Age Of Horses Research Articles

Hypoechoic ultrasonographic findings in the patellar ligaments are common in riding and trotting horses in training (116 cases).

Patellar ligament (PL) injuries are increasingly being reported in horses, but few studies have described the normal PL ultrasonographic appearance in horses. The aims of this prospective observational study were to describe the ultrasonographic appearance of the PLs and infrapatellar fat pad in a population of horses in training and to relate the ultrasonographic findings to objectively measured movement asymmetry. B-mode and color Doppler ultrasonographic examination of the PLs and infrapatellar fat pad in both hind limbs and objective gait analyses were performed on the 116 riding and trotting horses included in the study. The association between ultrasonographic findings, horse age, and movement asymmetry during the trot was then investigated. Distinct or diffuse hypoechoic regions were commonly found in the intermediate PL (24/116; 20.7%), especially in the caudal aspect of the mid-third of the ligament. The infrapatellar fat pad had a hypoechoic striated appearance in all horses except one, in which it was hyperechoic. No association was found between ultrasonographic findings in the PLs and infrapatellar fat pad and lameness. It is important to recognize that there is biological variation in PL appearance, which may or may not be associated with pain in this area, therefore emphasizing the use of local analgesia to determine the location of the lameness.

A spectral cavalcade: Early Iron Age horse sacrifice at a royal tomb in southern Siberia

Abstract Horses began to feature prominently in funerary contexts in southern Siberia in the mid-second millennium BC, yet little is known about the use of these animals prior to the emergence of vibrant horse-riding groups in the first millennium BC. Here, the authors present the results of excavations at the late-ninth-century BC tomb of Tunnug 1 in Tuva, where the deposition of the remains of at least 18 horses and one human is reminiscent of sacrificial spectral riders described in fifth-century Scythian funerary rituals by Herodotus. The discovery of items of tack further reveals connections to the earliest horse cultures of Mongolia.

Analysis of the jumping performance of young warmblood horses based on the results of breeding competitions in the Czech Republic

The aim of the study was to evaluate the performance of warmblood horses in the Czech Republic based on the results of the Criteria of Young Horses (CYH) breeding competitions. In this study, we focused on the evaluation of horses in jumping competitions for mares, stallions and geldings aged 4 to 6 years. The statistical evaluation is based on the official CYH methodology, which takes into account the different difficulty of competitions for horses of different ages. Data from 2017 to 2021 were used for the evaluation. During this period, 645 horses participated in the competitions with 2691 starts. The statistical analysis evaluated the influence of age, sex, country of origin and breed group on the performance of the horses. Analysis of variance was used for comparison and Scheffe's test was used for subsequent post hoc analysis. Six-year-old horses were rated the highest (22.95 points) despite receiving the highest penalty points (3.29 penalty points). In the sex analysis, the overall rating for stallions was highly significant (P ≤ 0.01) higher than that of geldings and mares. Stallions were the least represented in terms of numbers (22.33%), but they had the highest number of starts per horse (4.75 starts) and the best mean score (23.32 points). A total of 76.12% of the horses that participated in the CYH were of Czech breeding, but their scores were statistically highly significant lower (P ≤ 0.01) than those of imported horses, with a difference in mean scores of 0.91 points. In terms of breed, the most numerous breeds were the Czech Warmblood (43.26%) and then the Czech Sport Horse (17.52%), but these breeds were below average in the overall evaluation (CZEWB 22.53 points, CSH 22.48 points). The third most represented breed was the Holstein horse, which, on the contrary, achieved the best average results (22.83 points) and the performance of representatives of this breed differed highly significantly (P ≤ 0.01) from most other breeds.

Survey of ocular abnormalities in a population of Turkmen horses.

