parasites in dogs

Parasites In Dogs You Should Know About

Reviewed by Lauren Cannon, DVM

Parasites in dogs have many forms and can be extremely disturbing to dogs and cats.

They  can cause serious health issues and carry disease.

They can cause mild irritation and in some cases, serious disease.

Dog owners can identify fleas and ticks easily. However, internal parasites can be present without you knowing.

Internal parasites can be very annoying to your pet and cause health problems.

Parasites can also transmit disease to humans. Children are at most serious risk, especially if they play in an environment where dogs or cats feces may be present, such as in a sandbox.

Read more to know more about common parasites and how to prevent them from causing serious health problems for your dog and family members.

What Are Parasites in Dogs?

parasites in dogs

The center for disease control defined a parasite as “an organism that lives on or in a host organism and gets its food from or at the expense of its host.”

Many dogs will be infected with parasites at some point in their life, according to the Companion Animal Parasite Council (CAPC).

There are two main categories of parasites in dogs: Internal parasites and external parasites.

Internal parasites live inside the body of an animal and can be transferred in various ways, such as tapeworms, hookworms, and roundworms. These parasites can affect many organs.

External parasites which are easier to identify,  live on the body of the host and produce an infestation, such as fleas and ticks.

Symptoms of Parasites in Dogs

parasites in dogs

Symptoms of parasites in dogs range from mild discomfort and loose stool, to serious issues such as anemia and skin disease.

That’s why it’s so important to prevent infestations, and to know how to treat your dog quickly if they caught a parasite.

Symptoms of parasites can vary depending on the type of parasite, where it lives and the level of infestation.

Most internal parasites do not show symptoms until the infestation has grown in a large amount.

Symptoms of internal parasites include:

  • Difficulty breathing
  • Vomiting
  • Diarrhea
  • Loss of appetite and weight loss
  • Low energy
  • Coughing
  • Presence of worms segments in the feces, such as tapeworms

Symptoms of external parasites include:

  • Inflamed or red skin
  • Hair loss
  • Skin discoloration
  • Presence of fleas dirt
  • Presence of black debris inside the ears
  • Scaly appearance

Different Types Of Parasites in Dogs

parasites in dogs

There are internal and external parasites. Internal parasites can be harder to detect and can cause serious health problems for your dog, especially in young puppies.

However, in adult dogs internal parasites are not always life threatening. It mostly depends on the dog’s immune system. Dogs with weak immune systems are most likely to suffer from these parasites.


Fleas are tiny insects that feed on dogs and other mammals. Fleas go through a life cycle where the eggs grow to become reproductive, blood sucking adults.

Fleas can cause itching and skin infections and may lead to flea allergy dermatitis. They can also carry tapeworm eggs and infest the dog if they ate a flea.

A large infestation of fleas can lead to anemia in dogs. If you notice fleas on your dog, it’s important to get rid of them as quickly as possible, before the population grows.

You may be able to notice dark fleas on the skin, especially at the base of the ears and the rump. Another way to diagnose fleas is by observing the fur that’s shed by the dog and look for tiny black specks, the size of poppy seeds.

These are flea feces, which is digested blood. If you’re not sure whether you’re looking at “flea dirt” or just plain dirt, place it on a damp piece of white tissue.

After a minute or so, a small red spot will become visible if it’s flea feces, because the blood will re-hydrate and diffuse into the tissue.


Ticks can cause dogs various serious diseases such as, lyme disease, rocky mountain spotted fever, babesiosis, bartonellosis, and ehrlichiosis.

Some species of ticks can also cause a dog to become paralyzed, usually starting at their back end and going up towards their head.

If the muscles that control breathing become paralyzed, this can be fatal. However, the paralysis will go away as long as the tick can be found and removed.

Annual visits to the vet to check for ticks is important, to help treat ticks as soon as possible. In addition, if you notice a tick on your dog, take it off immediately.

The best way to remove ticks is to numb it with alcohol, then pulling it off with a tweezer. After that, put it in a container of alcohol to eliminate it.

