Epistaxis: What the Research Says
Evidence from 22 peer-reviewed studies
What Professionals Should Know
- •Heavier horses competing in flat racing face substantially higher epistaxis risk; veterinary clearance and pre-race assessment should account for body weight as a modifiable risk factor
- •Environmental and track-specific factors (certain venues, cooler temperatures, softer going) present identifiable epistaxis risk situations where enhanced surveillance and preventive protocols may be warranted
- •Older horses, females, and geldings competing over shorter distances in poor conditions represent the highest-risk population for epistaxis events on race day
- •Overground endoscopy should be performed at multiple exercise intensities, as many obstructions appear only at lower speeds and may be missed with high-speed testing alone
- •Expect to find multiple concurrent upper airway abnormalities in barrel racing horses with respiratory complaints or performance issues—single-abnormality cases are less common
- •Nasopharyngeal collapse and palatal instability are the most frequent findings in this performance group; management strategies should address these primary obstructions and any secondary abnormalities identified
- •Poor racing performance is the dominant concern triggering veterinary examination in flat racing—trainers and veterinarians should investigate systemic issues when horses underperform rather than assuming catastrophic injury
- •Step-up in race class significantly increases incident risk; careful conditioning and gradual class progression may reduce injuries in Thoroughbred flat racers
- •Epistaxis screening and exclusion protocols appear effective at reducing race-day bleeds, suggesting similar pre-entry health screening for other conditions could be beneficial
- •EIPH is highly prevalent (55%) in racing Thoroughbreds but does not necessarily limit racing career length or number of starts in the absence of furosemide prophylaxis
- •Endoscopy is most effective for EIPH diagnosis after racing when clinical signs are most apparent; severity grading helps predict retirement outcome
- •Horses with mild EIPH can sustain productive racing careers and are typically retired for unrelated reasons, whereas severe EIPH becomes the limiting factor
- •Monitor horses transitioning from flat to jump racing (especially those with >75% flat racing history) as they face elevated epistaxis risk; consider additional pre-race examinations for these individuals
- •Track and manage horses with prior epistaxis episodes carefully, as recurrence risk is significantly elevated; implement enhanced respiratory monitoring protocols
- •Be aware that firmer ground conditions increase epistaxis risk across all jump racing types; this information can inform race scheduling and track maintenance decisions
- •Epistaxis in racehorses has a heritable component (h²=0.27-0.50), suggesting selective breeding decisions could reduce incidence in populations
- •Age and sex significantly influence epistaxis risk, so management strategies should account for individual horse characteristics rather than relying solely on modifiable race conditions
- •Track and race management factors (surface, distance, going, starters) did not significantly affect epistaxis occurrence, indicating genetic predisposition may be more important than environmental race conditions
- •Track watering to reduce ground hardness may be an achievable measure to reduce epistaxis incidence in racehorses, particularly in jump racing.
- •Older horses and those competing in hurdle/steeplechase disciplines warrant closer monitoring for EIPH signs.
- •Poor race performance may indicate subclinical EIPH; epistaxis should prompt investigation into underlying pulmonary haemorrhage and consideration of race type suitability.
- •Forelimb soft tissue injuries, particularly affecting flexor tendons and suspensory ligaments, are the dominant injury pattern in racing — farriers and veterinarians should prioritize preventive strategies for these structures through surface selection and workload management
- •Chase racing carries significantly higher injury and fatality risk (6-fold higher than flat racing) — owners and trainers must weigh these risks when selecting racing types and implement enhanced welfare protocols for jump racing
- •Older horses carry substantially elevated injury risk — trainers should adjust training intensity and racing frequency based on age to mitigate this evidence-based risk factor
- •Include leptospirosis in your differential diagnosis for horses presenting with acute systemic inflammation, acute renal failure, epistaxis, or hepatic disease, even though cases are rare
- •Perform both urine PCR and MAT serology together to maximize detection; urine PCR alone was positive in only 55% of confirmed cases
- •Be aware that affected horses commonly show multi-organ involvement (kidney, lung, liver); expect high mortality risk with approximately 1 in 3 cases fatal
- •Facial masses in equines with concurrent anorexia, epistaxis, and nasal discharge warrant imaging investigation and biopsy to rule out hemangiosarcoma
- •Advanced imaging (CT) is valuable for assessing extent of disease and guiding prognosis when malignant tumors are suspected
- •Disseminated hemangiosarcoma carries a poor prognosis; early diagnosis through clinical suspicion may allow informed owner decisions regarding euthanasia timing
- •Free swimming appears safe for endurance horse conditioning and rehabilitation without risk of EIPH under typical training protocols
- •Concerns about tethered swimming causing epistaxis may be specific to that method rather than swimming exercise itself
- •Practitioners can confidently recommend free-swimming sessions for fitness conditioning and musculoskeletal rehabilitation without EIPH concerns
- •This novel standing endoscopic technique offers a minimally invasive alternative to traditional approaches for diagnosing and accessing sphenopalatine sinus pathology without general anesthesia
- •Practitioners should consider epistaxis with radiographic evidence of sphenopalatine sinus masses as a potential indication for this diagnostic procedure to obtain tissue samples for definitive diagnosis
- •The two-stage procedure design accommodates intraoperative hemorrhage management while maintaining standing sedation, making it a practical option for field or clinic-based cases
- •Salpingopharyngostomy is an effective surgical alternative for GPM that provides rapid resolution of nasal discharge (10-30 days) and allows outpatient treatment with lower costs
- •This technique should not be used in horses with active or recent epistaxis due to safety concerns
