Introduction: Reindeer are adapted to long distance migration. This species can cope with variations in substrate, especially in ice and snow environment. However, few detailed studies about reindeer hoof are available. Thus this article describes the results of studies on macro- and micro-structures of reindeer hoof.Material and Methods: The gross anatomy of the reindeer hooves was examined. Stereo microscope (SM) and a scanning electron microscope (SEM) were used to observe four key selected positions of reindeer hooves. Moreover, element contents of the three selected positions of reindeer hooves were analysed using the SEM equipped with energy dispersive spectroscope.Results: Hoof bone structures were similar to other artiodactyl animals. In the microscopic analysis, the surfaces of the ungula sphere and ungula sole presented irregular laminated structure. Ungula edge surfaces were smooth and ungula cusp surfaces had unique features. Aside from C, O, and N, reindeer hooves contained such elements as S, Si, Fe, Al, and Ca. The content of the elements in different parts varied. Ti was the particular element in the ungula sole, and ungula edge lacked Mg and S which other parts contained.Conclusion: The macro- and micro-structures of the reindeer hooves showed high performance of skid and abrasion resistance. It is most probably essential to the long distance migration for the animals.

OBJECTIVE To determine the locomotor response to the administration of fentanyl in horses with and without the G57C polymorphism of the μ-opioid receptor. ANIMALS 20 horses of various breeds and ages (10 horses heterozygous for the G57C polymorphism and 10 age-, breed-, and sex-matched horses that did not have the G57C polymorphism). PROCEDURES The number of steps each horse took was counted over consecutive 2-minute periods for 20 minutes to determine a baseline value. The horse then received a bolus of fentanyl (20 μg/kg, IV), and the number of steps was again counted during consecutive 2-minute periods for 60 minutes. The mean baseline value was subtracted from each 2-minute period after fentanyl administration; step counts with negative values were assigned a value of 0. Data were analyzed by use of a repeated-measures ANOVA. RESULTS Data for 19 of 20 horses (10 horses with the G57C polymorphism and 9 control horses without the G57C polymorphism) were included in the analysis. Horses with the G57C polymorphism had a significant increase in locomotor activity, compared with results for horses without the polymorphism. There was a significant group-by-time interaction. CONCLUSIONS AND CLINICAL RELEVANCE Horses heterozygous for the G57C polymorphism of the μ-opioid receptor had an increased locomotor response to fentanyl administration, compared with the response for horses without this polymorphism. The clinical impact of this finding should be investigated.

Objective—To develop a parsimonious statistical model to predict incidence of lameness in the subsequent lactation by use of data collected at cessation of lactation in dairy cows. Animals—574 cows. Procedures—At cessation of lactation during hoof trimming, body condition score (BCS), visual locomotion score, digital cushion thickness (DCT), and digital lesions were assessed. Results—140 (24%) cows were treated for claw horn disruption lesions (CHDLs) at cessation of lactation (114 with sole ulcers [pododermatitis circumscripta] and 26 with white line disease). The BCS was highly associated with DCT. Cows with CHDLs at cessation of lactation had significantly lower DCT, compared with other cows. All 3 logistic regression models predicted the incidence of CHDLs in the subsequent lactation with good accuracy; the area under the receiver operating characteristic curves was 0.76, 0.76, and 0.77 for the first, second, and third logistic regression models, respectively. Conclusion and Clinical Relevance—Evaluation of 3 logistic regression models indicated that lameness could be predicted with good accuracy by use of all 3. The ability to predict lameness will facilitate the implementation of lameness prevention strategies by targeting specific cows.

High-speed cinematography was used to record the movements of 12 cutting horses performing a standard test with a mechanical flag. Based on their previous competitive performances, horses were classified into 2 groups: group 1, composed of 5 moderately successful or average performers that had won less than $35,000 in purse money; and group 2, composed of 7 highly successful or elite performers that had amassed greater than $35,000 in competition earnings. Analysis of the results indicated that, compared with horses of the average group, the elite horses had faster reaction times in response to the start and cessation of flag movement (P less than 0.01), and were positioned closer to the flag during all stages of the trial (P less than 0.05). Discriminant analysis was used to construct a mathematical formula that could be used to classify an individual horse into 1 of the 2 alternative groups, based on the set of measurements. Two predictor variables were selected that described the maximal distance between the horse and the flag during the run and the part of the body that was moved first in response to the initial flag movement. The accuracy of the predicted group membership, compared with the actual group membership, was 100%.