The aim of this study was to detect and describe ocular abnormalities in a population of Turkmen horses. A total of 55 Turkmen horses (33 mares and 22 stallions) from one herd were evaluated in this study. Demographic data (Age, Sex, Coat color) were recorded. All animals underwent complete ophthalmic examination. The Schirmer tear test -I (STT-I) was performed for all horses prior to other diagnostic tests. Neuro-ophthalmic examinations (menace response, dazzle reflex, pupillary light reflex, maze test, and visual tracking) were carried out in different lighting situations (bright and dim lights). Slit lamp biomicroscopy, direct and indirect ophthalmoscopy, fluorescein staining, and tonometry were performed for each horse. The mean (standard deviation) age of horses was 5.7 (4.6) years (range of 1-17 years). In total, 18 horses (32.7%) had ocular-related lesions. Cataract, iris hyperpigmentation and corneal edema were the most identified conditions in the horses of this study. About one-third of studied horses had at least one ocular abnormality. No ocular abnormalities attributed to the distinct cream/gold coat color were identified, which the Turkmen horse is known for.

Detection of Gastrointestinal Pathogens with Zoonotic Potential in Horses Used in Free-Riding Activities during a Countrywide Study in Greece.

The objectives of this study were (a) to detect zoonotic gastrointestinal pathogens in faecal samples of horses using the FilmArray® GI Panel and (b) to identify variables potentially associated with their presence. Faecal samples collected from 224 horses obtained during a countrywide study in Greece were tested by means of the BioFire® FilmArray® Gastrointestinal (GI) Panel, which uses multiplex-PCR technology for the detection of 22 pathogens. Gastrointestinal pathogens were detected in the faecal samples obtained from 97 horses (43.3%). Zoonotic pathogens were detected more frequently in samples from horses in courtyard housing (56.0%) than in samples from horses in other housing types (39.7%) (p = 0.040). The most frequently detected zoonotic pathogens were enteropathogenic Escherichia coli (19.2% of horses) and Shiga-like toxin-producing E. coli stx1/stx2 (13.8%). During multivariable analysis, two variables emerged as significant predictors for the outcome 'detection of at least one zoonotic pathogen in the faecal sample from an animal': (a) the decreasing age of horses (p = 0.0001) and (b) the presence of livestock at the same premises as the horses (p = 0.013). As a significant predictor for the outcome 'detection of two zoonotic pathogens concurrently in the faecal sample from an animal', only the season of sampling of animals (autumn) emerged as significant in the multivariable analysis (p = 0.049). The results indicated a diversity of gastrointestinal pathogens with zoonotic potential in horses and provided evidence for predictors for the infections; also, they can serve to inform horse owners and handlers regarding the possible risk of transmission of pathogens with zoonotic potential. In addition, our findings highlight the importance of continuous surveillance for zoonotic pathogens in domestic animals.

Assessing the Peripheral Levels of the Neurotransmitters Noradrenaline, Dopamine and Serotonin and the Oxidant/Antioxidant Equilibrium in Circus Horses.

Due to the paucity of information on circus management effects on the welfare of horses, this study investigated the plasma concentrations of noradrenaline, dopamine and serotonin, known to be indices of mental status, as well as the reactive oxygen metabolites (d-Roms) and the biological antioxidant potential (BAP), likely to denote the oxidant/antioxidant equilibrium of organisms, in horses managed in different Italian circuses. For the study, 56 circus horses of different breeds and ages were enrolled and divided into six groups according to the horses' management (circus management, groups G1-G5; classic riding management representing the control group, CG). From each horse, blood samples were collected in order to assess the concentration of selected parameters. One-way ANOVA showed no differences (p > 0.05) in serotonin, dopamine, noradrenaline, d-Roms and BAP values between circus and control horses. No differences related to the breed of the horses enrolled in the study were found in the values of all investigated parameters (p > 0.05). Furthermore, neurotransmitters showed overlapping levels between the different age classes of investigated horses (p > 0.05); contrariwise, the age of the horse displayed a significant effect on BAP values, with the oldest horses (16-21 age class) exhibiting lower BAP values compared to 4-5, 6-10 and 11-15 age classes (p < 0.05), whereas the d-Roms showed similar values in horses of different age classes (p > 0.05). The results gathered in the present study suggest that the mental status of horses under circus management was not compromised; however, better attention and care in the management of older horses is advocated, as they showed a lower biological antioxidant potential than younger horses; thus, they could be more susceptible to oxidative stress.

