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Jackson, R. R., Pollard, S. D., Li, D., & Fijn, N. (2002). Interpopulation variation in the risk-related decisions of Portia labiata, an araneophagic jumping spider (Araneae, Salticidae), during predatory sequences with spitting spiders. Anim. Cogn., 5(4), 215–223.
Abstract: The extent to which decision-making processes are constrained in animals with small brains is poorly understood. Arthropods have brains much smaller and simpler than those of birds and mammals. This raises questions concerning limitations on how intricate the decision-making processes might be in arthropods. At Los Banos in the Philippines, Scytodes pallidus is a spitting spider that specialises in preying on jumping spiders, and Portia labiata is a jumping spider that preys on S. pallidus. Scytodid spit comes from the mouth, and egg-carrying females are less dangerous than eggless scytodids because the female uses her chelicerae to hold her eggs. Held eggs block her mouth, and she has to release them before she can spit. The Los Banos P. labiata sometimes adjusts its tactics depending on whether the scytodid encountered is carrying eggs or not. When pursuing eggless scytodids, the Los Banos P. labiata usually takes detour routes that enable it to close in from behind (away from the scytodid's line of fire). However, when pursuing egg-carrying scytodids, the Los Banos P. labiata sometimes takes faster direct routes to reach these safer prey. The Los Banos P. labiata apparently makes risk-related adjustments specific to whether scytodids are carrying eggs, but P. labiata from Sagada in the Philippines (allopatric to Scytodes) fails to make comparable risk-related adjustments.
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Endy, T. P., & Nisalak, A. (2002). Japanese encephalitis virus: ecology and epidemiology. Curr Top Microbiol Immunol, 267, 11–48.
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Scott, L. D. (2006). Living donor liver transplant--is the horse already out of the barn? Am J Gastroenterol, 101(4), 686–688.
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Christie, J. L., Hewson, C. J., Riley, C. B., McNiven, M. A., Dohoo, I. R., & Bate, L. A. (2006). Management factors affecting stereotypies and body condition score in nonracing horses in Prince Edward Island. Can Vet J, 47(2), 136–143.
Abstract: In North America, there are few representative data about the effects of management practices on equine welfare. In a randomized survey of 312 nonracing horses in Prince Edward Island (response rate 68.4%), owners completed a pretested questionnaire and a veterinarian examined each horse. Regression analyses identified factors affecting 2 welfare markers: body condition score (BCS) and stereotypic behavior. Horses' BCSs were high (mean 5.7, on a 9-point scale) and were associated with sex (males had lower BCSs than females; P < 0.001) and examination date (P = 0.052). Prevalences of crib biting, wind sucking, and weaving were 3.8%, 3.8%, and 4.8%, respectively. Age (OR = 1.07, P = 0.08) and hours worked weekly (OR = 1.12, P = 0.03) were risk factors for weaving. Straw bedding (OR = 0.3, P = 0.03), daily hours at pasture (OR = 0.94, P = 0.02), and horse type (drafts and miniatures had a lower risk than light horses; P = 0.12) reduced the risk of horses showing oral stereotypies. Some of these results contradict those of other studies perhaps because of populations concerned.
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McGreevy, P. D., Cripps, P. J., French, N. P., Green, L. E., & Nicol, C. J. (1995). Management factors associated with stereotypic and redirected behaviour in the thoroughbred horse. Equine Vet J, 27(2), 86–91.
Abstract: A greater knowledge of the effect of management factors is required to investigate the ontogeny of abnormal behaviour in the stabled horse. A postal survey of racehorse (flat) trainers yielded information about 22 yard and management factors. The relationship of the factors to the prevalence of abnormal behaviour was analysed by logistic regression. Management factors related to the time spent in the stable showed the strongest associations with stereotypic behaviour. The risk of horses performing abnormal behaviour increased: 1) as the amount of forage fell below 6.8 kg/day, 2) when bedding types other than straw were used, 3) when the total number of horses on the yard was fewer than 75, 4) in association with box designs that minimised contact between neighbouring horses, 5) when hay, rather than other types of forage, was used.
