External parasites

Parasites that live on the outside of our pets are known as external parasites, or ectoparasites. They are better known as fleas, ticks, lice, and ear mites. Fortunately, infestation by these parasites is very treatable and preventable with the proper steps. Animal Humane Society diagnoses and treats these parasites before they have a chance to spread to any other animals. While initial treatment is done at AHS prior to adoption, any follow-up treatments after the adoption will be at the adopter’s expense.

The following are general descriptions of the most common external parasites in dogs, cats, and other animals:

  • Fleas: Fleas are a tough parasite because they are good at infesting an environment. Adult fleas (the ones that bite) make up only 5 percent of the total flea population. The rest are eggs, larvae, and pupae that live in the environment. We treat animals that we suspect may have fleas with medications that not only kill adult fleas, but treat the whole life cycle. The medications we give last a full month. Fleas are prevalent throughout Minnesota, so ongoing prevention/treatment is recommended. Please discuss a flea prevention/treatment plan with your veterinarian.
  • Ticks: Ticks are very common in Minnesota. They transmit diseases like Lyme disease to dogs and people, and are also very hardy parasites. Treatments that kill fleas quickly take much longer to kill ticks. Full-grown and baby ticks (nymphs) can bite and spread disease. We apply topical insecticides that kill ticks to any animals that we suspect may be infested. Like with fleas, the medications we give last a full month. Ticks have been seen late into the fall and very early in the spring. Ongoing prevention/treatment is recommended. Please discuss a tick prevention/treatment plan with your veterinarian.
  • 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 very species-specific, so the type of lice pets get cannot infest people. If we diagnose an animal with lice, they are isolated, treated, and sent to the adoption center once they are deemed clear.
  • Ear Mites: Ear mites are tiny parasites that can live in the ear canals of dogs and cats. They do not infect people, but are contagious to other dogs and cats, causing excess black wax and extreme itchiness in the ears of affected animals. We start treatment the moment we diagnose mites. We give a topical medication call Revolution that is very good at killing these parasites. We also physically remove as many mites as we can by flushing and cleaning the ears. Rarely, follow up treatments are necessary. If your pet has been diagnosed with ear mites, please keep them away from animals that are not infected until you get approval from your veterinarian.

Prevention is always the goal with parasites. There are many excellent external parasite treatments and preventives on the market. Please discuss your pet’s risk and exposure with your veterinarian to make a comprehensive parasite prevention plan. 

Intestinal parasites

Intestinal parasites are very common in all animals, especially those that are strays or not in a controlled environment. Roundworms, hookworms, tapeworm, whipworms, Coccidia, and Giardia are all parasites seen in dogs and cats. Pets are usually infected by ingesting eggs or larval versions of parasites found in the environment. Eating birds, rodents, or fleas can also be a source of infection. Puppies and kittens can also become infected by their mother in utero.

Considering the prevalence of intestinal parasites, all dogs and cats at AHS are given a general de-wormer upon arrival. If they show further signs of parasites while in our care, like having diarrhea, a fecal test will be run to check for any evidence of specific parasites. The only good way to test for parasites is to check their stool for eggs, which are microscopic. After leaving the shelter, adopters will also want to monitor stool for the presence of worms or diarrhea, and your veterinarian will likely want to do additional parasite testing and treatment, as well as discuss a prevention plan. 

The following are general descriptions of the most common intestinal parasites in dogs and cats:

  • Roundworms: Roundworms are the most common intestinal parasite in dogs and cats. Adults are about 2-6 inches long. The worms can migrate throughout the body, but they live off food in the intestinal tract of their host. Eggs are shed by female worms in the stool, and ingestion of those eggs is how an animal becomes infected. Roundworms can be killed by most de-wormers, but repeat doses are usually necessary. Human infection is possible with roundworms if the eggs are ingested. Practicing good hygiene can greatly reduce any risk.
  • Hookworms: Hookworms are relatively common parasites as well. Adult worms are very small and thin, often not noticed in the stool. The worms “hook” into the lining of the intestines and actually feed off the host’s blood. Eggs are shed by female worms in the stool, but the eggs quickly hatch to become larva. These larvae can infect other animals, including people by being eaten or penetrating through bare skin.
  • Whipworms: Whipworms are small, thin worms with an even thinner tail that looks like a whip. They dig their tail into the lining of the large intestine, causing irritation and diarrhea. Eggs are shed by female worms. These eggs are not shed all the time, so seeing them on tests can be difficult, and the eggs can live in the environment for months at a time.
  • Tapeworms: Tapeworms are usually diagnosed by actually seeing little “rice-grain” segments around an animal’s rectum.  Tapeworms live off food in the intestines. Pets get tapeworms by eating an intermediate host like a mouse or flea. 
  • Coccidia: Coccidia are microscopic organisms called protozoa that live in the lining of the gut and can cause diarrhea. They are shed as cysts and are ingested to re-infect animals. There are many different ways to treat Coccidia. 
  • Giardia: Giardia are intestinal parasites that live in moist environments, especially ones where there is standing water. Giardia can cause vomiting and diarrhea. They are also shed as cysts into the environment and are ingested to re-infect animals. People can also be infected if they should ingest contaminated water or food.

Prevention is always the goal with intestinal parasites. Fortunately, most heartworm preventives contain general de-wormers. Good hygiene is crucial to prevent infection for dogs, cats, and people. Always pick up and properly dispose of your pet’s stool, and when possible, clean the affected area. Never let children handle stool of an infected pet. Always wash your hands after playing with your pet. Please discuss testing, prevention, and treatment of intestinal parasites with your veterinarian.