Spirocerca lupi Esophageal Granulomas in 7 Dogs: Resolution after Treatment with Doramectin

Abstract

Seven dogs with Spirocerca lupi esophageal granulomas were identified based on the site of involvement (ie, distal esophagus) and characteristic endoscopic appearance. Six dogs presented with signs of esophageal disease and 1 dog was asymptomatic. Ova were only identified in the feces of 2 dogs. On thoracic radiographs, 4 dogs had evidence of a caudodorsal mediastinal mass, and 2 of these dogs had spondylitis of midthoracic vertebrae. On endoscopy, single esophageal nodules were observed in 5 dogs, 1 dog had 3 nodules, and 1 dog had 6 nodules. All 7 dogs were treated with doramectin at a dosage of 200 microg/kg SC at 14-day intervals for 3 treatments. Dogs had physical and endoscopic examinations at 2, 4, and 6 weeks after treatment. By 6 weeks, clinical signs had resolved in 6 dogs (1 dog was asymptomatic), and the esophageal nodules had completely resolved in 4 dogs, and incompletely resolved in 3 dogs. Two dogs with incomplete resolution were treated again with doramectin at 500 microg/kg PO daily for an additional 6 weeks. Complete resolution of the esophageal nodules was confirmed by endoscopy in all dogs. Nodules had resolved in 4 dogs by 6 weeks, in 2 dogs by 12 weeks (after 6 weeks additional daily oral therapy), and in 1 dog 22 months after the initial 200 microg/kg treatment regimen. No dog experienced adverse effects to the drug, and all symptomatic dogs have been free of disease for periods ranging from 3 to 4 years.

Occurrence of Spirocerca lupi Infection in Hungarian Dogs Referred for Gastroscopy

“…Some literature resources claim disophenol to be the only confirmed adulticide drug, but it does not affect juvenile worms and is not available on the market (Lobetti 2013). Other sources claim that macrocyclic lactones are an effective treatment for benign esophageal alterations caused by Spirocerca lupi (Berry 2000, Kelly et al 2008, Lobetti 2012, Austin et al 2013), while effective prevention is possible with avermectins, milbemycin and moxidectin , Kelly et al 2008, Kok et al 2010, 2011, Le Sueur et al 2010, Nolan et al 2012). In our experience, doramectin-treated patients become symptomfree, but use of the drug is greatly hindered by off-label application and the risk of complications.…”

The Efficacy of a Topically Applied Imidacloprid 10 % / Moxidectin 2.5 % Formulation (Advocate®, Advantage® Multi, Bayer) against Immature and Adult Spirocerca lupi Worms in Experimentally Infected Dogs

“…Therefore control of Spirocerca lupi in the final host by medical prevention or therapy seems to be the only viable option. Most studies in which macrocyclic lactones were tested for efficacy against S. lupi focused on therapeutic efficacy (Berry 2000;Lavy et al 2002;Kelly et al 2008), and although some treatment regimens have indicated promising preventative efficacy (Lavy et al 2003;Kok et al 2010;Le Sueur et al 2010), this issue remains largely unresolved. The present study was designed to evaluate both preventative and therapeutic efficacy in experimentally infected animals.…”

“…Various radiographic changes such as a caudal oesophageal mass with accompanying thoracic vertebral periosteal reactions are also supportive of a diagnosis (Dvir et al 2001), but direct visualisation of oesophageal nodules or neoplastic masses by means of an endoscopic examination remains the most sensitive method of diagnosis (van der Merwe et al 2008). Up until the time of this study, the most effective treatment for non-neoplastic spirocercosis appeared to be doramectin, administered subcutaneously in varying regimens (Berry 2000;Lavy et al 2002;van der Merwe et al 2008), although concerns exist about its extra-label use, mode of administration and breed-specific toxicity (Kok et al 2010). Orally administered milbemycin oxime has also been shown to have some efficacy against Spirocerca lupi (Kelly et al 2008;Kok et al 2010Kok et al , 2011.…”

“…2). The pathological changes associated with S. lupi infections are brought about by the migration of the larvae through the various tissues and organs as well as their persistent presence in the body (Berry 2000;Gal et al 2005). The most significant lesions include aortic aneurysms, posterior thoracic spondylitis and oesophageal nodule formation which often progresses to metastatic sarcoma (Bailey 1963;Dvir et al 2010).…”

“…There is no age or sex predilection, although animals under six months of age, even if infected, will not show clinical signs of infection because oesophageal spirocercosis develops gradually as the worms mature over an approximately six months period (van der Merwe et al 2008). Although S. lupi appears to have a worldwide distribution (Lavy et al 2003), it occurs most often in warmer tropical and subtropical climates (Bailey 1972;Berry 2000;van der Merwe et al 2008). The widespread importance of this parasite is demonstrated by numerous prevalence studies conducted in a number of countries over the last 5 decades (Brodey et al 1977;du Toit et al 2008;Haralabidis et al 1988;Lobetti 2000;Murray 1968;Mylonakis et al 2001;Oliveira-Sequeira et al 2002;Pandey et al 1987;Pence and Stone 1978;Ramírez-Barrios et al 2004).…”