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Murray, J. K., Singer, E. R., Morgan, K. L., Proudman, C. J., & French, N. P. (2004). Memory decay and performance-related information bias in the reporting of scores by event riders. Preventive Veterinary Medicine, 63(3-4), 173–182.
Abstract: We used data from a case-control study investigating risk factors for horse falls in the cross-country phase of eventing in Great Britain (GB) to examine evidence for memory decay and information bias. Responses to two questions obtained by telephone for 173 cases and 521 controls were examined for evidence of differential reporting according to the respondent's case-control status and performance in the dressage and cross-country phases of competitions. Information bias was found in the accuracy of reporting dressage penalty scores when analysed as a function of performance level (good/poor). Poor dressage performers were less likely to report accurate dressage scores than good performers. The accuracy of reporting dressage scores decreased as the time between the event and questionnaire completion increased, with no case-control interaction. Competitors who incurred cross-country jumping penalties at the event preceding the selected event reported their cross-country scores with less accuracy when compared with competitors who incurred no penalties. No information bias was found when the reporting of dressage and cross-country scores were analysed as a function of respondent category (case/control).
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Nagy, K., Schrott, A., & Kabai, P. (2008). Possible influence of neighbours on stereotypic behaviour in horses. Appl. Anim. Behav. Sci., 111(3-4), 321–328.
Abstract: Revealing risk factors of abnormal stereotypic behaviour (ASB) in horses can help in the design of protective measures. Previous epidemiological studies indicate that social isolation, housing, management conditions, and feeding regime have a strong effect on developing ASB. The common belief that exposure to a stereotypic horse increases the risk of ASB has never been substantiated. Here we report that a generalised linear mixed models (GLMM) analysis of data on 287 horses of nine riding schools revealed that exposure to a stereotypic neighbour is a significant risk factor for performing stereotypy. Also, aggressive behaviour towards other horses increased the odds of stereotypy in the aggressor. These correspondences are unlikely to be a riding-school effect, because riding schools were treated as random factor in the GLMM. Risk factors identified by epidemiological studies cannot be treated as causal agents without independent evidence. Our aim in presenting these findings was to draw attention to the possibility of neighbour effects so that other researchers would include this variable in their surveys.
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Senior, J. M., Pinchbeck, G. L., Allister, R., Dugdale, A. H. A., Clark, L., Clutton, R. E., et al. (2006). Post anaesthetic colic in horses: a preventable complication? Equine Vet J, 38(5), 479–484.
Abstract: REASONS FOR PERFORMING STUDY: There is little information on the prevalence of, and risk factors associated with, post anaesthetic colic (PAC) in horses undergoing nonabdominal operations. OBJECTIVES: To undertake the first prospective study of prevalence of PAC and identify risk factors in its development in nonabdominal procedures. METHODS: A multicentre prospective case-control study was conducted, on every horse undergoing anaesthesia for a nonabdominal procedure between April 2004 and June 2005. Colic cases were defined as any horse with recognised signs of abdominal pain within 72 h of general anaesthesia that could not be attributed to any concurrent disease. Five control horses per case were selected randomly from the study population at all hospitals. Multivariable logistic regression analysis was used to examine the relationship between predictor variables and the risk of developing PAC. RESULTS: The estimated mean prevalence of PAC in the study population was 5.2% (95% CI, 2.8, 8.0). However, the prevalence of colic varied between each centre. The most commonly diagnosed cause of colic was impaction. Multivariable analyses showed that the centre involved and the type of surgery performed were associated with an increased risk of PAC. Preoperative food deprivation and the use of opioid drugs were confounding factors. CONCLUSIONS: Prevalence of PAC varied significantly between the 4 hospitals studied; there may be hospital-related covariates that account for this. The type of surgery performed influenced the risk of PAC. POTENTIAL RELEVANCE: Identifying the risk factors for PAC is a prerequisite for its prevention. This study indicates horses at increased risk of PAC that might benefit from a more critical evaluation of post anaesthetic gastrointestinal function and/or the provision of preventative measures. Further investigation is required to explain the variation in prevalence of PAC between centres.
