Worms in Dogs: Prevent, Diagnose, and Treat Different Types of Worms (2024)

The idea of worms in our dogs is always unpleasant. Nobody wants to think about creepy crawlies infesting their dog’s internal organs. But understanding the risks, symptoms, and treatment options for wormsin dogs is an important part of responsible dog ownership.

“Serious health problems can occur if worms in dogs are left untreated,” says Dr. Jerry Klein, AKC’s chief veterinary officer. “Worms can be picked up from your dog’s stool and contaminated soil. They can infect other dogs, and in some cases, people can contract certain types of worms. That’s one reason it’s important that you always carefully clean up your dog’s stool.”

There are five main types of worms that commonly affect domestic dogs: roundworms, tapeworms, hookworms, whipworms, and heartworms. Learn what you need to know about worms in dogs to keep your dog safe.

Symptoms of Dogs With Worms

While each parasite affects dogs differently, there are some general warning symptoms that dog owners should be aware of. Intestinal worms may cause:

• Diarrhea
• Abdominal pain
• Weight loss
• Vomiting
• Poor coat appearance
• Pot-bellied appearance
• Lethargy
• Dehydration
• Deficiencies in nutrition and anemia
• Intestinal blockage or pneumonia
• Blood in stool (either bright red or darker purple)

Heartworms can also be accompanied by respiratory symptoms such as coughing, exercise intolerance, weak pulse, weight loss, abdominal distension and in extreme cases, labored breathing, pale gums, and death.

Roundworms

Roundworms are some of the most common intestinal worms in dogs. There are two types of roundworms in dogs: Toxocara canis (T. canis) and Toxascaris leonina. T. canis is more common in puppies and can also be transmitted to humans.

Many puppies are born with roundworms which they obtain from their dam. Therefore, it’s vital that newborn puppies receive appropriate veterinary care. Roundworms are diagnosed by a fecal sample and are treated with deworming medications. If left untreated, roundworms can lead to poor growth and death in severe cases.

A rare type of roundworm that can infect dogs is the raccoon roundworm, Baylisascaris procyonis (B. procyonis), found in parts of North America. Dogs may become infected via ingestion of infectious eggs or infected hosts such as rodents, rabbits, and birds. According to the Merck Veterinary Manual, because of the potential for the B. procyonis eggs to spread from animals to humans, it is important to diagnose infections in dogs promptly and administer appropriate treatment immediately.

Tapeworms

Tapeworms are an intestinal parasite that dogs acquire by eating infected fleas or by consuming wild animals infested with tapeworms or fleas. Once the dog eats the flea, the tapeworm egg hatches and attaches to the dog’s intestinal lining. Dipylidium caninum is the most common type of tapeworm found in dogs in the U.S. It can be passed from fleas to dogs, giving you one more reason to take flea prevention seriously.

Infected dogs may pass segments of tapeworms in their stool. These may be visible and resemble little pieces of rice. Sometimes affected dogs may scoot their bottoms along the ground. If you see signs in your dog’s stool or notice your dog scooting, take a stool sample to your veterinarian for diagnosis.

If your vet finds eggs or tapeworm segments, your dog will receive a treatment regimen to eliminate the tapeworms. A drug is administered orally or by injection. Treatment also involves ridding any fleas from your dog and your home environment.

Hookworms

Hookworms are intestinal parasites that cause anemia in dogs and can be fatal in puppies if left untreated. Several different kinds of hookworms can affect dogs. They are very small (about 1/8 of an inch) but ingest large amounts of blood when they attach to the dog’s intestinal wall.

Your dog can get hookworms from ingesting hookworm larvae from the environment or, in the case of Ancylostoma caninum, the infective larvae can pass from a bitch’s milk to her puppies. Infected dogs can pass hundreds of microscopic eggs in their stool, where they hatch and can remain alive in soil for as long as several months. A dog may eat the infected dirt or lick it from the bottom of its paws, or sniff infected dog feces. Humans can also become infected with hookworms.

Hookworms are diagnosed with a microscopic examination of a stool sample called fecal flotation, when the stool is mixed with a solution that causes the hookworm eggs to float to the top. Dogs are treated with deworming medications, usually administered twice – to catch the adult worms and then two-to-four weeks later to catch those that are newly developed.

Whipworms

Whipworms are a type of worm in dogs that lives in the cecum (the beginning of the large intestine) and colon, where they pass their eggs into the dog’s feces. Dogs get whipworms from ingesting an infested substance, which can include soil, food, water, feces, or animal flesh.

The eggs can survive for up to five years in suitable environments (warm and moist), which is one of the reasons why cleaning up after your dog immediately is so important for general sanitation and health.

Whipworms don’t necessarily cause symptoms in mild cases. But in severe cases, they can lead to inflammation, weight loss, diarrhea, and occasionally anemia. Your veterinarian can diagnose your dog for whipworms with a fecal sample and will prescribe a treatment plan suitable to your dog’s needs – often three monthly treatments are required. Whipworm eggs are not as easy to find on all fecal samples and false negatives are not uncommon, which is why repeat fecal exams are recommended if your dog is exhibiting signs of blood in their stool.

Heartworms

Of all of the types of worms in dogs, the most worrisome — and the most preventable — are heartworms. Mosquitoes transmit the parasite, and since avoiding mosquitoes is nearly impossible in most places, vets recommend regular heartworm preventatives to keep your dog safe. Heartworms grow and multiply within the heart, causing severe lung disease, heart failure, other organ damage, and ultimately leading to death if left untreated.

According to the U.S. Food and Drug Administration, heartworm disease is most common along the Atlantic and Gulf coasts of the United States from the Gulf of Mexico to New Jersey and along the Mississippi River and its major tributaries, but it has been reported in dogs in all 50 states. In addition to dogs, coyotes, wolves, and foxes can be carriers.

Prevention is the best approach to dealing with heartworms. Treatment is lengthy, expensive, and can have serious side effects. To make matters worse, treating heartworm in dogs usually requires confinement and exercise restrictions. This can be hard on dogs and owners alike. Regular testing is recommended because heartworm preventives don’t kill adult heartworms. They may even be harmful to a dog that is already infected.

How to Diagnose Worms

Although tapeworms can be seen in the dog’s stool, other types of intestinal worms must usually be diagnosed by looking for eggs via the microscopic examination of a stool sample. If your dog exhibits any of the symptoms listed above, your veterinarian will ask you to bring a stool sample so worms can be detected or ruled out as a cause. Even when there are no symptoms, it is wise to take a stool sample to your vet when your dog is having his annual examination.

Heartworms can usually be detected by a blood test. In some cases, though, a radiograph, ultrasound, or echocardiogram is required.The American Heartworm Society says that in the early stages of the disease, many dogs show few symptoms or no symptoms at all, yet the earlier treatment begins the higher the success rate. That’s why regular annual testing for heartworms is a good idea.

Your vet can recommend deworming medications to treat different types of intestinal parasites and heartworms, as well as preventative medications. Since puppies are susceptible to receiving worms from their mothers, they must also have their stool tested regularly.

“In summary, prevention, regular testing, flea control, and hygiene offer the best course of action to prevent serious consequences to your dog caused by worms,” advises Dr. Klein.