Intestinal parasites are common in dogs; most will contract a parasitic infection at some point during their lifetime. Every time you take your dog for a walk, you potentially expose them to parasites. In addition, many parasites are transmitted from a mother to her puppies before birth or through milk. Several parasites also can cause health issues for humans and put you and your family at risk if your dog is infected. The most common intestinal parasites that affect dogs include the following:

• Roundworms — Toxocara canis (i.e., roundworms) are the most common parasitic worms found in dogs. Roundworm infection can occur by ingesting eggs from the environment, through the mother’s placenta before birth, through the mother’s milk, and by eating infected small animals. Roundworms typically don’t cause illness in a healthy, adult dog, but the parasites can stunt a puppy’s growth and cause significant gastrointestinal upset. Infected puppies often exhibit a potbellied appearance. Roundworms can cause eye, lung, heart, and neurological problems in humans, and children are at increased risk.

• Hookworms — Hookworms, including Ancylostoma caninum, Ancylostoma braziliense, and Uncinaria stenocephala, are intestinal parasites that get their name from the hook-like mouth parts they use to anchor themselves to a dog’s intestinal lining. These parasites ingest blood from vessels in the intestinal wall. A significant infection can cause intestinal inflammation and anemia, especially in puppies. Hookworm infection can occur through ingestion, the skin, and the mother’s placenta and milk. Hookworm larvae can burrow into human skin, usually through the feet, causing itching. In rare cases, hookworm larvae can migrate through the body, damaging eyes and internal organs.

• Tapeworms — Dipylidium caninum (i.e., tapeworms) are flat, segmented parasites that attach to a dog’s intestinal lining. Tapeworms are transmitted when a dog ingests an infected flea. Tapeworms typically don’t cause significant health problems for adult dogs, but the irritation to their perineal area may cause them to drag their hindquarters on the ground. Heavy tapeworm infections in puppies can lead to poor growth, anemia, and intestinal blockage. Fleas can also infect humans if they are accidentally ingested.

• Whipworms — Trichuris vulpis (i.e., whipworms) live in the dog’s large intestine and irritate the intestinal lining. Signs include bloody diarrhea, weight loss, and general debilitation. Transmission occurs when a dog eats a microscopic whipworm egg. Eggs can remain infective for up to five years. Whipworms are not infectious to people.

Preventing Parasites in Dogs

You can take steps to protect your dog from intestinal parasites:

• Clean your dog’s environment — Regularly remove your dog’s fecal material from your yard to help eradicate parasite eggs, larvae, and cysts.

• Avoid wildlife — Do not allow your dog to eat wild animals or carcasses.

• Avoid fecal matter — Do not allow your dog to come into contact with fecal matter from other dogs or cats.

• Avoid standing water — Do not allow your dog to drink from standing water because it can be contaminated with fecal matter. Bring fresh water and a portable water bowl when you go on outings to ensure you can offer your dog a clean drink when thirsty.

• Obtain regular fecal checks — Ask your veterinarian to perform a fecal check on your dog at least once a year. 

• Deworm your dog — Puppies should be dewormed at 2, 4, 6, and 8 weeks, and adults should be dewormed monthly.

Choosing the Best Dewormer for Your Dog

Regularly deworming your dog is crucial to ensure they remain parasite-free, but numerous products are available. Deciding which dewormer is best can be confusing. Keep reading to learn important criteria you should look for when choosing a dewormer for your dog. 

1. Ensure the product is FDA-approved
   When the U.S. Food and Drug Administration (FDA) approves a medication, it ensures the product is safe and effective when used according to the label. In addition, approval ensures the drug’s strength, quality, and purity are consistent from batch to batch, and the drug’s label is truthful, complete, and not misleading. The drug must undergo rigorous testing to meet the FDA’s requirements, and choosing an FDA-approved dewormer ensures the product is safe and effective for your dog.
2. Ensure the product is broad-spectrum
   Your dog is likely exposed to many intestinal parasites daily, and you want a product that protects against as many of them as possible. Several products also protect against fleas, ticks, and heartworms.
3. Ensure the product is easy to administer
   Deworming medication isn’t helpful if you can’t get your dog to take it! Administration options include chewable flavored tablets, powders, oral liquids, and spot-on treatments. Ensure the product comes in a form your dog will readily accept.
4. Ensure the product is suitable for your dog
   Ensure the product you choose is safe for your dog, and read the label carefully so you can administer the correct dose based on your pet’s weight. Some products are unsuitable for puppies or pregnant dogs, and others have particular age, weight, and breed guidelines. In addition, some products are contraindicated if your dog has a preexisting health condition. 

Intestinal parasites can cause significant health issues for your dog, but you can keep your pet parasite-free by choosing an appropriate dewormer. Consult your veterinarian if you have questions about which dewormer is best for your dog.