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Kasashima, Y., Takahashi, T., Smith, R. K. W., Goodship, A. E., Kuwano, A., Ueno, T., et al. (2004). Prevalence of superficial digital flexor tendonitis and suspensory desmitis in Japanese Thoroughbred flat racehorses in 1999. Equine Vet J, 36(4), 346–350.
Abstract: REASONS FOR PERFORMING STUDY: Overstrain injuries to the superficial digital flexor tendon (SDFT) and suspensory ligament (SI) are among the most common musculoskeletal injuries which contribute to the considerable wastage of racing Thoroughbreds. Many epidemiological studies have demonstrated the prevalence of and risk factors for tendon injury when racing but have not included those injuries sustained during training. However, since tendon injury during training is seen commonly in clinical practice, it is appropriate to determine the overall prevalence of tendon injury sustained during both training and racing. OBJECTIVE: To determine the prevalence of overstrain injury to the SDFT and SL during training and racing among Thoroughbred flat racehorses in Japan in 1999. METHODS: A retrospective study was performed using a sample population of 10,262 Thoroughbred racehorses. The medical information database of Thoroughbred racehorses registered by the Japan Racing Association (JRA) in 1999 was analysed for SDFT and SL overstrain injury diagnosed by a veterinarian employed by JRA during training and racing. Jump racehorses were excluded from this study. RESULTS: The prevalence of forelimb SDFT tendonitis and SL desmitis was 11.1% (1130 cases) and 3.61% (370 cases) of the population, respectively. In the hindlimb, there were 0.06% (6 cases) and 0.14% (14 cases), respectively. Risks of SDF tendonitis in the forelimb in 3-year-olds or older horses were significantly higher than in 2-year-olds. In contrast, the risk of SL desmitis in the forelimb at age 3 and 4 years was 2.23 and 2.11 times higher, respectively, than in 2-year-olds, but this increased to 5.07 times in those age > or = 5 years. Entire males were at greater risk in comparison to females and geldings. CONCLUSIONS: The results suggest that the prevalence of SDF tendonitis and SL desmitis in the forelimb was associated with the horse's age and sex. The prevalence of SL desmitis increased further with age compared with SDF tendonitis, possibly reflecting a more rapid accumulation of degeneration in this structure. POTENTIAL RELEVANCE: The age-related risk demonstrated in this study provides further support that overstrain injuries are associated with accumulated degeneration. These data provide a valuable resource for further research into the aetiology of tendon injury in the racehorse.
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Bachmann, I., Audige, L., & Stauffacher, M. (2003). Risk factors associated with behavioural disorders of crib-biting, weaving and box-walking in Swiss horses. Equine Vet J, 35(2), 158–163.
Abstract: REASONS FOR PERFORMING STUDY: Studies on the prevalence of behavioural disorders in horses and on associated risk factors have revealed inconsistent results. There are many studies on the neuropharmacological, surgical or mechanical therapy of stereotypies, but little is known about their causation. OBJECTIVES: To explore risk factors associated with the occurrence of behavioural disorders in horses. METHODS: A sample of horse owners, selected randomly and representative for Switzerland, was contacted in a postal survey. Answers were provided for 622 stables (response rate 35.2%). Individual data of 2,341 horses were examined with path analysis (multivariable linear and logistic regression), and adjustment made for possible confounding effects due to age and breed. RESULTS: Out of 60 possible risk factors, 11 were associated with the outcome at the univariable level (null-hypothesis path model) and 3 factors remained after the backward logistic regression procedure. Mature Warmbloods and Thoroughbreds, assessed by the owners to be reactive, fed 4 times a day and without daily pasture, had increased odds of displaying crib-biting, weaving and box-walking. Furthermore, indirect associations of 5 factors with the outcome were identified. CONCLUSIONS: The final logistic regression model of risk factors leads to the hypotheses that causal prevention of stereotypic behaviours should be based upon housing and management conditions which allow tactile contact with other horses (e.g. mutual grooming), daily free movement (paddock or pasture), as well as the provision of high amounts of roughage but of little or no concentrates. POTENTIAL CLINICAL RELEVANCE: It is one of the aims of population medicine to prevent the development of behavioural disorders. Further research is needed to test the concluding hypotheses in experimental studies or to verify them in the context of similar observational studies.
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