New aspects on canine spirocercosis

Spirocerca lupi is a nematode parasite of carnivores affecting mainly the dog. Although S. lupi infection is often asymptomatic, esophageal granulomas and/or sarcomas, aortic aneurysms, thoracic discospondylitis or spondylosis deformans, hypertrophic osteopathy and salivary gland necrosis may be detected in various combinations upon the necropsy of dogs, originating from the endemic areas. When spirocercosis turns symptomatic, regurgitation, vomiting, odynophagia, hypersalivation, progressive loss of body weight, dyspnea and episodic melena are the most common clinical signs noticed. Diagnosis will be confirmed by fecal examination (egg detection), using flotation or sedimentation techniques, thoracic radiography (posterior mediestinal mass, vertebral lesions) and especially esophagoscopy, which allows the direct visualization of S. lupi nodules either granulomatous or neoplastic. Avermectins, such as doramectin and ivermectin, have been emerged as promising medications in the treatment and possibly in the prevention of canine spirocercosis. Their use, in both the spontaneous and experimental disease, has resulted in the remission of esophageal dysphagia, complete or partial regression of esophageal parasitic granulomas and cessation of egg shedding.

Canine spirocercosis-associated extraskeletal osteosarcoma with central nervous system metastasis

A five-year-old male Boerboel presented for examination, collapsed for an unknown period of time. On clinical examination, multifocal subcutaneous masses and enlarged prescapular lymph nodes as well as neurological deficits that suggested a multifocal neurological syndrome were found. Fine needle aspirates of the prescapular lymph nodes revealed cells suggestive of osteosarcoma. Radiographs showed foci of mineralisation within the soft tissue masses as well as diffuse pulmonary metastasis and a caudodorsal mediastinal mass believed to be a Spirocerca lupi nodule. Computed tomography imaging, necropsy and histopathology confirmed S. lupi oesophageal neoplastic transformation (extraskeletal osteosarcoma), believed to be the primary lesion, and the majority of secondary metastasis to the brain, spine, heart, multiple muscular groups and abdominal organs. This is the first known report of extraskeletal osteosarcoma metastasis to the brain and spinal cord in a dog.

Salivary gland enlargement and sialorrhoea in dogs with spirocercosis: A retrospective and prospective study of 298 cases

This longitudinal cross-sectional clinical study investigated the incidence of sialorrhoea in dogs with spirocercosis and determined whether breed, body weight and the extent of the oesophageal involvement was associated with this presentation. A retrospective analysis was performed on the medical records of 233 dogs and information pertaining to 65 dogs was collected as part of a prospective study. All the animals were client-owned. Patients from the retrospective study underwent thoracic radiography or oesophageal endoscopy to diagnose and characterise the infection and were placed on therapy with a macrocyclic lactone, whereas the patients in the prospective study had both radiography and endoscopy routinely performed and biopsies of the oesophageal nodules collected where possible. Tru-cut biopsies of affected salivary glands were taken in 10 of 13 patients demonstrating clinical signs of sialorrhoea and salivary gland enlargement. The entire salivary gland was sectioned in an additional three dogs with spirocercosis and no sialorrhoea that were presented for post mortem examination. Sialorrhoea was present in 33/298 cases (11%). Fox terrier breeds were over-represented in the patients with sialorrhoea, comprising 36% of cases, whereas they only comprised 1.5% of the patients without sialorrhoea (p < 0.001, chi squared test) and 5% of the combined group. Dogs weighing 12 kg or less were significantly over-represented in the sialorrhoea group, 69% versus 19.5% (p < 0.001, chi square test). Age was not significantly different between the two groups (p < 0.08, Mann-Whitney test). The number of oesophageal nodules per case was significantly higher in the non-sialorrhoea cases (p = 0.048, Mann-Whitney test). The prevalence of distal oesophageal and lower oesophageal sphincter involvement, and neoplastic transformation of the nodules were not statistically different between the two groups. None of the fox terriers in either group showed neoplastic transformation of the parasitic nodules even though they were over-represented as a breed. Mandibular salivary glands were affected in 86% of cases showing sialorrhoea. Histopathology revealed acinar hyperplasia in all cases with concurrent necrosis detected in only two cases.Sialorrhoea and salivary gland enlargement has an incidence of 11% (33/298 cases) in canine spirocercosis. Small breeds (≤ 12 kg) and particularly fox terrier breeds are over-represented in the group demonstrating sialorrhoea and this appeared to be the only risk factor.The conclusion was that sialorrhoea secondary to canine spirocercosis occurs frequently and its presence should prompt further investigation for oesophageal and gastro-intestinal disease. Severely affected patients can be managed with phenobarbitone to control the dysphagia in addition to the routine macrocyclic lactones treatment.

The sensitivity of direct faecal examination, direct faecal flotation, modified centrifugal faecal flotation and centrifugal sedimentation/flotation in the diagnosis of canine spirocercosis

Several faecal examination techniques have shown variable sensitivity in demonstrating Spirocerca lupi (S. lupi) eggs. The objective of this study was to determine which faecal examination technique, including a novel modified centrifugal flotation technique, was most sensitive to diagnose spirocercosis. Ten coproscopic examinations were performed on faeces collected from 33 dogs confirmed endoscopically to have spirocercosis. The tests included a direct faecal examination, a faecal sedimentation/flotation test, 4 direct faecal flotations and 4 modified faecal centrifugal flotations. These latter 2 flotation tests utilised 4 different faecal flotation solutions:NaNO3 (SG 1.22),MgSO4 (SG 1.29),ZnSO4 (SG 1.30) and sugar (SG 1.27). The sensitivity of the tests ranged between 42 %and 67 %, with theNaNO3 solution showing the highest sensitivity in both the direct and modified-centrifugal flotations. The modified NaNO3 centrifugal method ranked 1st with the highest mean egg count (45.24±83), and was superior (i.e. higher egg count) and significantly different (P< 0.05) compared with the routine saturated sugar,ZnSO4 andMgSO4 flotation methods. The routine NaNO3 flotation method was also superior and significantly different (P < 0.05) compared with the routine ZnSO4 andMgSO4 flotation methods. Fifteen per cent (n=5) of dogs had neoplastic oesophageal nodules and a further 18 % (n = 6) had both neoplastic and non-neoplastic nodules. S. lupi eggs were demonstrated in 40%of dogs with neoplastic nodules only and 72.9 % of the dogs with non-neoplastic nodules. The mean egg count in the non-neoplastic group (61) was statistically greater (P = 0.02) than that of the neoplastic group (1). The results show that faecal examination using a NaNO3 solution is the most sensitive in the diagnosis of spirocercosis. The modified centrifugal flotation faecal method using this solution has the highest egg count. The study also found that dogs with neoplastic nodules shed significantly fewer eggs than dogs with non-neoplastic nodules.