Horse Sex Research Articles

Occurrence of gastrointestinal helminths in horses and risk factors for infection

This study aimed to monitor the occurrence of gastrointestinal parasites in horses evaluating different rural properties in Santa Catarina State, Southern Brazil. Fresh samples of feces were collected and processed by the McMaster technique, quantifying the number of eggs per gram of feces (EPG), followed by coproculture for identification of helminths. The population investigated was composed of 111 horses of varying ages (1–27 years, 63 males and 48 females). Among all the animals evaluated, 76 animals showed EPG ≥50, representing 63.96 % (IC95 % 54.24–72.70) of samples positive for gastrointestinal helminths. The EPG values ranged from 0 to 5600, with EPG average set as 490. There was a great variation among EPG in different farms. The anthelmintic treatments were carried out in all properties, most of them ranging from 30 to 90 or more 90 days. However, when we correlated the interval of treatment with EPG values, we did not observe significant difference for these variables (P > 0.05). Similarly, there was also no relation between EPG with age and sex of horses (P > 0.05), showing that the EPG values are not dependent of these two independent variables. In coproculture, 40 % of the evaluated properties had only the presence of Strongylus spp., while 60 % had mixed infection of Strongylus sp. and Trichostrongylus sp. With our results, we conclude that approximately 64 % of the horses of this study were positive for gastrointestinal parasites.

Case series evaluating the use of absorbable staples compared with metallic staples in equine ventral midline incisions

SummaryThe objective was to evaluate the use of subcuticular absorbable staples (SAS) and compare them with metallic staples (MS) in abdominal skin closure for equine abdominal surgery in terms of surgical site infection (SSI) reduction. A prospective, randomised clinical trial was carried out on client owned horses presenting for abdominal surgery (n = 42 horses). During surgery, horses were randomly assigned to receive either SAS or MS. Preoperative criteria recorded included age, breed and sex of horse; surgical variables included lesion type, anaesthetic, surgical and stapling times; post operative variables included an anaesthetic recovery quality score and an incisional assessment score. Mean ± s.d. anaesthesia times for small intestinal surgeries between the MS and SAS (228 ± 58.8 min, 234 ± 38.7 min, respectively) and surgical times between MS and SAS (158 ± 58.8 min, 174 ± 26.5 min, respectively) were not significantly different from each other. There was no significant difference in closure times for the MS and SAS (61 ± 14.1 s, 85 ± 35.3 s, respectively). Wound scores for the MS (median score 6) were significantly greater than the SAS (median score 3) until Day 14, after which there was no significant difference between the 2 techniques. No horses in this case series developed a SSI. Although no SSIs were identified in either group, the superior wound score with the SAS together with other in vitro and clinical evaluations in other species suggest that the use of SAS may be potentially beneficial in horses.

Correlation between dichromatic colour vision and jumping performance in horses

There is general agreement that horses have dichromatic colour vision with similar capabilities to human beings with red–green colour deficiencies. However, whether colour perception has an impact on equine jumping performance and how pronounced the colour stimulus might be for a horse is unknown. The present study investigated the relationship between the colour of the fences (blue or green) and the show jumping performance of 20 horses ridden by two riders using an indoor and outdoor set of green and blue fences.In the indoor arena, significantly more touches and faults were made on blue fences in comparison to green fences (median difference of 2.5 bars). When only touched bars were included, a significant median difference of one bar was found. Mares (n = 4) demonstrated more faults and had a significantly greater difference in touches and faults between the two colours than male horses (n = 16). Repeating the same experiment with eight horses in an outdoor grass arena revealed no significant differences between the two colours. In order to draw any definite conclusions, more research concerning the colour perception, influence of contrast with the arena surface and sex of horse is required.

