8 Parasites That Can Infect Your Small Animal

Laurie Hess, DVM, DABVP
By Laurie Hess, DVM, DABVP on Jun. 20, 2016
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8 Parasites That Can Infect Your Small Animal

By Laurie Hess, DVM, Dipl ABVP (Avian Practice)


Just as dogs and cats can get parasites, so can pet rabbits, guinea pigs, chinchillas, and small rodents. While there are hundreds of possible parasites that animals can carry, some are more common than others, and not all of them are transmittable to people. The best way to prevent your small animal from succumbing to these infections is to have him or her thoroughly examined by your veterinarian to identify any potential external parasites and to have the stool checked to catch any internal parasites. In addition, if you note any changes to your pet’s fur, skin, appetite, weight, or stool, be sure to have your veterinarian take a look.


Unfortunately, not all parasites are completely preventable. Here are some of the more common parasites treated in small mammals and how you can help prevent them in your pet: 

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Mites and Lice

Both mites and lice are external parasites and can infect a number of small animals. Rabbits can get microscopic ear mites through direct contact with infected rabbits, bedding, or other contaminated material. Ear mites cause a thick, red-brown crust to form inside the visible, external ear, along with head-shaking, itching, and ear drooping. Mites also can spread into the internal ear where they can rupture the ear drum and cause neurologic signs like head tilting. Crusts should not be removed, as this can be very painful; they will eventually fall off with treatment. The environment needs to be treated with flea products to prevent reinfection. While transmission of rabbit ear mites to people isn’t common, it is possible.


Rabbits also get fur mites, which cause mild itching and hair loss and are commonly transmissible to people, cats, and dogs. On rabbits, this mite, often called “walking dandruff,” looks like a mobile white dandruff flake crawling across the skin in dry, scaly patches. Treatment involves topical or injectable anti-parasitic drugs, plus thorough environmental cleanup and disinfection with flea products.


Guinea pigs also get skin mites through contact with infected guinea pigs, bedding, or other objects. These mites bury deep beneath the skin, causing intense itchiness to the point that the animal looks like it is seizuring. The skin has yellow crusts and is often bloody or scabbed from scratching. Treatment is typically with topical or injectable anti-parasitic medication and complete environmental disinfection. Some species of guinea pig mites are transmittable to humans.


Guinea pigs and rats can also get lice, which is manifested by a mild skin inflammation and crustiness, hair loss and overall dull coat. Lice are species-specific and don’t affect humans. Treatment is with flea shampoos safe for kittens or injections of anti-parasitic medication, and the environment must be disinfected with flea products once the animals have been removed.

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Fleas commonly infect rabbits housed with cats and dogs, causing a dull hair coat, loss of hair, itchiness, plus skin redness and crustiness. Guinea pigs also may become flea infested. Diagnosis is through microscopic identification of fleas and their eggs. Treatment is with topical flea products as well as environmental disinfection. However, not all flea products used on cats and dogs are safe for rabbits or other small mammals. Consult your veterinarian to determine which flea products are non-toxic and effective in rabbits.


The best way to prevent flea infestation in small mammals is to keep them inside and away from cats and dogs. Fortunately, tick infestation of small mammals is very rare if animals are housed inside, and Lyme disease, transmitted to cats and dogs through ticks, does not occur in small animals. Thus, flea and tick prevention is not typically recommended for small mammals housed indoors.

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Giardia is a microscopic parasite that, in small animals, is most commonly found in chinchillas. Many chinchillas and some mice, rats, and hamsters carry this parasite in their intestines without any signs. Very young chinchillas and mice, or adults stressed by other diseases, may develop diarrhea, decreased appetite, weight loss, dull fur, and potentially death as a result of a giardia infestation. Diagnosis is through microscopic identification of this parasite in the stool. Treatment involves oral administration of anti-parasitic drugs.


Cysts containing giardia can persist in the environment for weeks, so the animal’s environment must be completely disinfected with dilute bleach, with all porous materials (such as wooden toys) being replaced. Treatment of infected chinchillas may simply suppress clinical signs, with treated animals remaining a chronic source of cyst shedding. Giardia is potentially transmissible to people.

