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Nath LC, Saljic A, Buhl R, Elliott A, La Gerche A, Ye C, Schmidt Royal H, Lundgren Virklund K, Agbaedeng TA, Stent A, Franklin S. Histological evaluation of cardiac remodelling in equine athletes. Sci Rep 2024; 14:16709. [PMID: 39030282 PMCID: PMC11271503 DOI: 10.1038/s41598-024-67621-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Accepted: 07/14/2024] [Indexed: 07/21/2024] Open
Abstract
Approximately 1-2 per 100,000 young athletes die from sudden cardiac death (SCD) and extreme exercise may be associated with myocardial scar and arrhythmias. Racehorses have a high prevalence of atrial fibrillation (AF) and SCD but the presence of myocardial scar and inflammation has not been evaluated. Cardiac tissues from the left (LAA) and right (RAA) atrial appendages, left ventricular anterior (LVAPM) and posterior (LVPPM) papillary muscles, and right side of the interventricular septum (IVS-R) were harvested from racehorses with sudden cardiac death (SCD, n = 16) or other fatal injuries (OFI, n = 17), constituting the athletic group (ATH, n = 33), and compared to sedentary horses (SED, n = 10). Horses in the ATH group had myocyte hypertrophy at all sites; increased fibrosis at all sites other than the LAA; increased fibroblast infiltration but a reduction in the overall extracellular matrix (ECM) volume in the RAA, LVAPM, and IVS-R compared to SED horses. In this horse model, athletic conditioning was associated with myocyte hypertrophy and a reduction in ECM. There was an excess of fibrocyte infiltration and focal fibrosis that was not present in non-athletic horses, raising the possibility of an exercise-induced pro-fibrotic substrate.
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Affiliation(s)
- L C Nath
- University of Adelaide, Adelaide, Australia.
| | - A Saljic
- University of Copenhagen, Copenhagen, Denmark
| | - R Buhl
- University of Copenhagen, Copenhagen, Denmark
| | - A Elliott
- University of Adelaide, Adelaide, Australia
| | - A La Gerche
- St Vincents Institute Medical Research, Fitzroy, Australia
| | - C Ye
- University of Copenhagen, Copenhagen, Denmark
| | | | | | | | - A Stent
- University of Melbourne, Parkville, Australia
| | - S Franklin
- University of Adelaide, Adelaide, Australia
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2
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Kapusniak A, Nath L, Hebart M, Franklin S. Heritability of sudden cardiac death in Thoroughbred racehorses. Equine Vet J 2024. [PMID: 38984817 DOI: 10.1111/evj.14130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 06/05/2024] [Indexed: 07/11/2024]
Abstract
BACKGROUND Sudden cardiac death (SCD) is an important cause of exercise-associated fatalities in Thoroughbred racehorses. Equine deaths share similarities with fatalities in human athletes that result from inherited cardiac disease. Whilst genetic causes have been postulated in horses, these have not been confirmed and heritability of SCD has not previously been estimated in Thoroughbred racehorses. OBJECTIVES To determine the heritability of SCD in a sample population of Thoroughbred racehorses. STUDY DESIGN Retrospective case-control study. METHODS Steward and post-mortem reports of Thoroughbred racehorses in Australia between 2007 and 2020 were reviewed to identify horses with SCD. Control horses were randomly selected from races in which SCD occurred or from races on the date of the case fatality. A five-generation integrated pedigree chart was collected for each horse. Estimates of heritability were obtained using an animal model in the ASReml-R program with variance components estimated assuming SCD was normally distributed, and on the logit transformed scale. Inbreeding coefficients were calculated and the risk of producing SCD-affected progeny was calculated for stallions that sired ≥5 individuals in the case-control population. RESULTS Ninety-three horses with SCD and 465 control horses were identified. Heritability on the underlying scale was 0.15 ± 0.09 (logit animal) and 0.24 ± 0.12 (normal animal). Inbreeding coefficients were not significantly different between groups. Of the 16 first generation sires that appeared ≥5 times in the case-control data set, two sires more frequently produced affected progeny (OR 7.95-10.41). MAIN LIMITATIONS Challenges in definitively confirming SCD may lead to misclassification of some cases. Some control horses may have not been exposed to environmental influences of SCD. Case numbers are low and the studied population may not represent the entire Thoroughbred genetic pool. CONCLUSION The heritability of SCD in this population was relatively low. However, individual stallions appear more likely to produce affected progeny. Further studies are required to understand the genetic and environmental influences that contribute to disease expression.
