Long-term outcome of transendoscopic oesophageal mass ablation in dogs with Spirocerca lupi -associated oesophageal sarcoma

Veterinary Clinics: Tumor Ablation

Over the past decade, interventional oncology techniques have become integrated into the treatment plans of companion animals with cancer on a regular basis. Although procedures such as stenting are performed commonly, other less frequently utilized techniques for locoregional therapy, such as embolization and ablation, are emerging and demonstrating promise. Tumor ablation techniques are categorized into two subgroups: chemical ablation and energy-based ablation. Increased utilization of ablation will allow for the determination of specific indications and evaluation of outcomes for these techniques.

Postmortem detection and histopathological features of canine spirocercosis-induced putative esophageal chondrosarcoma

Aim:

The objective of this study was to describe and characterize the postmortem and histopathological findings of putative esophageal chondrosarcoma associated with Spirocerca lupi.

Materials and Methods:

Spirocerca-associated esophageal nodules were collected from 54 dogs at postmortem examination and were stained with hematoxylin and eosin. Of the cases examined, 15 were selected randomly for further investigation, of which 11 were classified as non-neoplastic nodules while 4 had changes reflecting a neoplastic process.

Results:

In all four neoplastic cases, the wall of the esophageal nodules contained islands and nests of highly proliferative atypical chondroblasts within a cartilaginous matrix. However, there was no statistically significant association between gender (p=0.228), age (p=0.568), and breeds (p>0.05) with the occurrence of spirocercosis. Moreover, all esophageal nodules identified were located near the caudal segment, and their diameters ranged from 1 to 6 cm (4.7±1.5 cm). A number of worms in each nodule varied from 5 to 25 (11.3±5).

Conclusion:

Histopathology and cytology revealed that the wall of the esophageal nodules contained islands and nests of highly proliferative atypical chondroblasts within a cartilaginous matrix, a rare finding, and clinical challenge in spirocercosis.

Evaluation of a spot-on imidacloprid-moxidectin formulation (Advocate®) for the treatment of naturally occurring esophageal spirocercosis in dogs: a double-blinded, placebo-controlled study

Background

Dogs are the definitive hosts of Spirocerca lupi. Spirocercosis is treated by prolonged avermectin administration by injection or daily oral doses. In this prospective, double-blinded, placebo-controlled, clinical trial, the efficacy of imidacloprid and moxidectin spot-on formulation (Advocate®) was compared to injectable doramectin (Dectomax®). Dogs diagnosed with benign esophageal spirocercosis were divided randomly into doramectin (400 μg/kg IM) or moxidectin and imidacloprid spot-on (2.5–6.25 mg/kg and 10–25 mg/kg, respectively) groups and treated weekly for 12 consecutive weeks. Dogs were followed for 20 weeks by physical examination, owners’ questionnaire, blood work, fecal floatation, PCR and endoscopy.

Results

All the doramectin group dogs (n = 10) completed the treatment and follow-up, and the disease had completely resolved in all by week 12. Of the Advocate® group (n = 10), four had complete resolution at week 12, four had partial resolution, one dog did not respond to treatment, and one dog was switched to the doramectin protocol on week 5 due to persistent severe clinical signs. PCR analysis was more sensitive in detecting S. lupi eggs compared to fecal floatation. Discrepancies were detected on 22 occasions, of which on 20 occasions, the PCR was positive while fecal floatation was negative, and only on two occasions the PCR results were negative while fecal flotation was positive.

Conclusions

The present results indicate that weekly Advocate® spot-on administration may be effective for treating benign esophageal spirocercosis, but is less effective than the currently used injectable doramectin therapy at the dose and duration used herein.

Spirocerca lupi induced oesophageal neoplasia: Predictors of surgical outcome

Canine spirocercosis is caused by the nematode Spirocerca lupi. Migration results in oesophageal fibro-inflammatory nodules that may undergo neoplastic transformation. No studies have assessed pre- or post-surgical prognostic indicators in dogs that undergo intervention for S. lupi induced oesophageal neoplasia. This observational, multi-center study aimed to assess the outcome of dogs with Spirocerca induced sarcoma undergoing endoscopic-guided ablation (n = 12) or surgery (n = 18), and identify prognostic indicators. Parameters evaluated included: age, weight, gender, presenting complaints, duration of clinical signs, complete blood count, serum biochemistry, neoplasia size, placement of percutaneous endoscopically-placed gastrostomy tube, histopathological mitotic indices, days to discharge and chemotherapy administration. Kaplan-Meier survival curves showed no difference in survival between ablation and surgery {(median: 73.5 days (range: 0-1511) vs. 108 days (range: 0-1550), respectively (p = 0.982)}. Reduced survival was documented in patients presenting with weight loss (P = 0.027), hypochromasia (MCHC <33 g/dL, P = 0.023) or leucocytosis (>15 × 10⁹/L, P = 0.017) with a hazard ratio of 2.51 (CI_95% = 1.071-6.018, P = 0.034), 2.71 (CI_95% = 1.10-6.65, P = 0.03) and 4.39 (CI_95%: 1.21-15.97, P = 0.025) respectively. In the dogs surviving more than 21 days, Ht <36% and leucocytosis >15.0 × 10⁹/L at presentation were associated with reduced survival (p = 0.016, p = 0.021 respectively) and hazard ratio of 3.29 (CI_95% = 1.18-9.2, P = 0.023) and 3.81 (CI_95% = 1.15-12.55, P = 0.028) respectively. Intra-intervention-group survival analysis identified increased survival time in dogs receiving chemotherapy, but only within the surgical group (P = 0.02).The hospitalisation time of dogs undergoing ablation (median: 0 days, range: 0-4) was significantly shorter than dogs undergoing surgery (9 days, 1-21) (P < 0.001). In this study, no clear benefit was identified for surgery, thus when ablation is technically possible it should be considered advantageous, as hospitalisation time is significantly shorter. Weight loss, hypochromasia and leucocytosis were identified as long-term prognostic indicators at presentation.