What foods cause parasites in dogs?

Parasites are a common problem for dogs and can be contracted through food sources. Some of the most common food-borne parasites that affect dogs include various worms, protozoa, and other microscopic organisms. Feeding dogs raw meat or fish, exposure to stool from wildlife, contaminated water sources, and unsanitary conditions are some of the main ways dogs can acquire harmful parasites from food.

Raw Meat

Feeding raw meat to dogs can expose them to a few different types of parasitic worms. Raw meat may contain the eggs or larvae of roundworms, tapeworms, hookworms, and other worm parasites. When infected raw meat is consumed, these immature worm stages can hatch and mature inside the dog’s intestines. Some examples of parasitic worms dogs can get from raw meat and their effects include:

  • Roundworms – One of the most common parasites in dogs. Roundworm larvae migrate through the body and can cause respiratory illness and intestinal infections.
  • Tapeworms – Transmitted by fleas and larvae in raw meat. Tapeworm segments may be visible near the rear of an infected dog.
  • Hookworms – Larvae burrow into the intestinal lining and feed on blood. Can cause anemia, diarrhea, weight loss.
  • Whipworms – Live in the cecum and colon. Cause chronic bloody diarrhea, weight loss, and colitis.

To kill any parasitic ova or larvae, meat should be frozen (-4°F for 7 days or -31°F for 6 hours) or cooked thoroughly before feeding. Raw meat is best avoided to prevent parasite transmission.

Raw Fish

Raw fish also poses a risk for parasitic infections including:

  • Salmon Poisoning Disease – Caused by a fluke parasite found in raw salmon and trout. Leads to vomiting, fever, diarrhea.
  • Herring Worm Disease – A roundworm in uncooked herring and related fish. Larvae migrate and damage tissues.
  • Cod Worm Disease – Anisakid roundworm larvae in undercooked cod, haddock, flounder etc. May cause abdominal pain.
  • Diphyllobothrium Tapeworms – Transmitted through raw salmon, perch, trout and other fish. Can grow over 15 feet long in a dog’s intestines.

Freezing or cooking fish adequately destroys these parasites. Raw fish is best avoided.

Wildlife Stool Contamination

Dogs can pick up parasites like Giardia, coccidia, or cryptosporidium from exposure to contaminated water or stool from wildlife. Rivers, lakes, puddles, and groundwater sources may be contaminated with feces from wild animals harboring these parasites. Drinking this water or eating food exposed to it can infect dogs. Dangers include:

  • Giardia – Microscopic protozoan parasite causing diarrhea, gas, greasy stools.
  • Coccidia – Intestinal protozoa leading to watery diarrhea, abdominal pain, nausea.
  • Cryptosporidium – Microscopic protozoan that spreads rapidly and causes severe diarrhea.

Preventing dogs from accessing potentially contaminated water sources can reduce risk. Promptly cleaning areas contaminated by wildlife stool on walks also helps avoid exposure.

Contaminated Water

Along with wildlife fecal contamination, unsanitary water sources expose dogs to parasites through drinking. Parasites that may infect dogs via contaminated water include:

  • Giardia
  • Coccidia
  • Cryptosporidium
  • Toxoplasmosis – Caused by a single-celled protozoan parasite called Toxoplasma gondii.
  • Neospora caninum – Single-celled protozoan parasite causing neuromuscular disorders.

Preventing dogs from accessing potentially contaminated puddles, ponds, lakes and other water sources reduces parasite risk. Providing dogs with clean, fresh drinking water is recommended.

Unsanitary Conditions

Dogs exposed to unsanitary conditions are also more prone to picking up food-borne parasites. Areas where dogs may encounter parasites include:

  • Dog parks
  • Kennels
  • Pet stores
  • Groomers
  • Boarding facilities
  • Doggy daycares
  • Backyards contaminated by wildlife stool

Regular cleaning and proper sanitization protocols at such facilities reduce environmental parasite contamination. Dogs with compromised immune systems may be especially susceptible.

