The parasitic hookworm gets its name from the hook-like mouthparts they use to attach themselves to the intestinal wall. Despite being very small — about 3 mm long — they can suck substantial amounts of blood from tiny vessels in the intestinal wall, and a large infestation can cause anaemia. Hookworm is most commonly seen in puppies but adult dogs can become infected.
Dogs can get hookworms by four routes: through the mothers placenta before birth; via the mother’s milk; by swallowing hookworm larvae in the milk, or; through the skin.
If a pregnant dog has hookworm, the pregnancy may reactivate the larvae. The larvae will then enter the female’s circulatory system and pass to the puppy through the placental blood flow. Infection through the mothers milk is another source, and considered an important route of infection for puppies. Finally infection may also be by the infected larvae penetrating the skin and then migrating to the bowel where the worms complete their life cycle.
SEVERITY: Moderate to Serious if left untreated.
The presence of pale gums, diarrhoea, or weakness might suggest the need to specifically determine the dog’s red blood cell count. Some dogs experience significant weight loss, bloody diarrhoea, or failure to grow properly with hookworm infection.
Skin irritation and itching can be one of the common signs of a heavily infested environment. The larvae burrow under the skin and cause the dog a great deal of itching and discomfort. Kennels can sometimes have a problem with hookworms.
Hookworms are easily detected by a microscopic examination of a small sample of the suspect animal’s faeces. In puppies large numbers of worms must usually be present before eggs are shed into the faeces, hence faecal examination may be less reliable in very young puppies than in adult dogs.
There are several very effective drugs that will kill hookworms. These are given by injection or orally and have few, if any, side-effects. However, these drugs only kill the adult hookworms. It is necessary to treat again in about 2-4 weeks to kill any newly formed adult worms that were larvae at the time of the first treatment.
In some dogs with severe anaemia caused by heavy, untreated infestations, a blood transfusion may be necessary.
The dog’s environment — kennel, bedding, runs etc. — can also be laden with hookworm eggs and larvae and will need to be chemically treated to avoid recurring infection. There are some available that are safe to use on grass.
Hookworm is fairly easy to prevent with modern broad spectrum worm treatments. All pups should be treated at 2-3 weeks of age and periodic deworming is advisable to prevent any cross-contamination to other household pets, particularly if they are walked frequently. Nursing females should be treated concurrently with their pups, as nursing can reactivate the infection in the mother.
Good hygiene is also important, particularly the prompt disposal of dog faeces.
Adult hookworms do not infect humans. Where bare skin has come into direct contact with moist, hookworm infested soil it is possible for the larvae to burrow into human skin and cause itching. The worms do not mature into adults. In rare cases, the canine hookworm will penetrate into deeper tissues and partially mature in the human intestines.