Spirocercosis in Dogs

Spirocerca lupi, also known as the esophageal worm, is a red or bright pinkish worm and ranging in size from 4 to 7 cm long. They generally are located within nodules in the esophageal, gastric, or aortic walls. These nodules in an infected host can inhibit swallowing, breathing, and blood circulation. This worm can prove fatal in dogs.

 

Life Cycle & Transmission

The disease is transmitted via infected dung beetles. The dogs eat infected dung beetles in the feces or leftover food in which the beetle lives. Dogs can also be infected if they eat an animal that has eaten an infected dung beetle, for example: bird, mouse, lizard, and so on.

The egg, containing the infective first stage-larva, is passed in the feces and eaten by a dung beetle, in which the larva develops to the infective third stage larva. When the dog eats these beetles, the larva penetrates through the stomach wall, and migrates in the arteries, eventually reaching the thoracic aorta in about 3 weeks. After about 10 to 12 weeks in the aorta the larva will migrate to the esophagus where it forms a cystic nodule which is connected by a fistula to the lumen of the esophagus. Here it develops to the adult stage. Eggs are laid in the cyst, pass out to the lumen of the esophagus and pass out with the feces. The prepatent period is between 5 and 6 months.  With time a granuloma forms around the cyst and eventually develops into a sarcoma of the esophagus. A mature worm can penetrate the trachea, lungs, stomach, kidneys, muscle sheath, and under the skin.

Damage caused

Larvae damage: In their travels, larvae can damage blood vessels and tissue, which often results in internal bleeding.

Worm damage: The worms can cause aorta and spinal column injury. Once encysted, the worm can cause various forms of tumors.

Symptoms

• Loss of appetite
• Difficulty of swallowing
• Cough
• Difficulty of breathing
• Salivation
• Vomiting
• Diarrhea
• Weight loss
• Sudden death due massive internal bleeding
• Symptoms of the disease can vary, sometimes, there are no symptoms at all

Diagnosis

• Fecal flotation test to detect eggs in feces
• Contrast radiography to see the nodules in oesophagus
• Oesophageal endoscopy to direct visualization of the granuloma

Treatment

• Treatment by injection with ivomectin or doramectin 3 doses at 2 week intervals is given after diagnosis of infection to destroy the larvae or mature worms in the body of the dog. 
• Prednisolone - orally, 0.5 mg/kg BW, every 12 h, for a total of 3 weeks.

Prevention

• Dogs are exposed to Spirocerca lupi infection daily, while walking in parks, around cow sheds, grassy areas, open fields and cattle farms.
• Have your dogs vaccinated by your veterinarian every 3 months with Ivomec or Dormectin to kill any parasites that might be in the system before they can cause damage. 
• Walk your dogs with a muzzle  if they tend to eat everything. 
• Don’t allow your dogs to wander freely without a leash.
• Prevent your dogs from eating stool or grass where the dung beetles may be present. 
• Collect your dogs' stool in public areas and throw it into garbage cans, thus helping to reduce the number of infected animals.