Hookworms are rarely found in the UK but infections can be seen to occur more commonly in North America. Animals affected by this internal parasite, depending on the type of hookworm, are generally cats, dogs and foxes. In the most severe cases, where advanced anaemia may occur, the infection can result in the death of the infected animal.
Hookworm in Dogs
The parasite that is the hookworm has three types, all of which can infect dogs. These are Ancylostoma caninum, Ancylostoma braziliense and Uncinaria stenocephala. Upon entering the animal, the hookworm is found to be present in the intestines and also the blood, which it feeds on, of the infected dog. Hookworms are able to attach themselves to the intestines by using what can only be described as its “teeth” to hold on to the intestinal wall It is here that they then suck the dog’s blood.
Dogs that are more susceptible to an infection from the hookworms are younger dogs and puppies. This is because puppies have a weaker immune system than their older counterparts and so are less likely to be able to fight off an infection. The parasite is more commonly known to be transmitted via the animal feeding on, and thus ingesting, soil contaminated with the hookworm’s larvae.
The signs and symptoms following hookworms infecting dogs include diarrhoea, vomiting and anaemia. There can be varying degrees of signs in the animals affected by the parasitic disease. This is a zoonotic disease and this means it can be transmitted to humans where the skin is severely, adversely affected.
Transmission of Hookworms
Hookworms are transmitted following the ingestion of contaminated materials. These materials are contaminated with the hookworm larvae, which as well as infection occurring via ingestion can enter through the animal’s skin. The infected animal defecates and thus passes the eggs laid by the worms in its faeces. The eggs then hatch into larvae.
Contaminated materials can include faeces, soil, water, toys, grass and even other infected animals including rodents. The materials are required to be moist or damp for efficient transmission. These other animals are therefore known as transport hosts. Puppies may be born infected with the parasite in their lungs. They then cough up and swallow the parasite. This is because the uterus of an infected mother can be a source of infection to the foetus. Puppies suckling from the mammary glands of infected mothers may also be infected by the contaminated milk.
Outside of the host, the hookworm is able to survive in the right conditions in the environment for a few weeks. These conditions should be cold and moist since hotter and drier temperatures and destroy the hookworm. Freezing also kills the parasitic organism.
Signs and Symptoms of Hookworms in Dogs
The signs and symptoms of a hookworm infection vary in degrees of severity. Some animals may not even present any signs at all, that is to say they are asymptomatic. Infected dogs commonly vomit and have diarrhoea. Stools may be dark and tar-like in colour or bloody. There will also be a loss of appetite resulting in a large weight loss, weakness and stunted growth. The condition of the dog’s coat may deteriorate.
The hookworms suck the animal’s blood and so severe anaemia is often a result of infection. The infected dogs have pale gums. In cases where the infection becomes so advanced that the anaemia is especially severe, death can occur. If the animal coughs then the infection will have spread to the lungs and fatal pneumonia is a possibility.
Treatment for Hookworm Infections
There are many wormers that can be used to treat a hookworm infection and these can be given to puppies as young as two weeks of age depending on the wormer used. Wormers containing pyrantel pamoate are currently effective. Generally the wormers are administered orally.
The infected animals are treated using two doses in order to successfully treat the parasitic disease. This is because once the adults are initially destroyed; any larvae present will survive and simply re-infect the dog. Thus, the second dose of medication will prevent this from happening. If the symptoms presented are particularly severe, blood transfusions may be necessary.
Prevention of Hookworm Infections
It is vital for infected animals to be treated successfully and isolated until full recovery in order to prevent the spread of the hookworm to other animals. High levels of hygiene and the removal of sources of infection, such as faeces, are important methods of prevention.
Good hygiene, on surfaces which can be contaminated, can be maintained with most bleach solutions. Animals should not be allowed to ingest bleach solutions. Boarding kennel owners should especially clean the areas where dogs and other animals can come into contact with. Food bowls and toys should be regularly cleaned with animal friendly products. Faeces should always be picked up. Beaches provide the perfect environment for the hookworm and so dogs should never be allowed to pass their faeces here. If they do, any faecal matter should be immediately picked up.
Diagnosis of a Hookworm Infection
Initially, a diagnosis of a hookworm infection is made based on the clinical signs presented by the affected animal. Medical history is also normally used for both the animal and of possible outbreaks in the area.
Following this, faecal samples are taken and tested. The faeces are searched to find any eggs belonging to the parasite. Two samples may be taken within a period of a day to determine the presence of hookworm.
Prognosis of Hookworm in Dogs
If caught in time, treatment can be successful and so in these cases, the prognosis is good. However, where severe anaemia or pneumonia is a result of an infection, then fatalities can occur.