Capillariasis is a parasitic disease that is caused by the Capillaria worm, three species of which are relevant to dogs. The infection is commonly misdiagnosed because the clinical signs are non-specific, and the parasite’s eggs, which are necessary for correct identification of the disease, are shed intermittently. Infection typically happens when a dog comes into contact with contaminated food or water.

Many dogs with capillariasis are asymptomatic, though some animals may exhibit symptoms arising from the infection. Symptoms are not specific to capillariasis and vary according to the type of infection. They include:

Capillariasis is caused by the Capillaria worm, which is a parasitic nematode found worldwide and which can be spread through contaminated food, water, or feces. It varies in size and appearance according to species and more commonly occurs in wild animals than in dogs or cats. Capillaria boehmi is responsible for nasal capillariasis, Capillaria aerophilus for pulmonary capillariasis, and Capillaria plica for capillariasis in the bladder. Infection is more likely to occur in dogs that live in endemic regions.

Because the symptoms of capillariasis are non-specific, the veterinarian will need to examine your dog in order to correctly diagnose the infection. If your dog is exhibiting unusual behavior or general discomfort, visit your veterinarian. Your veterinarian will perform an initial examination and take down your dog’s history, which will help establish a complete medical profile.

The veterinarian may conduct laboratory testing as part of a routine exam, though blood tests and radiographs are not useful in determining capillariasis. A diagnosis is confirmed by the identification of Capillaria worm eggs in the urine, nasal fluids, or feces. Adult Capillaria boehmi worms may also be sighted during rhinoscopy, and a biopsy of affected tissue may reveal the presence of Capillaria worms buried in the body. With careful inspection beneath a microscope, the veterinarian will be able to determine which type of worm has infected your dog.

Capillariasis can be treated with anti-parasitic medication, such as ivermectin. If no complications have arisen due to the infection, treatment may be unnecessary, as the parasite may clear out so long as your dog is not reinfected. The veterinarian will reexamine your dog’s feces following treatment to ensure that eggs are no longer present.

Make sure that your dog has access to fresh food and clean water both during and after the recovery process, and avoid contact with material that may contain Capillaria eggs, such as urine or fecal matter. If your dog exhibited symptoms while ill, monitor him or her daily for any unusual signs. The symptoms should clear as the infection is resolved, though the veterinarian will need to conduct another examination in order to ensure that the parasite has been removed.

Reinfection is possible, especially if you live in an endemic region. The prognosis for capillariasis is good overall.