Spirocerca Lupi – Spirocercosis

The silent killer not everyone is aware of.

Spirocerca Lupi is a red worm that normally goes and sits and grows in your dog’s oesophagus.

This worm burrows into the oesophagus after migrating from the stomach after ingestion, creating a nodule that, in turn, is extremely irritant to your pet. As a result, it causes vomiting and in some cases haemorrhage into the stomach, leading to black coloured faeces.

Infections in domestic cats have been rare to nonexistent. Experimentally, it has been possible to cause lesions in cats although they have not been described under normal circumstances.

Animals infected with Spirocerca lose weight rapidly, due to all the vomiting. In some cases, infected animals can die acutely from burst aneurisms.

In severe cases, the nodule can turn cancerous if left untreated. These worms also migrate to different parts of the body via arteries and veins, which could cause blockages.

All of these things could, if not prevented and left untreated for too long, possibly lead to the death of your pet.

Animals generally get infected by ingesting the larvae that develops inside certain dung beetles. They can even get infected by eating other critters that have enjoyed the dung beetle as a meal.

An intermediate host (the dung beetle) and a final host (your pet) are required to complete this worm’s life cycle. The larvae are present had hatch in the beetle, when ingested by a dog, they start to wreak havoc.

Spirocerca Lupi can be prevented and treated if detected before the nodule has become cancerous.

The Signs and Symptoms of Dogs Suffering From Spirocercosis

Most dogs with S. lupi infection show no clinical signs, but when signs are present, they most commonly include weight loss, coughing and difficult/laboured breathing. When the oesophageal lesion is very large (usually when it has become neoplastic), the dog has difficulty swallowing and may vomit repeatedly after trying to eat. These dogs salivate profusely and eventually become emaciated. In addition, dogs may develop thickening of the long bones characteristic of hypertrophic osteopathy.

Now, sometimes dogs will vomit, retch or regurgitate. Other times, it may be more subtle. Dogs may just be off their food, lick their lips, cry when swallowing, ‘cough’ or ‘retch’. Some dogs just lose weight but continue eating.

Apart from the manifestations and consequences mentioned, the worm can also kill patients by damaging the aorta, obstructing the oesophagus, migrate to places other than those expected or the nodules can become cancerous, usually malignant osteosarcomas, which can spread to other organs, especially the lungs.

Occasionally, dogs may die suddenly as the result of massive bleeding into the thorax after rupture of the aorta that had been damaged by the developing worms.


Spirocerca lupi is most frequently diagnosed with the help of radiographs of the chest, as well as endoscopy of the oesophagus, where the clinician will see red nodules or scarring. As the worms grow bigger, the granuloma/nodule grows bigger. One obvious problem is in swallowing.
In rare instances, S. Lupi eggs can be seen on a faecal float, however, eggs are sporadically voided in faeces and can be difficult to find.

The characteristic lesions are aneurysms of the thoracic aorta, reactive granulomas of variable size around worms in the oesophagus and exostoses, benign outgrows from cartilage. Oesophageal cancer, which often spread (metastasis) to other areas of the body, is sometimes associated with S. lupi infection. Dogs with Spirocerca-related cancers often develop hypertrophic osteopathy (Marie’s Disease).

Treatment and Prevention

Treatment of clinical cases is often not practical. However, efficacy has been demonstrated with specific anthelmintics combined with COX-2 inhibitors, although none of these treatments have been approved. There are also certain anthelmintics that have adverse effects on certain breeds. Surgical removal usually is unsuccessful because of the large areas of the oesophagus involved.

Milbemax tablets and Advocate spot on are now registered to control Spirocerca with monthly treatment.

Preventing Spirocerca is actually fairly easy.

Keeping the garden clear of dog faeces will help in reducing the number of dung beetles. Monthly treatment with Milbemax tablets or Advocate spot on works effectively if given consistently.

We recommend all dogs to be put on a monthly preventative programme from a young age.

Unfortunately this will work to kill the worms, but the tumours and other complications will often not respond to treatment as the disease is often only noticed once there are tumours that have formed. Therefore prevention is extremely important.



Great news! You can purchase Milpro or Milbemax from our online store! Check it out here – https://kimvet.co.za/product-category/dogs/dog-deworming-tick-flea/

Andrew S. Peregrine , BVMS, PhD, DVM, DEVPC, DACVM, Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada

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