Can Rats Harm Dogs and Cats?

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For many cats and dogs, it is instinctive to pursue small prey like rodents and birds. Since wild animals may carry a variety of pathogens that cause diseases, pets and public health can be affected. Pet owners should consider training their pets to refrain from hunting wild animals.  


Rodents, such as mice and rats, may become infected with the protozoan parasite, Toxoplasma gondii, which causes toxoplasmosis. Some rodents come in contact with this parasite from water or soil. Dogs that eat rodents infected with Toxoplasma protozoans may experience diarrhea or harms to their nervous system. In contrast, if a rodent that is infected with T. gondii is ingested by a healthy cat, it is possible that no symptoms of the infection will be observed in the cat. However, the cat’s digestive tract may become infected with the protozoans, thereby causing the cat to shed these protozoans when defecating. 

Can humans be harmed from contact with infected pets?

Each year, more than 1 million humans are affected by toxoplasmosis in the United States. Humans can become infected with Toxoplasma protozoans from eating undercooked meat, unwashed fruits and, raw oysters, among other ways. Pet owners cleaning the litter boxes for cats that live indoors and outdoors may also become infected with the protozoan.

If a human is infected with Toxoplasma protozoans, the condition called toxoplasmosis may develop. Toxoplasmosis is generally asymptomatic in healthy humans. However, flu-like symptoms may be experienced, and in immunocompromised children and adults, more serious symptoms may occur. Pregnant women infected with Toxoplasma protozoans may experience complications during pregnancy due to toxoplasmosis, hence pregnant women are advised not to handle cat feces. There is currently no vaccine in use against toxoplasmosis in cats and humans (Jones et al. 2014).

More information on toxoplasmosis can be found from the American Veterinary Medicine Association and the Centers for Disease Control and Prevention.

What about roundworms?

Roundworms can harm rodents and birds (Toxocara spp.). If a pet eats an infected animal, such as a rodent, the pet can also become infected. Roundworms can cause intestinal issues in dogs and cats. Contact your veterinarian if you suspect your pet has been exposed to roundworms. There are a variety of medications that can be administered (in consultation with your veterinarian) to pets to help prevent and/or treat infections with different types of worms.

Further, roundworms can be passed on to humans. People who experience the disease (toxocariasis) associated with these worms, face a variety of symptoms including fever, headache, rash, digestive issues, vision loss and others (MacPherson 2013). There are a variety of anti-worm treatments that can be employed by medical and/or veterinary professionals, depending on the specifics of each case.

Although the exposure of outdoor pets to rodents and potential related pathogens is likely inevitable, pest control professionals can help. Professionals like Terminix can develop surveillance and prevention plans to minimize the occurrence of rodent populations, hence minimizing this rodent-pet interaction.