14 min

Dog Parasites: Signs, Treatment & Prevention For Heartworm & More

Dog parasites are common and disgusting. These are the types of parasites dogs can get (like Heartworm and Roundworm) and how to treat infection.

Vanessa Armstrong

Updated December 14, 2022 • Published March 03, 2020

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Dog Parasites: Signs, Treatment & Prevention For Heartworm & More

Dogs get into, well, everything. And sometimes sticking their nose, tongue, or muzzle in certain unsanitary areas can have repercussions, specifically parasites. That’s right, parasites: tiny organisms that invade your dog’s body and live off their host, often to the detriment of a dog’s health. There are many types of dog parasites, including: heartworms, hookworms, and tapeworms as well as fleas, ticks, and lice.

How do you know if your dog has parasites? We put together a list of internal, intestinal, and external dog parasites. Read on to learn the different types of dog parasites, their symptoms, and recommended treatments.

Read More: Itchy Dog? Why Your Dog Is Scratching & How To Treat It

Types Of Dog Parasites

  1. Internal Dog Parasites

  2. Intestinal Dog Parasites

  3. Non-Worm Intestinal Dog Parasites

1. Internal Dog Parasites


According to Dr. Ernest Ward and Dr. Catherine Barnette of VCA Hospital, heartworm disease is a life-threatening condition that any dog can get from a mosquito bite, where an adult mosquito injects its larvae into the dog’s bloodstream, where they travel to your dog's lungs or heart.

It take about six months for heartworms to mature into reproducing adults. If left untreated, these heartworms will clog crucial arteries and vessels, preventing blood flow. Heartworms is dogs can lead to lung disease, organ damage, and even heart failure, which is why it is crucial you take preventative measures against it.

Signs your dog has heartworms

Common symptoms of heartworms in dogs include fatigue, coughing, difficulty breathing, weight loss, and general unwellness. If left untreated, heartworms can damage a dog’s heart and lungs, and is considered to be, according to Drs. Ward and Barnette, “one of the most serious conditions seen in small animal practice." Most dogs with heartworms do not show any symptoms so it's important to be tested regularly.

How to diagnose heartworms in dogs

If you're wondering how to tell your dog has heartworm, it's through a blood test — and it's one you can ask for (and may already be included) in your annual vet visit.

The most common way to test for heartworm is dogs is an antigen test that detects specific heartworm proteins ("antigens") in the bloodstream. Heartworms can only be detected five months after infestation, which leaves a short window before they can really do damage to your dog's health. Test regularly and take precautions.

How to treat heartworms in dogs

It sounds clichéd but the best treatment is to make sure your dog doesn't get heartworm in the first place. Otherwise, treatment for heartworm can be difficult and expensive. Talk to a veterinarian about the best course of treatment.


Roundworm is the most common parasite found in dogs, and affects puppies more than adult dogs. Puppies can be infected from birth if their mother has roundworm, or they can contract the disease immediately after birth from nursing. Even if their mother isn’t infected, puppies are still prone because they’re more likely to eat the roundworm eggs found in the feces of an infected animal.

Signs your dog has roundworms

If a puppy gets roundworms, their growth may be stunted. Other common symptoms of roundworm include coughing, vomiting, diarrhea, and a “pot-belly.” In severe cases, you might be able to see the roundworms — long spaghetti-like creatures — in your dog's feces or vomit.

Read More: Dog Diarrhea: Causes, Treatment & Prevention

How to treat roundworms in dogs

Once a vet has identified your dog has roundworms (by checking their poop under a microscope for eggs), you can begin the deworming process. Your veterinarian will recommend the best medication for your dog to take. Monthly heartworm preventatives are also effective in treating and preventing roundworms in dogs.


Dogs contract hookworm by eating the feces of an infected animal or by simply playing (and then licking) infected dirt. These parasites attach to the intestines and then siphon off a dog’s blood. The level of blood loss can be particularly harmful to puppies and can also result in malnourishment, stunted growth and anemia. Dark, sticky diarrhea can also be a symptom of hookworms.

Signs your dog has hookworms

These hookworms are microscopic and thus won't be easy to spot. Signs your dog has hookworms include pale gums, anemia, bloody stool, diarrhea, and weight loss. You may also notice your dog's paws are itchy and that growth may be stunted.

How to treat hookworms in dogs

If your veterinarian believes your dog has hookworms, they will perform a fecal float test that will check the stool for eggs (of which there would be many!). General treatment for hookworms in dogs includes oral medications that target adult eggs. To be safe, most vets will recommend multiple treatments to make sure all the eggs are gone.


