Overview

Whipworms are an intestinal parasite that occurs in dogs worldwide and get their name from the whip-like shape of the adult worms. Dogs get by whipworms after ingesting an egg that passes through the stool of an infected dog left in the soil or other contaminated environments. While some dogs may have no clinical signs of infection, others may experience intermittent soft stool or diarrhea with blood or mucus. Whipworm eggs are extremely hardy in the environment, so prevention with monthly parasite prevention is critical. 

Cause

A nematode parasite, Trichuris vulpis causes whipworm infections in the large intestine (colon and cecum) in dogs. When an infected dog passes a whipworm egg in their stool, the egg is not infective to another dog (i.e., larvated) until 9-21 days in the environment. The eggs are quite hardy in the environment and can survive in the soil for years. Dogs become infected by whipworms after ingesting a larvated egg from a contaminated environment. The larvae enter the small intestine for a few days before moving to the colon and cecum to mature into adult whipworms. The adult worms take quite long before they start producing eggs (74-90 days), and then each female produces over 2,000 a day.

Clinical signs

Many dogs with whipworms may show no signs of infection. The most common clinical signs of whipworms may include any of the following:

• Blood or mucus in feces
• Straining to defecate
• Weight loss
• Anemia, lethargy, pale mucus membranes
• Soft stools or diarrhea
• Dehydration
• Decreased appetite 

Severe whipworm infections may sometimes cause vomiting, weakness, decreased heart rate, muscle tremors and abdominal pain. Rarely, heavy whipworm infections can also cause a serious intestinal condition called intussusception or even death. 

Diagnosis

Whipworms are diagnosed by bringing a fecal sample from your dog to your veterinarian to check for parasite eggs under a microscope (fecal flotation with centrifugation). Sometimes this test may not detect eggs despite the presence of a dog’s clinical signs of infection due to the long time it takes for adult worms to produce eggs or intermittent shedding of eggs in the feces. Repeat serial samples may be needed, or an ELISA test (Enzyme-Linked Immunosorbent Assay) can be used to detect whipworm antigens to confirm a diagnosis if whipworms are suspected but no eggs were detected.

If more significant signs of illness are present, your veterinarian may recommend additional testing such as bloodwork or abdominal imaging.

Treatment

Several anthelmintic medications, such as Panacur (fenbendazole) or Drontal Plus (febantel/pyrantel pamoate/praziquantel), are approved for treating whipworms in dogs. These treatments target adult worms only. Because the lifecycle of whipworms is quite long, this treatment must be repeated monthly for three months to treat the newly emerging adults as they mature.

Alternatively, after initial treatment, many monthly heartworm preventatives containing milbemycin or moxidectin (e.g., Interceptor, Sentinel, Trifexis, Advantage Multi) are approved for the monthly treatment and prevention of whipworms.

For more serious whipworm infections, fluid therapy or nutritional support may be needed.

Outcome

Most dogs with whipworms respond well to treatment and environmental control. Your veterinarian may recommend periodic fecal exams to monitor for infections. Persistent infection or reinfection is likely due to re-exposure to a contaminated environment. 

Prevention

• Prompt feces removal to prevent contaminating the environment with whipworm eggs
• Keep dogs on monthly parasite preventives to help prevent infections
• Use caution when bringing pets to areas where other dogs frequent (e.g., dog parks)

Updated Aug. 2024