Know Your Parasites

Parasites may be small, but these creatures can cause life-threatening illnesses and wreak havoc on your pet’s health. The most common pet parasites include fleas, ticks, ear mites, heartworms, intestinal worms (like roundworms, hookworms, tapeworms, and whipworms), and single-celled (protozoan) parasites like coccidia and giardia.

Read on for more info on what each parasite is, how they’re spread, symptoms, treatments and preventatives available, and how prevalent they are.


Found on the skin of cats and dogs, fleas survive by ingesting the blood of their hosts.

  • Fleas can get inside your home on your pets, your shoes or clothes, and through doors and windows. Their life cycle is long, and they can make themselves at home in your yard or carpeting.
  • Symptoms: extreme discomfort, scratching, chewing, biting, fur loss, restlessness, flea allergy dermatitis, and behavioral problems. In severe cases, anemia and death are possible. Fleas are especially dangerous for kittens and puppies, and can infect your pet with tapeworms and bacterial infections.
  • Fleas are easily managed with monthly preventatives for both cats and dogs.
  • Fleas are the most common external parasite among companion animals.


Ticks are small arachnids that feed on the blood of mammals and are known to spread diseases among humans and animals.

  • Ticks can get inside your home on your pets, your shoes or clothes, and through doors and windows.
  • Symptoms: skin irritation; allergic reactions; and diseases like lyme disease, Rocky Mountain spotted fever, ehrlichiosis, anaplasmosis, tick paralysis, haemobartonellosis (feline infectious anemia), and tularemia (rabbit fever), and more.
  • Tick-borne diseases represent a widespread and growing public hazard to dogs and cats, treatments for these diseases can be costly and stressful. Tick prevention is easy to achieve with a monthly preventative.
  • In 2017, 1 in 30 dogs test positive for lyme disease in Indiana.
  • Learn more: Lyme Disease in Dogs; The Who, What, When, Where and Why.

Ear Mites

These are small surface mites that hang out around your pets’ ears, feeding off debris in the ear canal.

  • Highly contagious, these mites can pass easily between pets and infected hosts.
  • Symptoms: severe irritation; red, itchy, painful ears; dark brown discharge; damage to ears caused by extensive scratching; and head shaking.
  • Treatable with licensed topical or injectable medications for both cats and dogs. Cats have preventative options.
  • Responsible for 90% of ear infections in cats.


These parasitic worms make themselves at home in your pet’s heart, lungs, and arteries.

  • Transmitted by mosquitoes, heartworms can affect dogs, cats, and, in rare instances, humans.
  • Symptoms: Most dogs and cats show few or no signs of heartworm infection in the early stages of the disease. As the infection progresses, the affected pet can develop a cough, vomiting, fatigue, difficulty breathing, decreased appetite, and weight loss. By the time these symptoms are revealed, the pet’s heart and lungs may already have irreparable damage. Dogs are a natural host for heartworms, if left untreated a dog may have several hundred adult worms in their body. Conversely, cats are not a typical host for heartworms and most worms in cats do not survive to the adult stage, if they do, there may only be a few.
  • Although specific medication is available for dogs, the treatment regimen and need to restrict the pet’s exercise can be challenging. Drugs are administered multiple times over a 4-month period. No approved medical treatment is available for cats and the disease can be fatal.
  • In 2018, 1 in 67 dogs were heartworm positive in Indiana. Feline heartworm was especially prevalent in Marion County.
  • Learn more: Why Your Pet Needs a Heartworm Test Every Year and Heartworm + Flea Preventions: Does My Pet Really Need This?


The most common intestinal parasite found in dogs and cats, these parasitic worms can be found in the small intestine.

  • Pets can become infected by contaminated soil, dirt on our shoes, or coming into contact with infected prey like rodents and bugs.
  • Symptoms: pot-bellied appearance, vomiting, diarrhea, weight loss, a dull coat, coughing, loss of appetite, and even stunted growth in younger animals.
  • Preventatives and treatment are available for both dogs and cats.
  • 1 in 36 dogs and 1 in 18 cats tested positive for roundworm in Indiana in 2018.


Similar to roundworms, these bloodsucking parasites use their hook-like mouthpiece to anchor themselves to the intestinal wall.

