|
Hernandez, J., & Hawkins, D. L. (2001). Training failure among yearling horses. Am J Vet Res, 62(9), 1418–1422.
Abstract: OBJECTIVE: To compare financial returns between pinhooked yearling horses (ie, bought and trained for approximately 5 months with the goal of selling the horse at “2-year-olds in training” sales) that had mild or severe training failure and horses that had planned versus nonplanned training failure. ANIMALS: 40 Thoroughbred pinhooked yearling horses. PROCEDURE: During the period from September 1998 through and April 1999, 20 horses had mild training failure (1 to 11 days lost), and 20 horses had severe training failure (13 to 108 days lost). Horses were assigned to these 2 groups on the basis of frequency distribution (median) of days lost during training. Horses were also categorized on the basis of type of training failure (planned vs nonplanned training failure). The outcome of primary interest was financial return. Median financial returns were compared among groups by use of the Mann-Whitney U test. RESULTS: Median financial returns for horses that had severe training failure ($1,000) were significantly different, compared with horses that had mild training failure ($24,000). Analysis of results also indicated that median returns were significantly different among horses that had planned training failure (-$2,000; eg, horses with radiographic abnormalities detected during routine prepurchase examinations that required surgical treatment, resulting in days lost during training), compared with horses that did not ($10,000). CONCLUSIONS AND CLINICAL RELEVANCE: Training failure has an economic impact on revenues in pinhooked yearling horses. Lameness, planned training failure, respiratory disease, and ringworm were common and important causes of training failure.
|
|
|
McDonnell, S. M., Freeman, D. A., Cymbaluk, N. F., Schott, H. C. 2nd, Hinchcliff, K., & Kyle, B. (1999). Behavior of stabled horses provided continuous or intermittent access to drinking water. Am J Vet Res, 60(11), 1451–1456.
Abstract: OBJECTIVE: To compare quantitative measures and clinical assessments of behavior as an indication of psychologic well-being of stabled horses provided drinking water continuously or via 1 of 3 intermittent delivery systems. ANIMALS: 22 Quarter Horse (QH) or QH-crossbred mares and 17 Belgian or Belgian-crossbred mares (study 1) and 24 QH or QH-crossbred mares and 18 Belgian or Belgian-crossbred mares (study 2). PROCEDURE: Stabled horses were provided water continuously or via 1 of 3 intermittent water delivery systems in 2 study periods during a 2-year period. Continuous 24-hour videotaped samples were used to compare quantitative measures and clinical assessments of behavior among groups provided water by the various water delivery systems. RESULTS: All horses had clinically normal behavior. Significant differences in well being were not detected among groups provided water by the various delivery systems. CONCLUSIONS AND CLINICAL RELEVANCE: Various continuous and intermittent water delivery systems can provide adequately for the psychologic well-being of stabled horses.
|
|
|
Atwill, E. R., Mohammed, H. O., & Lopez, J. W. (1996). Evaluation of travel and use as a risk factor for seropositivity to Ehrlichia risticii in horses of New York state. Am J Vet Res, 57(3), 272–277.
Abstract: OBJECTIVES--To determine whether mean annual frequency and destination of equine travel was associated with exposure to Ehrlichia risticii and whether these associations were modified by horses' place of residence. DESIGN--Cross-sectional study. SAMPLE POPULATION--511 equine operations containing 2,587 horses were visited in New York state from a target population of 39,000 operations. PROCEDURE--Each horse was tested for serum antibodies against E risticii, using indirect fluorescent antibody. Information on the horse's travel history, farm's management practices, and surrounding ecology was obtained by personal interview and resource maps. Statistical analyses were performed on 2 cohorts of animals: all horses enrolled in the study and horses born on the property or that resided at least 4 years on the farm. Three county-based risk regions (RR) were identified by use of cluster analysis. RESULTS--Mean seroprevalence for each of the 3 RR was 2.4 (low risk), 8.5 (moderate risk), and 18.5% (high risk) for cohort 1 and 2.5, 8.0, and 18.4% for cohort 2. Among cohorts 1 and 2, pleasure riding and breeding trips were associated with exposure to E risticii, but horse residence (low, moderate, or high RR) was an effect modifier for these associations. Among cohort 1 and stratifying the analysis according to the RR for the travel destination, trail riding at low RR and trail riding at high RR were associated with exposure. Among cohort 2 and stratifying the analysis according to the RR for the travel destination, breeding trips were associated with exposure, and strong effect modification was present for horse residence (low, moderate, or high RR). CONCLUSIONS--Only certain types of travel to specific RR were associated with higher risk of exposure to E risticii. In many instances, travel was not associated, or was associated, with a reduced risk of exposure.
|
|
|
Clayton, H. M. (1995). Comparison of the stride kinematics of the collected, medium, and extended walks in horses. Am J Vet Res, 56(7), 849–852.
