Spirocerca Lupi: The South African Worm Most Owners Have Never Heard Of

An unusual life cycle

Spirocerca lupi is a worm that a dog acquires by eating a dung beetle, or by eating something that has eaten a dung beetle — a lizard, a bird, a frog.

From the stomach, the larvae migrate through the body wall and along the aorta before settling in the wall of the oesophagus, where they form a nodule.

It is common across the warmer parts of South Africa, particularly Gauteng, Limpopo, Mpumalanga and KwaZulu-Natal. Many owners have never heard of it until their dog is diagnosed.

Why it is serious

The nodule in the oesophagus can transform into a malignant tumour, usually an osteosarcoma or fibrosarcoma. Once that happens the prognosis is poor.

The migration along the aorta can also cause aneurysm and, rarely, fatal rupture.

Caught in the nodular stage before transformation, it is treatable. That is the whole reason for knowing the signs.

The signs

• Regurgitation — food coming back up undigested, without the heaving of true vomiting
• Difficulty swallowing, or repeated attempts to swallow
• Weight loss despite a normal appetite
• Coughing or retching, sometimes mistaken for kennel cough
• Excessive salivation
• In advanced cases, swelling of the limbs and lameness from a bone reaction

Regurgitation is the key one. If your dog is bringing food back up in a tube shape without abdominal effort, that is oesophageal and it needs investigation.

Diagnosis and treatment

Diagnosis is usually by endoscopy, where the nodule is seen directly, sometimes with radiographs or CT. Faecal testing is unreliable because eggs are shed intermittently.

Treatment is a course of specific antiparasitic medication, often over weeks to months, with repeat endoscopy to confirm the nodule is shrinking. Where transformation to cancer has occurred, options narrow considerably.

Prevention

Some monthly parasite preventatives include cover against spirocerca. In endemic areas this is worth asking your vet about specifically, because standard deworming tablets do not cover it.

Discourage dung beetle and lizard eating where you can. In practice this is difficult, which is why the preventative matters more than the supervision.