Tapeworms are large, segmented worms found in the intestines of dogs. While extremely gross, the good news is they cause relatively little harm to your pup. Dogs contract tapeworms by eating contaminated animals, such as adult fleas or small mammals. Symptoms can include mild diarrhea and a change in appetite. Often times, there can be no symptoms at all, though you may see some segments of the worm by your dog’s anus or in their feces. If you’re lucky, like this writer once was, you might get a full tapeworm coming out of your pet’s anus — which you at first unthinkingly pull off because it looks like a spaghetti noodle, not an intestine — latching parasite.

Signs your dog has tapeworms

The most common sign your dog has tapeworms will be your dog scooting their butt across the floor or rug. Another unfortunate sign is witnessing these worms themselves in your dog's poop or around your dog's anus. This area will be the most agitated in the event of tapeworms, so note if your dog has any general discomfort or is licking/biting their butt area.

How to treat tapeworms in dogs

After a vet has checked your dog's stool, they can confirm whether your dog has tapeworms or not. Thankfully, tapeworms aren't as serious as other parasites and can be treated with either an oral medication or an injection. There are a few other methods to rid your dog of tapeworms, so talk to a vet about which option is right for you and your dog.


Whipworms are shorter worms, often only 1/4 of an inch long, and end up in a dog’s large intestine when the pup (once again) sniffs around in or eats infected dirt or feces.

Signs your dog has whipworms

If your dog has whipworms, they may not immediate show any signs. Whipworms will generally cause agitation with the digestive tract, so symptoms here again are chronic diarrhea and weight loss.

How to treat whipworms in dogs

After a veterinarian has analyzed your dog's stool sample and identified whether your dog has whipworms, your vet will put you on a deworming medication to lessen the worst of the symptoms. Unfortunately, whipworms are stubborn parasites with long life cycles and high levels of re-infestation so prepare to be fighting these guys for a while.

3. Non-Worm Intestinal Dog Parasites

Tired of worms? Don’t worry — there are non-worm parasites as well, since parasites are nothing if not plentiful.


Despite how it may sound, ringworms are not, in fact, worms, but a fungus. They get their name from the round, inflamed, red circle they leave on their hosts. These parasites are superficial and can live on the hair, skin, and nails of dogs.

Signs your dog has ringworms

Because of how contagious ringworms are, recognizing the signs is important. Signs your dog has ringworm include aggravated, inflamed skin and dry, brittle hair and nails.

How to treat ringworms in dogs

Treating your dog for ringworms is a three-prong process of oral medications, topical creams, and a thorough cleaning of everything/everyone your dog has come into contact with.


Coccidia is most often found in puppies. These single-celled parasites lodge into the intestine after a dog swallows infected soil or dog feces.

Signs your dog has Coccidia

Diarrhea, especially of the watery kind, is the most common symptom of this disease, and in some cases can be fatal if not treated. Other signs your dog has Coccidia may include vomiting or dehydration.

How To Treat Coccidia

After your vet has confirmed your dog has Coccidia, they will recommend an oral medication. Depending on how severe your dog's symptoms (like diarrhea and vomiting) were prior to the diagnosis, your vet may also recommend an IV.


Giardia is a single-celled parasite that affects older dogs more often than puppies. Dogs contract the disease by drinking infected water (AKA water that has been in contact with contaminated feces).

Signs your dog has Giardia

Symptoms of Giardia can be nonexistent. If your dog is exhibiting symptoms of Giardia, they would include the usual parasite signs, such as diarrhea, vomiting, and weight loss.

How To Treat Giardia

If your dog has Giardia and your vet has confirmed, there is an oral medication. The treatment will take about two weeks and your dog may require special hygiene routines at the end of it as cysts can develop.

How To Treat Parasites In Dogs

If your dog has any of the symptoms mentioned above, the immediate step is to make an appointment with your veterinarian so they can properly diagnose your pup. Once the particular parasite is identified, your doctor can then guide you through the correct course of treatment.

How To Prevent Parasites In Dogs

If you want to reduce the risk that your dog ever gets infected with parasites, the good news is there are some preventative measures you can take. There are monthly pills as well as vaccinations and collars.

As you can guess from the way most dogs contract parasites, the way to prevent infection is to make sure the area your pup plays in is free of dog feces (or any other type of feces, for that matter) and regularly cleaned. Who really wants fecal matter near them anyway? If you clean it up regularly, you, your dog, and your neighbors will thank you.

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