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Affiliation(s)
- Amie Kapusniak
- School of Animal & Veterinary Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Laura Nath
- School of Animal & Veterinary Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Michelle Hebart
- School of Animal & Veterinary Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Samantha Franklin
- School of Animal & Veterinary Sciences, University of Adelaide, Adelaide, South Australia, Australia
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Durando MM, Slack J, Birks E, Belcher C, Kohn C. Premature depolarisations in horses competing in United States Eventing Association and Fédération Equestre Internationale-sanctioned 3-day events. Equine Vet J 2024; 56:59-68. [PMID: 37248851 DOI: 10.1111/evj.13948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 05/04/2023] [Indexed: 05/31/2023]
Abstract
BACKGROUND Injuries and sudden death during the cross-country (XC) phase of eventing have raised interest in the frequency and types of cardiac arrhythmias occurring in these equine athletes. OBJECTIVES To characterise the frequency and types of rhythm disturbances and examine possible risk factors for premature depolarisations (PDs) occurring during the XC phase of United States Eventing Association (USEA) and Fédération Equestre Internationale (FEI)-sanctioned events. STUDY DESIGN Prospective, cross-sectional study. METHODS Continuous electrocardiographic (ECG) recordings were obtained from horses prior to, during and immediately following the XC competition. Physiological rhythms pre-XC were included in the arrhythmia group for analysis. The frequency of PDs was calculated for all horses, as well as by division. PDs were categorised by complexity (singles, couplets, triplets, complex) and variably grouped for statistical analysis. Multiple logistic regression was used to identify risk factors for the presence of specific cardiac arrhythmia groupings during XC. RESULTS PDs were identified in 42/75 horses (56% [45, 67]) during XC. Horses competing in the upper divisions of eventing had higher odds for having any PD during XC compared to the lower divisions (OR = 17.5 [4.3, 72.01], p = 0.006). The amount of time the heart rate (HR) was greater than 199 beats per minute (BPM) was associated with more complex arrhythmias (triplets, salvos and tachyarrhythmias) (OR = 1.01 [1.0, 1.02], p = 0.005). An arrhythmia at rest (physiological or PD) was associated with arrhythmia in the early recovery period (OR = 3.5 [1.1, 10.8], p = 0.03). MAIN LIMITATIONS Convenience sampling and technical challenges of continuous ECG recordings under competition settings limited the number of enrollments. CONCLUSIONS PDs were seen in a high percentage of horses during the XC competition. Upper levels and time the HR was greater than 199 BPM were related to PD presence and complexity.
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Affiliation(s)
- Mary M Durando
- Equine Sports Medicine Consultants, Newark, Delaware, USA
| | - Joann Slack
- New Bolton Center, University of Pennsylvania, Kennett Square, Pennsylvania, USA
| | - Eric Birks
- Equine Sports Medicine Consultants, Newark, Delaware, USA
| | - Carolyn Belcher
- Georgia Department of Natural Resources, Coastal Resources Division, Brunswick, Georgia, USA
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Gibson MJ, Legg KA, Gee EK, Rogers CW. The Reporting of Racehorse Fatalities in New Zealand Thoroughbred Flat Racing in the 2011/12-2021/22 Seasons. Animals (Basel) 2023; 13:612. [PMID: 36830402 PMCID: PMC9951738 DOI: 10.3390/ani13040612] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 02/08/2023] [Accepted: 02/08/2023] [Indexed: 02/12/2023] Open
Abstract
Race day fatalities as a consequence of catastrophic musculoskeletal injury and cardiac failure are both a welfare concern and provide a challenge for the social perceptions of equine welfare within the racing industry. To reduce race day fatalities, the risk factors under New Zealand racing conditions need to be identified. The aim of this study was to examine race and horse-level risk factors for fatalities in New Zealand Thoroughbred flat racing using retrospective race day data from the 2011/12-2021/22 racing seasons. Horse and race-level factors associated with a suspected cardiac failure and fatal fracture were identified by merging fatality data with the master race dataset for the corresponding seasons. Most fatalities were associated with fatal fracture (0.4 per 1000 starts, 95% CI 0.4-0.5). Horses which raced over distances > 1600 m were 1.7 times (95% CI 1.2-2.5) more likely to sustain a fatal fracture than horses racing ≤ 1600 m. Male horses and firmer track conditions were also associated with an increase in the risk of fatal fracture. Horses aged 5 years and older were 2.1 (95% CI 1.1-4.6) times more likely to suffer a suspected cardiac failure than younger horses. Changes in the industry reporting system improved the level of detail provided for fatalities, enabling the identification of specific risk factors.
