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Diagnosis and Therapeutic Management of Oestrosis in Small Ruminants.

Abstract

Two goats and three sheep ageing around 1-2 years were presented with history of muco-purulent nasal discharges, laboured breathing, depression, anorexia and head pressing. The farmer had 12 goat and 18 sheep and were housed together. During the clinical examination a larvae came out from nostrils of one goat which was diagnosed as Oestrus ovis based on the keys. After confirmatory diagnosis of Oestrus ovis infestation, the animals and all contact animals were treated with Ivermectin along with supportive therapy. Clinical improvement and animal recovery was observed.

Keywords: Goat; ivermectin; larvae; nasal myiasis; Oestrus ovis.

Introduction

Myiasis is the infestation of living humans or animals with larvae of dipteran flies, which at least for a certain period feed on the host's dead or living tissues, body substances or ingested foods. The nasal bot fly, Oestrus ovis are well-known parasites in nasal cavities and frontal sinuses, sometimes also in maxillary sinuses of domestic sheep, goats and some wild ruminants worldwide causing the clinical picture known as oestrosis or nasal myiasis (Soulsby, 1992; Sharma et al., 2014). The disease is widely prevalent in sheep but clinical reports are rare in goat. The present report describes the cases of Oestrus ovis infestation (nasal bots) in goat and sheep.

History and Diagnosis

A farmer having a total of 12 non-descript goat and 18 sheep housed together brought 2 ailing goats and 3 sheep ageing around 1-2 years with history of muco-purulent nasal discharges (Fig.1), laboured breathing, depression, anorexia in coordinated gaits and head pressing in varying degrees. These animals were under treatment with nervine tonics without clinical improvement. During the clinical examination, one of the goats sneezed violently resulting in expulsion of 2.7 cm long larva from nasal opening of the animal (Fig.1). The same occurred in sheep during the 2nd day in the course of treatment (Fig. 2). The larvae were collected using camel brush in 70% Alcohol for further study. The larvae were identified as the larvae of Oestrus ovis (nasal botfly) based on the characteristic morphology as per Whitlock (1960) and Soulsby (1992) viz. a pair of sharp, dark brown, oral hooks which were connected to large internal cephalopharyngeal skeleton and by tufts of numerous brown hooks on anterior margins of each body segment dorsally (Fig.3). The last segment had posterior spiracle having characteristic 'D' shaped stigmal plate with one large opening communicated with several accessory openings. Based on history, clinical findings and microscopic examination, the condition was diagnosed as Oestrus ovis larva migration of nasal cavity. Therefore, it was decided to go for therapeutic therapy to relieve the animals from the ailment.

Treatment and Discussion

Based on the severity of infection, the animals were treated with fluid therapy (5% DNS). Inj. Intamox (a) (Amoxycillin and Cloxacillin) @ 4 mg/kg b. wt., inj. Melonex (a) (Meloxicam) 0.2 mg/kg b. wt. intramuscularly to control the infection of upper respiratory tracts. Inj. Ivermectin (Neomec (a)) @ 0.2 mg/kg b. wt., subcutaneously in therapeutic doses was given as specific endectoparasiticidal agent. All in contact sheep and goats were prophylactically treated with inj. Ivermectin to safeguard them against myiasis. Clinical improvement was noticed and animals completely recovered after third dose of Ivermectin. The farmer was instructed to apply fly trap and clean the premises thoroughly.

Oestrus ovis is a dipteran fly, an obligate parasite of sheep. The short lived, adult female deposits larvae by darting over the nostrils of animals unlike other dipteran flies that lay eggs over various sites. The larvae ascends to sinuses and feed on mucus secreted by nasal epithelium following irritation. Three moultings occur in sinuses and the third stage instar/larva when gets matured is removed from nostrils and burrows in soil to pupate. The main clinical signs of infection in host are sneezing and nasal discharges. Involvement of brain may produce nervous symptoms like 'gid' caused by Coenurus cerebralis and thus oestrosis is also referred as 'false gid' (Soulsby, 1992; Sharma et al., 2014).

The pathogenesis of oestrosis is related to traumatic effects caused by cuticular spines and oral hooks during larval migration, but is mainly caused by molecules secreted and excreted by larvae that induce hypersensitivity immune reaction. Such stimuli are responsible for pathological damage and local systemic immunostimulation (Jagannath et al., 1989). Aberrant infestation in goats are mostly common when sheep and goats are housed together. Moreover, oestrosis in goats is seldom detected in live animals and are usually diagnosed at thorough post mortem examination (Sharma et al., 2014; Bakhraibah, 2016). As in the present report too, the animals were treated for encephalitis with no clinical improvement. Therefore, it is concluded that myiasis, curable with therapeutic doses of Ivermectin should also be considered while dealing with encephalitis in small ruminants.

References

Bakhraibah, A. O. (2016). Prevalence and organ distribution of larval Oestrus ovis (Diptera: Oestridae), Cysticercus tenuicollis and Echinococcus granulosus (Cestoda:Taenidae) in slaughtered sheep and goats at Jeddah in Saudi Arabia. Indian J. Appl. Res. 6: 501-04.

Jagannath, M.S., Cozab, N. and Vijayasarathi, S. K. (1989). Histopathological changes in the nasal passage of sheep and goats infested with Oestrus ovis (Diptera: Oestridae). Ind. J. Ani. Sci. 59: 87-91.

Sharma, N., Nayakwadi, S., Pawaiya, R. S., Kumar, S., Tailie, W. A., Paul, S., Mishra, A. K., Gururaj, K., Kumar, A., Gupta, V. K. and Chaturvedi, V. (2014). Parasitic encephalomyelitis in goats due to aberrant infestation with botfly Oestrous ovis larvae. Adv. Anim. Vet. Sci. 2: 8-11.

Soulsby E.J.L. (1992). Helminthes, Arthropods and Protozoa of Domestic Animals, 7th Ed. Lea and Febiger (eds), Philadelphia, USA, p. 357-07.

Whitlock, J.H. (1960). Diagnosis of Veterinary Parasitism. Lea and Febiger, Philadelphia, USA, p. 34-35.

Devesh Kumar Giri, Govina Dewangan and Deepak Kumar Kashyap (1)

Veterinary Polytechnic Chhattisgarh Kamdhenu Vishwavidyalaya (CGKV) Surajpur - 497229 (Chhattisgarh)

(1.) Corresponding author. E-mail: deepakkashyap31@gmail.com

(a) - Brand of Intas Animal Health, Ahmedabad
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Title Annotation:Clinical Article
Author:Giri, Devesh Kumar; Dewangan, Govina; Kashyap, Deepak Kumar
Publication:Intas Polivet
Article Type:Report
Date:Jul 1, 2016
Words:978
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