Successful resolution of oesophageal spirocercosis in 20 dogs following daily treatment with oral...
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Short Communication Successful resolution of oesophageal spirocercosis in 20 dogs following daily treatment with oral doramectin Remo Lobetti ⇑ Bryanston Veterinary Hospital, PO Box 67092, Bryanston 2021, South Africa article info Article history: Accepted 7 September 2011 Keywords: Spirocerca lupi Long acting avermectin Dog abstract The purpose of this study was to evaluate the effect of a daily oral dose of doramectin in dogs with spi- rocercosis. Twenty naturally infected dogs were treated with 0.5 mg/kg doramectin administered orally once daily for 42 days. In 13 of the dogs there was resolution of the nodules after 42 days. Nodules were eliminated in five of the remaining seven dogs following treatment for an additional 42 days. In the remaining two dogs, treatment continued for a further 42 days (total 126 days), resulting in complete res- olution. No adverse events associated with treatment were observed. This study concluded that doramec- tin at 0.5 mg/kg once a day is effective in the elimination of Spirocerca lupi nodules in dogs. Ó 2011 Elsevier Ltd. All rights reserved. Spirocercosis is caused by the nematode Spirocerca lupi, which occurs widely in tropical and subtropical areas and affects the dog and other Canidae. Over the years a number of different drugs have been used for treatment, some with considerable limitations. Diethylcarbamazine has been proven to ameliorate the clinical signs of infection but does not eliminate egg shedding and has no effect on the adult worms. Disophenol is highly effective against adult worms but has a narrow therapeutic margin (Seneviratna et al., 1966). A combination of nitroxynil and ivermectin was shown to be successful in 81.6% of dogs in one study (Reche-Emont et al., 2001), while another study used a combination of ivermectin and prednisolone, resulting in lesion regression after 60–180 days in five dogs (Mylonakis et al., 2004). Doramectin given at 0.2 mg/kg subcutaneously at 14-day inter- vals for three treatments to naturally infected dogs resulted in res- olution of clinical signs and regression of nodules within 42 days in 4/7 dogs (Berry, 2000). In the same study, two dogs that still had nodules were treated with daily oral 0.5 mg/kg doramectin for 6 weeks, resulting in resolution of the nodules by day 84. In exper- imentally infected dogs, 0.4 mg/kg doramectin at 14-day intervals for six treatments and then monthly intervals for up to 20 treat- ments resulted in nodule resolution after 35–544 days in 6/7 dogs (Lavy et al., 2002). In a study by Kelly et al. (2008), there was regression of oesophageal nodules in six dogs treated with oral milbemycin in 95–186 days. The purpose of this study was to evaluate the time that it would take to resolve S. lupi granulomas with a daily oral dose of 0.5 mg/kg of doramectin in naturally infected dogs. The reason for this dose and route is that in one study this regimen was successful in two dogs (Berry, 2000) and that oral dosing would also be easier and more convenient for owners, thus improving compliance. Twenty client-owned dogs with endoscopically-confirmed S. lupi nodules were investigated in this study. All dogs were natu- rally infected and were presented for evaluation of clinical signs of spirocercosis. Exclusion criteria were prior treatment with iver- mectin, doramectin, or milbemycin and if the nodule(s) appeared cauliflower-like, necrotic, or ulcerated on oesophagoscopy. All pro- cedures and therapy were performed with the written consent from the dogs’ owners. After diagnosis, all dogs were treated with 0.5 mg/kg of an injectable doramectin solution (Dectomax, Pfizer Animal Health) given orally once a day for 42 days. A repeat oesophagoscopy was then performed and dogs with nodules were treated for an additional 42 days, followed by repeat oesophagoscopy, and a fur- ther 42 days of treatment if the nodules still remained after that. To monitor for adverse effects, owners were contacted weekly and a full clinical examination was done prior to follow up endoscopy. Breeds included the German shepherd dog (GSD) (n = 9); Labra- dor, Jack Russell terrier (n = 2) and German shorthair pointer (n = 2), and one each of Bull terrier, Airedale terrier, Alaskan mala- mute, Border collie and Rottweiler breeds. When compared to the general hospital population, the GSD was significantly over-repre- sented (OR 12.2). Ten males and 10 females were included in the study and their median age was 59 months (range 13–116 months). The number of nodules present on oesophagoscopy ranged from 1–7 and all had a smooth and regular appearance without any 1090-0233/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.tvjl.2011.09.002 ⇑ Tel.: +27 11 7066023. E-mail address: [email protected] The Veterinary Journal 193 (2012) 277–278 Contents lists available at SciVerse ScienceDirect The Veterinary Journal journal homepage: www.elsevier.com/locate/tvjl
Transcript of Successful resolution of oesophageal spirocercosis in 20 dogs following daily treatment with oral...
