5 Most Common Veterinary Parasites

Nothing can be quite as heartbreaking as seeing your furry friend scratch mercilessly throughout the day or not seem like themselves. One of the most common reasons that this can happen is because of common parasites, with almost every pet having to suffer from them at least once during its lifetime.

Thankfully, treatment (especially if done quickly) is available for just about every parasite. If you suspect that something is wrong with your pet, try to get them to the veterinarian to get treated as quickly as possible. They could be suffering from one of the more common veterinary parasites, with these five being the most frequently seen.


Taenia, most commonly known as Tapeworms, is derived from the Greek word “tainia” meaning ribbon. Out of the 6,000 species of parasitic tapeworms, different varieties can affect humans, marine animals, vertebrates, and invertebrates. The most common version that plagues cats and dogs is called Dipylidium.

These animals typically become infected after accidentally eating a host (usually fleas) already carrying the parasites. The parasite latches onto the animal’s intestinal walls, where it lives and thrives until treated with medication. Surprisingly, they aren’t all that harmful and are more of a nuisance to the animals.  


Hookworms, specifically Ancylostoma Caninum, are blood-feeding parasites that infect some animals, like cats and dogs. Hookworms usually make their way into the intestines of said creatures by ingestion, sometimes from grooming their feet or sniffing contaminated soil and feces.  

The extremely small parasites hook their bodies onto the lining of the animal’s intestines, where they suck large amounts of blood from surrounding small blood vessels. Animals infected with hookworms can develop anemia, intestinal bleeding, dehydration, and diarrhea. Some animals develop anemia severe enough to require blood transfusions. Treatment includes being given anthelmintics to kill adult hookworms in the body.  


Heartworm, or Dirofilaria immitis, is a serious condition affecting mainly dogs, cats, and ferrets.  The parasite is only spread through bites from infected mosquitos. The worms make their home inside the heart, lungs, and surrounding blood vessels of the animals, creating what’s known as a “worm burden” consisting of many of the worms bunched together in the same area.  

Heartworms can live inside an animal for 5-7 years and can cause severe damage to the heart, lungs, liver, and other organs, ultimately ending the life of the host if left untreated. Treatment is expensive and consists of a series of injections of the FDA-approved drug “Melarsomine dihydrochloride” into the animal’s back muscles. The best treatment is prevention by way of topical, or oral medications.  


Fleas are the most common external parasite that affects mammals and birds alike. Pets can come into contact with fleas through contact with infected animals or their environment. Fleas are incredibly small and can jump nearly two feet at a time, making traveling from surfaces and hosts to unassuming victims extremely effortless. Fleas can spread tapeworms to their animal host and can cause hair loss, itching/biting, as well as pale lips and gums. 

Fleas consume almost 20 times their body weight in blood to survive, resulting in anemia and large amounts of blood loss in some animals, especially puppies and kittens. Treatment for fleas consists of topical and oral medications, medicated shampoos, sprays, and powders.  

Ear mites 

Ear mites, or Otodectes cynotis, are external parasites that can affect cats, dogs, ferrets, and rabbits. They live on the skin, or usually inside the host’s ear canal. The extremely small mites go easily unnoticed and spread through contact with an infested animal.  

Symptoms of animals with ear mites include rashes, blood blisters, discharge, and excessive scratching around the ears. Insecticidal medications are the common treatment for ear mites, as well as topical and injection medications.  

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