Ultrasonography of the suspensory ligament branches in yearling and 2-year-old Thoroughbred sales horses: Prevalence, progression of findings and associations with racing performance.

Equine suspensory ligament branch (branch) ultrasonography is becoming increasingly commonplace presale. No ultrasonographical branch reference data exists for Thoroughbred sales horses. To define the prevalence of ultrasonographical findings in the forelimb suspensory branches of yearling and 2-year-old sales Thoroughbreds and to analyse associations with racing performance. To track changes in branch findings between 1 and 2 years of age in horses that present for sale at both ages. Prospective cohort study using an enrolled sample. Horses were enrolled from a 2016 yearling sale and five 2017 2-year-old sales with consignor permission. Ultrasonography was performed immediately prior to the sales. Ultrasonographical findings relating to branch size, fibrillar pattern, the presence of hyperechoic foci, periligamentar tissue thickness and the adjacent proximal sesamoid bone surface were examined. Associations with racing performance from 2 to 4 years of age were investigated using multivariate regression analyses. Clinical follow-up was sought to ascertain why horses that did not race never started. A total of 593 sales yearlings and 367 2-year-olds had forelimb branch ultrasonography performed. Grade ≥2 fibrillar branch change was present in 8.9% of yearlings and 14.4% of 2-year-olds. A 0.25 cm increase in branch width was associated with a 49-day delayed start to racing careers (P < 0.001, 95% confidence interval (95% CI): 21-77 days). The presence of grade 2 hyperechoic foci was associated with significantly lower total earnings (P = 0.01, 95% CI: $2000-$16 022) and lower earnings per start (P = 0.003, 95% CI: $349-$1718) in United States Dollars. Grade 3 fibrillar branch change had clinically important reductions in the probability of racing, the calibre of racing performance and earnings. Grade 1 fibrillar pattern was associated with significantly higher earnings per start (P = 0.004, 95% CI: $2641-$5759). The findings are applicable to horses prepared for public auction and deemed fit to be entered for sale. The results may underestimate the proportion of severe lesions in horses not entered for sale. Reference values specific to young Thoroughbreds have been established. Grade 1 fibrillar branch change should be regarded as an acceptable appearance in sales yearlings and 2-year-olds. Approximately one-third of grade 2 yearling branches progressed to a grade 3 lesion. Evidence of enlarged branch width and grade 2 hyperechoic foci at 2-year-old sales constitute a risk to racing performance.

Transrectal ultrasonographic assessment of the fetal proximal phalanx: A new tool to assess fetal age and bone development in horses

Fetal age in Quarter Horses can be predicted within 2 weeks from 100- to 200- days of gestation using femur length, biparietal diameter (cranium diameter) and eye approximated volume. However, as pregnancy advances, the femur and cranium become too large to be imaged in their entirety using ultrasound and the corresponding biometric parameters can no longer be measured. In this longitudinal study, the proximal phalanx (P1) was evaluated as a novel biometric parameter for late gestation to predict fetal age and bone maturation. Transrectal ultrasound was performed in ten pregnant mares with known ovulation dates, every two weeks from 240- days of gestation until parturition. P1 was imaged in 69 % of the examinations. Inability to image P1 was due to obstructive positioning such as carpal or fetlock flexion, or posterior presentation of the fetus. Advancing fetal age did not affect visibility of P1. P1 length correlated significantly with days of gestation and a correlation equation was established: y = 0.3837x -69.55 where y is the predicted value of P1 length and x is the day of gestation (with day 0 being the day of ovulation). When P1 length was equal to or larger than the width of the ultrasound image (52.5 mm), 90 % of mares (9/10) were above 300- days of gestation. Ossification of the proximal and distal epiphysis of P1 typically appeared between 277- and 303 -days of gestation (mean: 288 days). The proximal epiphysis did not close before parturition whereas the distal one closed between 306- and 333-days of gestation (mean: 320 days). P1 epiphyseal appearance and closure occurred chronologically reflecting bone maturation. Radiographic findings at birth and prenatal ultrasound findings were in agreement, apart from timing of P1 distal epiphyseal closure. In conclusion, P1 length can be used as a new fetal biometric parameter to assess fetal age and growth after 240- days of gestation. The knowledge of P1 bone maturation process in utero as a marker for fetal bone development, may also be valuable in clinical decision-making when considering inducing parturition in the mare.