Common Parasite Transmission Routes

The most common food-related routes dogs acquire dangerous parasites include:

  • Consuming raw meat or fish infected with larvae or eggs
  • Drinking contaminated water containing parasite cysts/oocysts
  • Eating food exposed to contaminated fecal matter
  • Licking/ingesting parasite eggs in contaminated environments
  • Eating infected rodents or wildlife

To reduce transmission risk, the following precautions are recommended:

  • Avoid feeding raw meat, fish, eggs
  • Cook animal products thoroughly
  • Prevent access to standing water sources
  • Pick up and dispose dog stool promptly
  • Clean food/water bowls regularly
  • Don’t allow dogs to scavenge dead wildlife

Most Common Parasites in Dogs

Some of the most prevalent parasites passed to dogs via contaminated food include:


– Very common intestinal worm in dogs

– Passed in larval form through animal tissue or stool

– Causes diarrhea, vomiting, weight loss, poor coat


– Intestinal blood-feeding worm

– Larvae enter through skin/ingestion

– Anemia, bloody stool, weight loss common


– Segmented flatworms residing in small intestine

– Transmitted through fleas or infected meat

– Often asymptomatic but may cause mild digestive upset


– Live in cecum/colon

– Cause chronic bloody diarrhea, weight loss, colitis

– Transmitted by ingesting soil contaminated with eggs


– Single-celled protozoan parasite

– Passed through cysts in contaminated water/soil

– Diarrhea, gas, greasy stools common


– Microscopic protozoa parasite

– Found in infected soil, water, feces

– Leads to watery diarrhea, nausea, and abdominal pain


– Microscopic protozoan parasite

– Passed through oocysts in contaminated water/soil

– Causes severe, chronic watery diarrhea

Signs of Parasites in Dogs

Some common signs that may indicate a dog has an intestinal parasite include:

  • Diarrhea – Loose stools, often intermittent
  • Vomiting
  • Weight loss
  • Lethargy
  • Increased appetite
  • Constantly hungry but maintains poor body condition
  • Distended abdomen
  • Dull, dry coat
  • Evidence of worms in vomit/stool

More severe symptoms associated with some parasites include:

  • Bloody stool
  • Anemia
  • Dehydration
  • Fever
  • Coughing
  • Neurological impairment

Young puppies with heavy parasite burdens may also show slowed growth and failure to gain weight appropriately. Contacting a veterinarian is recommended if intestinal parasites are suspected.

Diagnosing Parasites in Dogs

Several methods veterinarians use to diagnose parasites include:

  • Fecal examination – Microscopic examination of a stool sample for parasite eggs, larvae, or protozoan cysts.
  • Fecal flotation – Using a solution to float and concentrate parasite eggs for easier identification.
  • Fecal smear – A thin layer of stool on a slide examined under a microscope.
  • Fecal antigen testing – Detecting parasite proteins and antigens through immunoassays.
  • PCR testing – Detecting parasitic DNA in feces using polymerase chain reaction assays.
  • Biopsy – Examining intestinal tissue samples for parasites.

Certain symptoms and history may also indicate a high parasite likelihood prompting testing. Puppies should be routinely screened.

Treating Parasites in Dogs

Most intestinal parasites are treatable with prescription deworming medications. Common anti-parasitic drugs used in dogs include:

  • Fenbendazole
  • Milbemycin
  • Praziquantel
  • Pyrantel
  • Ivermectin
  • Metronidazole

Multi-drug treatments targeting different parasites at once may be prescribed. Follow-up fecal exams are recommended to confirm elimination after treatment. Environment disinfection, proper hygiene, and preventing re-exposure are also key.

Preventing Parasites in Dogs

Some tips to help prevent dogs from acquiring parasites through food include:

  • Avoid feeding raw meat or fish
  • Thoroughly cook any animal product fed
  • Wash hands after handling raw meat
  • Clean food bowls regularly
  • Don’t allow access to standing water sources
  • Pick up dog stool promptly
  • Treat water to eliminate parasites
  • Bathe and groom dogs regularly
  • Use monthly heartworm and intestinal parasite prevention medication
  • Avoid dog exposure to wild animal feces

Promptly treating any parasites found through routine fecal screening is also crucial. With vigilance and proactive steps, intestinal parasites can be avoided and dogs kept healthy.


Parasitic infections pose serious health risks to dogs when acquired through contaminated food sources or environments. Roundworms, hookworms, whipworms, tapeworms, giardia, coccidia, cryptosporidium, and toxoplasma are examples of common parasites transmitted via food. Feeding raw meat, fish and exposure to infected fecal matter from wildlife or dogs are prime routes of transmission. Preventive measures include: cooking animal products fed, cleaning food/water bowls, preventing standing water access, promptly removing dog stool, controlling wildlife and not allowing dogs to scavenge dead animals. Monthly preventatives, routine fecal testing and proper hygiene are key in keeping dogs parasite-free.

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