The Veterinary Journal 193 (2012) 277–278
Contents lists available at SciVerse ScienceDirect
The Veterinary Journal
journal homepage: www.elsevier .com/ locate/ tv j l
Short Communication
Successful resolution of oesophageal spirocercosis in 20 dogs following dailytreatment with oral doramectin
Remo Lobetti ⇑Bryanston Veterinary Hospital, PO Box 67092, Bryanston 2021, South Africa
a r t i c l e i n f o a b s t r a c t
Article history:Accepted 7 September 2011
Keywords:Spirocerca lupiLong acting avermectinDog
1090-0233/$ - see front matter � 2011 Elsevier Ltd. Adoi:10.1016/j.tvjl.2011.09.002
⇑ Tel.: +27 11 7066023.E-mail address: [email protected]
The purpose of this study was to evaluate the effect of a daily oral dose of doramectin in dogs with spi-rocercosis. Twenty naturally infected dogs were treated with 0.5 mg/kg doramectin administered orallyonce daily for 42 days. In 13 of the dogs there was resolution of the nodules after 42 days. Nodules wereeliminated in five of the remaining seven dogs following treatment for an additional 42 days. In theremaining two dogs, treatment continued for a further 42 days (total 126 days), resulting in complete res-olution. No adverse events associated with treatment were observed. This study concluded that doramec-tin at 0.5 mg/kg once a day is effective in the elimination of Spirocerca lupi nodules in dogs.
� 2011 Elsevier Ltd. All rights reserved.
Spirocercosis is caused by the nematode Spirocerca lupi, whichoccurs widely in tropical and subtropical areas and affects thedog and other Canidae. Over the years a number of different drugshave been used for treatment, some with considerable limitations.Diethylcarbamazine has been proven to ameliorate the clinicalsigns of infection but does not eliminate egg shedding and hasno effect on the adult worms. Disophenol is highly effective againstadult worms but has a narrow therapeutic margin (Seneviratnaet al., 1966). A combination of nitroxynil and ivermectin wasshown to be successful in 81.6% of dogs in one study (Reche-Emontet al., 2001), while another study used a combination of ivermectinand prednisolone, resulting in lesion regression after 60–180 daysin five dogs (Mylonakis et al., 2004).
Doramectin given at 0.2 mg/kg subcutaneously at 14-day inter-vals for three treatments to naturally infected dogs resulted in res-olution of clinical signs and regression of nodules within 42 days in4/7 dogs (Berry, 2000). In the same study, two dogs that still hadnodules were treated with daily oral 0.5 mg/kg doramectin for6 weeks, resulting in resolution of the nodules by day 84. In exper-imentally infected dogs, 0.4 mg/kg doramectin at 14-day intervalsfor six treatments and then monthly intervals for up to 20 treat-ments resulted in nodule resolution after 35–544 days in 6/7 dogs(Lavy et al., 2002). In a study by Kelly et al. (2008), there wasregression of oesophageal nodules in six dogs treated with oralmilbemycin in 95–186 days.
The purpose of this study was to evaluate the time that it wouldtake to resolve S. lupi granulomas with a daily oral dose of0.5 mg/kg of doramectin in naturally infected dogs. The reason
ll rights reserved.
for this dose and route is that in one study this regimen wassuccessful in two dogs (Berry, 2000) and that oral dosing wouldalso be easier and more convenient for owners, thus improvingcompliance.
Twenty client-owned dogs with endoscopically-confirmedS. lupi nodules were investigated in this study. All dogs were natu-rally infected and were presented for evaluation of clinical signs ofspirocercosis. Exclusion criteria were prior treatment with iver-mectin, doramectin, or milbemycin and if the nodule(s) appearedcauliflower-like, necrotic, or ulcerated on oesophagoscopy. All pro-cedures and therapy were performed with the written consentfrom the dogs’ owners.