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Affiliation(s)
- Michaela J. Gibson
- School of Veterinary Sciences, Massey University, Palmerston North 4442, New Zealand
| | - Kylie A. Legg
- School of Veterinary Sciences, Massey University, Palmerston North 4442, New Zealand
| | - Erica K. Gee
- School of Veterinary Sciences, Massey University, Palmerston North 4442, New Zealand
| | - Chris W. Rogers
- School of Veterinary Sciences, Massey University, Palmerston North 4442, New Zealand
- School of Agriculture and Environment, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand
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Nath L, Stent A, Elliott A, La Gerche A, Franklin S. Risk Factors for Exercise-Associated Sudden Cardiac Death in Thoroughbred Racehorses. Animals (Basel) 2022; 12:ani12101297. [PMID: 35625143 PMCID: PMC9137751 DOI: 10.3390/ani12101297] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 05/12/2022] [Accepted: 05/16/2022] [Indexed: 02/04/2023] Open
Abstract
Cardiac arrhythmias resulting in sudden cardiac death (SCD) are an important cause of racehorse fatalities. The objective of this study was to determine risk factors for SCD in Thoroughbreds by evaluating a sample with a policy of mandatory post-mortem following racing or training fatalities. Risk factors were compared between case horses with SCD (n = 57) and control horses with other fatal injury (OFI, n = 188) by univariable and multivariable logistic regression. Survival in years for horses with SCD was compared to OFI using the Kaplan−Meier method with log rank test. The following variables were most important in the multiple logistic model: Horses with SCD were more likely to die during training than during racing, SCD (42/57, 74%) vs. OFI (82/188, 44%; odds ratio [OR], 95% confidence interval [CI], 2.5, 1.2−5.4; p = 0.01), had fewer lifetime starts, median (interquartile range [IQR]), SCD (3.0 [0.0−9.0]) vs. OFI (9.0 [0.0−22.8]; OR, 95% CI, 0.96, 0.9−1.0; p = 0.02 and were less likely to be entire (uncastrated) males, SCD 9/57 (16%) vs. OFI (46/188, 25%; OR, 95% CI, 0.47, 0.1−0.9; p = 0.03). Survival in years (median (IQR)) for horses with SCD was 3.6 (3.1−4.4), which was shorter than OFI (4.5 [3.1−6.0], hazard ratio, 95%CI, 1.6,1.2−2.3; p < 0.001). SCD occurs more commonly in training than racing, which suggests exercise intensity is less important in precipitating this fatality. In this study, SCD occurred early in the careers of affected horses.
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Affiliation(s)
- Laura Nath
- School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy 5371, Australia;
- Correspondence:
| | - Andrew Stent
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee 3030, Australia;
| | - Adrian Elliott
- Centre for Heart Rhythm Disorders, University of Adelaide, Adelaide 5005, Australia;
| | - Andre La Gerche
- Baker Heart and Diabetes Institute, Melbourne 3004, Australia;
| | - Samantha Franklin
- School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy 5371, Australia;
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Hellings IR, Skjerve E, Karlstam E, Valheim M, Ihler CF, Fintl C. Racing-associated fatalities in Norwegian and Swedish harness racehorses: Incidence rates, risk factors, and principal postmortem findings. J Vet Intern Med 2022; 36:778-786. [PMID: 35060194 PMCID: PMC8965266 DOI: 10.1111/jvim.16364] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 01/03/2022] [Accepted: 01/07/2022] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND There are no reports on the number of fatalities or causes of death in the Norwegian and Swedish harness racehorses. OBJECTIVES The incidence rates (IRs), risk factors, and postmortem findings in horses that died or were euthanized associated with racing between 2014 and 2019 were investigated. ANIMALS Thirty-eight Standardbreds and 10 Norwegian-Swedish Coldblooded Trotters died or were euthanized associated with racing. A total of 816 085 race-starts were recorded. METHODS Incidence rates were calculated for both countries and horse breeds. Risk factors for sudden death were identified using a case-control logistic model. Postmortem examinations were performed in 43 horses. RESULTS The overall fatality IR was 0.059/1000 race-starts. Traumatic injuries accounted for 14.5%, while sudden death for 85.5% of fatalities. Only minor differences between countries and breeds were recorded. The number of starts within the last 30 days increased the risk of sudden death (5 starts odds ratio (OR) 228.80, confidence interval (CI) 10.9-4793). An opposite non-linear effect was observed in number of starts the last 180 days (>10 starts OR 0.12, CI 0.02-0.68). Seven horses were euthanized because of catastrophic injury. Acute circulatory collapse because of suspected cardiac or pulmonary failure or both was recorded in 30 horses, while major hemorrhage after vessel rupture was the primary cause of death in 10 cases. One horse collapsed and died but was not submitted for autopsy. CONCLUSIONS AND CLINICAL IMPORTANCE Comparatively low rates of catastrophic orthopedic fatalities were reported, while causes and IR of sudden death were similar to previous studies.