  • They can be transmitted by ingestion of infected intermediate hosts, soil or feces, by microscopic larvae penetrating the pads of a dog’s paws, and puppies can get hookworms through their mother’s milk.
  • Symptoms: anemia, bloody diarrhea, poor appetite, vomiting, poor coat, pale gums, dark stool, constipation, weakness, and weight loss. Can be fatal, especially to kittens and puppies.
  • Preventatives and treatment are available for both dogs and cats.
  • In 2018, 5,316 dogs tested positive for hookworms in Indiana.


Another intestinal parasite, these suckers rob our pets of nutrients and take up space in their organs.

  • They are transmitted by ingesting tapeworm larvae residing in a host, like rodents or fleas.
  • Symptoms: weight loss, lethargy, extended abdomen, vomiting, and diarrhea.
  • Preventatives and treatment are available for both dogs and cats.
  • Tapeworms are twice as prevalent in cats than in dogs.


Parasitic worm with a whip-shaped body that is found in your pet’s cecum (the equivalent of your appendix).

  • They are transmitted by ingesting soil or playing with toys that have been infected.
  • Symptoms: bloody stool, dehydration, weight loss, dehydration, anemia, and, in extreme cases, death.
  • Preventatives and treatment are available for both dogs and cats.
  • Approximately 18.7% of shelter dogs in the US are infected.


Giardia is a single-celled parasite that lives in your pet’s intestine.

  • Giardia is easily spread through stagnant water and infected feces.
  • Symptoms: diarrhea, vomiting, and weight loss.
  • No preventatives for giardia exist, but it is completely treatable for both cats and dogs.
  • 1 in 16 dogs and 1 in 26 cats tested positive for giardia in Indiana in 2018.
  • Learn more: Giardia.


These tiny, single-celled parasites live in your pet’s digestive tract wreaking havoc.

  • Spread by ingesting infected matter or being exposed to infected feces. Both cats and dogs can be infected, but it cannot spread between species.
  • Symptoms: bloody stool, diarrhea, and, in severe cases, can cause death (especially to puppies or kittens).
  • No preventatives available, but it is treatable for dogs and cats.
  • Canine coccidia is prevalent in about 8% of dogs less than 6 months old.


1. Year-round preventative care isn’t necessary.

A flea’s life cycle is long and they can live for months indoors. That means fleas can infect your pet with tapeworms year-round.

Mosquito species change and adapt to frigid climates and some species successfully live through winter. Even in regions where cold weather prevails, pets have been diagnosed with heartworms.

Check out this prevalence map to see how pets are affected in your area.

2. Indoor-only animals don’t need preventative care.

Fleas and ticks can hitchhike inside on other animals, your clothes and shoes, and can simply walk in through windows and doors. They can then live in your carpet and mattress undetected for months.

It’s impossible to completely mosquito-proof a home, leaving your pets susceptible to heartworms. 1 in 4 heartworm positive cats are considered to be indoor cats.

Tips to Avoid Parasites

  • Pick up after your pet. One of the best ways to reduce your pet’s exposure risk to parasites is through proper sanitation. Because many parasitic worms are shed into an animal’s feces, yards contaminated with fecal matter can be a source of exposure for many months. In this same vein, don’t let your pet eat feces.
  • Don’t let your pet drink standing water. This is a prime source for giardia.
  • Bring in a fecal sample to your pet’s next yearly or bi-yearly exam to have your veterinarian do a check.
  • Some pets infected with parasites don’t show any signs of illness, but when symptoms do appear, it helps to know what to watch for. Contact your veterinarian if you see any of the signs listed above.
  • Keep your pet on preventatives year-round. At the time of writing this blog, our clinics carry seven different kinds of preventative products. Our team is happy to go over preventative options with you to find what’s right for your pet based on breed, age, weight, cost, lifestyle, and administering efficiency (chewable tab, injectable, or liquid on skin).

Several of these preventatives are available through our online pharmacies. To shop online for your pet’s foods and medications, visit:

Fall Creek Place’s Online Pharmacy
Mass Ave’s Online Pharmacy
Fountain Square’s Online Pharmacy