- •Complete fungal plaque resolution takes 1-6 months; clients should be counseled on the extended timeline despite rapid improvement in clinical signs
- •Consider sphenopalatine sinus disease in differential diagnoses for unilateral epistaxis, nasal discharge, exophthalmos, or blindness, though it remains rare
- •Request CT imaging rather than radiographs when sphenopalatine sinus pathology is suspected—it provides diagnostic information and reveals anatomical variation critical for surgical planning
- •Standing sinoscopic examination and biopsy of the palatine portion of the sphenopalatine sinus can be performed for diagnosis and treatment, though access to the sphenoidal portion is surgically limited
- •Although rare, M. bovis tuberculosis should be considered in the differential diagnosis for horses presenting with chronic respiratory signs and epistaxis, particularly given potential zoonotic transmission risk to handlers
- •Fluoroquinolone monotherapy (enrofloxacin) may offer a treatment option for equine M. bovis infections, with observable clinical improvement achievable within 3 months
- •Horses with M. bovis may be more susceptible and easier to treat compared to cattle and other livestock, making early diagnosis and isolation important for herd health management
- •Transarterial coil embolization is a viable minimally invasive alternative to surgical ligation for managing severe epistaxis from palatine artery pseudoaneurysms
- •Advanced imaging (CT and angiography) is essential for precisely locating the bleeding source before attempting intervention
- •Consider this technique when severe epistaxis is unresponsive to conservative management or when surgical access to the maxillary sinus is difficult
- •GT is not a practical concern in screening Quarter Horses and Warmbloods in Brazil based on current prevalence data
- •Veterinarians encountering unexplained hemorrhage or epistaxis in these breeds should consider differential diagnoses, as GT is effectively absent in the Brazilian populations studied
- •Breeders importing horses from regions with documented GT prevalence (USA, Canada, Japan, Australia) should consider genetic screening
- •CCA ligation with topical antimycotic therapy is a reasonable salvage option when transarterial catheter occlusion is not financially or technically feasible, but carries meaningful mortality risk from rebleeding
- •Endoscopic mechanical debridement of the fungal membrane combined with topical treatment may improve outcomes and reduce treatment frequency
- •Expect multiple treatments (average 6) will likely be needed; clients should be counseled on the 16-20% risk of recurrent life-threatening epistaxis
- •Prognosis in guttural pouch mycosis is guarded with 50% survival regardless of treatment approach; dysphagia severity should guide euthanasia decisions
- •Nasal discharge, epistaxis, and cough warrant investigation for guttural pouch mycosis, but dysphagia indicates a poorer prognosis
- •Medical and surgical treatments appear equally effective, so choice should be based on individual case factors and horse owner preferences rather than expected outcome differences
- •TCE is an effective first-line treatment for guttural pouch mycosis with excellent long-term outcomes and no recurrence during extended follow-up
- •Epistaxis related to GPM responds well to TCE alone without requiring additional medical or surgical intervention in most cases
- •Horses with severe neurological complications (particularly dysphagia) may have a guarded prognosis despite intervention
- •Consider transarterial coil embolization as a rapid and safe alternative to conventional antifungal therapy for guttural pouch mycosis in horses with appropriate vascular access
- •Bilateral common carotid artery occlusion is an effective emergency field treatment for life-threatening epistaxis when other options are unavailable
- •The mechanism by which arterial occlusion resolves fungal infection without antifungal drugs suggests novel immunological or physiological processes worth investigating
- •Disorders affecting the sphenopalatine sinuses can cause unpredictable neurological signs due to close proximity to multiple cranial nerves—clinical presentation will vary between horses
- •Age-related changes in sinus size and complexity mean that sinus conditions in young versus mature horses may present differently and require consideration of developmental anatomy
- •The thin sinus walls mean significant hemorrhage and rapid spread of infection into surrounding structures are serious risks; early diagnosis and treatment of sphenopalatine sinus disease is critical
Key Research Findings
Epistaxis occurred in 616 of 475,709 race starts (1.30 per 1000 starts; 95% CI, 1.20-1.40) in Japanese flat racing over 20 years
Body weight per 20 kg increase was significantly associated with epistaxis risk (OR 1.33; 95% CI, 1.25-1.41)
Specific racecourses showed elevated epistaxis risk compared to reference (Sapporo OR 4.74, Hakodate OR 4.66, Kokura OR 4.14 versus Kyoto)
Lower ambient temperature, soft surface conditions, shorter racing distances (≤1400 m), increasing age, and female/gelding sex were significantly associated with epistaxis
15% of barrel racing horses had no upper airway obstructions during exercise, while 56% of affected horses had two or more concurrent abnormalities
Nasopharyngeal collapse was most prevalent (49%), followed by palatal instability (42%) and intermittent dorsal displacement of the soft palate (39%)
Abnormalities were significantly more frequent at low-speed exercise (55%) compared to high-speed exercise (22%)
Multiple upper airway obstructions are common in barrel racers presenting with respiratory clinical signs and/or poor performance
Poor performance was the most common reason for non-incident examinations at 10.3 per 1000 races
Musculoskeletal injuries occurred at 1.3 per 1000 races and fractures at 0.6 per 1000 races, remaining low and consistent with historical New Zealand data
Horses in open-class races had significantly greater odds of incident reports compared to lower-rating class horses
Epistaxis incidence was low at 0.8 per 1000 races, likely due to trainer screening of susceptible horses prior to race entry
55% of 822 Thoroughbred geldings were diagnosed with EIPH via endoscopy, with varying severity grades
EIPH was diagnosed most frequently (63%) after racing rather than during training
No significant difference in racing career longevity or number of starts between EIPH+ and EIPH- horses trained without furosemide
Evidence Base
Risk Factors for Epistaxis in Thoroughbred Flat Races in Japan (2001-2020).
