Dog - Hookworm Infection

Hookworms are small worms (approx. 1 cm in length) that attach to the lining of the dog’s small intestine by their hooked mouthparts.

Two types are found in the UK. Uncinaria stenocephala, the northern hookworm, and Ancylostoma caninum, the so-called tropical hookworm whose presence has increased in Britain as a result of milder climatic conditions and relaxation of quarantine, allowing dogs to travel from areas where Ancylostoma is prevalent and return to the UK under PETS without undergoing quarantine.

Ancylostoma infections are more serious since they can cause anaemia due to the parasites ability to suck blood from the bowel while attached. Ancylostoma can also be passed to litters by infected bitches. The parasite may remain dormant in the bitch until she is pregnant when larvae can be passed via the milk to the puppies. This can result in severe anaemia in the litter.

How is hookworm infection transmitted?

Uncinaria and Ancylostoma larvae can infect the host dog either by mouth or by 'percutaenous' (through the skin) infection. Larvae shed in infected dogs’ stools (faeces) particularly in wet grassy areas can burrow through the skin of passing dogs’ feet. Larvae from both types of hookworm can cause serious pedal (foot) dermatitis. With Uncinaria larvae, once the skin of the feet have been penetrated, they usually do not develop further whereas Ancylostoma larvae, by contrast, can enter the bloodstream, complete another larval moult in the lungs from where they are coughed up, swallowed and end up in the small intestine where the mature lungworms develop. These soon produce copious eggs, thus completing the life cycle.

The life cycle of Uncinaria spp is similar except its completion depends entirely upon ingested larvae. The various stages of that life cycle are completed in the bowel.

In both types of hookworm the period from initial infection to shedding infective larvae in the faeces is about a fortnight.

What are the signs of hookworm infection?

Both kinds of hookworm can cause diarrhoea and general unthriftiness due to bowel irritation. Ancylostoma also causes anaemia due to the blood sucking ability. Dogs kept in kennels with heavily infested grass runs can be affected with severe pedal dermatitis due to larval penetration through the skin of the feet.

How is hookworm infection diagnosed?

Diagnosis depends on demonstration of the larvae in faeces.

What is the treatment?

In kennels control is dependent on adequate kennel hygiene. Faeces must be collected and runs washed with appropriate disinfectants. If hookworm is a problem access to grass runs must be restricted.

When diagnosed in a domestic pet dog there are very effective antiparasitic preparations available. However the majority of these preparations kill only adult hookworms and therefore repeat treatments are required. We will be happy to discuss this with you if necessary.

Can we become infected?

Adult hookworms do not infect humans. In heavily contaminated grassy areas, larvae are capable of burrowing into human skin and causing a condition known in some countries as 'ground itch'. The worms do not mature into adults.