In this issue – August 2014

Bovine viral diarrhoea virus (BVDV) type 1 is endemic in Australian cattle populations, costing the national industry an estimated AUD57.9 million annually.1 BVDV control programs based on identifying and removing persistently infected cattle have been efficiently and effectively implemented in Europe and are gaining pace in New Zealand. This review discusses the challenges to BVDV control in Australia, including availability of infrastructure, reliability and availability of diagnostic tests, stakeholder compliance and the potential of other species, particularly sheep, to act as a potential reservoir host for the virus. Network analysis of the movements and connections of Australian beekeepers showed the nomadic beekeeper network was fragmented into 34 disconnected components.2 The largest component network linked 288 locations from Duaringa in central Queensland to Nelson in the far south-west of Victoria. Almond orchards and lucerne seed production were locations of major hive congregations driven by the opportunity to provide paid pollination services. In the 3 months after completion of almond pollination, movement of hives occurred to 49 locations spread over >2000 km, ranging from south-east Queensland to southern Victoria. This highlights how rapidly pests or diseases could spread if introduced to major congregation areas. The authors discuss the implications of these findings for improving surveillance and disease control policy for the honeybee industry. A study conducted at Charles Sturt University reports that Echinococcus granulosus is still present in Tasmania and being transmitted at low levels between dogs and cattle, although provisional eradication of E. granulosus from Tasmania was declared in 1996.3 Faecal samples from 1425 rural domestic dogs from Tasmania to south-eastern Queensland were tested for the presence of E. granulosus and other intestinal helminth infections. A total of 45 dogs (3.2%) were found to be E. granulosus coproantigen-positive, with 24 of these dogs originating from Tasmania and 16 from NSW. Three of the Tasmanian dogs were also positive for E. granulosus on coproPCR. The study also found that owner behaviour perpetuates the transmission of E. granulosus. Most owners did not deworm their dogs frequently enough to ensure they could never have a patent infection of E. granulosus. In addition, approximately 45% of the dog owners surveyed reported feeding offal of lambs or mutton and whole rabbits to their dogs, and >74% of owners admitted their dogs had opportunities to access carcases of wildlife or livestock. This month's case report is the first reported case of leucocyte adhesion deficiency type III (LAD III) in a dog in Australia and the first reported case of LAD III in a mixed-breed dog worldwide.4 This condition is attributable to a mutation in the KINLIN-3 gene that impairs activation of β-integrins, resulting in absence of neutrophil chemotaxis and adhesion and platelet adhesion and aggregation. Affected patients exhibit recurrent infections, marked leucocytosis and a severe bleeding tendency causing increased mucosal haemorrhage and prolonged postoperative haemorrhage. The authors describe the clinical signs, diagnosis and management of LAD III in a 16-month-old male German Shepherd × Rottweiler dog. A survey of Thoroughbred and Standardbred trainers investigated the magnitude of and risk factors associated with horse wastage in the Australian racing industry during the 2002–03 race year.5 The results showed an overall exit rate of around 40% in Thoroughbred and Standardbred stables. Poor performance was the most commonly reported reason for leaving, followed by illness/injury. Unsuitable temperament/behaviour was less frequently reported. A larger percentage of Standardbreds than Thoroughbreds went to different trainers or directly to knackeries, while a higher percentage of Thoroughbreds went to stud, auctions or entered ridden equestrian pursuits. Statistically significant risk factors influencing the destinations of both Thoroughbred and Standardbred racing horses included whether the trainer owned the horses, horse sex and age and reasons for leaving. A study conducted at Oregon and Colorado State Universities reviewed the clinical features and factors associated with short- and long-term survival of New World camelids with acquired urethral obstruction caused by urolithiasis.6 The most common clinical signs included straining to urinate, dribbling urine and anorexia, which are also frequently observed in small ruminants with obstructive urolithiasis. Prognosis appeared to be worse and occurrence of complications appeared to be more frequent than in small ruminants, particularly after tube cystostomy and bladder marsupialisation. Incomplete urethral obstruction at admission and surgical treatment were associated with increased odds of short-term survival. Recurrence of urethral obstruction had a poor prognosis for long-term survival.

