Journal of Equine Veterinary Science

The Relationship Between the Positive Identification of the Embryo Proper in Equine Pregnancies Aged 18-28 Days and its Future Viability: A Field Study

John R. Newcombe, Juan Cuervo-Arango — 2011-10-21

Abstract: Early embryonic loss (EEL) negatively affects the reproductive efficiency of equine reproduction. A sign of future EEL is when the embryo proper (EP) fails to develop within the embryonic vesicle after 30 days of gestation. The earlier the identification of impending EEL, the earlier the mare can be rebred to allow a second chance of pregnancy. The objectives of this study were to determine the percentage of embryonic vesicles with a visible EP at 18-28 days of gestation and to study the association between the presence/absence of the EP at different days of gestation and the future viability of the pregnancy. A total of 1,256 pregnancies were identified and followed by transrectal B-mode ultrasonography 12-45 days post ovulation in mares of the same Thoroughbred farm. The identification of the EP was attempted once during days 18-28. Pregnancy reconfirmation was performed on days 35-45. The percentage of vesicles with an EP increased gradually from days 18 (2.8%) to 21 (86.9%) (P < .05). From day 20 onward, the EEL rate of mares with vesicles without an EP was significantly higher (P < .05) than that of vesicles with a positive identification of an EP. In conclusion, the EP of the equine vesicle can be identified reliably with B-mode ultrasonography in the majority of mares (>71%) on day 20 of gestation. The lack of a positive identification of an EP from day 20 onward is associated with a higher EEL rate.

Effects of Steel and Aluminum Shoes on Forelimb Kinematics in Stock-Type Horses as Measured at the Trot

Elodie E. Huguet, Kylee J. Duberstein — 2012-02-10

Abstract: To meet the needs of sport horses, horseshoes of various styles and materials have been implemented to enhance performance. Steel shoes are commonly used for their affordability and longevity; however, the use of aluminum horseshoes is being adopted to satisfy the various requirements of certain equestrian activities. Owing to the importance of the allure of movement in many aspects of competitive riding, the lightweight nature of aluminum horseshoes has been recognized to accentuate foreleg action. By performing a repeated-measures crossover study on nine healthy stock-type horses, the effects of these two horseshoe types on forelimb action were analyzed at the trot using two-dimensional kinematics. Horses were trotted in hand for three repetitions over a distance of 50.1 meters on days 4, 18, 32, and 46 postshoeing for two 6-week shoeing cycles. Video footage was collected and analyzed using gait analysis software (EquineTec) for each repetition. The measured stride length, fetlock extension, elbow and knee range of motion, and minimum and maximum elbow angle remained constant between treatments. However, there was a significant treatment effect on minimum carpal angle and maximum hoof height, with aluminum shoes having a larger minimum carpal angle than those in steel shoes (P < .05) and a lower maximum hoof height (P < .05). An overall 3-degree difference in minimum carpal angle and approximate 2.5-cm difference in maximum hoof height was observed between treatments. This finding is of particular importance to performance horse disciplines for which a lesser degree of knee action is desirable.

Evaluation of Urinary Variables as Diagnostic Indicators of Acute Kidney Injury in Egyptian Draft Horses Treated With Phenylbutazone Therapy

Maged R. El-Ashker, Hussein S. Hussein, Mahmoud G. El-Sebaei — 2011-12-16

Abstract: The present study was undertaken to evaluate the diagnostic significance of various urinary variables to detect acute kidney injury (AKI) in Egyptian draft horses treated with phenylbutazone (PBZ) therapy. Medical records of 52 draft horses, with a history of musculoskeletal painful conditions and treated frequently with various daily doses of injectable PBZ, were reviewed. Of those 52 horses, 38 were enrolled in this study. AKI was tentatively diagnosed based on thorough history and clinical findings and in conjunction with multiple biochemical screening tests. Accordingly, diseased horses were categorized into two main groups; the first group included 14 horses with prerenal azotemia, whereas the second group included 24 horses with renal azotemia. Biochemically, urinary malondialdehyde, urinary gamma-glutamyl transferase/creatinine (Cr) ratio, urinary protein/Cr ratio, urinary glucose, urinary sodium, fractional excretion of sodium, and renal failure index were significantly higher (P < .05) in horses of group 2 than those of group 1. However, values of urinary Cr, urine/plasma Cr ratio, urinary urea, and urine/plasma urea ratio were significantly decreased (P < .05) in horses of group 2. Analysis of receiver operating characteristic curve showed high sensitivity and specificity of most tested urinary variables as well as their derived indices for detection of AKI in diseased horses. Our findings suggest that the examined urinary variables as well as their ratios are helpful in documenting AKI associated with PBZ nephrotoxicity in Egyptian draft horses; however, their interpretation should be done in the light of the specific clinical setting and in conjunction with a thorough clinical and physical examination.

