one end enlarged. They shed few eggs therefore are often very difficult to identify.
How do dogs get worms?
Worm eggs or larvae are passed in faeces, and taken up by licking or sniffing. Eggs or larvae can survive on the ground for weeks or months therefore dogs just wandering in a contaminated area can pick up worms. Some worm eggs are quite sticky and can adhere to the coat or even to humans and then be transferred to the dog.
Hook worm larvae can burrow directly through skin and can also be ingested by the dog whilst grooming.
Tape worms and lung worms usually have a complicated lifecycle and require an ‘intermediate host’ (another species of animal) that the worm lives in for part of its lifecycle. When a dog eats all or part of this intermediate host, the dog becomes infected. In the case of tape worms, such intermediate hosts can be fleas, small rodents or larger animals like cattle or sheep. Dogs that have got fleas, hunt or receive raw meat as part of their diet are at an increased risk of acquiring tape worms. The intermediate hosts for lung worm are slugs and snails and the worms are often transmitted by dogs licking or drinking where these hosts have been.
Most of the worms live in the intestines (or airways in the case of lung worm), but there are some that are hidden away in other organs in an inactive form. These inactive forms are not reached by any worming product, and they can become active at any time. Such inactive worm stages become particularly activated when a bitch is pregnant. Toxocara roundworms can then invade the unborn puppies inside the uterus or be transmitted through the mother’s milk. Hookworms can also be transmitted from the mother to the puppies.
What are the clinical signs of worms in dogs?
Unless an adult dog is severely infested or has tape worm, it is not possible to notice the worms in faeces as usually microscopically small eggs are passed. Clinical signs are rare in light infestations.
Heavy worm infestations can cause severe clinical signs and can be dangerous in puppies. Puppies can present with a pot belly, failure to gain weight, vomiting and diarrhoea, rectal prolapse and death. Hookworms and occasionally whipworms can cause severe anaemia.
Dogs of any age with heavy worm burdens can show weight loss, poor coat quality, vomiting and diarrhoea, respiratory problems, skin and anal irritation (dogs often scoot), anaemia and occasionally problems in other organs.
Can humans get worms from dogs?
Unfortunately some types of worms can also infect humans especially children, the elderly or immuno-compromised adults. The larvae of Toxocara migrate through various organs causing liver disease, seizures and blindness.
Children are more susceptible to infection given their propensity to play in, and sometimes eat, contaminated soil.
Hookworm larvae can directly burrow themselves into the skin of both dogs and humans. In humans this can cause an intensely itchy form of dermatitis which is usually self-limiting. Skin contact with infected damp and sandy soil is necessary.
What can be done to prevent problems?
The best way to prevent worm related disease both in dogs and humans is regular worming of dogs and diligent removal of dog faeces from the environment. At Frontier Veterinary Services we recommend that puppies are wormed at 2, 5, 8 and 12 weeks of age, and then monthly until they are 6 months old. The mother should be wormed at the same time as the puppies until they are weaned.
Adult dogs should be wormed at least every 3 months. Dogs with close contact to children, the elderly or immuno-compromised adults can safely be wormed every six weeks. Step advised by your vet to control any associated flea problems should accompany worm prevention.