Dogs can get parasites in many everyday ways: from other animals, from their environment, and even before they’re born or while nursing. Knowing the main routes of infection makes prevention much easier.

Main ways dogs get parasites

  • Eating parasite eggs or larvae in contaminated soil, grass, puddles, food, or water, usually from feces left by an infected animal.
  • Sniffing or licking contaminated surfaces , like sidewalks, parks, kennels, or dog areas where infected stool has been.
  • From their mother (before or after birth) : some worms (like roundworms and hookworms) can cross the placenta or pass through the milk to puppies.
  • Bites from other parasites , such as mosquitoes (heartworm) and fleas or ticks (tapeworms and blood parasites).
  • Eating infected prey or raw meat , like rodents, rabbits, or offal, which can carry tapeworms and other internal parasites.

Internal parasites: how they get in

Intestinal worms and other internal parasites usually enter through the mouth or skin. Some also use insects as carriers.

  • Fecal–oral route (most common)
    • Dog eats or licks something with microscopic eggs/larvae on it (grass, toys, paws, fur, soil, water, food bowls).
* Common for roundworms, hookworms, whipworms, and some protozoa (like Giardia, coccidia).
  • Before birth or via milk
    • Roundworm larvae can cross the placenta into unborn puppies, so they’re born already infected.
* Hookworm larvae can be in the mother’s first milk (colostrum), infecting newborn pups while nursing.
  • Through the skin
    • Certain hookworm larvae can penetrate skin, especially paws or thin skin of young puppies, after contact with contaminated soil.
* These larvae then migrate through the body to the intestines, where they mature.
  • Insect-borne internal parasites
    • Mosquitoes inject heartworm larvae when they bite; the larvae then develop inside the dog’s bloodstream and heart.
* Some blood parasites are spread by **ticks** , entering the bloodstream during a tick bite.
  • Eating prey or raw animal products
    • Dogs that hunt or eat raw meat/offal can ingest cysts or larvae of tapeworms and other parasites living in those tissues.
* Dogs also get the common tapeworm _Dipylidium caninum_ from eating infected fleas during grooming.

External parasites: fleas, ticks, mites, lice

External parasites live on the skin, coat, or ears and are picked up mostly by contact and environment.

  • Direct contact with other animals
    • Fleas, ticks, lice, and mites can move from one dog (or wild animal, cat, etc.) to another during close contact.
  • Infested environments
    • Fleas and mites can linger in bedding, carpets, grass, kennels, and dog parks; a passing dog brushes by and picks them up.
* Ticks wait on vegetation and attach when a dog walks past.
  • Ear parasites
    • Ear mites are often caught from close contact with another infected animal, especially in young or shelter dogs.

Everyday risk factors and “normal” scenarios

Several very common dog activities raise parasite risk.

  • Visiting dog parks, sidewalks, and public grass where many dogs defecate and not all owners pick up.
  • Drinking from puddles, ponds, or shared water bowls that may contain parasite stages from infected animals.
  • Living with or near multiple pets (kennels, rescues, multi-dog homes) without consistent deworming and flea/tick control.
  • Puppy age , seniors, and immune-compromised dogs are more likely to get sick from parasites and to carry higher loads.
  • Outdoor, hunting, suburban, or rural dogs have more contact with wildlife and soil, so they see more worms and tapeworms.

How to lower the risk

While parasites are common, routine prevention drastically reduces problems.

  • Use monthly parasite preventives (heartworm, intestinal worms, fleas, ticks) recommended by a vet.
  • Deworm puppies on a schedule, then adult dogs at intervals your vet suggests.
  • Pick up poop quickly and avoid letting your dog eat or sniff stool, dead animals, or unknown “snacks” outside.
  • Keep flea and tick control consistent year-round in most climates, not just in summer.
  • Avoid raw or undercooked meat/offal unless guided by a vet, and keep hunting dogs on strict parasite control.

Meta description: Learn how dogs get parasites—from worms and protozoa to fleas, ticks, and heartworm—including common infection routes, real-life risk factors, and key prevention tips to keep your dog safer.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.