Determination of equine fetal sex by Doppler ultrasonography of the gonads

The identification of fetal sex in horses by location of the genital tubercle between 55 and 70 days of pregnancy is hampered by the large amount of allantoic fluid, extensive fetal movements and the extremely long umbilical cord; however, reliable results have been achieved by ultrasonographic evaluation of the fetal gonads at 110-150 days of pregnancy. The aim of this study was to diagnose the sex of equine fetuses using B-mode and/or colour Doppler transrectal ultrasonography in fetuses of different ages. Cross-sectional study comparing 2 methods of determining fetal sex. The evaluations were performed in 86 mares at 90-180 days of pregnancy using transrectal B-mode and colour Doppler mode ultrasonography. Fetuses that had gonads with a homogeneous texture and a thin central longitudinal echogenic line were considered to be male. Females were identified by the presence of gonads with a central circular echogenic structure surrounded by a hypoechogenic external halo. Using B-mode ultrasonography, it was possible to determine the sex of 75% of the males, while determination of sex based on differences between the medullary and cortical layers of the ovary allowed 91.1% of females to be correctly identified. Using Doppler ultrasonography, 100% of males were successfully identified, while characteristic vascularisation of the female gonad could be detected in 98% of the evaluated female fetuses. Colour Doppler ultrasonography combined with B-mode ultrasonography allows the determination of fetal sex with greater accuracy than B-mode ultrasonography alone, particularly for the identification of the male gonad. The use of Doppler ultrasonography enables the identification of sex in older fetuses.

Salivary Cortisol Levels in Horses and their Riders During Three-Day-Events

Abstract The group of 36 warm-blooded half-bred horses (18 stallions and 18 mares) and their riders (20 men and 16 women), who ended three-day-events, were selected for the study. The horses were aged 4 to 6 years, while the riders were 19 to 34-year-old. The saliva samples were collected after each phase of the competitions. The cortisol concentration was determined using an immunoassay method. The following factors were considered: type of competition, horse sex, and rider gender. In horses, the statistically important correlation was found between the results obtained for the dressage and cross-country, for the cross-country and show jumping, and for the dressage and show jumping. An analogous comparison for the riders suggests a statistically significant correlation between the data obtained for the cross-country and show jumping. Comparing the data of horses and their riders, a significant correlation coefficient was found for the cross-country group of woman and the dressage group of men. In conclusion, the salivary cortisol level in individual horses in each phase of three-day-event was found to be repetitive. Therefore, the salivary cortisol test is demonstrated to be a useful method to evaluate the horse response to each type of competition during three-day-events.

Postoperative Septic Arthritis After Elective Equine Arthroscopy Without Antimicrobial Prophylaxis

To determine the frequency of postoperative septic arthritis after elective arthroscopy in the absence of prophylactic antimicrobial therapy and to report complication rate of 444 consecutive equine arthroscopies. Retrospective case series. Horses (n = 444). Medical records of 444 consecutive elective equine arthroscopies (2008-2010) were reviewed. Horses that had septic arthritis on admission or those admitted for tenoscopy and bursoscopy, or had arthroscopic assisted internal fracture fixation were not included. Age and sex of horse, duration of anesthesia, joint examined, number of portals, surgeon, postoperative complications, date of complication, and number of septic joints were recorded. For 444 horses, 636 joints were explored. Nineteen horses had 20 complications (fever [n = 9], surgical site infection [3], cellulitis [1], wounds associated with inappropriate bandaging [2], limb swelling postsuture removal [1], medical colic [1], septic joint [3]). Horses with septic joints did not have any other complications. The incidence of sepsis was 0.5% joints or 0.7% horses. All horses survived and returned to function. Joint infection rate in the horse population that had elective arthroscopy without antimicrobial prophylaxis compares favorably with other reports citing 0.9% sepsis in horses after arthroscopy in which horses received either no antimicrobials or were administered pre or perioperative antimicrobial therapy.

