This disease is caused by a potentially lethal parasitic worm, spirocerca lupi, which is carried by dung beetles that ingest the spirocerca eggs present in faecal matter. Dung beetles are naturally coprophagic ( = feeding on excrement) and, having ingested spirocerca eggs, the immature larvae hatch inside the dung beetle. Dogs are infected when they are directly coprophagic themselves (eating faeces and manure), and so ingest the infected dung beetles.
They can also become parasitized when eating raw chicken meat, birds, rats, mice, lizards and frogs. Dogs with a tendency to forage and scavenge are at risk of incidentally ingesting dung beetles too.
Once the now-dead beetle is in the stomach of the dog, the larvae emerge and burrow through the stomach wall, entering the blood vessels, migrating “upstream” in the blood vessel walls until they reach the aorta. The larvae can live in the aortic wall for a few months, maturing into young adult worms and causing a weakening in the aortic wall, with the potentially fatal risk of an aortic aneurysm.
The young adult worms then migrate directly across the aortic wall into the oesophagus, and we most commonly find the parasitic nodules in the oesophagus with oesophagoscopy (= fibre-optic scoping ). These parasites can migrate anywhere throughout the body, via the blood vessels, and so nodules are not limited to the thoracic oesophagus. As the pathology progresses, radiological (= x-ray) changes are visible as the nodules increase in size and number.
Initially symptoms are vague and non-specific. Dogs may have an intermittent and undiagnosed Fever (fever-of-unknown-origin), they may salivate prolifically ( thick stringy saliva), and may intermittently regurgitate their meals (food not passing comfortably past the nodules in the oesophagus). They may have a hoarse retching cough, as though trying to clear their throat.
(Imagine trying to swallow a dry capsule yourself, and it gets “stuck” halfway down towards the stomach.) Eventually, untreated, this parasitic nodule evolves into a cancerous mass, and the dog will struggle to keep food down and be losing a dramatic amount of weight.
Spirocercosis is regarded as being an endemic problem in the Greater-Kyalami area, with the incidence of this disease being very high here. We CAN TREAT this worm both preventatively, and therapeutically in the EARLIER stages of the disease. Once the disease has progressed though, it is irreversible, severely debilitating, and ultimately fatal. You are welcome to discuss the diagnosis, treatment, and prevention of this disease with any of our vets.