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Affiliation(s)
- Ingunn Risnes Hellings
- Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine and BiosciencesNorwegian University of Life SciencesÅsNorway
| | - Eystein Skjerve
- Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine and BiosciencesNorwegian University of Life SciencesÅsNorway
| | - Erika Karlstam
- Department of Pathology and Wildlife DiseasesThe Swedish National Veterinary InstituteUppsalaSweden
| | - Mette Valheim
- Department of Pathology and High‐Risk PathogensThe Norwegian Veterinary InstituteÅsNorway
| | - Carl Fredrik Ihler
- Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine and BiosciencesNorwegian University of Life SciencesÅsNorway
| | - Constanze Fintl
- Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine and BiosciencesNorwegian University of Life SciencesÅsNorway
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Haughan J, Manriquez M, Cohen N, Robinson M, de Solis CN. Comparison of novel wearable cardiac monitors to yield accurate exercising ECG and heart rate data in horses. COMPARATIVE EXERCISE PHYSIOLOGY 2021. [DOI: 10.3920/cep200080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Exercise associated deaths (EADs) in horses are a problem for the equestrian industry. Sudden death (SD) is responsible for approximately 20% of EADs. The underlying cause of SD is suspected to be cardiovascular disease but often cannot be determined post-mortem. User-friendly cardiac monitors are needed for large scale investigations of arrhythmias associated with SD in horses. We hypothesised that novel wearable devices would provide exercising electrocardiograms (ECGs) of sufficient diagnostic quality for this purpose. Diagnostic quality of ECGs generated by two wearable devices (W2nd™ and Polar Equine™) were compared to simultaneous recordings with a telemetry unit (Televet™) in 5 Thoroughbreds completing 43 separate submaximal exercise tests on a high-speed treadmill. Maximal heart rate (HRmax) generated by mobile applications (HRmaxapp), HRmax after manual correction (HRmaxcorr), percentage of diagnostic ECGs (%diag) at the gallop, and overall quality assessed by visual analogue scale (VAS) were assessed by a blinded observer. HRmaxcorr did not differ significantly between groups. HRmaxapp was significantly lower for W2nd (166.8/min, 95% confidence interval (CI): 160.5-173.1/min) but did not differ significantly between Televet (178.8/min 95% CI: 165.8-191.1/min) and Polar (181.3/min, 95% CI: 174.5-188.1/min). HRmaxcorr was accurate and precise in all runs. HRmaxapp was within a priori limits of agreement in 16/23 W2nd and 18/19 Polar recordings. %diag was significantly lower (77.1%, 95% CI: 67.4-86.8) for W2nd than Polar (100%, 95% CI: 89.9-110.3). VAS was lower for W2nd (46.2, 95% CI: 35.5-57.0) than Polar (90.6, 25% CI: 79.4-101.9). In conclusion, wearable devices appear to be promising tools for investigation of equine exercising arrhythmias in large-scale studies.