Epidemiology, diagnosis and therapy of Theileria equi infection in Giza, Egypt

Aim: To study the prevalence of Theileria equi among horses in different age groups, both sexes, months and seasons of the year, and regions of Giza governourate. Studying the changes in the blood picture, blood chemistries, liver enzymes associate with T.equi infections in horses. Evaluating IFA and CFT at different dilutions in the serodiagnosis of T.equi infections in horses. Evaluating four anti-Theileria medication regimens (diminazine aceturate, imidiocarb 7%, buparvaquone and a combination of imidiocarb 7% and buparvaquone) in treatment of T.equi infections in horses. Materials and Methods: Total of 149 horses were examined by clinical signs and blood smears. Fortey whole blood samples from T.equi infected horses were examined to measure haemoglobin, total RBCs count and PCV. Fortey serum samples from T.equi infected horses were examined to measure total bilirubin, direct bilirubin, ALT and AST enzymes. Serum samples from T.equi infected (40) and non infected (14) horses were tested by indirect fluorescent antibody test (IFA) and complement fixation test (CFT) at different dilutions. Four groups of T.equiinfected horses (A,B,C,D), each group was represented by 10 horses and was separately treated with diminazine aceturate, imidiocarb 7%, buparvaquone and a combination of imidiocarb 7% and buparvaquone respectively. Results: the prevalence of T.equi was 41.61% in totally examined horses. The prevalence was higher in males than females. The highest prevalence was among age group ranged from 5-10 years as (22.81%). The highest prevalence was in July and was recorded as (25.81%) and the disease was more prevalent in summer than winter. The highest prevalence was recorded in Nazlet-alsamman as (51.61%). Equine theileriosis was clinically characterized by fever, haemoglobinuria, oedema, anaemia and icterus. The best dilution for IFA was 1/160 where sensitivity, specificity and accuracy were the highest for this test as (98%), (92.86%) and (97.44%) respectively. The best dilution for CFT was 1/32 where sensitivity, specificity and accuracy were collectively the best as (90%), (92.86%) and (90.74%) respectively. Conclusion: It was concluded that T.equi is prevalent among horses in Giza governourate, its prevalence is varied according to the age, sex of horses, months, seasons and regions. T.equiinfections in horses are accompanied with changes in blood pictures, blood chemistries and liver enzymes. Both IFA and CFT could be used for the serodiagnosis of T.equi . The used four anti-Theileria medication regimens have the same ability to eradicate T.equi from the infected horses.

P-Cresol: A Sex Pheromone Component Identified from the Estrous Urine of Mares

Previously it was shown that m- and p-cresols in the urine of mares exhibits a temporally reproducible pattern that is dependent on ovarian activity and, thus, provides information about the timing of ovulation. New behavioral data demonstrate 1) that stallions spend significantly more time sniffing p-cresol as compared to o-, and m-cresols, and, 2) that the extent of stallions' erections differ significantly in response to different types of samples. The lowest erection level was recorded for the pure-water control, a moderate erection level was elicited by the urine of diestrous mares, and the highest erection level was elicited by urine of a diestrous mare containing synthetic p-cresol at a quantity equivalent to half of the amount of p-cresol found in the urine of estrous mares. Consequently, p-cresol is at least one of the components of a horse sex pheromone.

Determination of sex differences in personality and trainability of yearling horses utilizing a handler questionnaire