Interstitial fluid pressures, as a possible function of limb load, were measured at 2 sites within the digital coronary dermis of both cranial digits in 10 standing horses. Fluid pressure changes and digital load measurements were simultaneously detected and recorded by use of, respectively, modified wick-in-needle and force plate transducers coupled to a microcomputer. Mean pressures, recorded at limb loads between 50 and 80 kg, were 2.29 +/- 3.17 mm of Hg at the toe and 2.49 +/- 5.91 mm of Hg at the heel. Mean pressures, recorded between 150 and 180 kg, were 5.01 +/- 5.23 mm of Hg at the toe and 1.28 +/- 7.69 mm of Hg at the heel. These data indicate that, in the static limb, no statistically significant change in interstital fluid pressure occurs at loads up to 180 kg.

Six horses, highly trained for dressage competition, were used to study the stride kinematics of the walk, and to compare the kinematics of the collected, medium, and extended walks. Horses were filmed in a sagittal plane at a rate of 150 frames/s; temporal, linear, and angular data were extracted from the films. Results of ANOVA and Duncan's multiple range test indicated that the speed of the collected walk (1.37 m/s) was significantly (P < 0.01) slower than that of the medium (1.73 m/s) and extended (1.82 m/s) walks, values for which were not significantly different from each other. The increase in speed was associated with a significant increase in stride length, from 157 cm in the collected walk to 193 am in the extended walk. This was a result of an increase in the over-tracking distance, whereas there was no significant difference in the distance between lateral placements of the limbs. Stride duration decreased (P < 0.01) from the collected walk (1,159 ms) to the extended walk (1,064 ms). Angles of the metacarpal and metatarsal segments, measured on the palmar/plantar aspect, were higher at impact and lower at lift off in the collected than in the extended walk (P < 0.01). This indicated greater range of angular motion of this segment during the stance phase in the extended walk. Only 1 of the 6 horses had a regular 4-beat rhythm of the footfalls, with equal time elapsing between the lateral and diagonal footfalls.

Using a force plate, ground reaction force (GRF) patterns at take-off and landing between the hooves and the ground were recorded for all limbs of 5 Dutch Warmbloods jumping a 0.8-m vertical fence from the right-leading canter. Distribution of the GRF and force impulses over the 4 limbs at take-off and landing were considerably different from those recorded at the normal canter. At take-off, the propulsory GRF of the hind limbs were 3 to 5 times higher than at the normal canter, depending on the jumping technique of the horse. At landing, the propulsory GRF were mainly increased in the trailing forelimb and in both hind limbs. The vertical GRF amplitudes and force impulses were of similar magnitude to those at the canter, although increases up to 160% were found in the hind limbs of the horse with the worst jumping technique. The trailing forelimb carried the highest loads, up to twice the animal's body weight; GRF amplitudes tended to increase when higher fences were used. However, the jumping technique of the horse may have more influence, because an easily jumping horse could clear a 1.3-m-high fence with similar loads on the limbs.

Two types of sensory receptors were located in the equine foot, using anatomic techniques. Histologic examination of stained hoof sections revealed lamellated corpuscles in the hoof dermis, which had many of the morphologic characteristics of Pacinian corpuscles. These sensory receptors were restricted to the palmar (caudal) aspects of the solar dermis of the heel. A second type of receptor was detected by use of immunocytochemistry, indicating apparently naked nerve endings containing the neuropeptide calcitonin gene-related peptide-like immunoreactivity in skin, solar dermal tubules, and the digital cushion. This peptide is an example of a sensory neurotransmitter contained in dorsal root ganglion cells and is believed to exist only in unmyelinated sensory nerve fibers. These 2 morphologic structures may be used for detection of sensory stimuli, such as pressure (or vibratory senses) and pain, respectively, in horses during various locomotory gaits.