Pneumoesophagography and the appearance of masses in the caudal portion of the esophagus in dogs with spirocercosis.

OBJECTIVE: To determine the usefulness of pneumoesophagography, compared with that of survey radiography, for characterization of esophageal pathological changes in dogs with endoscopically confirmed intraluminal Spirocerca lupi nodules in the caudal portion of the esophagus. DESIGN: Diagnostic test evaluation. ANIMALS: 30 dogs with endoscopically confirmed spirocercosis. PROCEDURES: Dorsoventral (DV) and right lateral recumbent (RLR) thoracic survey radiographs were obtained for each dog. Endoscopy was subsequently performed, the esophagus was inflated with air, and left lateral recumbent, RLR, DV, and ventrodorsal thoracic radiographs were obtained. The amount of esophageal and gastric distention was recorded. Visibility, location, and surface characteristics of lesions and total length of esophageal involvement were recorded independently for each radiograph and modality and compared with each other. RESULTS: Survey DV radiographs were more reliable than survey RLR radiographs for detecting caudal esophageal pathological changes. Lateral pneumoesophagograms showed more esophageal air and had more visible nodules than did their orthogonal counterparts. Right lateral recumbent pneumoesophagograms allowed for evaluation of the air-filled stomach, particularly the cardiac portion, for additional pathological changes. Pneumoesophagography allowed the mural position (47% located dorsally) and surface characteristics of Spirocerca nodules to be determined. Six of 9 dogs with confirmed malignant disease had an irregular nodule surface suggestive of neoplastic transformation. CONCLUSIONS AND CLINICAL RELEVANCE: Pneumoesophagography was easily performed in dogs with spirocercosis and showed promise as a cost-effective and safe initial diagnostic procedure for further evaluation and characterization of suspected caudal esophageal lesions.

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.

Serum alkaline phosphatase activity is not a marker for neoplastic transformation of esophageal nodules in canine spirocercosis.

BACKGROUND: Spirocerca lupi is a nematode of Canidae that matures within the esophageal wall to form fibroblastic nodules with potential for malignant transformation. Diagnosis is based on histopathologic examination, but false-negative results may be obtained from samples collected by endoscopy. Serum alkaline phosphatase (ALP) activity, frequently increased in hepatobiliary disease, is also increased in a variety of neoplastic conditions in dogs, including appendicular osteosarcoma, and has also been reported to be increased in dogs with spirocercosis. OBJECTIVE: The aim of this study was to evaluate serum ALP activity as a marker for malignant transformation of esophageal nodules in S. lupi-infected dogs. METHODS: In this retrospective study, medical records of dogs diagnosed with spirocercosis from 1991 to 2008 were reviewed, and serum ALP activity determined at presentation was compared between dogs with nonneoplastic and neoplastic nodules. Owing to use of multiple analyzers, ratios of ALP activity to the upper reference interval for ALP were calculated and compared. RESULTS: Median ALP activity ratios were 0.65 (0.07-4.00) and 0.86 (0.10-3.40) for dogs with nonneoplastic (n=88) and neoplastic (n=32) nodules, respectively, with no significant difference (P=.18) and substantial overlap between groups. Tumors included osteosarcoma (15 dogs), fibrosarcoma (15 dogs), and anaplastic sarcoma (2 dogs); there was no difference in ALP activity between the dogs with osteosarcoma and fibrosarcoma. CONCLUSION: ALP is a poor marker of malignant transformation in canine spirocercosis.

The effect of positioning on the radiographic appearance of caudodorsal mediastinal masses in the dog.

In this prospective study, the effect of thoracic positioning on the visibility and size of caudal esophageal masses caused by spirocercosis was investigated. Dorsoventral (DV), ventrodorsal (VD) as well as left lateral recumbent (LLR) and right lateral recumbent (RLR) thoracic radiographs of 28 dogs, diagnosed endoscopically with spirocercosis, were evaluated. The radiographic findings were compared with those of esophageal endoscopy. Masses were seen equally well in left vs. right recumbency as well as in DV vs. VD positions but in DV/VD views 86% of masses were detected whereas in lateral views only 50% of masses were identified. In spirocercosis-endemic areas DV and RLR views are advised as they also allow for better visualization of descending aorta aneurysms and to avoid interpreting the potentially normally visible esophagus in LLR in large dogs as a mass.