Very little scientific evidence exists to quantify differences in trainability and personality between sex of horses in spite of numerous industry stereotypes. It could be of great benefit to the horse industry to categorize personality differences and isolate strengths and weaknesses of each sex. This could potentially lead to modifications of training programs based on sex differences. There are multiple methods of personality evaluation used in equine studies including measurement of physical reactions (e.g., heart rate), measurement of learning ability, or utilization of a personality questionnaire. The current study was undertaken to determine if personality and trainability differences do exist between mares (intact female horses) and geldings (castrated male horses) based on a previously validated handler questionnaire. Eighteen yearling horses were used in a paired t-test study performed in conjunction with an undergraduate course offered at the University of Georgia. Each student in the class was randomly assigned two yearling horses to handle for the semester (15 weeks). Nine students were assigned one mare and one gelding to handle for the semester, while two students were assigned two horses of the same sex. All students were given surveys at the midpoint and end of the semester to assess personality traits and skill levels of mares and geldings. Students were not told of the purpose of the surveys, and surveys were given in conjunction with a written exam. All students filled out surveys but results were only used from the nine students who worked with both a mare and a gelding. These measures were taken to avoid the chance that students may guess the purpose of the study. The survey asked handlers to rate their horses on personality traits that can be grouped into the following main factors: anxiety, trainability, and affability. Handlers also rated their horses on their first reaction, quickness to learn, and retention of concepts for skills typical of a yearling horse in training. After analyzing survey results for individual personality traits from the midpoint of the study, mares were found to be more aggressive, tense, and excitable as well as panic easier as compared to geldings at the P < 0.05 level, as well as showing a trend toward being more skittish ( P < 0.10). When grouped into personality factors, mares showed more anxiety and less affability than geldings at the P < 0.05 level at both the midpoint and end of the study. The results for the anxiety factor were still significant after adjustment using Bonferroni's correction. When skills were grouped into classifications of sensitizing and desensitizing skills, geldings rated higher on skills that required desensitizing in the areas of first reaction, quickness to learn, and retention of concept at the midpoint of the study ( P < 0.05). These were still significant after adjustment using Bonferroni's correction. By the end of the study, geldings still rated more favorably than mares in desensitizing skills in the areas of first reaction and retention of concepts ( P < 0.05). However, when adjusted using Bonferroni's correction, only differences in retention of concept were significant. Differences noted in personality as well as trainability could be potentially utilized to modify common training regimes used in the horse industry.

Homeopathic prescribing for chronic conditions in equine veterinary practice in the UK

Twelve Faculty of Homeopathy veterinarians recorded data systematically at 777 consecutive homeopathic appointments for horses over a period of 12 months. A spreadsheet enabled the recording of information, which included...

Return to work following unilateral enucleation in 34 horses (2000–2008)

REASONS FOR STUDY: The effect of unilateral enucleation on vision and potential loss of performance in horses has received little study. To evaluate the likelihood of return to prior discipline following unilateral enucleation in horses, assessing the role of age at enucleation, equine discipline, reason for enucleation, time to vision loss and eye enucleated. Unilateral enucleation has no significant effect on likelihood of return to work in horses, for both right and left eyes, across age and discipline. A retrospective review of medical records identified 92 horses that underwent unilateral enucleation at the University of Pennsylvania New Bolton Center from April 2000-April 2008. Case variables determined from the medical record included breed and sex of horse, age at enucleation, which eye was enucleated, reason for enucleation and onset of vision loss. Pre- and post operative occupations were determined by telephone interview with the owner or trainer of each horse. Based on hospital surgery logs, 92 enucleations were performed over the 8 year period and 77 records were available for review, with follow-up information available for 34 horses. Of these, 29/34 (85%) horses returned to work in pleasure or trail riding (11/13), flat racing (7/10), hunter/jumpers (4/4), dressage (3/3), group lessons (1/1), eventing (1/1), steeplechase (1/1) and as a broodmare (1/1). Four of 5 horses (4/34, or 12% sample) that did not return to work (2 pleasure and 2 racing) were retired due to anticipated or perceived decrease in performance or behaviour change following unilateral enucleation, with the remaining horse retired from racing for lameness issues unrelated to enucleation. Twenty-two of 25 horses (88%) with acute vision loss and 7/9 horses (78%) with gradual vision loss returned to their previous discipline. Horses are able to return to a variety of occupations after unilateral enucleation.

THE INFLUENCE OF THE AGE, SEX AND PERFORMANCE LEVEL OF HORSES ON THEIR SUCCESS IN THE SHOW JUMPING COMPETITION

The aim of this thesis is to clarify the effect of the horse age, the horse sex and the performance rating of the horse on the resulting course passing. Altogether it was judged 1 825 horses during 44 courses. It represents 20 457 passed fences. The cogency of detected differences was determinated by the F-test and the following t-test with the signifi cance levels P≤0,05(+) , P≤ 0,01(++) a P≤0,001(+++). From the results analysis emerged the following statistically confi rmative establishment and fi ndings: The stallions reach higher percentage of clear jumping than the mares and the geldings. The jump refuse is more frequent in mares (3,62 %). The best results in course passing reach horses between the ages of 12 – 13 years, the performance of older horses declines.The fence passing is not differs markedly after the performance level of the horse. Better results reached horses in the courses of “Z” level (1,24) and the „T“ level (1,36). It indicates that 100 cm high is not very diffi cult to pass over for young horses and through the courses of the „T“ level are the best horses.