Dry matter concentration, particle size distribution and sand presence in faeces from horses with and without colic

A study comprising 74 colic and 74 control horses admitted to an animal hospital was performed. Faecal samples were collected and analysed for dry matter concentration, particle size distribution using wet-sieving, and sand presence through a sand sedimentation test. Data on horse breed, age, gender and basic feeding variables was collected and analysed using χ2-tests. Faecal dry matter concentration, particle size distribution and sand score was compared between colic and non-colic horses, and between horses with different colic types, using one-way ANOVA. Results showed that colic and non-colic horse groups were similar in breed, age, gender and basic feeding variables. Faecal dry matter concentration, particle size distribution and sand score were similar among colic and non-colic horses. Horses diagnosed with “unknown colic cause” had higher proportion of particles >0.5 <1.0 mm size compared to horses with colic due to impactions in caecum or colon, torsion or gas accumulation (P<0.05), but this difference was very small and most likely not of biological importance. Faecal dry matter concentration and sand score were similar among horses with different types of colic. Increased knowledge of the composition of particles of different size in equine faeces may enhance our understanding of digesta passage rate in colic and non-colic horses, which is needed to develop preventative measures of certain types of colic.

Strongylids of Domestic Horses in Eastern Slovakia: Species Diversity and Evaluation of Particular Factors Affecting Strongylid Communities

PurposeThis study aimed to examine the species diversity and structure of the strongylid community in domestic horses in Eastern Slovakia. Also, an analysis of the impact of age, sex, and collection location factors on the strongyid communities was performed.MethodsTwenty-seven horses 1.5–21 years old from two farms in eastern Slovakia with different horse-management conditions were studied. Strongylids were collected after horse treatments with Noromectin (0.2 mg ivermectin); 66,170 specimens were collected and identified. Faecal egg count reduction test (FECRT) was performed following fenbendazole (FBZ) and ivermectin (IVM) treatments.ResultsTwenty-four strongylid species were found; horses were infected with 6 to 16 (average = 11.7) species. Six cyathostomin species (Cylicocyclus nassatus, Cyathostomum catinatum, C. pateratum, Cylicostephanus longibursatus, C. goldi, C. calicatus) were the most prevalent; C. catinatum was the dominant species in both farms (Berger-Parker index 0.34 and 0.42). The structure of the strongylid community was multimodal with dominant, subdominant, background, and rare species. The Mantel test showed that horse age and sex did not significantly affect the nematode infracommunity composition (p > 0.05), while the impact of the collection location (farm) was significant (p = 0.03). Additionally, C. longibursatus was identified as the species contributing significantly to the observed farm differences. Strong resistance to FBZ was documented on both farms (FECRT was 36.4% and 22.7%); IVM resistance was not observed (FECRT = 100%).ConclusionThis study presents the first report on the strongylids parasitizing domestic horses in Eastern Slovakia and gives basic information for further studies of horse parasites and their control in the region.