Ear Mites

Ear mites are microscopic mites that infect a dog’s ears. Ear mites cause thick black debris and discomfort.

They are highly contagious. Your dog can become infested by direct contact with another infested animal.

Symptoms include head shaking, scratching at the ears, and crusty discharge from the ears that looks like coffee grounds.


Hookworms are small and thin worms. They are less than one inch long. Dogs can pick up hookworm by ingesting the eggs or larvae that live in the soil. Or through the skin, particularly the feet.

Puppies can acquire them from their mothers while nursing. Hookworms attach to the lining of the intestinal wall and feed on the dog’s blood which may lead to anemia because of severe blood loss.

Eczema and secondary bacterial infection can result due to irritation. In addition, diarrhea and weight loss are common symptoms of hookworm.

The veterinarian can detect hookworms by examining a stool sample under a microscope.


Whipworms are internal parasites that are common in dogs. They are small, thin and have a whip-like front end and a thick back end. They live in the dog’s  large intestine and attach themselves to intestinal walls of the dog to feed on blood.

Dogs can acquire whipworms by ingesting, licking, or smelling stool found in the soil. Severe infection can cause weight loss, diarrhea, and anemia.

A different medication is usually used for whipworms, because they are resistant to many of the usual dewormer medications. Prevent your dog from having whipworms by keeping the environment clean of feces.


Roundworms are very common parasites in dogs. Puppies are usually more at risk than adult dogs. They are white, rounded strips that look like spaghetti and they are one to three inches long.

These parasites feed on the nutrients from the food that the dog eats, which causes weight loss and dietary deficiency. Infections occur when the dog ingests eggs or larvae found in stool, or can be transmitted from mother’s milk while nursing.

Symptoms of roundworms include coughing, diarrhea, vomiting, and have a pot-like belly. A regular deworming system is needed to prevent reinfection.

Roundworms can be transmitted to humans, and can cause inflammation.


Tapeworms such as Dipylidium caninum are carried by fleas. Your dog can acquire tapeworms by ingesting a flea or raw meat in some cases. They rarely cause serious disease.

They will cause discomfort for your dog, and can cause weight loss, and occasional diarrhea. It may also cause irritation around the anus, due to shedding of  segments of the worm.

Infestation can cause poor nutrition for the dog and in severe cases, an intestinal blockage may occur.

The best way to prevent  tapeworms is to keep your dog away from fleas, dead animals and garbage.


Heartworms will enter the dog’s bloodstream from the bite of an infected mosquito. Once they enter the bloodstream, they will mature and grow in the dog’s heart, and they can grow up to one foot long and clog the heart.

This will cause inflammation in the dog’s arterial wall and affect the blood flow. Symptoms of a heartworm disease include coughing, low energy, fatigue, reduced appetite, and if left untreated it can cause heart failure.

You may not know that your dog has a heartworm disease because most dogs won’t show clinical symptoms until the vet detects it using screening tests.

This is why it’s important to visit the vet regularly for regular checkups. Treatment includes multiple injections of medications given over a course of several months to kill the parasite.

Heartworm prevention can be done by using heartworms and intestinal parasites preventatives on a daily or monthly basis.

Treating Parasites in Dogs

parasites in dogs

There is no single medication that can treat all types of parasites. Once the vet can identify the type of parasite, they can find the most suitable and effective treatment for your dog.

Your vet may recommend deworming medications to treat and control infections.

In rare cases of heartworm disease, a surgery will be required to remove them.

When to See a Veterinarian

parasites in dogs

If you suspect that your dog ate infected flea or ingested infected stool, smelled it, or was around an infected animal. And the dog started to show symptoms like coughing, scooting, difficulty breathing, scratching, weight loss, diarrhea or vomiting.

It would be a good idea to call your veterinarian to check if a parasite is present. Your vet will identify the type of the parasite and recommend the right treatment and preventatives.

Regular routine check ups with the vet are important to prevent any infestation and eventually serious illnesses.

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