Predictors of biting fly harassment and its impact on habitat use by feral horses (Equus caballus) on a barrier island

Feral horses on Assateague Island, Maryland, were observed in June and August 2000 to determine what behavioral and ecological factors affect the intensity of biting fly harassment and whether habitat use by horses was influenced by biting flies. Fly counts and frequencies of comfort movements (i.e., movements designed to dislodge insects) were recorded during focal animal samples, as well as data on sex, group size, habitat type, temperature, humidity, wind speed, and behavior. Seasonal habitat use patterns were assessed using 7 years of monthly census data on the horses. The number of biting flies on the horse was affected by horse sex, habitat, temperature, and group size. The number of comfort movements a horse showed was affected by habitat, temperature, wind speed, group size, and number of horses within one body length of the focal. The number of comfort movements made by a horse was found to be highly correlated with fly numbers. Though marshes were used most throughout the year, the pattern of use of dune, scrub, and human-altered habitats reflects a pattern of biting fly avoidance and refuge-seeking by the horses.

Effect of daily administration of pyrantel tartrate in preventing infection in horses experimentally challenged with Sarcocystis neurona

To determine whether daily administration of pyrantel tartrate can prevent infection in horses experimentally challenged with Sarcocystis neurona. 24 mixed-breed specific-pathogen-free weanling horses, 10 adult horses, 1 opossum, and 6 mice. Sarcocystis neurona-naïve weanling horses were randomly allocated to 2 groups. Group A received pyrantel tartrate at the labeled dose, and group B received a nonmedicated pellet. Both groups were orally inoculated with 100 sporocysts/d for 28 days, 500 sporocysts/d for 28 days, and 1000 sporocysts/d for 56 days. Blood samples were collected weekly, and CSF was collected monthly. Ten seronegative adult horses were monitored as untreated, uninfected control animals. All serum and CSF samples were tested by use of western blot tests to detect antibodies against S. neurona. At the end of the study, the number of seropositive and CSF-positive horses in groups A and B were compared by use of the Fisher exact test. Time to seroconversion on the basis of treatment groups and sex of horses was compared in 2 univariable Cox proportional hazards models. After 134 days of sporocyst inoculation, no significant differences were found between groups A and B for results of western blot tests of serum or CSF There were no significant differences in number of days to seroconversion on the basis of treatment groups or sex of horses. The control horses remained seronegative. Daily administration of pyrantel tartrate at the current labeled dose does not prevent S. neurona infection in horses.

Prevalence of Equine Gastric Ulceration in Standardbred Racehorses in Czech Republic

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Synteny and regional marker order assignment of 26 type I and microsatellite markers to the horse X- and Y-chromosomes.

The hypothesis that the conservation of sex-chromosome-linked genes among placental mammals could be extended to the horse genome was tested using the UCDavis horse-mouse somatic cell hybrid (SCH) panel. By exploiting the fluorescence in-situ hybridization (FISH) technique to localize an anchor locus, X-inactivation-specific transcript (XIST) on the horse X chromosome, together with the fragmentation and translocation of the X- and Y-chromosome fragments in a somatic cell hybrid panel, we regionally assigned 13 type I and 13 type II (microsatellite) markers to the horse X- and Y-chromosomes. The synteny groups that correspond to horse X- and Y-chromosomes were identified by synteny mapping of sex-specific loci zinc finger protein X-linked (ZFX), zinc finger protein Y-linked (ZFY) and sex-determining region Y (SRY) on the SCH panel. A non-pseudoautosomal gene in the human steroid sulfatase (STS) was identified in both X- and Y-chromosome-containing clones. The regional order of the X-linked type I markers examined in this study, from Xp- to Xq-distal, was [STS-X, the voltage-gated chloride channel 4 (CLCN4)], [ZFX, delta-aminolevulinate synthase 2 (ALAS2)], XIST, coagulation factor IX (F9) and [biglycan (BGN), equine F18, glucose-6-phosphate dehydrogenase (G6PD)] (precise marker order could not be determined for genes within the same brackets). The order of the Y-linked type I markers was STS-Y, SRY and ZFY These orders are the same arrangements as reported for the human X- and Y-chromosomes, supporting the conservation of genomic organization between the human and the horse sex chromosomes. Regional ordering of X-linked type I and microsatellite markers provides the first integration of type I and type II markers in the horse X chromosome.