Abstract: 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 cm 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.
|
|
|
Polley, L. (1986). Strongylid parasites of horses: experimental ecology of the free-living stages on the Canadian prairie. Am J Vet Res, 47(8), 1686–1693.
Abstract: Each month for a 1-year period (October through September), equine fecal masses containing eggs of strongylid nematodes were placed outdoors on small grass plots in Saskatchewan, Canada. Thereafter, feces and grass from the plots were sampled after intervals of 1 week or longer, and the strongylid eggs and larvae recovered were counted. These observations were made over a 2-year period. Development of eggs to infective larvae occurred in all experiments, except those established in October, December, and January. Infective larvae from experiments set up in April through September survived that winter. During the summer, there was a gradual build up of infective larvae in the fecal masses, which reached a peak in August and September and then decreased into the winter. These results are discussed in the context of the control of strongylid parasites of horses on the Canadian prairie and in other areas of the world with a similar climate and similar horse management practices.
|
|
|
Keiper, R., & Houpt, K. (1984). Reproduction in feral horses: an eight-year study. Am J Vet Res, 45(5), 991–995.
Abstract: The reproductive rate and foal survival of the free-ranging ponies on Assateague Island National Seashore were studied for 8 years, 1975 to 1982. Most (52%) of the 86 foals were born in May, 13% were born in April, 22.6% in June, 10.4% in July, and less than 1% in August and September. The mean foaling rate was 57.1 +/- 3.9% and the survival rate was 88.3 +/- 3.6%. Forty-eight colts and 55 fillies were born (sex ratio 53% female). Mares less than 3 years old did not foal and the foaling rate of 3-year-old mares was only 23%, that of 4-year-old mares was 46%, that of 5-year-old mares was 53%, and 6-year-old mares was 69%. The relatively poor reproduction rate was believed to be a consequence of the stress of lactating while carrying a foal when forage quality on the island was low. The hypothesis was supported by the higher reproductive rate (74.4 +/- 2.4%) of the ponies in the Chincoteague National Wildlife Refuge on the southern part of the island. Their foals are weaned and sold in July each year. Despite the low reproductive rate on Assateague Island National Seashore , the number of ponies increased from 43 to 80, a 90% increase in the 8-year period or greater than 10%/yr. There were 24 deaths and 8 dispersals from the study area.
|
|
|
Parry, B. W., Gay, C. C., & McCarthy, M. A. (1980). Influence of head height on arterial blood pressure in standing horses. American Journal of Veterinary Research, 41(10), 1626–1631.
|
|
|
Herron, M. A., Martin, J. E., & Joyce, J. R. (1978). Quantitative study of the decussating optic axons in the pony, cow, sheep, and pig. Am. J. Vet .Res., 39(7), 1137–9.
|
|
|
Knill, L. M., Eagleton, R. D., & Harver, E. (1977). Physical optics of the equine eye. Am J Vet Res, 38(6), 735–737.
Abstract: The equine eye was treated as a general lens system and calculations were done to determine image position in relation to the retina for objects at a distance of infinity, 100 m, and 1 m. The retina is 19.1 mm behind the posterior surface of the lens; therefore, the image appears 14.6 mm posterior to the retina at infinity and at 100 m, and 16.3 mm at 1-m distance on a horizontal axis. The animals studied were hyperopic. It is evident that the horse must move its head or eye, or both, for optimal visual acuity. At the same time, some objects in the total field of vision are imperceptible or indistinct.
|
|
|
Mellor, P. S., & Hamblin, C. (2004). African horse sickness. Vet Res, 35(4), 445–466.
Abstract: African horse sickness virus (AHSV) causes a non-contagious, infectious insect-borne disease of equids and is endemic in many areas of sub-Saharan Africa and possibly Yemen in the Arabian Peninsula. However, periodically the virus makes excursions beyond its endemic areas and has at times extended as far as India and Pakistan in the east and Spain and Portugal in the west. The vectors are certain species of Culicoides biting midge the most important of which is the Afro-Asiatic species C. imicola. This paper describes the effects that AHSV has on its equid hosts, aspects of its epidemiology, and present and future prospects for control. The distribution of AHSV seems to be governed by a number of factors including the efficiency of control measures, the presence or absence of a long term vertebrate reservoir and, most importantly, the prevalence and seasonal incidence of the major vector which is controlled by climate. However, with the advent of climate-change the major vector, C. imicola, has now significantly extended its range northwards to include much of Portugal, Spain, Italy and Greece and has even been recorded from southern Switzerland. Furthermore, in many of these new locations the insect is present and active throughout the entire year. With the related bluetongue virus, which utilises the same vector species of Culicoides this has, since 1998, precipitated the worst outbreaks of bluetongue disease ever recorded with the virus extending further north in Europe than ever before and apparently becoming endemic in that continent. The prospects for similar changes in the epidemiology and distribution of AHSV are discussed.
|
|