Preliminary Analysis of the Results of Selective Therapy Against Strongyles in Pasturing Horses

2011-12-15

Abstract: Control of horse parasites often omits application of measures to eradicate the free-living stages in pastures and frequently relies on chemotherapy only. Selective therapy was used for Spanish Sport horses grazing either in the same pasture (continuous) or in rotated meadows. In each group, equines exceeding a cutoff value of 300 strongyle eggs per gram of feces received ivermectin or moxidectin. Efficacy of the treatment was assessed by estimating reduction of fecal egg counts and the number of horses shedding parasite eggs (PHR). Coprocultures revealed presence of the cyathostomins Cyathostomum and Gyalocephalus spp. In all treated groups, a 100% value for both reduction of fecal egg counts and PHR against cyathostomins was obtained, and PHR values ranged from 100% to 12%. The longest strongyle egg reappearance period was observed in horses undergoing rotation grazing and receiving ivermectin (9 weeks), compared with a 6-week period recorded for the other treated equines. Our results seem to point that the efficacy of selective therapy in equine herds could be reduced if the horses with fecal egg counts below the threshold value (thus not receiving chemotherapy) remain grazing in the same pastures with the treated ones. It is strongly suggested that interested parties consider performing periodic fecal analyses to monitor fecal egg counts, together with the percentage of horses passing eggs in feces, to improve the effect of this procedure.

Periparturient Arterial Rupture in Mares: A Postmortem Study

Neil M. Williams, Uneeda K. Bryant — 2012-01-27

Abstract: There are limited reports characterizing the occurrence of rupture of uterine and other arteries associated with pregnancy in mares. Cases were retrieved from the records of horses submitted for necropsy to the University of Kentucky Veterinary Diagnostic Laboratory over a 15-year period (1993-2007). Five hundred thirteen horses were diagnosed with periparturient arterial rupture, representing 1.5% of the total equine necropsy cases. Arterial rupture was diagnosed predominately in older mares, with 78% of the horses being ≥15 years of age. Ruptures occurred most commonly during parturition but also were diagnosed before and after parturition. Additionally, during a consecutive 3-year period within this time interval, an extensive workup of cases was performed. In these 71 cases, the area of the arterial rupture was carefully dissected, and the location, size, and appearance of the arterial tear were determined. The uterine artery was the most commonly affected vessel. Although there was overlap, mares with uterine artery rupture tended to be older than those with rupture of other arteries. There was no predilection for the left or right sides, and the uterine artery rupture occurred most often in the first 20 cm from the origin.

Efficacy of Deslorelin Acetate (SucroMate) on Induction of Ovulation in American Quarter Horse Mares

2011-12-23

Abstract: Equine clinicians rely on ovulation induction agents to provide a timed ovulation in mares for optimal breeding management. Numerous studies have been performed on the efficacy of human chorionic gonadotropin (hCG) to induce ovulation in the mare, but limited clinical data are available for the new deslorelin acetate product SucroMate. This study was designed to evaluate the efficacy of SucroMate (deslorelin) in comparison with hCG to induce ovulation. American Quarter horse mares (n = 256) presented to Colorado State University for breeding management were used in this study. Mares received either deslorelin or hCG when a follicle ≥35 mm was detected by transrectal ultrasound in the presence of uterine edema. Ultrasonographic examinations were subsequently performed once daily until ovulation was detected. Deslorelin was administered to 138 mares during168 estrous cycles, and hCG was given to 118 mares during 136 estrous cycles. Mares administered deslorelin had a similar (P < .05) higher ovulation rate (89.9%) within 48 hours following drug administration than mares administered hCG (82.8%). There are no effects of season or age on ovulation rates in either treatment group. Twenty-one mares administered deslorelin and 11 mares administered hCG were monitored by transrectal ultrasound every 6 hours to detect ovulation as part of a frozen semen management program. Average intervals from deslorelin or hCG administration to ovulation were 41.4 ± 9.4 and 44.4 ± 16.5 hours, respectively. Results of this study indicate that SucroMate is effective at inducing a timed ovulation in the mare.