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Affiliation(s)
- J. Haughan
- Department of Clinical Studies, University of Pennsylvania School of Veterinary Medicine, New Bolton Center, 382 West Street Road, Kennett Square, PA 19348, USA
| | - M. Manriquez
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-447, USA
| | - N.D. Cohen
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-447, USA
| | - M.A. Robinson
- Department of Clinical Studies, University of Pennsylvania School of Veterinary Medicine, New Bolton Center, 382 West Street Road, Kennett Square, PA 19348, USA
- Pennsylvania Equine Toxicology & Research Center, West Chester University, 220 E. Rosedale Ave West Chester, PA 19382, USA
| | - C. Navas de Solis
- Department of Clinical Studies, University of Pennsylvania School of Veterinary Medicine, New Bolton Center, 382 West Street Road, Kennett Square, PA 19348, USA
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Trachsel DS, Calloe K, Mykkänen AK, Raistakka P, Anttila M, Fredholm M, Tala M, Lamminpää K, Klaerke DA, Buhl R. Exercise-Associated Sudden Death in Finnish Standardbred and Coldblooded Trotters - A Case Series With Pedigree Analysis. J Equine Vet Sci 2021; 104:103694. [PMID: 34416991 DOI: 10.1016/j.jevs.2021.103694] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 04/30/2021] [Accepted: 06/19/2021] [Indexed: 10/21/2022]
Abstract
Exercise-associated sudden deaths (EASDs) are deaths occurring unexpectedly during or immediately after exercise. Sudden cardiac death (SCD) is one cause of EASD. Cardiac arrhythmias caused by genetic variants have been linked to SCD in humans. We hypothesize that genetic variants may be associated with SCD in animals, including horses. Genetic variants are transmitted to offspring and their frequency might increase within a family. Therefore, the frequency of such variants might increase with the inbreeding factor. Higher inbreeding could have a negative impact on racing performance. Pedigree data and career earnings from racehorses diagnosed with SCD between 2002 and 2017 were compared using non-parametric tests with 1) control horses that died due to catastrophic musculoskeletal injuries and 2) horses that raced during the same period without reported problems. Diagnosis of SCD was based on necropsy reports, including macroscopic and microscopic examinations. Death was registered in the study period for 61 horses. Eleven of these horses were excluded due to missing autopsy reports. In 25 cases, the diagnosis remained unknown and death was possibly caused by cardiac arrhythmia, in two cases cardiac disease was identified, in seven cases a rupture of a major vessel had occurred. In addition, 16 horses died or were euthanized due to severe musculoskeletal injuries. No significant differences in inbreeding coefficients or in career earnings were found between the groups or between horses with EASD compared with other horses racing during the same period. The study provides no evidence for increased inbreeding factor in Finnish racehorses with SCD.
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Affiliation(s)
- Dagmar S Trachsel
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark; Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark.
| | - Kirstine Calloe
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Anna K Mykkänen
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Pia Raistakka
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Marjukka Anttila
- Veterinary Bacteriology and Pathology Research Unit, Finnish Food Authority, Helsinki
| | - Merete Fredholm
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Martti Tala
- Suomen Hippos, the Finnish Trotting and Breeding Association
| | | | - Dan A Klaerke
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Rikke Buhl
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
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Nath LC, Elliott AD, Weir J, Curl P, Rosanowski SM, Franklin S. Incidence, recurrence, and outcome of postrace atrial fibrillation in Thoroughbred horses. J Vet Intern Med 2021; 35:1111-1120. [PMID: 33604980 PMCID: PMC7995445 DOI: 10.1111/jvim.16063] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 01/25/2021] [Accepted: 02/02/2021] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Atrial fibrillation (AF) impacts performance and horse and jockey safety. Understanding the outcomes of AF identified postrace will better inform regulatory policy. HYPOTHESIS/OBJECTIVES To investigate the outcomes after episodes of AF identified postrace and determine whether affected horses are at increased risk of additional episodes compared to the general racing population. ANIMALS Total of 4684 Thoroughbred racehorses. METHODS Race records for Thoroughbred horses racing in Hong Kong from 2007 to 2017 were reviewed. Horses that performed below expectation were examined by cardiac auscultation and ECG. Incidence and recurrence of AF were compared between horses with and without a history of AF and between horses with paroxysmal and persistent episodes using Fisher's exact test. RESULTS There were 96 135 race starts during the study. Atrial fibrillation was identified in 4.9% of horses, with an overall incidence of 2.7 episodes per 1000 starts. The incidence of AF in horses after any previous episode (12.8 per 1000 starts) was higher than for horses with no previous episode (2.4 per 1000 starts; odds ratio [OR], 5.3; 95% confidence interval [CI], 3.8-7.6). Recurrence was seen in 64% of horses previously treated for persistent AF, which was higher than recurrence in horses with paroxysmal AF (23%; OR, 5.9; 95% CI, 1.6-21.2). Median duration between episodes was 343 days (range, 34-1065). CONCLUSIONS AND CLINICAL IMPORTANCE Thoroughbreds are at increased risk of recurrent AF after both paroxysmal and persistent episodes, but the duration of time between episodes varies widely. These findings support a substantial burden of AF among individual Thoroughbred racehorses.
