DS research

Blood samples from 138 donkeys were examined, ranging in age from 4-24 years. Data from 18 haematological and 20 biochemical analytes were analysed using non-parametric statistical testing. Reference interval transferability was calculated showing 15/18 haematological and 14/19 biochemical RIs were transferable between previous donkey RIs and these RIs. Of particular clinical note when comparing the new donkey RI with that reported previously is a narrowing of the RI for triglycerides with the upper limit of the range being 2.8 mmol/l as compared with the previous 4.3 mmol/l. It is very important that veterinarians note this difference as this upper limit of triglycerides is commonly used to determine the risk of a donkey becoming hyperlipaemic.

Stable fly abundance increased over the course of the summer with peak numbers occurring in September. A high degree of variation in abundance was observed between different trapping sites. Multiple factors appear to affect their local abundance including availability of breeding sites, weather and availability of hosts.  Through pteridine flourescence analysis it was established that there appears to be a continuous emergence of adults throughout the season rather than discrete age-related cohorts.  Population peaks reflected overlapping generations.  Mass trapping for fly population control was not an effective method for supressing the stable fly population. 

Gastric ulcers recorded in 41% of 426 donkeys necropsied. Of which 89% of these donkeys had ulceration of the margo plicatus (squamous area), and 10% of had ulceration of the glandular area. 49% of ulcers were medium size (>2cm squared but <10cm squared), 28% small and 23% extensive. Donkeys on cereal based supplementary feed had 55% prevalence rate, donkeys on fibre based supplementary feed had 33% prevalence rate, donkeys on forage only had 34% prevalence rate. Chi-square test found association between cereal based diet and presence of ulcers.

1) Amongst the greatest constraints of donkey keeping were diseases including trypanosomiasis. As far as trypanosomiasis is concerned, findings indicate that the inhabitants of the Island were knowledgeable about the link between trypanosomiasis and tsetse. Apart from tsetse, the other vectors that affected donkeys included ticks, mites and biting flies. However, the distinction between tsetse flies and various biting flies was difficult for the respondents to make. The presence of wounds in donkeys and indications from key informants about overloading, over beating and poor watering practices as constraints may be a pointer to the need for increased sensitization of keepers for improved donkey management practices and increased productivity. The management of donkey health problems was perceived as a role to be played by the Donkey Sanctuary personnel. Community ownership of donkey management in terms of diseases and deworming was low. The majority of FEC results (McMasters) were negative, 84 and 72.3% in the dry and wet seasons respectively. Scarcity of feed and pasture for donkeys was also singled out as a constraint. 2) Trypanosomes were encountered in 3.1 and 7.5% of donkeys examined in dry and wet season respectively, the association between prevalence and season was significant at p<0.05. There was no significant difference in prevalence rates between villages. Infection rates were higher in donkeys in poor body condition ranging from 12 to 46% percent of poor donkeys in the dry and wet season respectively as opposed to 1.9 and 6.1% of those in good body condition. During both seasons mean PCVs of infected, young, female and donkeys in poor condition were lower than that of uninfected, adult, male and good condition donkeys. Anaemia (PCV <25%) was present in 88 and 71% of infected donkeys compared to 34.1 and 37.7% of uninfected donkeys in the dry and wet seasons respectively. Full results of PCR analysis are not available but preliminary indications are that there may be a number of sub-patent infections accounting for the anaemia. 3) Three species of trypanosomes were detected via BCT and Giemsa staining: Trypanosoma congolese Broden (68.7% of cases), Trypanosoma vivax Zieman (21.8%), Trypanosoma brucei Plimmer and Bradford (6.2%) and 6.2% of donkeys had mixed infections. BCT technique has limitations in cases of chronic infection and PCR analysis for a more accurate identification of prevalence is still pending, initial results indicate further species of Trypanosomes may be present and confirm suspicions of false negative results using smears. Drug sensitivity evaluation was hampered by difficulties with in vitro cultivation and was ceased. Ticks were identified in 51 and 43% of donkeys in dry and wet seasons respectively, although mean number of ticks were very few at 4.2 and 2.6 for dry and wet seasons. Dry season donkeys were found to be free from tick-borne disease, however Babesia was identified in 6 donkeys sampled in the wet season. Prevalence of ticks varied between villages in the wet season (p=0.0002), results showed that donkeys regularly driven through seawater would have fewer ticks. 4) The entomological surveys revealed the presence of Glossina pallidipes Austen species of tsetse fly and other biting flies Stomoxys spp. Linnaeus, Tabanus spp. Linnaeus and Haematopota spp. Linnaeus were also caught. Tsetse fly dissection did not reveal any trypanosomes, however PCR sample results may be a truer measure of trypanosome challenge as dissection may underestimate true infection rates.