Worming your dog
What types of worms can affect dogs?
Round worms resemble white pieces of string and can be up to 18cm long. A number of different round worms like Toxocara, hookworm or whipworm can affect your dog. Round worms are rarely seen because they stay in the intestines and are only very rarely shed. If round worms are passed in faeces or vomited up, for example by puppies, it usually means that there are huge numbers of worms in the intestines.
Tape worms are long flat worms made up of many small segments. They can occasionally reach a length of several metres. Tape worms constantly shed segments filled with eggs that can often be seen in faeces and then resemble small - and occasionally mobile - grains of rice.
Lung worms do not live in the intestines, but usually in bronchi (the airways in the lungs). However, worm larvae can also cause problems with other organs, sometimes resulting in severe disease. Lung worms have not been around for very long in the UK, but are becoming an increasing problem.
How do dogs get worms?
Most worm eggs or larvae are taken up by licking or sniffing. Often eggs or larvae can survive on the ground for weeks or months, some can be transported by air and larvae can move actively, so the dog does not have to lick at an obviously soiled area to catch worms. Some worm eggs are quite sticky and can adhere to the coat or even to clothes or human skin and then be transferred to the dog (or people!).
Hook worm larvae can burrow through skin into the dog (and people!), and can also be licked up by the dog cleaning it's paws after a walk.
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 worm larvae can settle inside the dog and grow to maturity. In the case of tape worms, such intermediate hosts can be fleas, small rodents or larger animals like cattle or sheep, depending upon the type of worm. Dogs that have got fleas, dogs that hunt and dogs receiving raw meat as part of their diet are all at risk of acquiring tape worms. Intermediate hosts for lung worms are slugs and snails and the worms are often transmitted by dogs picking up small slugs while eating or licking at grass.
Most of the worms live in dogs' intestines (or bronchi in the case of lung worms), but there are always some that are hidden away in other organs or tissues and stay inactive for long periods. Those inactive stages are not reached by any worming product, and as they can become active at any time, a dog can suddenly have worms even if it has not been newly infected. Such inactive worm stages become particularly activated when a bitch is pregnant. Toxocara roundworms can invade the unborn puppies inside the uterus before they are born, and, after birth, worms can also be transmitted to the puppies through the mother's milk. This makes it important to treat young puppies frequently against worms. No matter how diligent breeders or previous carers have been, almost all puppies will have some roundworms!
What are the clinical signs of worms in dogs?
Light infestations of worms usually cause no clinical signs at all, especially in adult dogs - so the owner of an infected dog may feel sure that their pet does not have any worms.
Heavy worm infestations can cause severe clinical signs and can be dangerous in puppies. Puppies can present with a pot belly, slow growth, vomiting and diarrhoea, a rectal prolapse or even a fatal blockage of their bowel system. Hookworms and occasionally whipworms can cause severe anaemia, as these worms feed on blood from their host.
Dogs of any age with heavy worm burdens can show weight loss, poor coat quality, vomiting and diarrhoea, pneumonia and other respiratory problems, skin irritation, anaemia or bleeding disorders and occasionally problems in other organs.
Can humans get worms from pets?
Toxocara roundworms are not uncommonly transmitted to humans, although fortunately most infected people have no apparent symptoms. In humans the worms do not mature as they do in dogs - instead the larvae wander through various organs. Liver problems, epileptic seizures and blindness are among the (rarely) reported clinical signs in humans affected by Toxocara infection. Children and people with a compromised immune system are most commonly affected. Children are more susceptible to infection given their propensity to play in, and sometimes eat, contaminated soil. Treatment may or may not be curative and problems such as blindness in children can be permanent.
Hookworm larvae can 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 damp and, often, sandy soil is necessary to become infected, so children and adults fond of gardening or lying on beaches where dogs have been are at risk.
We obviously recommend regular worming to ensure that your dog stays healthy, but another important reason for recommending frequent worming of pets is to protect your family and other people in the community from worm-related health problems.
What can be done to prevent problems?
The best way to prevent worm related disease both in dogs and human beings is regular worming of dogs and diligent removal of dog faeces from the environment. Modern worming products available at your veterinary surgery have been tested for efficacy and safety to the pet. 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. Pets with close contact to small children or adults with inefficient immune systems can safely be wormed for roundworms on a monthly basis. Tablets are most commonly used, but effective spot-on products against round worms are also available. We will be happy to advise you on the most appropriate product for your pet.
If you have any queries or concerns, or if you would like to organise worming treatment for your dog, please do not hesitate to contact us.
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