After diagnosis, all dogs were treated with 0.5 mg/kg of aninjectable doramectin solution (Dectomax, Pfizer Animal Health)given orally once a day for 42 days. A repeat oesophagoscopywas then performed and dogs with nodules were treated for anadditional 42 days, followed by repeat oesophagoscopy, and a fur-ther 42 days of treatment if the nodules still remained after that.To monitor for adverse effects, owners were contacted weeklyand a full clinical examination was done prior to follow upendoscopy.
Breeds included the German shepherd dog (GSD) (n = 9); Labra-dor, Jack Russell terrier (n = 2) and German shorthair pointer(n = 2), and one each of Bull terrier, Airedale terrier, Alaskan mala-mute, Border collie and Rottweiler breeds. When compared to thegeneral hospital population, the GSD was significantly over-repre-sented (OR 12.2). Ten males and 10 females were included in thestudy and their median age was 59 months (range 13–116months).
The number of nodules present on oesophagoscopy ranged from1–7 and all had a smooth and regular appearance without any
278 R. Lobetti / The Veterinary Journal 193 (2012) 277–278
evidence of necrosis or ulceration. All dogs showed resolution ofclinical signs within 7–10 days after commencing therapy. In 13of the dogs, there was complete nodule resolution after 42 daysof treatment. In this group the number of nodules present on initialoesophagoscopy ranged from 1–5 (median 2), the median age was51 months (range 13–116), and there were six males and sevenfemales. In the other seven dogs, nodules were still evident andnodule size remained unchanged after the first 42 days of treat-ment. In this group, the number of nodules present on initialoesophagoscopy ranged from 1–7 (median 2), the median agewas 64 months (range 46–112), and there were four males andthree females. Of the seven dogs, six were GSD with an OR of9.35 when compared to the rest of the group. Repeat treatmentwith 42 days of doramectin in these seven dogs resulted in com-plete resolution of the nodules in five dogs. The remaining twodogs both initially had a single nodule evident; one was male,one female; their ages were 46 and 47 months, respectively; onewas a GSD and the other an Airedale. Repeat treatment with42 days of doramectin resulted in complete resolution of thenodules in both dogs. The number of nodules in the dogs thatcleared their lesions within 42 days was not statistically differentto those dogs that took longer to clear their nodules.
This study showed that the oral administration of doramectinwas safe and effective in treating oesophageal spirocercosis. Alldogs showed a rapid resolution of clinical signs after commencingtherapy; 65% had complete resolution of the oesophageal nodulesafter 42 days; 25% after 84 days; and 10% after 126 days of therapy.Previous studies have reported resolution after 42–84 days (Berry,2000); 35–544 days (Lavy et al., 2002); 60–180 days (althoughonly one dog showed complete nodule resolution; Mylonakiset al., 2004); and 95–186 days (Kelly et al., 2008).
The dose of doramectin we used was much higher than that re-ported in the literature, i.e. 0.2 mg/kg subcutaneously every14 days for three treatments (Berry, 2000) and 0.4 mg/kg subcuta-neously every 14 days for six treatments, followed by monthlytreatment up to 20 treatments. Experimentally infected dogs givena daily dose of doramectin at 0.5 mg/kg for 91 days showed mild,transient, and reversible side effects (Conder et al., 2002). Noneof the dogs in this study showed any clinical adverse effects asso-ciated with the daily administration of doramectin. Given eitherorally or subcutaneously, the drug has been shown to be highlylipophilic with a half-life of approximately 3e days and a mean tis-sue residence time of approximately 5 days in the dog (Gokbulutet al., 2006). This suggests that dosing every 3–4 days may be
required to provide the prolonged exposure necessary to kill theparasite instead of dosing every 14 days, as has been previouslyreported (Lavy et al., 2002; Berry, 2000). However, evidence fromthis study suggests that some dogs require daily long-term admin-istration of doramectin.
The GSD was over represented in this study, confirming previ-ous published reports (Dvir et al., 2001). Seven of the GSDs in thisstudy did not respond to the initial course of therapy, which couldimply that the GSD may metabolise doramectin differently, absorbit less effectively, or that a longer duration of doramectin therapy isrequired before there is resolution of the oesophageal nodules inthis breed.
Conflict of interest statement
The author of this paper does not have a financial or personalrelationship with other people or organisations that could inappro-priately influence or bias the content of the paper.
References
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