Comparison of daily heart rate and heart rate variability in trained and sedentary aged horses

Athletic horses are usually retired from equestrian competition at an advanced age. Aged horses may then continue to have regular exercise or are sedentary. The comparison of autonomic regulation between sedentary aged horses (SAH) and trained aged horses (TAH) after retirement remains unpublished. This study compared daily heart rate (HR) and heart rate variability between 11 SAH and 11 TAH over 22 h (07.00 h to 05.00 h on an alternate day) and during the day and night. An increase in mean beat-to-beat (RR) intervals (p < 0.01-0.0001) and parasympathetic nervous system (PNS) index (p < 0.05-0.0001), corresponding to the decreased HR and sympathetic nervous system (SNS) index (p < 0.01-0.0001), was observed at night. Compared to SAH, lowered mean HR and SNS index, corresponding to elevated mean RR intervals and very-low-frequency bands, were marked in TAH during the day (p < 0.05 for all variables). Whereas the standard deviation of the RR intervals index was higher in TAH than in SAH during the day and night (p < 0.05 for both periods). It was suggested that aged horses with different physical activities revealed distinct autonomic responses. TAH demonstrated higher HRV than SAH during the day. A decreased HR in TAH is prone to result from a reduced SNS role, leading to a shift toward more PNS activity during the day. More research is warranted to determine to what extent the autonomic regulation is modulated by accompanying higher exercise volume or programmed exercise in aged horses.

Career profile and pattern of racing for Thoroughbred jumps-racing horses in New Zealand

Context Racing structure and focus for racehorses differs across jurisdictions and is poorly described. In New Zealand and Australia, jumps racing accounts for a small proportion of total Thoroughbred races each year, as opposed to the larger jumps-racing (National Hunt) industry with purpose-bred horses found in the UK and Ireland. Aims This study aimed to describe the career profile and pattern of racing for Thoroughbred jumps-racing horses in New Zealand. Methods Metrics from every horse with a full jumps-racing career (n = 1276, 89% geldings) between the 2005/06 and 2021/22 racing seasons (n = 40,302 starts) were examined. Descriptive statistics, box plots and heat maps were used to describe the data, by using horse age as a proxy for career progression. Key results Jumps-racing horses had a median of 17 flat starts (IQR 9–30) before their first jumps-racing start. The median career of a jumps-racing horse was 3.7 years (IQR 2.3–5.2) and 29 starts (IQR 16–44). Older horses had a decreasing number of flat-racing starts and an increasing proportion of steeplechase-racing starts. However, the majority of horses still had at least one flat-race start per calendar year, often prior to the first jumps race. Most horses had one spell each season (length 194 days, IQR 124–259), and a condensed preparation length over the winter months, with a median of 14 days (IQR 10–21) between starts. Conclusion The career pattern for jumps-racing horses in New Zealand reflects the industry retention of horses with a prior career in flat racing into a secondary jumps-racing career. Successful horses have increased focus on preparation for the winter jumps-racing season. Implications Jumps racing provides a secondary racing career for some flat-racing horses, particularly geldings. This strategy reduces wastage of horses from the industry.

Diamond burr debridement of calcific band keratopathy in 24 eyes of 22 horses.

To evaluate the safety and effectiveness of diamond burr debridement (DBD) for the treatment of calcific band keratopathy (CBK) in horses. Medical records from horses with CBK were reviewed over a period of 4 years. Diagnosis of CBK was based on slit-lamp examination findings, and DBD was performed on standing sedated horses. Follow-up was obtained by clinical reevaluation of the treated eyes or a telephone survey with the referring veterinarian. Twenty-two horses of different ages (median: 11 years; range: 5-23) representing 24 CBK-affected eyes (14 left eyes and 10 right eyes) were included in the study. The patients had a medical history of chronic and recurrent uveitis, which required repeated long-term treatments with various combinations of ophthalmic corticosteroids. DBD alone cleared the cornea in 22 affected eyes (92%), but it was combined with blade scraping in two cases with thick calcium plaques. The postoperative medication included a topical antibiotic, atropine drops, and oral flunixin meglumine. Corneal healing was achieved in 21 eyes (87%), 5-21 days (median time 13 days) postoperatively. The three remaining horses were lost to follow-up. Recurrence occurred in 5 of the 21 (24%) reexamined eyes, 3-12.5 weeks (median 8 weeks) postoperatively, and required a second DBD. Four of the 21 eyes ended up being enucleated due to sequelae of uveitis. The main limitations of the study include those inherent to all retrospective clinical data collections. Mechanical DBD can readily and safely clear the cornea in horses with CBK, but recurrence of calcium deposition is possible.