Fertility of Mares Inseminated With Frozen-Thawed Semen Processed by Single Layer Centrifugation Through a Colloid

2011-12-26

Abstract: The aim of this study was to determine whether there was an increase in pregnancy rates when frozen-thawed stallion semen was processed by single layer centrifugation (SLC) through a colloid before insemination. In addition, changes in semen parameters, including motility, were determined before and after SLC. Twenty light-horse mares (aged 3-16 years) and one Thoroughbred stallion (aged 16 years) having average fertility with fresh and cooled semen (>50% per cycle) and displaying a postthaw motility of >35% were used. Control mares were inseminated using 4- × 0.5-mL straws (200 × 106/mL) of frozen-thawed semen. Treatment mares were inseminated with 4 × 0.5 mL of frozen-thawed semen after processing by SLC. Pregnancy rates were compared using Fisher exact test, and continuous parameters were evaluated by a Student t test. The pregnancy rates at day 14 were not different for the mares inseminated with control versus SLC-processed semen, despite the difference in sperm number (171 × 106 ± 21, 59 × 106 ± 25 progressively motile sperm). After frozen-thawed semen was processed by SLC, the percentage progressively motile sperm improved (P < .05), and SLC processing resulted in a 21.8% recovery of spermatozoa. In summary, centrifugation of frozen-thawed semen through a single layer of colloid increased the percentage of motile spermatozoa, but did not improve pregnancy rates after deep horn insemination.

A Multiplex Polymerase Chain Reaction Assay for Direct Detection and Differentiation of β-Hemolytic Streptococci in Clinical Samples from Horses

Silvia Preziuso, Vincenzo Cuteri — 2011-12-15

Abstract: Streptococcus equi subspecies equi, S equi subspecies zooepidemicus, and S dysgalactiae subspecies equisimilis are β-hemolytic Streptococci, often isolated from horses with respiratory or genital diseases. The aim of this study was (i) defining and validating a multiplex polymerase chain reaction (PCR) protocol for identifying these Streptococci in bacterial cultures and for detecting them directly in equine clinical specimens, and (ii) defining and validating a cheap DNA extraction protocol for clinical specimens. When respiratory and genital samples from symptomatic and asymptomatic horses were tested by bacterial culture and by multiplex PCR, all the 150 samples culture-positive for S equi, S zooepidemicus, or S equisimilis were also positive by PCR. Of 150 culture-negative samples, 143 were negative by PCR. Seven samples were positive by PCR but negative by bacteriology. The multiplex PCR protocol described in this study is proven suitable for a sensitive, specific, and rapid detection and identification of S equi, S zooepidemicus, and S equisimilis in cultured bacterial colonies, as well as in clinical specimens from symptomatic or asymptomatic horses. The inclusion of internal control primers in the PCR protocol excludes false-negative results. A cheap DNA extraction method has been also validated for swabs, tracheal aspirates, bronchoalveolar lavage, and guttural pouches lavage samples.

Sick Neonatal Foals Do Not Demonstrate Evidence of Oxidative Stress

Martin Furr, Linda Frellstedt, Ray Geor — 2011-12-15

Abstract: Critical illness in humans is associated with alterations in oxidative stress and the concentration of antioxidant molecules; however, this association has not been examined in equine neonates. The purpose was to determine the concentration of various antioxidant molecules, as well as a marker of oxidative stress, in the serum and plasma of normal and sick neonatal foals and their dams. Results demonstrated that the concentration of selenium was less (61.71 vs. 77.93 ng/mL; P = .002) in sick versus healthy neonates, whereas the concentration of vitamin E was slightly higher in sick compared with healthy foals (4.36 vs. 3.17 mg/mL); however, this did not achieve statistical significance (P = .31). The vitamin E concentration was greater (5.37 vs. 3.43 mg/mL; P = .01) and serum selenium was less in sick mares (129.50 vs. 184.78 ng/mL; P = .0001) compared with healthy mares. In addition, the serum concentration of selenium is lower in neonates than in their dams in the perinatal period (70.10 vs. 173.34 ng/mL; P = .0001). Glutathione peroxidase activity was less in sick foals (7.04 nmol/min/mL) compared with healthy foals (9.13 nmol/min/mL) (P = .19), and 3-nitrotyrosine (3-NT) concentration/mg protein was less in sick foals versus healthy foals (geometric mean, 1.24 vs. 2.07 nmol 3-NT/mg protein). This difference did not achieve statistical significance (P = .09); however, when a subset of critically ill foals was examined, the assayed concentration of 3-NT/mg protein was even less (0.99 nmol 3-NT/mg protein) and did statistically differ from healthy foals (P = .03).

