Worming your dog

What are worms?

Worms are a type of parasite in animals which affect the internal areas of the body. They are able to adversely affect health and in some circumstances even lead to death. Many worms found in dogs are zoonotic. This means that they can be transmitted to and from humans and so are considered an even greater problem.

How do dogs become infected with worms?

Transmission of these endo-parasites often results from the exposure of contaminated environments either following ingestion, the parasite’s larvae burrowing through the animal’s skin to gain access to the tissues or even as a result of a transport host such as a flea. Dogs in particular love to roll in, lick, eat, and sniff the environment and so are especially prone to exposure. As a result, they often become infected with worms. Different internal parasites can survive in the environment and outside the host for varying periods of time. This also contributes to the risks of infection. Sometimes, unborn puppies are transmitted certain worms in the uterus and so are infected after birth.

How do I know if my dog has worms?

Different signs and symptoms may also be observed depending on the type of parasite, the animal affected and how far the infestation has progressed. In severe cases, untreated animals may die following an infection of some internal worms.

Some dogs are asymptomatic following infection from internal parasites. Others present signs of vomiting, diarrhoea and subsequent dehydration and weight loss. An infected animal may cough if the parasite has infected the lungs. Coughed up worms are later swallowed and ingested, thus re-infecting the animal. Evidence of worms, larvae or eggs may be observed in the animal’s stool.

In terms of medically diagnosing an infection from worms, faecal samples and testing are often the preferred method. Clinical signs and symptoms are also taken into account. There are various methods of testing faeces and these differ depending on the type of internal parasite. The faeces are usually used to search for the eggs or larvae of that particular worm.

Can dogs with worms be treated?

Generally dogs that show signs of a worm infestation are able to be successfully treated. This does however depend on the endo-parasite it is infected with. To ensure complete treatment, the dog is given more than one dose over a certain length of time since many wormers only destroy the adult worms and not the larvae. The second dose will then kill the larvae which by then will have developed into adults.

Periodic de-worming, by the use of wormers, is often given twice every year for adult dogs. Young puppies as young as two weeks old should be wormed more regularly depending on the wormer used. These wormers are usually given whether or not the animal is diagnosed with worms and are used as preventative measures.

Can I get worms from my dog?

When parasites are able to be transmitted to humans they are known as zoonotic. Many internal parasites in dogs are able to be transferred to and from humans. It is for this reason that we have to be extra careful when dealing with an infected dog. Children, in particular, become infected as they are constantly putting their hands in their mouths; hands which may have come into contact with an infected dog or contaminated material. Therefore, high levels of hygiene are a necessity for both dog and owner.

What worms can my dog catch?

Here is a list of the more well known worms put in alphabetical order which dogs may be likely to become exposed to and therefore become infected with:


Coccidiosis is a disease caused by internal parasites known as Coccidia. Transmission occurs following the ingestion of contaminated faecal matter and in some cases death can result from an infection of this disease. Some dogs are asymptomatic while others may show signs including bloody diarrhoea covered in mucous. There are treatments available for infected animals although preventative measures such as maintaining high levels of hygiene are preferable.


Giardiasis is a disease caused by endo-parasites called Giardia canis. As is the case for most worms, they are transmitted following the ingestion of oocyst contaminated faeces. Infected dogs have foul smelling diarrhoea that is yellow in colour. Treatment programmes are not always successful when dealing with giardiasis. As a result prevention of infection is essential in maintaining a healthy dog. Good hygiene is a necessity.


A rare disease, gnathostoma is caused by Gnathostoma spinigerum. Intermediate hosts are usually the sources of gnathostoma infection on dogs. If symptoms are presented these may include fever, oedema, tissue damage and pain. Treatment methods are not well known due to the fact that it is such as rare disease. Severe cases can result in fatalities.


The three types of hookworms which are able to infect dogs are known as Ancylostoma caninum, Ancylostoma braziliense and Uncinaria stenocephala. The worm is transmitted after contaminated materials are ingested by the dog and infection occurs when the parasite enters the small intestine. Diarrhoea, vomiting and anaemia are all signs and symptoms of a hookworm infection. Hookworms are zoonotic parasites.


Toxascaris leonina and Toxocara canis are both types of roundworm which can infect dogs. Ingestion of the parasite often leads to transmission of roundworm but T. canis can also be transferred in the uterus from the mother to her unborn puppy. Infected animals show signs of a “pot belly” and may vomit or have diarrhoea. Wormers are available to treat infected dogs and to prevent any possible infection.


Many tapeworms can infect dogs although the most common is Dipylidium caninum.  Fleas act as sources of infection for this particular type of tapeworm. Infected dogs may vomit, have diarrhoea or lose weight. The worm can be easily treated and regular worming is advised. The disease can be transferred to and from humans, especially children.


Dogs are infected by the species of threadworm called the Strongyloides stercoralis. The larvae of this worm burrow into the skin of the dog once contact has been initiated. Dogs may be asymptomatic, experience diarrhoea or have difficulties with their breathing. The success of treatments is limited since the larvae can migrate deep inside the dog’s tissues. It is a zoonotic disease.


The whipworm that infects dogs is scientifically known as Trichuris vulpis. Ingestion of contaminated materials is the main source of infection of this disease. Diarrhoea and weight loss are both signs of infection and it is the cecum and the large intestine which the parasite infects. Wormers should be given regularly to prevent the spread of these worms.  


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