Like many parasitic worms, whipworms are acquired through the fecal-oral route. A dog who consumes or licks something contaminated with whipworm eggs may contract the infection. Whipworms begin as eggs which hatch upon contacting the commensal bacteria in the small intestine. Once there, the larvae burrow into the villi of the intestine, which are protruding structures that aid in nutrient absorption. The dog’s immune system reacts to this by releasing inflammatory factors that aid in attacking the worms. A side affect of this inflammation is the flattening of these villi, which can reduce the dog’s ability to absorb nutrients.

As the larvae mature, they move further down the digestive tract into the large intestine, where they thread themselves into the mucous lining and feed on the various secretions. Although the worms do not feed on blood, their action and associated inflammation can cause bleeding. If your dog has lost weight, seems weak or lethargic, and has passed bloody, soft stools, they may be infected with whipworms. While many light cases of whipworms may persist for months or years without any symptoms, another illness that draws the attention of the immune system elsewhere may allow an outbreak to occur. Schedule a veterinarian visit if you suspect your dog may have whipworms.

If you notice a change in your dog’s weight or eating habits not explained by a change in diet or exercise, monitor the animal’s gastrointestinal health, and see a veterinarian if your dog has begun to pass loose, bloody stools or is behaving lethargically, as these may indicate a parasitic infection.

A veterinarian will likely request a stool sample to diagnose whipworms. By mixing a sample with water and centrifuging it, the eggs may be separated and viewed under a microscope. The large, double-ended eggs do not float as readily as those of other parasitic infections like hookworms, and are present in smaller numbers.

If the secondary symptoms of whipworms are severe, such as inflammation of the gut, the veterinarian may order an ultrasound as a “first look” at the problem. Ultrasound is an easy way to image the body, and can be done painlessly in even a small office. The vet will apply a small amount of conductive gel to the abdomen of your dog, and move the imaging wand around. Images of the intestines will appear on the screen and can show inflammation and dilation. If these symptoms do not improve with treatment of the whipworms, more detailed imaging may be required, such as MRI or CT scans. These may need to be done in a larger animal hospital, as local veterinarians usually cannot accommodate such large machines.

The treatment for whipworms is an anti-parasitic agent, usually taken orally in pill form. Fenbendazole, milbemycin, and oxantel are often the first choice for treatment. As with antibiotics, the full course of treatment should be taken even as symptoms begin to improve. This ensures complete eradication of the disease.

If the inflammation and irritation of the digestive tract persists in spite of treatment, anti-inflammatory drugs may be prescribed to control swelling and restore absorption capability to the small intestine. Additional supportive actions may be necessary if your dog is severely weakened or anemic. These often include IV fluids and iron supplements.

In the vast majority of cases, symptoms are not overly severe, and recovery is swift. Improvement can be seen in as little as a week, and full recovery in about 4. Unlike many parasite eggs, whipworm eggs are highly susceptible to desiccation (drying out) and thus dying rather than going dormant. Maintaining a clean, dry living space and supervising your dog’s outdoor play dramatically reduces the chance of re-infection. Hookworms are transmissible to humans and other dogs, so make sure to clean contaminated areas wearing gloves and using 10% bleach solution, which will kill the parasites. Keep your dog away from children and other dogs while it is recovering from whipworms.