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Worms in dogs: What are the types, symptoms and treatments

Rachel Murphy
May 8, 2019
Image via Thinkstock.com

Your dog hasn't been behaving normally over the past few weeks. You talk to your dog walker or doggy day care about it, and they say that they've noticed a change in your dog's bathroom habits. You check in with your dog sitter after you get back from a trip, and he notes that your dog hadn't eaten any of his food. Finally, you call your vet, who recommends that you check for worms. 

Worms?!?  Here's everything you need to know about symptoms, treatment and more. 

Symptoms of worms in dogs

It can take 2 to 4 weeks after the original infection for the animal to exhibit symptoms associated with worms, says Dr. Julie Reck, a veterinarian and founder of Veterinary Medical Center of Fort Mill in South Carolina.

While the initial symptoms of worms in dogs are similar to those of other illnesses, it's important that you know what to be on the lookout for. According to Dr. Reck, these are the five most common symptoms of worms in dogs:

  • Change in, or loss of, appetite
  • Vomiting and diarrhea
  • Weight loss
  • Lethargy
  • Changes to the dog's coat (e.g., dandruff, loss of sheen or luster)

"By design, a parasite really wants to have that symbiotic relationship, and in most cases, it won't cause fatal illness," she said. "That really only happens in young puppies, but it can still have noteworthy symptoms that pet owners will notice."

Different types of worms may also bring about additional symptoms that you should keep an eye out for. It can be difficult to differentiate between the symptoms of these parasites. If your dog exhibits any of the above symptoms, you should get your dog proper veterinary care as soon as possible. 

Different types of intestinal worms

Here are the five main types of worms that dogs can contract, in order of prevalence:

  • Roundworms
    Roundworms are the most common internal parasite a dog can contract, and can grow to be several inches long, according to the AVMA. Typically, dogs get infected by roundworms when they come into contact with contaminated feces. Many puppies are born with roundworms — or get them from their mother's milk — and, if left untreated, can cause respiratory issues. 

    “The theory behind the ‘runt of the litter’ is that those puppies suffered more so from an in-utero parasite infection than the others, or got a heavier load of that in the mother's milk than the other puppies,” said Dr. Reck. “We see fewer runts when the mother is under the proper prenatal care and getting the deworming medication she needs. This is common with the majority of puppy litters.”

    Once they enter the body, roundworms lodge themselves in the dog's intestinal tract. If left untreated, roundworms can cause "serious health problems," such as brain, liver, and lung damage. And, according to the AVMA, this infection could even cause permanent or partial blindness.
  • Hookworms
    Hookworms can enter through the dog's mouth or skin, and usually cause a creeping, itchy eruption. Puppies are at the greatest risk of contracting hookworms.

    Once this parasite enters the body, it latches on to the dog's intestines and lives off of the dog's blood. According to Dr. Reck, this can result in major blood and nutrient loss. As you can imagine, the parasites can become deadly if they aren't treated in a timely fashion. 
     
  • Heartworms
    According to the AVMA, heartworms are a "preventable, but serious and potentially fatal" infection. Dogs usually contract heartworms after being bitten by an infected mosquito. The heartworm larvae are deposited into the body through the bite wound, but may not produce symptoms for six months or more. In addition to the symptoms listed above, dogs who have heartworms may also develop a cough or fatigue.

    As opposed to other types of worms, this parasite can usually can be diagnosed with a blood test. 
     
  • Tapeworms
    Tapeworms don't typically harm dogs. These parasites are long, flat, and white, with visible body segments. According to the AVMA, tapeworms are usually transmitted through fleas, lice, and rodents.

    Once inside the body, these parasites bury their heads in the lining of the small intestines and absorb a small portion of the nutrients that flow through. 
     
  • Whipworms
    Whipworms are the least common of the parasites and, like a whip, they're tiny, threadlike, and wider at one end. According to the AVMA, these parasites typically enter the body after a dog has come into contact with soil that's been polluted with fecal matter containing whipworm larvae. Unlike hookworms and roundworms, whipworms live in the large intestine. The parasite then tends to irritate the large intestine, which causes the dog to develop chronic diarrhea.

    "Most often, dogs with whipworms are generally pretty happy and healthy, but have a very runny stool," Dr. Reck said. "Since whipworms only shed eggs once every three weeks, they can be hard to diagnose through fecal tests. If a dog is experiencing diarrhea, most vets will go ahead and administer an effective and safe treatment for whipworms as a preventative measure."

    Dr. Reck said that whipworms are most common in areas that don't experience a hard freeze.

How do dogs get worms?

The most common way for dogs to get worms is when they expose themselves to other dogs' stool that has been contaminated with worm eggs. The worms "lay eggs that are passed in the dog's stool and infect other dogs when they eat contaminated soil, lick contaminated fur or paws, or drink water contaminated with the stool from infected dogs," according to the American Veterinary Medical Association (AVMA). That said, different worms can enter the body in different ways.

Your dog's likelihood of contracting worms depends largely on where in the U.S. you live. Different regions and climates of the country are going to present varying levels of vulnerability. 

For example, intestinal parasites are a huge problem in the Southeast, says  Dr. Julie Reck, a veterinarian and founder of Veterinary Medical Center of Fort Mill in South Carolina.

