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Theses

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2001 - 20022
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Subject: Veterinary Parasitology × Author: KAU × End date: 2002 × Start date: 2001 ×
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    ThesisItemOpen Access
    Prevalence, pathology and treatment of coccidiosis in rabbits
    (Department of Veterinary Parasitology, College of Veterinary and Animal Sciences, Mannuthy, 2002) Shameem, H; KAU; Devada, K
    A detailed study on the prevalence, pathology and treatment of coccidial infections in rabbits belonging to all age groups, breeds and sex was undertaken at the Rabbit Research Station, Mannuthy and at six local rabbi tries in and around Thrissur during the period from October 2001 to September 2002. The overall prevalence was observed as 18.54 per cent. The prevalence of , coccidiosis was found to be high in young rabbits below three months and in female rabbits ofNew Zealand Whiteduring the months of heavy rainfall. The infection was diagnosed by the microscopical examination of faecal samples and clinical signs which included diarrhoea, soiled fur, anorexia and loss of condition. Subclinically affected rabbits showed no apparent signs except growth retardation and reduced feed intake. Six eimerian species causing coccidial infections in rabbits were I identified. Mixed infections were common and the commonly encountered species were E. magna, E. perforans and E. media. They were found as Eimeria media (80 per cent), E. magna (86 per cent), E. perforans (86 per cent), E. coecicola (50 per cent), E. jlavescens (15 per cent) and E. piriformis (8 per cent). Gross lesions found in the dead rabbits brought for postmortem at the Centre of Excellence in Pathology, College of Veterinary and Animal Sciences, Mannuthy comprised of oedematous, thickened intestine with circumscribed greyish white foci on the mucosa. Histopathological examination of the intestine revealed characteristic lesions of intestinal coccidiosis with schizonts and gametogonic stages in the / epithelium of the intestine. Active inflammatory reaction with mononuclear infiltration was noted. The tips of villi showed necrotic changes and desquamation of epithelial cells resulted in villous atrophy. Haematological studies of infected animals revealed reduction in the values of PCV, Hb and erythrocyte count and a slight increase in leucocyte count when compared to the apparently healthy animals. Therapeutic trials against rabbit coccidiosis usmg drugs like sulphadimidine sodium (200 mg per kg body weight for three days), furazolidone (10 mg per kg body weight for five days) and metronidazole (40 mg per kg body weight for three days) orally, showed sulphadimidine sodium as the drug of choice. The other two drugs did not give satisfactory results. The mean clearance values of the three drugs were 99.68 per cent, 85.48 per cent and 69.92 per cent respectively.
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    Development of a precocious strain of Eimeria tenella
    (Department of Veterinary Parasitology, College of Veterinary and Animal Sciences, Mannuthy, 2001) Sangeetha, R; KAU; Devada, K
    Studies on the prevalence of caecal coccidiosis in chicken, by referring to the postmortem registers maintained at the centre of Excellence in Pathology, College of Veterinary and Animal Sciences~ Mannuthy revealed that 48.4 per cent of 550 coccidia positive viscera was due to Eimeria tenella. A pure line of E. tenella was established in the laboratory by single oocyst isolation technique from a virulent field case of caecal coccidiosis in chicken. A stabilised strain of E. tenella was developed by administering a dose of 1.5x103 sporulated pure line E. tenella oocysts per bird orally to six three to five day old coccidia free White Leghorn chicks and harvesting the caecal contents at 168 hr pi for 15 cyclic~l passages. For the development of a precocious strain of E. tenella a dose of 1.5x103 sporulated E. tenella oocysts per bird was administered orally to six, three to five day old White Leghorn chicks. The caecal contents were harvested at 136 hr pi and the oocysts were allowed to sporulate and subsequently repassaged by applying selection pressure in increments of one hour reduction at each passage. At the end of 18 cyclical passages, oocysts obtained at 125 hr pi were designated E. tenella. as the precocious strain of. A comparative study between the precocious and stabilised strain of E. tenella revealed the following observations~ The prepatent period of the precocious strain was 125 hr while that of the stabilised strain was 135 hr. The oocyst morphology did not reveal any significant difference between the two strains. The precocious strain was less pathogenic and produced milder clinical signs than the stabilised strain. The gross lesions of caeca were less morbid in the precocious strain infected group. Weight gain was more in the precocious strain infected group than in the stabilised strain infected group. The precocious strain produced less mortality and showed a drop in oocyst production. Endogenous study revealed an accelerated growth in the early stages of the asexual life cycle in the precocious strain infected group.