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Item Studies on Bunostomum trigoncephalum [i.e. trigonocephalum] the hookworm of sheep : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Veterinary Science at Massey University(Massey University, 1969) Graham, J. M.This thesis records a series of experimental observations on Bunostomum trigonocephalum. The studies were made under the following broad headings: a) pre-parasitic development b) comparison of routes of infection and studies of the mechanism of infection including exsheathment of the infective larvae c) the pathogenesis and patnogenicity of the parasite for the sheep host. The morphology and development of the first 1 second and third larval stages was examined, The moult of the first to the second stage was observed and the first stage cuticle appeared to disintegrate rather than be cast as an intact sheath. This moult occurred after about 5 days incubation at 21°c. Little larval growth occurred after the first moult and the second moult followed comparatively quickly, 80% of the larvae were in the infective stage after 7 days incubation. 0 0 Survival of infective larvae was compared at temperatures of 0 C, 10 c, 0 0 0 0 20 C, 27 C and 37 C. Larvae survived longest at 10 C. Infective larvae were administered to sheep intravenously, subcutaneously, intraruminally, orally and percutaneously. The largest infections were established after percutaneous administration. Infective larvae applied to the skin of sheep exsheathed rapidly and penetrated the keratinised layers of the skin. They were also found to exsheath on and penetrate into the skin of calves, gtli.nea pigs and rabbits. There was evidence that larvae migrated to the lungs in the guinea pigs and patent infections were established in some calves, During exsheathment the anterior portion of the sheath appeared to disintegrate allowing the larvae to emerge, This is unlike the processes which have been described in other strongylate nematodes. A variable proportion of the infective larvae were found to exsheath "spontaneously" in faecal cultures, Attempts were made to find what stimulates the infective larvae to exsheath, The results were inconclusive. The highest rate of exsheathment was obtained by·exposing larvae to buffer of pH 2. The addition of co2 enhanced the exsheathment rate but only at pH 2. Even so, the results were variable and difficult to reconcile with conditions on the skin surface. After infection of sheep the prepatent period was found to range from 54 to 60 days. The 24 hour egg-output per female worm was estimated in 5 infected sheep and was found to range from 2579 to 10480 eggs. Most of the Bunostomum were found in the intestine between 5 and 35 feet posterior to the gastric pylorus. Numbers of Bunostomum in excess of 2-300 caused a significant and progressive decline in haemoglobin, packed cell volume and total serum protein levels over observation periods of up to 16 weeks after infection, The serum protein decline was primarily due to a fall in albumin concentration. The animals so affected also showed evidence of anorexia, retarded growth rate and loss of weight, Diarrhoea occurred sporadically.Item Prevalence of selected infectious diseases in Samoan dogs : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Science at Massey University, Manawatu, New Zealand(Massey University, 2013) Carslake, Rosalind JaneSamoa has a tropical island climate ideally suited to many infectious diseases, and vectors for some infectious diseases are known to be present. Dogs are very commonly owned in Samoa with 88% of households owning an average of two dogs. Many canine infectious diseases are zoonotic and there is limited preventative medicine available for dogs in Samoa. There are very few studies into the presence of zoonotic pathogens in Samoa or other South Pacific islands, and the role of dogs as a reservoir for zoonotic diseases is unknown. The prevalence of selected infectious diseases was evaluated in 242 dogs undergoing surgical sterilisation in Samoa in July 2010 and August 2011. Data were obtained from dogs’ owners by interview, including age, environment and any previous preventative medication. Serum and faecal samples were collected, and the skin examined for external parasites. Seroprevalence of Leishmania infantum, Anaplasma phagocytophilum, Ehrlichia canis, Borrelia burgdorferi and Dirofilaria immitis were assessed using point of care qualitative ELISA assays. Faecal flotation was performed on fresh faecal samples to screen for intestinal parasites. Ninety-three faecal samples were also tested for Giardia and Cryptosporidium spp. The median age of dogs was one year, with a range of four months to eight years and 73.3% were male. The vast majority of dogs were owned, the remaining were stray animals. Prevalence of D. immitis was 46.8% and A. phagocytophilum seroprevalence was 8.4%. All serum samples tested negative for E. canis, B. burgdorferi and L. infantum. Prevalence of hookworm was 92.6%. Trichuris vulpis, Dipylidium caninum, Toxocara canis and Capillaria spp. were also detected. Prevalence of Giardia spp. was 29.0% while no Cryptosporidium was detected. Fleas were found on 83.7% of the dogs, ticks on 42.1% and lice on 8.1%. Identified ticks were Rhipicephalus sanguineus, with no Ixodes spp. found. The results indicate a very high prevalence of hookworm, D. immitis, and external parasites in Samoan dogs. This study provides valuable information on canine health and suggests dogs could play a role in the spread of some zoonoses in Samoa. Further studies are required to review the public health implications of this study.