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Affiliation(s)
- Laura C. Nath
- School of Animal & Veterinary SciencesUniversity of AdelaideRoseworthySouth AustraliaAustralia
| | - Adrian D. Elliott
- Centre for Heart Rhythm Disorders, Adelaide Medical SchoolUniversity of AdelaideAdelaideSouth AustraliaAustralia
| | - Joe Weir
- Hong Kong Jockey Club, Veterinary Clinical ServicesEquine HospitalHong Kong SARHong Kong
| | - Peter Curl
- Veterinary RegulationHong Kong Jockey ClubHong Kong SARHong Kong
| | | | - Samantha Franklin
- School of Animal & Veterinary SciencesUniversity of AdelaideRoseworthySouth AustraliaAustralia
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Goto Asakawa M, Mehmood W, Ali M, Oikawa MA. Idiopathic multifocal myocardial atrophy with fibrosis and fatty infiltration involving Purkinje fibres in a 13-year-old Arabian broodmare: Histopathological features. Vet Med Sci 2020; 7:3-8. [PMID: 32940417 PMCID: PMC7840219 DOI: 10.1002/vms3.350] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 07/19/2020] [Accepted: 08/16/2020] [Indexed: 11/12/2022] Open
Abstract
Myocardial atrophy with fibrosis and fatty infiltration involving the cardiac conduction system is relatively unusual in horses. We herein report of such a case in a 13-year-old Arabian broodmare that had spontaneously died on a paddock. An autopsy revealed multifocal myocardial atrophy with concomitant fibrosis and fatty infiltration in both the ventricles and interventricular septum. The Purkinje fibres in the ventricles and interventricular septum were surrounded by thick fibrous or adipose tissues adjacent to atrophic myocardial cells. Myocardial fibrosis and fatty infiltration were likely secondary to myocardial atrophy, occurring as a pathological response triggered by the repair of muscular wall injury. However, there were no major vascular pathologies (e.g. atherosclerosis and arteriosclerosis); hence, the pathogenesis of myocardial atrophy was unclear. There was no evidence of myocardial atrophy ̵ induced pathologies such as infarct, ischaemic lesions, myocardial degeneration, myocarditis and endocarditis. However, such an unusual histopathological pattern may be associated with rapid clinical deterioration and death.
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Affiliation(s)
- Midori Goto Asakawa
- Clinical and Anatomic Pathology Unit, Veterinary Specialists and Emergency Center, Kawaguchi, Japan
| | - Wasiq Mehmood
- Diagnostic and Research Laboratory, Equine Veterinary Medical Center, Doha, Qatar
| | - Mohammad Ali
- Diagnostic and Research Laboratory, Equine Veterinary Medical Center, Doha, Qatar
| | - Masa-Aki Oikawa
- Diagnostic and Research Laboratory, Equine Veterinary Medical Center, Doha, Qatar
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Abstract
There have been some advances in understanding the genetic contribution to ventricular septal defects in Arabians, sudden death in racehorses, and atrial fibrillation in racehorses. No genetic analyses have been published for aortic rupture in Friesians or atrioventricular block in donkeys despite strong evidence for a genetic cause. To date, no genetic mutation has been identified for any equid cardiac disease. With the advancement of genetic tools and resources, we are moving closer to discoveries that may explain the heritable basis of inherited equid cardiac disease.
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Affiliation(s)
- Samantha L Fousse
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California Davis, Davis, CA, USA; Stern Comparative Cardiac Genetics Laboratory, UC Davis, 2108 Tupper Hall, One Shields Avenue, Davis, CA 95616, USA
| | - Joshua A Stern
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California Davis, Davis, CA, USA; Stern Comparative Cardiac Genetics Laboratory, UC Davis, 2108 Tupper Hall, One Shields Avenue, Davis, CA 95616, USA.
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