The effects of pressure and release training on equine behavior and discipline

In America, there are over 100,000 horse-related injuries per year (Mendell, 2006). It is important that all horses are properly trained to avoid dangerous accidents resulting from poor training involving the horse, rider, or spectators. This study aims to understand how a person should approach properly training a horse. It determines what training methods are the most effective and why it is important that owners understand how horses process discipline. Previous research indicates the common need for pressure, but fails to explore it as a training method. As such, a definite answer that explains how Pressure and Release Training affects equine behavior and discipline has not been determined. A physical experiment collecting and analyzing quantitative data was conducted in order to obtain the most accurate and specific results. Horses of various breeds, ages, sexes, and training levels were subjected to five different Pressure and Release Training exercises and scored on their completion (attempt &gt; accuracy). Each horse was tested twice on separate days to ensure replicability. All horses completed every exercise successfully without conflict behaviors or refusal (50/50). The experiment reveals that regardless of traits, Pressure and Release Training is an effective training method that horses understand even without previously consistent training. However, it is vital that trainers understand how horses process discipline so that they know if the training is effective and low stress for the horse.

Investigation of healthy horse eyes microbiota and evaluation of its antimicrobial susceptibility

SummaryBackgroundThe conjunctiva of the eye is a mucosal surface that is colonised by various bacteria. Following surgery, trauma or other underlying conditions the normal flora may cause eye infection such as conjunctival and corneal infections, or endophthalmitis.ObjectivesThis study aimed to investigate the bacterial population and antibiotic resistance of the conjunctiva in healthy horses.Study designRandom sampling of ocular samples from 20 horses during the winter (2019).MethodsSwab samples were collected from the eyes of 20 healthy horses of different breeds, ages and sexes in Tehran province, Iran. The swabs were cultured on blood agar and MacConkey agar and incubated at 37°C for 24–48 h. The isolated bacteria were characterised using cellular morphology, gram‐staining and biochemical tests. Sensitivity and resistance to 10 different antibiotics were measured using an antibiogram test.ResultsResults showed that the bacterial population consisted of various species, with Bacillus cereus being the most frequent. There were no significant differences in the frequency of isolated bacteria between sexes and age groups. There were no significant differences in the sensitivity of the bacterial flora of the eyes to colistin, ceftiofur, florfenicol, amoxicillin and ampicillin between either different age groups or different sexes of the horses (p &gt; 0.05). However, sensitivity to enrofloxacin and ciprofloxacin was significantly correlated with the age groups of the horses (p &gt; 0.05). A significant difference in sensitivity to trimethoprim‐sulfamethoxazole between various sexes of horses was observed.Main limitationsThe nonuniformity of the follow‐up examination, reliance on owners or caregivers of the horse for follow‐up information and lack of adequate financial resources to study more horses.ConclusionsThe study suggests that the frequency of individual bacteria comprising the bacterial flora in horses' eyes is influenced by housing and management conditions rather than age and sex.

