There are four types of intestinal worms that pose a risk to dogs in the UK, these include:
But there is also another type of worm, known as lungworm.
The changes to our UK climate are thought to be increasing the survival rates for some of these parasites affecting companion animals. Lungworm is now present in all areas of the UK, and as such, many veterinary practices are reporting the risk of infection is higher than previously thought.
Let’s take a look at them all in a little more detail, signs to look out for, how to manage the risk and options for treatment, if necessary.
Toxocara canis and toxascaris leonine are two species of roundworm that are known to affect dogs. Both are long, white and spaghetti-like in appearance and absorb nutrients from the infected dog.
Roundworm larvae will initially infect a dog’s intestinal tract but can burrow their way into other bodily tissues and organs. As the larvae mature, they will move onto the lungs to develop, then up to the airway before being coughed up and swallowed again, re-entering the intestine to complete their lifecycle. Toxascaris leonina however, do not move around the body and have a far simpler lifecycle. The prevalence is thought to be around 2.9% in dogs. https://www.mdpi.com/2076-0817/9/6/503/pdf
Infected dogs shed the microscopic roundworm eggs in their faeces. Other dogs may become infected by sniffing or licking these infected faeces. Roundworm eggs can also be spread by other animals like rodents, earthworms, and birds.
Roundworms are a concern for puppies. Since roundworms eat partially digested food in the intestinal tract, if there are large numbers of roundworms the puppy will miss out on vital nutrients to support their growth and development. In puppies, clinical signs of a roundworm infection include stunted growth, potbelly, and diarrhoea. Diagnosis is made by faecal examination.
Hookworms are intestinal parasites that get their name from the hook-like mouthparts they use to anchor themselves to the lining of the intestinal wall.
Despite their small size, they ingest large amounts of blood from the intestinal wall. A high burden of hookworms can cause inflammation in the dog’s intestine, as well as a decrease in the number of red bloods cells. This is known as anaemia. It is most common in puppies but can occur in adult dogs.
Hookworms are particularly common in warm, moist environments.
Female hookworms pass microscopic eggs in the faeces of infected dogs, where they contaminate the environment. Larvae hatch from the eggs and can remain infective in the soil for weeks or months. A dog may become infected when it swallows hookworm larvae, for example when it is grooming its feet, sniffing faeces or is exposed to contaminated soil.
Signs of infection include intestinal distress and anaemia. The parasites anchor themselves to the intestinal lining so that they can feed whilst at the same time injecting an anti-coagulant substance which prevents blood from clotting. Sadly, the dog can suffer blood loss from the hookworm’s feeding, as well as continued bleeding into the bowel from the attachment sites. This can result in anaemia and you will notice pale gums and weakness. Other symptoms include weight loss, diarrhoea, dull and dry coat, or failure to thrive. Some dogs will also have a cough as a symptom too.
Whipworms are intestinal parasites around 6 mm long. They live in the cecum (a pouch forming the first part of the large intestine) and large intestine of dogs. Here they cause irritation to the lining of the organs.
Signs and symptoms include:
- Watery, bloody diarrhea,
- Weight loss,
Whipworms pass microscopic eggs in the stool. Once laid, they mature to an infective stage in the environment and can re-infect a new dog in 10-60 days. The mature eggs are swallowed by the dog, they hatch, and then mature to adults in the lower intestinal tract.
Diagnosis includes a faecal examination, but these eggs are difficult to find. Whipworms pass small numbers of eggs on an inconsistent basis; so, some samples may be false negative. Multiple stool samples are often required to confirm a diagnosis.
Tapeworms are flat, segmented intestinal. They belong to the cestode family of intestinal worms.
The tapeworm uses its hook-like mouthparts to attach to the wall of the small intestine. The adult worms may reach 30 cm in length. As the adult matures, individual segments, called proglottids, are passed in the faeces of an infected dog. The proglottids are about 12 mm long and about 3mm wide. They are easy to recognise as grains of rice.
Tapeworms must first pass through an intermediate host, like a flea before they can infect a dog.
When tapeworm eggs are released into the environment, they must be ingested by flea larvae. Here, the tapeworm egg continues to develop as the flea matures into an adult.
During grooming, or in response to a flea bite, the dog ingests the tapeworm infected flea. As the flea is digested in the dog’s intestine, the tapeworm egg is released, it hatches, and then anchors itself to the intestinal lining.
Tapeworms don’t usually cause serious health problems in healthy adult dogs. Signs will include scooting across the floor, but this can also be a sign of anal gland issues, so it’s worth exploring this with your Vet.
Tapeworm segments are only passed intermittently and therefore are often not diagnosed on routine faecal examination.
Dogs pick up a lungworm infection by swallowing infective stages of the parasite. The exact means of picking it up, varies according to the life cycle of the parasite.
In some, the parasite larvae require an intermediate host – specifically a snail or a slug – to complete their development. Dogs usually pick up an infection by eating slugs or snails, or by eating another animal, such as a frog, mouse, or bird, that has eaten a slug or snail.
The life cycles of the other parasitic lungworms that infect dogs are more direct. Adult female worms lay their eggs in the tissues of an infected animal. With some species, the eggs are passed into the environment where they continue to mature into an infectious stage, while with other species, the eggs hatch into larvae which then mature into an infectious stage.
These infectious stages may remain in the saliva for further transmission or may be swallowed and pass through the intestines into the faeces.
A susceptible animal may pick up an infection through saliva or nasal secretions, or they may become infected through food or water that has been contaminated. Those that are transmitted mainly through the saliva most commonly occur when a mother grooms her puppies. For most other lungworms, infectious forms of the parasite are transmitted through the environment. Once swallowed, infective stages of the parasite complete their life cycle by travelling through the body from the intestinal tract to their ultimate destination; the nose, bronchi or lungs.
This is where you will notice the more common symptoms.
The symptoms of a lungworm infection depend on the number of parasites found in the lungs, the immune status of the infected dog, and the site of infection. Puppies again are of more concern than healthy adult dogs.
Symptoms can range from a slightly increased breathing rate to moderate coughing or sneezing to severe coughing, wheezing, respiratory distress, or exercise intolerance. In some cases, there aren’t even any visible symptoms of disease.
Prevention and Treatment
Worms are clearly a risk to dogs, but there are also concerns around the excessive use of worm treatments in the absence of any infection.
For that reason, here at Proflax we are stocking worm count kits.
These kits involve you taking a stool sample from your dog and sending it to a laboratory for parasite examination.
You therefore only treat a worm burden if it is present.
Whilst we don’t currently have a specific product for parasite control or prevention, you will find chamomile and marshmallow root in a range of our blends that can support intestinal hygiene. You will find chamomile in Calm and Collected, Puppy Power, Skin and Coat and Tummy Tastic, and you will find Marshmallow Root in the Puppy Power.
If you would like to learn more about the worm count test kits that can test for all of the worms we have explored above, please click the links below;
Worm Count Test Kits (toxocara, tapeworm, whipworm, hookworm or giardia)
Written by Lisa Hannaby - Bsc. Psych. Hons, MSc Human Nutrition