Live from CVC San Diego: Small animal parasites that you'd rather forget, but shouldn't
On Sunday morning, Nov. 3, veterinary parasitologist Dr. Andrew Moorhead discussed several small animal nematodes that, though less common than normal parasitic culprits, veterinarians will encounter often enough that they should be kept in mind. Here are few that he discussed.
These nematodes, known as stomach worms, have a "spiky" cuticular collar that can cause local gastric irritation and bleeding when attached to the stomach mucosa. They can cause chronic vomiting, anorexia, melena, and anemia. Diagnosis usually involves identifying the worm in the vomit (they are the same diameter as Toxocara species but shorter). An endoscopic diagnosis is possible, as is detection of eggs on fecal flotation. The eggs are heavy, so a sedimentation technique will bring about better chances of egg identification. Dr. Moorhead recommended treatment with fenbendazole, pyrantel, or ivermectin.
Dr. Moorhead discussed two different nematodes grouped in this class—Pearsonema species, the urinary capillarids, and Eucoleus species, the respiratory capillarids.
Pearsonema plica infects dogs and cats, and Pearsonema feliscati seems to be specific to cats. Adult worms embed themselves in the urinary bladder mucosa and shed unembryonated eggs. Affected animals are usually asymptomatic, although cystitis can occur, causing hematuria and the need to urinate frequently. Infection is diagnosed by observing eggs in the urine sediment.
Eucoleus aerophilus infects foxes, dogs, and cats. Adult worms live in the mucosa of the trachea, bronchi, and bronchioles. Infection is usually asymptomatic, but a chronic cough or wheezing are occasionally noted. In severe cases, infection can cause tracheobronchitis, dyspnea, and pneumonia. Definitive diagnosis involves detecting the eggs (greenish-brown, asymmetrical eggs with a granular shell, bipolar plugs, and a single-cell embryo) on fecal flotation, in the sputum, or from a transtracheal wash.
Eucoleus boehmi infects dogs. Adult worms live in the mucosa of the nasal turbinates and sinuses. Infection is usually asymptomatic but can cause inflammation, resulting in sneezing and mucopurulent nasal discharge. Definitive diagnosis involves detecting the eggs (symmetrical and golden eggs with bipolar plugs and a pitted surface) on a smear of nasal discharge or on fecal flotation.
Fenbendazole and ivermectin have been used to treat capillarid infections.
These adult worms are more prominent in the southeastern United States and should always be a differential for a coughing cat. Adult worms live in the terminal bronchioles and alveolar ducts. Radiographic changes may be evident, but definitive diagnosis involves identifying larvae using the Baermann technique (the most reliable method) or on sedimentation or centrifugal flotation. The larvae have S-shaped, kinked tails and subterminal dorsal spines. Larvae may also be seen in the sputum. Treatment consists of fenbendazole or ivermectin. Prednisone can be given to treat the coughing.