How Do Dogs Get Worms?

I adopted my terrier, Thisbe, from an L.A. County shelter, and have fostered a couple dozen dogs in the past four years. Inviting dogs from unknown or unwholesome circumstances to crash at my pad has given me a wealth of experience in regards to a variety of medical issues. One of the most common occurrences, albeit quite unpleasant, is when a parent discovers that his or her beloved dog has an infestation of parasitic worms. Luckily, these pesky helminths (the scientific term for parasitic worms) can normally be dispatched easily in the early stages of infection.

The Stray Dog

The difficult lifestyle of a stray dog is ideal for some parasitic worms, such as roundworms. The stray may contract a worm or worm egg from eating spoiled food out of trash cans, scavenging on dead animals, catching small prey, or grabbing morsels from the ground. Worm eggs will lay dormant in any of the aforementioned cases, and can be viable for many years even in the harshest conditions. After female stray dogs contract worms, they will pass the parasites on to their offspring during the gestational period and when nursing their young. Only human intervention will stop the malignant cycle of worm infection.


Tapeworm eggs can likewise be accidentally ingested via raw or undercooked meat, but a flea is usually the conduit for a tapeworm to develop into an adult within a dog. The tapeworm egg resides inside the flea, which is then ingested by the dog. The egg has then found the perfect environment for its growth. As a result, it is imperative that a canine receive routine flea treatment.


In locations where mosquitoes are rampant, dog lovers should be vigilant for heartworms. These destructive parasites are transmitted when mosquitoes feed on their victims. Heartworm screening can be costly, but it brings peace of mind to a dog parent. These worms can completely infest a dog’s heart, which will naturally cause the organ to cease functioning.

Raw Meat

Any species is at risk of contracting a worm when eating another animal. While feeding a dog a raw diet remains a controversial topic, the fact is that raw meat harbors a variety of bacteria and parasites. While animals in the wild eat raw meat, they most certainly are carriers of parasites. The droppings that untamed animals leave behind are another means for parasites to propagate. Whichever method you choose to feed your dog, eating raw meat remains a common way for worms to find a host.


The best way to prevent worms from attacking your dog is to give him or her a yearly deworming. Along with deworming, a dog must be consistently treated for fleas, even if the fleas are not readily apparent. Proper hygiene and grooming should always be a rule of thumb. Bathe your dog, take him or her to the groomer, and keep your dog in the house. If you let your dog run around outdoors often, then these methods of prevention must be employed more frequently.

Parasitic worms have many ways to infect their hosts. They are resilient and reproduce exponentially. Their presence is unobtrusive, and the harm they do to their hosts will be gradual but damaging if left untreated.

By Gabrielle Allemeier


The University of Georgia: College of Veterinary Medicine
VCA Animal Hospitals: Tapeworm Infection in Dogs

About the Author
Gabrielle Allemeier volunteers her free time as an animal rescuer and foster pet parent. As an animal lover, she enjoys sharing the knowledge she has gained from her experience with a variety of animals. Along with being an animal lover, Gabrielle is a globetrotter. She lives in Los Angeles, California with her terrier, Thisbe.