Equine recurrent uveitis - an update

UVEITIS may arise from a number of causes, including blunt or perforating injury to the globe and, rarely, haematogenous spread of bacterial pathogens such as Streptococcus equi var equi or...

Seroprevalence of antibodies to Sarcocystis neurona in horses residing in a county of southeastern Pennsylvania

Objective To determine seroprevalence of Sarcocystis neurona-specific antibodies in a population of horses residing in Chester County, Pa. Design Prevalence survey. Sample Population 117 serum samples from selected members of a population of 580 Thoroughbred horses. Procedure Serum was analyzed for antibodies to Sarcocystic neurona, using a western blot. Information regarding age, sex, and housing of horse was obtained by questionnaire. Data were analyzed, using multivariable logistic regression. Results Seroprevalence was 45.3% (95% CI, 36.3 to 54.3%). A relationship was not found between seroprevalence and sex of horse. Seroprevalence was greater in older horses (logistic regression; P = 0.16). Clinical Implications High seroprevalence of antibodies to S neurona and the lack of neurologic deficits among horses sampled indicate that positive results of serologic examination alone are of limited value for diagnosis of equine protozoal myeloencephalitis. Clinical signs consistent with the disease are the most important consideration in accurate diagnosis. (J Am Vet Med Assoc 1997;210:517–518)

Racing performance after hemicircumferential periosteal transection for angular limb deformities in Thoroughbreds: 199 cases (1987–1989)

Summary Racing records of 199 Thoroughbred foals with angular limb deformities surgically treated by hemicircumferential periosteal transection and elevation (hcpt) from 1987 through 1989 (principals) were compared with records of their 1,017 siblings (controls) for starting status; 2-, 3-, and 4-year-old starts; earnings and earnings per start; and starts percentile ranking number (spr). Principals had a slightly lower percentage of horses starting a race (45 vs 55%), fewer 2-year-old starts (1.06 vs 1.72), and lower spr (33.49 vs 49.18), compared with those of controls (P &lt; 0.05). Starting status was significantly (P &lt; 0.05) affected by surgery and the horse's sex, but not by anatomic site treated. Fillies were 1.74 times less likely to start than were colts, regardless of surgery, whereas principal fillies were 2.63 times less likely to start than were control colts. Difference was not detected between principals and controls in 3- or 4-year-old starts; 2-, 3-, or 4-year-old earnings, or earnings per start. Horses treated with distal metacarpal/metatarsal hcpt had fewer 2-year-old starts (1.09 vs 2.19), but did not have a significantly different spr or lower starting percentage, compared with values for controls. Horses treated with distal radial hcpt had lower starting percentage (48 vs 55%), fewer 2-year-old starts (1.22 vs 1.70), and lower spr (32.53 vs 53.32), compared with those of controls. Horses treated with hcpt in 2 or more anatomic sites (ie, distal part of radius and metacarpal bones) had a lower starting percentage (33 vs 53%), fewer 2-year-old (0.65 vs 2.74) and 3-year-old starts (2.93 vs 4.76), and lower spr (23.20 vs 37.25) than had controls. Performance in horses treated with hcpt at 2 or more anatomic sites thus was worse (ie, more performance measures differed from those of their siblings), compared with that in horses treated at the distal part of the metacarpal/metatarsal bone III or radius.