Clinical differentiation between dogs with benign and malignant spirocercosis.

Spirocerca lupi is a nematode infesting the canine oesophagus, where it induces the formation of a nodule that may transform into a malignant sarcoma. The current, retrospective study compared the clinical presentation, haematology, serum albumin and globulin and radiology of benign cases (n=31) and malignant cases (n=31) of spirocercosis. Dogs with spirocercosis-induced sarcoma were significantly older (6.4+/-1.91 years) than benign cases (4.93+/-2.87). In the malignant cases there were significantly (p=0.03) more sterilized females (10/31) and fewer intact males (4/31) compared to 2/31 and 13/31, respectively, in the benign cases. Hypertrophic osteopathy was observed in 38.7% of malignant cases and in none of the benign cases (p=0.0002). Common clinical signs included weight loss, regurgitation, anorexia, pyrexia (T>or=39.5 degrees ), respiratory complications and salivation but did not differ in prevalence between groups. On haematology, the malignant group had significantly (p<0.05) lower haematocrit (0.34+/-0.08 vs. 0.41+/-0.07) and higher white cell count (31.6+/-27.83 vs. 17.71+/-13.18 x 10(3)microl(-1)), mature neutrophil count (26.06+/-26.08 vs. 12.23+/-9.96 x 10(3)microl(-1)) and thrombocyte count (493.15+/-151.61 vs. 313.27+/-128.54 x 10(9)microl(-1)). There were no differences in the mean corpuscular volume and immature neutrophil count. On radiology, the mass length was not significantly different, but the height and the width of the malignant masses were significantly larger (62.59+/-15.15 mm and 73.93+/-20.94 mm) compared to the benign group (46.43+/-23.62 and 49.29+/-25.56, respectively). Spondylitis was more prevalent in the malignant group (67.86% vs. 38.46%, p=0.03). Examining secondary pulmonary changes revealed significantly higher prevalence of bronchial displacement in the malignant group (52% vs. 17%, p=0.008). Hypertrophic osteopathy appeared to be a very specific but relatively rare (poor sensitivity) marker of malignancy. Female gender, anaemia, leukocytosis, thrombocytosis, spondylitis and bronchial displacement are significantly more common in malignant cases, but appear in benign cases as well. However, if found together in a specific case, they should increase the index of suspicion for malignancy in a diagnosed spirocercosis case.

Spirocerca lupi infection in the dog: a review.

Spirocercosis is a disease occurring predominantly in Canidae, caused by the nematode Spirocerca lupi. Typical clinical signs are regurgitation, vomiting and dyspnoea. The life-cycle involves an intermediate (coprophagous beetle) and a variety of paratenic hosts. Larvae follow a specific migratory route, penetrating the gastric mucosa of the host, migrating along arteries, maturing in the thoracic aorta before eventually moving to the caudal oesophagus. Here the worm lives in nodules and passes larvated eggs which can be detected using zinc sulphate faecal flotation. Histologically, the mature oesophageal nodule is composed mostly of actively dividing fibroblasts. Spirocerca lupi-associated oesophageal sarcomas may occur and damage to the aorta results in aneurysms. A pathognomonic lesion for spirocercosis is spondylitis of the thoracic vertebrae. Primary radiological lesions include an oesophageal mass, usually in the terminal oesophagus, spondylitis, and undulation of the aortic border. Contrast radiography and computed tomography are helpful additional emerging modalities. Oesophageal endoscopy has a greater diagnostic sensitivity than radiography. Endoscopic biopsies are not sensitive for detecting neoplastic transformation. Doramectin is the current drug of choice, effectively killing adult worms and decreasing egg shedding. Early diagnosis of infection is still a challenge and to date no ideal regimen for prophylaxis has been published.