The effect of cortisol on equine monocyte–derived dendritic cell phenotype and cytokine production

AbstractBackgroundIncreased risk of infection in neonates, including foals, is associated with the naivety of the immune system and the immaturity of the endocrine system. Foal dendritic cells (DCs) are phenotypically and functionally less mature than adult horse DCs. Exposure of foal DCs to foal plasma alters DC phenotypic maturation, cytokine secretion and bacterial endocytosis. Specific plasma factors that impact equine DC activity are unknown. Endocrine dysfunction, resulting in altered cortisol availability, is common in foals. Cortisol impacts DC maturation and function in other species, but the effect of cortisol on equine DCs is not described. We hypothesized that exposure to cortisol would impact both the phenotype and function of equine monocyte–derived DCs (MoDCs), perpetuating an immature phenotype and altered cytokine profile.MethodsMoDCs were generated from foals (n = 8) on 1, 7 and 30 days of age and adult horses (n = 9). MoDCs were exposed to killed bacteria in the presence or absence of cortisol. The expression of surface markers (MHC class‐II, CD86 and CD14) was measured by flow cytometry. Supernatant cytokine concentrations (IL‐4, IL‐17, IFN‐γ and IL‐10) were quantified using a validated bead‐based immunoassay.ResultsCortisol exposure reduced the percentage of equine MoDCs expressing MHC class‐II and CD86 (p ≤ 0.03). Adult horse MoDCs exposed to bacteria and cortisol produced less IL‐4, IL‐17, IFN‐γ and IL‐10 than cells not treated with cortisol, and foal MoDCs secreted less IL‐10 and IL‐4 (p ≤ 0.009).ConclusionsIn sum, cortisol exposure perpetuates an immature MoDC phenotype and alters cytokine responses, which might impact the foal's susceptibility to infection.

Radiological findings in the proximal sesamoid bones of yearling and 2-year-old Thoroughbred sales horses: Prevalence, progression and associations with racing performance.

Radiological findings in the proximal sesamoid bones (sesamoids) are a persistent source of controversy at Thoroughbred sales, due to inconsistent classification and conflicting assignment of potential clinical importance. To define the prevalence of sesamoid findings on sales repository radiographs in yearling and 2-year-old Thoroughbreds and to analyse associations with racing performance. To track the changes in sesamoid findings between 1 and 2 years of age in horses that present for sale at both ages. Prospective cohort study using an enrolled sample. Horses were enrolled from a 2016 yearling sale and five 2017 2-year-old sales with consignor permission. Radiological findings relating to sesamoid vascular channel appearance, abaxial contour changes and sesamoid fragments were examined. Associations between sesamoid findings and racing performance from 2 to 4 years of age were examined using multivariate regression analyses. Clinical follow-up was sought to ascertain why horses that did not race never started. A total of 2508 yearlings and 436 2-year-olds were included for evaluation. Interobserver agreement using the new grading system was substantial. Yearling findings associated with a significantly reduced probability of starting a race were: Grade 3 vascular channels in forelimb sesamoids (0.52, P < 0.001, 95% confidence interval (CI): 0.37-0.67), abaxial new bone in forelimb sesamoids (0.62, P = 0.01, 95% CI: 0.49-0.73), apical or abaxial fragments in forelimb sesamoids (0.55, P = 0.005, 95% CI: 0.37-0.72). For affected horses that did race, Grade 3 vascular channels in forelimb sesamoids were associated with fewer race starts (9.9 starts, P = 0.03, 95% CI: 8.0-12.2) and Grade 3 vascular channels in hindlimb sesamoids were associated with a delayed start to racing careers (54 days, P = 0.01, 95% CI: 20-89). Abaxial new bone in forelimb sesamoids was associated with a 54% reduction in total earnings (P = 0.003, 95% CI: 24-72) and a 46% reduction in earnings per start (P = 0.002, 95% CI: 21-64). Abaxial concavity occurred predominantly in yearling medial forelimb sesamoids, had no impact on racing performance and mostly resolved by 2-year-old sale. These findings are applicable to horses presented for sale at public auction and may underestimate the prevalence of severe lesions in non-sales horses. Grade 3 vascular channels, forelimb sesamoid abaxial new bone and forelimb sesamoid fragments are important findings in sales repository radiology. The new grading scale assigns a numerical grade for vascular channel appearance that matches the number of enlarged vascular channels evident in a given sesamoid. Abaxial contour changes, when present in sesamoids that are Grade 0 for enlarged vascular channels, are noted separately as either abaxial new bone or abaxial concavity. Fragments are also noted and interpreted separately.

