There are many forms of parasites that can live both on the outside (external) and on the inside (internal) of your pet! The side effects of these parasites depend upon the type and where they are living on or in your pet! The good new is that most of these parasites are easily treatable. Contact your veterinarian if you think your pet may have a parasite.


Fleas are the most common external parasite of household pets, with adult fleas comprising only 5% of the flea population. The rest of the flea population is in the immature form that can live and mature in your home environment. Fleas are dark brown flat-bodies wingless insects that are able to jump great distances. Fleas survive on blood meals from biting your pet, but will also bite humans too. Symptoms you may see if your pet has fleas:

– itching and scratching

– biting and chewing

– fleas or flea dirt on the skin

Fleas can lay up to 50 eggs per day, which drop off the host and mature in the environment (including your home). Treatment of your pet is important for their comfort, but also because fleas can transmit other diseases. If eaten by your pet, fleas can infect your pet with tapeworms. Fleas are also the source of “cat scratch fever”, a disease passed to humans in cat scratch wounds.


Ticks are small parasites that are usually found in low-lying brush or wooded areas. Pets are normally infected by walking through these areas and brushing up against the tick. Once on the animal, the tick will bury or embed its head in your pets’ skin and feed on blood. It then slowly becomes engorged with blood and enlarges in size.

There are two groups of ticks: hard and soft shelled, but all are visible to the naked eye on our pets. Be sure to check your pets when returning from wooded areas by running your hand over their skin. Sites most commonly affected on our pets is where grooming is difficult: head, neck legs and between the toes. Removal is important as ticks can transfer disease to animals and humans including Lyme disease, Ehrlichiosis and Rocky Mountain Spotted Fever.

Products are available to treat and protect your pet.


Mange is a skin disease of dogs and cats that is characterized by severe itching, hair loss, scaling and sometimes scabbing of the affected skin. Lesions are typically found on the face, ears, and abdomen, but can spread to other areas as well. There are two different forms caused by different mites: sarcoptes and demodex. Most cases occur in puppies and kittens, but can also occur in adults. Mange is seen heavily in the coyote population, especially in the spring, but can be seen all year round. Mange is also transferable to humans, so if your pet is itchy, be sure to get it checked out right away. Products are available to treat mange.

Ear Mites 

Internal Parasites

Internal parasites are parasites that are living inside your pet’s body. These include: heartworm, intestinal worms and giardia.


Heartworm, or Dirofilaria immitis, is an internal parasite that lives in the bloodstream of infected animals, and matures into adult worms within their heart and pulmonary (lung) arteries. Heartworm is passed from infected animals to non-infected animals through mosquito bites and can occur in both dogs and cats. The immature heartworm, or microfilaria, will live within the infected mosquito bite and then the skin for up to several months while it is maturing into a larval form. Once mature, it then travels into the blood and then heart. Mature worms in the heart of affected animals can reach up to 35 cm in length and can end up causing significant damage to the heart and lungs. Symptoms of infection include coughing, exercise intolerance, laboured breathing and weight loss, however, many animals do not show any sign of infection. If left untreated, heartworm can be fatal. For this reason, it is important to ensure that your pet is protected against heartworm during the months of the year that mosquitos are present in areas where heartworm is prevalent. To learn more about heartworm testing and prevention, speak with your veterinarian

Intestinal Worms

There are several forms of intestinal worms that can infect your pet, including roundworms, tapeworms and hookworms.Animals of all ages can be affected, although it is most common in young cats and dogs, or those that hunt prey regularly. People, especially children can also become infected by their pet. Symptoms of infection in your pets include: diarrhea, anemia, pot belly or no symptoms at all.

Roundworm: the most common intestinal worm of cats and dogs; acquired by eating infected poop, animals, dirt or vegetation; can cause cysts in the body allowing pregnant dogs to pass the infection to their puppies in the uterus or after birth in the milk; larva (immature forms of the worm) can migrate throughout the body causing damage to internal organs or the brain

Hookworm: acquired in similar ways to roundworms, but can also burrow into the skin when in contact with contaminated environment; worms attach to the intestinal wall and feed on blood from your pet causing anemia, which can be lifethreatening in the very young or debilitated pet

Tapeworm: common in cats that hunt prey; is acquired by similar ways to roundworms, but is also carried by fleas and infection can occur by accidentally consuming a flea while grooming; tapeworm segments may be seen stuck in the fur around the anus looking like dried rice

A single worm living in the intestine of your pet can produce thousands of eggs per day which are spread in the poop and contaminate the environment they live in. Worm infestations are diagnosed with a simple fecal exam, and can be treated and prevented with regular deworming.


Giardia (called “beaver fever” in humans) is caused by a microorganism that is carried by wild animals and is acquired by drinking contaminated water or eating contaminated food or feces. Giardia prevents proper absorption of nutrients and damages the intestinal lining causing soft or frothy, peristent diarrhea; and often depression or decreased activity. Humans can also get a giardia infection, so proper personal hygiene is important in homes where a pet is infected, especially if children are present. Giardia is diagnosed by fecal examination and testing, and treatment is available.