First Report of Methicillin-Resistant Staphylococcus aureus ST5 and ST398 from Purebred Lusitano Horses

Natacha Couto, Paula Tilley, Joana Simões, José P. Sales Luis, Constança Pomba — 2011-12-15

Abstract: Methicillin-resistant Staphylococcus aureus (MRSA) was first described in horses in 1996. The frequency of MRSA colonization in horses varies among European countries, but it is unknown in Portugal. The aim of this study was to screen for MRSA nasal carriage in a sample of horses entering the Equine Unit, Large Animal Veterinary Teaching Hospital of the Faculty of Veterinary Medicine, Lisbon, Portugal. Seventy-one horses were swabbed, and MRSA was identified by selective isolation on a chromogenic medium. Two S aureus isolates showed resistance to oxacillin (minimum inhibitory concentration >4 μg/mL) and contained the mecA gene. Both strains were isolated from purebred Lusitano horses that lived in farms with more than 20 equines. These MRSA strains represented two different clones: isolate FMVA3/10 was an MRSA sequence type ST5 with a staphylococcal cassette chromosome mec VI, coresistant to erythromycin and clindamycin; and isolate FMVA16/10 was sequence type ST398, with a staphylococcal cassette chromosome mec IV, coresistant to tetracycline, gentamicin, and trimethoprim. Isolate FMVA3/10 represents a human epidemic clone not previously reported among horses in Europe, which once again reinforces the fact that transmission of MRSA clones between horses and humans occurs. Isolate FMVA16/10 represents the first report of the detection of MRSA ST398 among horses in Portugal. Lusitano horses can carry animal and human MRSA in the nostrils, acting as reservoirs, which can potentially be transmitted to humans.

Haematic Mummification in a Mare With Twin Pregnancy

2011-12-15

Abstract: Mummification occurs when the fetus dies during the second or third trimester of gestation and remains in the uterine cavity because of the persistence of the corpus luteum or existence of another live fetus. Generally, the mummified fetus and fetal membranes undergo desiccation. The hematic process is similar, but the fetus appears like melted chocolate and becomes lodged between the uterus and chorion. This report describes the treatment of dystocia in a mare with twin pregnancy, with one fetus having undergone hematic mummification. Although difficult to diagnose, the possibility of a second fetus should be investigated in mares with dystocia.

Atypical Radiologic Appearance of a Second Cervical Vertebral Fracture in a Horse

Anna Ehrle, Sara Jones, Patricia Klose, Christoph Lischer — 2011-12-15

Abstract: This report presents the case of a 21-year-old Warmblood mare referred to the clinic with neurological dysfunctions and considerable signs of discomfort. A fracture of the caudal vertebral body of C2 with a very unusual radiographic appearance was diagnosed, and the mare was euthanized due to deterioration in neurological status. Histology revealed no evidence of neoplasia or pathological fracture.

Editorial Board

2012-05-01

Journal of Equine Veterinary Science

The Relationship Between the Positive Identification of the Embryo Proper in Equine Pregnancies Aged 18-28 Days and its Future Viability: A Field Study

Effects of Steel and Aluminum Shoes on Forelimb Kinematics in Stock-Type Horses as Measured at the Trot

Evaluation of Urinary Variables as Diagnostic Indicators of Acute Kidney Injury in Egyptian Draft Horses Treated With Phenylbutazone Therapy

Preliminary Analysis of the Results of Selective Therapy Against Strongyles in Pasturing Horses

Periparturient Arterial Rupture in Mares: A Postmortem Study

Efficacy of Deslorelin Acetate (SucroMate) on Induction of Ovulation in American Quarter Horse Mares

Fertility of Mares Inseminated With Frozen-Thawed Semen Processed by Single Layer Centrifugation Through a Colloid

A Multiplex Polymerase Chain Reaction Assay for Direct Detection and Differentiation of β-Hemolytic Streptococci in Clinical Samples from Horses

Sick Neonatal Foals Do Not Demonstrate Evidence of Oxidative Stress

First Report of Methicillin-Resistant Staphylococcus aureus ST5 and ST398 from Purebred Lusitano Horses

Haematic Mummification in a Mare With Twin Pregnancy

Atypical Radiologic Appearance of a Second Cervical Vertebral Fracture in a Horse

Editorial Board

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