Well-developed immunological tissue is present in the rostral oral cavity of horses as revealed by histological and immunohistochemical examination

Horses have a well-developed mucosal-associated lymphoid tissue in the naso-oropharynx for immunological defence and the development of immunological tolerance. The different components of this lymphoid tissue have been documented, but not all areas of the equine oral cavity have been investigated. In the present study, samples for histological and immunohistochemical examinations were collected from slaughtered horses of different ages, focusing on the rostral part of the oral cavity. Dense lymphatic tissue was found in the mucosa covering the bar area of the mandibles and the floor of the oral cavity, and it was present in horses of different ages. The most prominent lymphatic tissue, with large aggregates of lymph nodules, was present on either side of the lingual frenulum. The rostral location of this lymphatic tissue in horses renders support for application of antigens in allergen-specific immunotherapy via the oral mucosa.

Understanding temporal and spatial distribution of intestinal nematodes of horses using faecal egg counts and DNA metabarcoding

This study reports the spatial and temporal distribution of ascarid and strongylid nematodes in Thoroughbred horses by age category across different climatic zones in Australia over an 18-month period. Faecal samples (n = 2046) from individual horses were analysed using the modified McMaster technique for faecal egg counts (FECs). Strongylids were identified using PCR-directed next-generation sequencing of the second internal transcribed spacer (ITS-2) of the nuclear ribosomal DNA. Yearlings had the highest prevalence (82%) of strongyle eggs followed by weanlings (79%), foals (58%), wet mares (49%) and dry mares (46%). For Parascaris spp., foals had the highest prevalence (35%) followed by weanlings (21%) and yearlings (10%). The highest mean FECs for Parascaris spp. were observed in foals (525 eggs per gram [EPG] of faeces) while those for strongyles were in yearlings (962 EPG). Among horses that were classified as adults at the time of sampling, 77% (860 of 1119) of mares were low (i.e., <250 EPG) strongyle egg-shedders. Mean strongyle FEC counts were highest in the Mediterranean (818 EPG) followed by summer (599 EPG), winter (442 EPG), and non-seasonal (413 EPG) rainfall zones. Twenty-six nematode species were detected, with Cylicostephanus longibursatus (26.5%), Cylicocyclus nassatus (23.7%) and Coronocyclus coronatus (20.5%) being the most frequently detected species. Their richness and relative abundance varied with horse age, season and climatic zone. In addition, Strongylus equinus and Triodontophorus spp. (T. brevicauda and T. serratus) were also detected. This comprehensive study elucidates spatial (climatic zone) and temporal (i.e., seasonal) trends in prevalence and burdens of intestinal nematodes in Australian horses using non-invasive conventional and molecular methods. The information presented in this study is crucial for developing integrated management strategies to control horse parasites in farmed horses.

Advances in dental management in the equine geriatric patient: strategies for improved welfare.

Geriatric horses have a high prevalence of dental disease, which is a culmination of age-related dental changes and dental disease throughout the life of the horse that may have long-term consequences. Wear abnormalities, diastemata with periodontal disease, pulpitis and endodontic disease, infundibular caries, and equine odontoclastic tooth resorption and hypercementosis become more prevalent with age. Recognition of age-related dental disease at an early stage can help to treat and possibly preserve teeth for longer. With a natural decrease in masticatory efficiency, it is even more important to preserve teeth where possible and prevent any painful dental disease. Regular routine dental examination and maintenance will help to prevent many dental conditions such as wear disorders and possibly secondary diastemata. Successful treatment and management of most dental diseases are possible even in older patients and will ensure that we are able to maintain a high standard of welfare as horses age.