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Health & Wellness

8 common parasites that affect dogs

Some parasites cause similar symptoms in dogs.

Pet parenthood means we’re in for all of it — the good, the bad and when creepy-crawly parasites affect our dogs. And unfortunately, our pups can be hosts to a number of these infectious invaders. 

Even though it’s not the most pleasant thing to think about, we spoke to Dr. Aliya McCullough, Fetch's on-staff veterinarian, about different parasites and how to protect pups from them.

What are some intestinal parasites in dogs? 

The main objective of intestinal parasites — the most common being worms and protozoa (microscopic parasites) — is to get into your dog’s gastrointestinal system.

You’ll want to know about these specific invaders:


These contagious, long, thin and white parasites spread when dogs eat eggs in the environment (they can lay dormant in the soil for a long time) or through an infected mother’s milk. Puppies with large, swollen bellies likely have roundworms.


The especially-contagious parasites that are out for (literal) blood are hookworms. They penetrate the skin, can be lethal to puppies and can even affect humans. Like roundworms, these parasites spread through an infected mother’s milk or the environment. 


Tapeworms thrive by stealing nutrients from their hosts. Your pup might end up with a tapeworm after eating fleas carrying their eggs, which can continue to spread the eggs to other animals.

One silver lining: Your dog isn’t contagious after contracting tapeworms. 


These microscopic parasites cause gastrointestinal infections in pups. Coccidia eggs are passed from an infected dog’s stool into the soil, where they can survive long enough to move onto another host. 


Giardia, like coccidia, can be spread from poop to soil. They also survive in water, so it’s important to keep your dog from drinking from lakes, rivers, pools or even puddles.

Symptoms of intestinal parasites in dogs

Intestinal parasites, be they worms or protozoa, typically cause similar symptoms. According to Dr. McCullough, some things to look out for include:   

  • Vomiting
  • Diarrhea
  • Pot-bellied appearance
  • Weight loss
  • Decreased appetite 
  • Poor hair quality
  • Decreased energy

Some dogs, especially adults, may not show any obvious signs of parasite infection, so routine fecal exams are a good idea to ensure your pup is in good health.

Can I see parasites in my dog’s poop?

Not all parasites are visible to the naked eye: protozoa, for example, can’t be seen. A dog with worms may not pass noticeable segments through their poop, either.

However, if you spot something in your best friend’s business, they'll look like white, rice-like bits or long, spaghetti-like strands.

Treatment for intestinal parasites in dogs

You'll want to visit your veterinarian for an exam to determine the best treatment method for your dog. Bringing a poop sample into the vet's office allows them to perform giardia tests or to look for eggs under a microscope. Sometimes, the sample will be sent away to a lab for further testing.

Veterinarians often prescribe oral dewormers for dogs with worm infections. According to Dr. McCullough, the medication will likely need to be repeated 2 to 3 weeks after the initial treatment — but your vet will tell you what's best for your pet.

Treatment options vary for those pesky protozoa. For example, coccidia is often treated with antiprotozoal medication (in severe cases, hospitalization might be necessary), while giardia infections usually require multiple medications to cure, Dr. McCullough explains.

You can prevent your pup from being reinfected by intestinal parasites by removing their stool from an environment ASAP, Dr. McCullough recommends.

RELATED:What to do if you find worms in your dog’s poop

What are common dog skin parasites? 

Skin parasites, or external parasites, vary in size, love to hitch rides on our pets and cause itching and other discomforts. Here are the most common pests that affect our dogs: 


These tiny arachnids can be a big pain for dogs (and their parents). They’re incredibly difficult to see with the naked eye and are easily spreadable. Different mites cause various conditions — like Demodex and sarcoptic mange while others cause your dog’s ears to be miserably itchy


Like mites, fleas are persistent pests that make dogs super itchy and can quickly spread to other animals. Left unchecked, these insects can infest your house and yard, so keeping your pup on year-round flea control is important.


Ticks are the largest skin parasites (and they get bigger as they drink your pup’s blood). These parasites carry and transmit harmful diseases such as Lyme disease and Rocky Mountain spotted fever.

What are the symptoms of skin parasites in dogs? 

According to Dr. McCullough, mites and fleas cause similar symptoms in dogs. Here’s what you should look out for: 

  • Intense itching, scratching, chewing or licking
  • Hair loss
  • Skin redness, scabs and crusts (from all of the scratching)
  • Presence of fleas or flea dirt (which is flea poop that appears as tiny black specks)
  • Weakness, lethargy and pale gums, especially in young dogs with heavy flea infestations

Regularly checking your dog’s skin around their head, legs, neck and chest — especially after being outdoors — is a great way to scope out ticks. Tick-borne diseases don’t always show obvious symptoms (sometimes they start around 6 weeks after a dog is bitten), so checking your pup for physical ticks can help prevent sickness. 

Treatment for skin parasites in dogs

Veterinarians determine the best treatment option for dogs after narrowing down what’s causing their itchiness. For example, if fleas are suspected, your veterinarian may inspect your pup’s fur with a medicated comb. On the other hand, veterinarians look at a sample of a dog’s skin or ear wax under a microscope to check for mites. 

Flea infestations are treated with preventive medications, which can also eliminate live insects within a few hours or less. Your home will also need to be cleaned, usually through replacing or washing pet bedding, vacuuming daily, removing unnecessary carpeting, discarding brush from the yard and keeping your grass trimmed. 

Mites can be treated with certain oral flea and tick preventives, topical medications or a lime-sulfur dip. Unfortunately, Sarcoptes (a type of mite) are difficult to find on a skin sample, so your veterinarian might treat your pup for mites even if they can’t find any under the microscope. 

For flea and mite infestations, your veterinarian may prescribe medications to help with your dog’s itch and treat subsequent skin infections.

Ticks can be physically removed, and the site of attachment should be disinfected and monitored for infection. Ask your veterinarian about preventives to stop future fleas or ticks from attaching to your dog. Lyme disease, Rocky Mountain spotted fever and anaplasmosis are usually treated through antibiotics.

The Dig, Fetch's expert-backed editorial, answers all of the questions you forget to ask your vet or are too embarrassed to ask at the dog park. We help make sure you and your best friend have more good days, but we’re there on bad days, too.

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