OMG. What's in my dog's poo?

And other musings on pet parasites

It’s a unique moment of dread that many pet owners can relate to. You’re hanging with your furry friend, doing something routine, like cuddling on the couch or picking up after them during a walk, and then you see it. Something moving, something alive, something that shouldn’t be there.


Yep — your pal’s got parasites.

Internal and external parasites are more common during warm summer months, but don’t panic. Animal Humane Society has you covered with the best ways to prevent and treat the little buggers.

Prevention is key for all parasites! We suggest year-round prevention to all pet owners.

External parasites

Parasites that live on the outside of our pets like fleas, ticks, lice, and ear mites are known as external parasites. These pesky ride-alongs can cause everything from mild irritation to severe medical issues. Fortunately, external parasites are easy to treat and preventable with the proper steps.

Flea/tick preventative
  • Fleas: Fleas are a tough parasite because they multiply fast and get right to infestation. They’re tiny, like a piece of ground, black pepper. You can identify a flea from other parasites by its ability to hop around on your pet.
  • Ticks: Ticks are common in Minnesota and can transmit illnesses like Lyme disease and Rocky Mountain spotted fever to dogs (and people, too). Yikes. These hardy parasites take longer to kill than other external parasites, which makes prevention even more important.
  • Lice: Lice are tiny parasites that live on the hair of their host. All types of animals, including people, can get lice. Fortunately, lice are “species-specific,” which means you can’t catch lice from your pet.

Prevention and treatment

Apply topical insecticides or give oral medications that kill fleas, ticks, and lice each month. Because all of these parasites are prevalent in Minnesota and have even been spotted in colder months we highly recommend year-round prevention. There are many options for external parasite prevention, and the majority are available without a prescription. Talk to your veterinarian about which is best for your pet.

  • Ear mites: Ear mites are tiny parasites that live in the ear canals of dogs and cats. They do not infect people, but are contagious to other dogs and cats. Ear mites are invisible to the naked eye, but pet owners can see evidence of them. Your pet will show signs of severe itchiness, and a peek inside their ear will reveal black earwax that looks like coffee grounds.

Prevention and treatment

Ear mites are treated with a topical medication as well as regular ear cleanings to remove the mites. You’ll need to see your vet to diagnose ear mites and provide the right topical medication for your pet. Ear mites usually resolve after a few weeks of treatment.

Dog rolling grass

Internal parasites

Internal parasites, especially those that affect the intestines, are common in all animals. Pets are usually infected by ingesting eggs or larval versions of parasites found in the environment. Eating birds, rodents, or fleas can be a source of infection. Puppies and kittens can also become infected by their mother in utero.

Some internal parasites (noted with an *) can spread to humans through contact with your animal’s feces. Good hygiene greatly minimizes any risk. Always pick up and properly dispose of your pet’s stool and clean the affected area when possible. Then wash those hands! 

  • *Roundworms: Roundworms are the most common intestinal parasite in dogs and cats. Adult worms are about 2-6 inches long and resemble thin spaghetti noodles in your pet’s stool.
  • Hookworms: Hookworms are relatively common parasites as well, but you’re not likely to see them in your furry friend’s feces. The worms “hook” into the lining of the intestines and actually feed off the host’s blood. This can cause anemia in small or very young animals.
  • Whipworms: Whipworms are small, thin worms with a tail that looks like a whip. They dig their tail into the lining of an animal’s large intestine, causing irritation and diarrhea.
  • *Tapeworms: Tapeworms are usually diagnosed when pet owners notice small white segments that look like grains of rice in their pet’s stool or around their rectum. Tapeworms live off food in your pet’s intestines. Pets get tapeworms by eating an intermediate host like a mouse or flea. 

Prevention and treatment

Roundworms, Hookworms, Whipworms, and Tapeworms can be killed with dewormers. Your vet will prescribe the right kind of dewormer for your pet’s needs. Repeat doses are usually necessary, so be sure to follow your vet’s instructions carefully. 

Itchy cat
  • *Coccidia: Coccidia are microscopic organisms that live in the lining of the gut and can cause diarrhea. Coccidia is spread from animal to animal through infected feces.
  • *Giardia: Giardia are intestinal parasites that live in moist environments, especially ones where there is standing water. Animals can become infected after ingesting the parasite in puddles or ponds, or coming in contact with another infected animal.

Prevention and treatment

There are many different ways to treat Coccidia and Giardia including dewormers, antibiotics, and supportive care. Both parasites can cause dehydration, which is especially dangerous for kittens and puppies. Visit your vet to determine the right treatment for your pet.

  • Heartworms: Heartworms are the most dangerous and harmful parasite for your pet. Potentially fatal, heartworms are spread through the bite of infected mosquitoes. Because prevention is somewhat costly, many pet owners only give their pet preventatives during the summer months. We recommend giving your pet preventatives year-round. If they contract heartworm, the cost of treatment can easily exceed thousands of dollars.

Prevention and treatment

Heartworm prevention comes in the form of an easy monthly pill — which usually also contain prevention for intestinal parasites. Bonus! You should note that giving your pet heartworm prevention while they’re infected with heartworm can be dangerous, so you should always test them before starting preventatives.

Think your pet has parasites and need an expert opinion? Reach out to your veterinarian. Or see if you qualify for Animal Humane Society Veterinary Centers where we provide high-quality care for pets and people in need.

For caring, compassionate advice and resources to address all your animal concerns.

Contact the Pet Helpline