"In South Carolina, we aren’t having the frost cycles that would normally kill the parasites in the ground, so a lot of our soils are naturally contaminated," she said. "It’s not a matter of if a pet will get intestinal parasites, it’s when." 

Specifically, areas that don't receive a hard freeze at least once during the winter are going to have a much heavier load of intestinal parasites than those areas that do. This is because worm eggs -- particularly roundworm eggs -- can stay alive in the soil for years if there isn't a hard freeze. 

"Once you get to upper Virginia and beyond on the East Coast, where you get at least the top three inches of soil frozen for a 12- to 24-hour period, you're going to see that intestinal parasites are more of a seasonal issue in the summer and less of a wintertime issue," she said.

How do you diagnose worms in dogs?

Veterinarians typically check stool samples to diagnose worms in dogs. According to Dr. Reck, "The diagnosis is made when feces is processed, then examined under a microscope for eggs shed by worms living inside the dog." Dr. Reck recommends bringing in a stool sample less than four hours old to your vet instead of collecting the fecal at the office, which can cause the dog discomfort.

That said, there are some worms (like heartworms), that you can diagnose through a blood test. 

Treatment for worms

The most common treatment for worms in dogs is deworming medication. Most deworming medications are very safe, but it's worth noting that your dog may experience loss of energy and appetite as the worms are expelled from the body. 

"We've administered a lot of doses [of these drugs], so we're confident in what you can typically expect from these medications," said Dr. Reck. "In my opinion, the lethargy and loss of appetite are less from the medication, but more of the dog's body responding to the worms exiting the body."

She said that there are roughly eight different deworming medications available, and while they're generally affordable for pet owners, Dr. Reck emphasized the importance of preventative drugs to help avoid worms in the future.

"More often than not, the worms won't cause disease in your pet," Dr. Reck said. "What they're going to do is steal nutrients from your pet, and  that’s going to leave them less healthy and more vulnerable to things like bacterial infections and dermatology issues. Having the veterinary guidance on the right medication, right dose, and at the right frequency is very important."

Once a dog is treated for worms with medicine from the vet, Dr. Reck said it can be normal to see worms in the stool for a few days after. 

How to prevent worms in dogs

There are several preventative steps that owners can take to help ward off worms in dogs. If you have a dog walker or dog trainer, check to see if they have a policy that requires all of their clients to regularly check their dogs for parasites. If they don't have such a policy, ask them if they'd consider instituting one.

Here are Dr. Reck's main recommendations for keeping your dog worm-free:

  • Clean up after your pup
    "The more that we can keep these parasites out of the environment, the less contaminated the soils will be," said Dr. Reck. "For instance, if your dog goes to the bathroom outdoors and you don't pick it up, the fecal matter then gets absorbed into the soil, thus increasing the spread of parasites. By cleaning up after your dog, you're helping to prevent the transmission of parasites."

    This is especially important in dog boarding kennels and other dog-friendly communities.
     
  • Take your dog for routine screenings
    Taking your dog for his annual checkup is extremely important not only for his overall health, but also for checking him for worms. Bring your dog to the vet a couple of times a year to check for parasites and consult your vet about the findings.
     
  • Bathe your dog regularly
    Since dogs lick themselves after coming in and out of the house, frequent baths will help keep your dog free of any fecal matter they may have picked up while outside. You may also wipe your dog's paws off with a warm washcloth after spending time outdoors.
     
  • Use a monthly preventative treatment 
    Heartworm prevention, when used once a month (or every six months for the injections), can help control some other types of worms as well, says Dr. Messonnier. Consult your veterinarian to find the best preventative option for your dog.


Can I get worms from my dog?

Yes, humans can get worms from their dogs. 

"The biggest reason to protect your dog from worms is that they can be transmissible to humans, which is known as a Zoonotic illness," said Dr. Reck. "We want to avoid that as much as possible, and the best way to do that is to keep the pet healthy first and to keep them from constantly spreading these parasites in the environment."

Worms are usually transferred through the fecal-oral route -- meaning that kids or adults may touch a dog with fecal material on her fur, crawl around near contaminated material, or even play with dog poop, and then touch their mouths or food. Sandboxes or beaches are common places for children to contract worms. Hookworms also pass through the skin, most commonly from walking outside barefoot in sandy or loamy soil, said Dr. David Haworth, a veterinarian and president and CEO of Morris Animal Foundation.

If you suspect that you've contracted worms from your dog, visit your doctor immediately, advised Dr. Messonnier. "Young children often experience eye symptoms," he added.

For a skin infection, which looks like a creeping eruption right below the skin, a dermatologist will be able to identify the type of lesion. Intestinal infections can be more difficult to diagnose, especially if they spread to other parts of the body. Once the doctor diagnoses a child or adult with worms, a deworming medication can often eliminate the issue.

As for preventing worm transferal to humans, regular hand-washing is essential, especially if you suspect that your dog may have worms.


* This article is for general informational purposes only. It is not intended nor implied to be providing medical advice and is not a substitute for such advice. The reader should always consult a health care provider concerning any medical condition or treatment plan. Neither Care.com nor the author assumes any responsibility or liability with respect to use of any information contained herein.

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