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E. cuniculi

Encephalitzoon cuniculi (E. cuniculi) is a microscopic, spore-forming parasite that causes inflammation of the nervous system (brain and spinal cord) very commonly in rabbits. It can cause neurologic signs such as head tilting, rolling, falling, and seizures, and can also cause kidney disease, abscesses within the eye, and glaucoma. Rabbits can carry this parasite without any signs for years and then develop signs when they are stressed or sick with another disease.


While not commonly transmitted to humans, people who are immunocompromised (transplant recipients, HIV-infected individuals, chemotherapy patients, very young children, or the elderly) are potentially susceptible. The parasite is transmitted in rabbits from mother to offspring in the uterus or during the first few weeks of life through exposure to spores in infected urine. Diagnosis of this parasite is difficult, as most rabbit owners don’t know their pets are affected until they are showing neurologic signs. Typically, diagnosis is made via blood testing, and treatment is a several-week course of an anti-parasitic drug given by mouth. Neurologic signs can persist even after treatment from inflammation caused by the parasite.


As part of treatment, infected urine must be thoroughly cleaned up. While rodents (hamsters and guinea pigs) are not commonly affected by this parasite, they can transmit spores through exposure to infected urine. Due to the potential for transmission of this parasite, immunocompromised humans should not handle rabbits, their urine, or their bedding material.

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This microscopic parasite is spread from animal to animal through ingestion of fecal material and commonly infect the gastrointestinal tract of rabbits under six months old. Adult rabbits may be infected but rarely show signs of illness unless they are immunocompromised from another disease. Young mice also may be affected. Signs of infection include diarrhea (with mucus or blood), weight loss, dehydration, and death if untreated. Diagnosis is through identification of the parasite in the stool. Treatment involves administration of an anti-parasitic drug orally plus thorough clean-up of all fecal material in the environment. Generally, these parasites are species-specific and do not infect people.


Coccidia also cause diarrhea, weight loss, dehydration, and potential death in young guinea pigs and chinchillas. Adults may be infected but remain asymptomatic. Diagnosis and treatment is similar to that described in rabbits.

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Pinworms occur commonly in rabbits and mice and less often in hamsters, gerbils, and rats, but this parasite does not typically cause significant problems in any species. In mice and rats, severe pinworm infestation can cause prolapse of the rectum due to straining. The worms, visible with the naked eye, live in the intestines and are passed, along with microscopic eggs, into the stool. Diagnosis is by seeing the small white worms in the stool or around the anus, or by microscopically identifying the eggs.


Although pinworms generally cause no signs in the animal, the presence of worms in the feces can be disturbing to many owners. Pinworms are treated with an oral deworming drug and are not transmissible to humans.

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Tapeworms can cause severe intestinal infection in gerbils, causing diarrhea and dehydration. Hamsters, mice and rats may also be infected but more often carry this parasite in their intestines without any signs. Diagnosis is through observation of the thread-like adult worms in feces with the naked eye or via microscopic identification of eggs in stool. Many species of tapeworm are spread from animal to animal via insects like beetles and fleas. Treatment is with oral deworming medication, elimination of insect carriers, and thorough environmental disinfection with dilute bleach. This parasite is transmissible to people through ingestion of fecal-contaminated food.

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Treatment and Prevention of Parasites

Whether your small animal has external or internal parasites, it is essential to follow your veterinarian’s treatment recommendations and not use over-the-counter drugs or medications prescribed for other pets, as not all dog and cat products are safe in these small creatures. Also, in addition to treating the animals, do not forget to thoroughly disinfect the environment to prevent reinfection. Consult your veterinarian as to specific agents that can be used safely to eliminate parasites from the environment around small pets. Be sure to protect yourself and your family members from becoming infected by always washing your hands after you handle the pet or change its litter. Get your small animal parasite-free, and he or she will be happier, healthier, and will likely live longer.