Abstract: In the horse, carbohydrate overload is thought to play an integral role in the onset of laminitis by drastically altering the profile of bacterial populations in the hindgut. The objectives of this study were to develop and validate microbial ecology methods to monitor changes in bacterial populations throughout the course of experimentally induced laminitis and to identify the predominant oligofructose-utilizing organisms. Laminitis was induced in five horses by administration of oligofructose. Faecal specimens were collected at 8 h intervals from 72 h before to 72 h after the administration of oligofructose. Hindgut microbiota able to utilize oligofructose were enumerated throughout the course of the experiment using habitat-simulating medium. Isolates were collected and representatives identified by 16S rRNA gene sequencing. The majority of these isolates collected belonged to the genus Streptococcus, 91% of which were identified as being most closely related to Streptococcus infantarius ssp. coli. Furthermore, S. infantarius ssp. coli was the predominant oligofructose-utilizing organism isolated before the onset of lameness. Fluorescence in situ hybridization probes developed to specifically target the isolated Streptococcus spp. demonstrated marked population increases between 8 and 16 h post oligofructose administration. This was followed by a rapid population decline which corresponded with a sharp decline in faecal pH and subsequently lameness at 24-32 h post oligofructose administration. This research suggests that streptococci within the Streptococcus bovis/equinus complex may be involved in the series of events which precede the onset of laminitis in the horse.

Abstract: REASONS FOR PERFORMING STUDY: Conformational traits are important in breeding, since they may be indicative for performance ability and susceptibility to injuries. OBJECTIVES: To study whether certain desired conformational traits of foals are related to lateralised behaviour while foraging and to the development of uneven feet. METHODS: Twenty-four Warmblood foals, born and raised at the same location, were studied for a year. Foraging behaviour was observed by means of weekly 10 min scan-sampling for 8 h. A preference test (PT) was developed to serve as a standardised tool to determine laterality. The foals were evaluated at age 3, 15, 27 and 55 weeks. The PT and distal limb conformation were used to study the relation between overall body conformation, laterality and the development of uneven feet. Pressure measurements were used to determine the loading patterns under the feet. RESULTS: About 50% of the foals developed a significant preference to protract the same limb systematically while grazing, which resulted in uneven feet and subsequently uneven loading patterns. Foals with relatively long limbs and small heads were predisposed to develop laterality and, consequently unevenness. CONCLUSIONS: Conformational traits may stimulate the development of laterality and therefore indirectly cause uneven feet.

Abstract: REASONS FOR PERFORMING STUDY: Dehydration and heat stress are serious welfare issues for equids working in developing countries. There is a lack of any standardised method or validated interpretation of the skin tent test in horses and donkeys. Owners of dehydrated and heat-stressed animals often depend on veterinary examination for identification of these conditions, leading to delays in treatment and unnecessary reliance on external sources to effect welfare improvement. OBJECTIVES: To validate a standardised skin tent test for dehydration and a behavioural measure of heat stress in working equids; and to examine the effect of heat stress and dehydration on tripping and staggering behaviour. METHODS: The study was carried out on 130 working horses and donkeys in Pakistan. Associations between skin tent and blood parameters (packed cell volume [PCV], serum total protein [TP], serum osmolality), clinical parameters, resting and drinking behaviour were examined. Heat stress behaviour (increased respiratory rate and depth, head nodding, flared nostrils, apathy) was observed in conjunction with rectal temperature. Tripping and staggering were assessed using a simple obstacle course. RESULTS: In both species, heat stress behaviour was significantly associated with increased rectal temperature (P<0.001). A positive skin tent test was not significantly associated with PCV or TP, although in donkeys it was significantly associated with lower serum osmolality (P<0.001). More animals age >15 years had a positive skin tent than those in younger age groups (P = 0.037). Very thin horses were more likely to have a positive skin tent than those in thin or moderate condition (P = 0.028). There was no significant correlation between skin tent and tripping or staggering in either species. CONCLUSIONS AND POTENTIAL RELEVANCE: Heat stress behaviour is related to increased body temperature in working horses and donkeys. Owners may use this to make judgements regarding rest and cooling, precluding the need to seek veterinary attention. The skin tent test for dehydration used in this study did not show a significant relationship with PCV or TP. However, the use of blood parameters to validate the skin tent test may be confounded by anaemia, hypoproteinaemia or electrolyte depletion. Alternative methods are needed to confirm or refute the validity of the skin tent test in working equids.

Abstract: REASONS FOR PERFORMING STUDY: The ability to shorten the duration of sedation would potentially improve safety and utility of detomidine. OBJECTIVES: To determine the effects of tolazoline and atipamezole after detomidine sedation. HYPOTHESIS: Administration of tolazoline or atipamezole would not affect detomidine sedation. METHODS: In a randomised, placebo-controlled, double-blind, descriptive study, detomidine (0.02 mg/kg bwt i.v.) was administered to 6 mature horses on 4 separate occasions. Twenty-five mins later, each horse received one of 4 treatments: Group 1 saline (0.9% i.v.) as a placebo control; Group 2 atipamezole (0.05 mg/kg bwt i.v.); Group 3 atipamezole (0.1 mg/kg bwt i.v.); and Group 4 tolazoline (4.0 mg/kg bwt i.v.). Sedation, muscle relaxation and ataxia were scored by 3 independent observers at 9 time points. Horses were led through an obstacle course at 7 time points. Course completion time was recorded and the ability of the horse to traverse the course was scored by 3 independent observers. Horses were videotaped before, during and after each trip through the obstacle course. RESULTS: Atipamezole and tolazoline administration incompletely antagonised the effects of detomidine, but the time course to recovery was shortened. CONCLUSIONS AND POTENTIAL RELEVANCE: Single bolus administration of atipamezole or tolazoline produced partial reversal of detomidine sedation and may be useful for minimising detomidine sedation.