Sugiyama Fumi, Takahashi Yuji, Nomura Motoi et al. (2023) — Animals : an open access journal from MDPI
Upper airway endoscopy in exercising horses: Findings in 164 barrel racing horses with respiratory clinical signs and/or poor performance.
Massie S L, Léguillette R (2023) — Veterinary journal (London, England : 1997)
Race-Level Reporting of Incidents during Two Seasons (2015/16 to 2016/17) of Thoroughbred Flat Racing in New Zealand.
Gibson Michaela J, Bolwell Charlotte F, Gee Erica K et al. (2022) — Animals : an open access journal from MDPI
Descriptive analysis of longitudinal endoscopy for exercise-induced pulmonary haemorrhage in Thoroughbred racehorses training and racing at the Hong Kong Jockey Club.
Preston S A, Riggs C M, Singleton M D et al. (2015) — Equine veterinary journal
Risk factors for epistaxis in jump racing in Great Britain (2001-2009).
Reardon Richard J M, Boden Lisa A, Mellor Dominic J et al. (2015) — Veterinary journal (London, England : 1997)
Heritability of epistaxis in the Australian Thoroughbred racehorse population.
Velie B D, Raadsma H W, Wade C M et al. (2014) — Veterinary journal (London, England : 1997)
Risk factors for epistaxis on British racecourses: evidence for locomotory impact-induced trauma contributing to the aetiology of exercise-induced pulmonary haemorrhage.
Newton J R, Rogers K, Marlin D J et al. (2005) — Equine veterinary journal
Racehorse injuries, clinical problems and fatalities recorded on British racecourses from flat racing and National Hunt racing during 1996, 1997 and 1998.
Williams R B, Harkins L S, Hammond C J et al. (2001) — Equine veterinary journal
Acute leptospirosis in horses: A retrospective study of 11 cases (2015-2023).
Ramsay Lynette, Eberhardt Christina, Schoster Angelika (2024) — Journal of veterinary internal medicine
Disseminated Hemangiosarcoma in a Mare Mule.
Beatriz Fuentes-Romero, Marta Valero-González, María Martín-Cuervo et al. (2023) — Journal of equine veterinary science
Free Swimming and Exercise-Induced Pulmonary Hemorrhage in Endurance Horses: A Preliminary Study.
Vinardell Tatiana, David Florent, Galezowski Angelica M et al. (2023) — Journal of equine veterinary science
Perez Jairo A, Hutton Anne E, Cudd Sarah K et al. (2021) — Veterinary surgery : VS
Salpingopharyngeal fistula as a treatment for guttural pouch mycosis in seven horses.
Watkins A R, Parente E J (2018) — Equine veterinary journal
Radiographic, computed tomographic and surgical anatomy of the equine sphenopalatine sinus in normal and diseased horses.
Tucker R, Windley Z E, Abernethy A D et al. (2016) — Equine veterinary journal
Isolation and molecular characterization of Mycobacterium bovis causing pulmonary tuberculosis and epistaxis in a Thoroughbred horse.
Hlokwe Tiny Motlatso, Sutton David, Page Patrick et al. (2016) — BMC veterinary research
Coil embolization of a palatine artery pseudoaneurysm in a gelding.
McClellan Nathaniel R, Mudge Margaret C, Scansen Brian A et al. (2014) — Veterinary surgery : VS
Prevalence of the Mutations Responsible for Glanzmann Thrombasthenia in Horses in Brazil.
Leite Raíssa O, Ferreira Júlia F, Araújo César E T et al. (2019) — Animals : an open access journal from MDPI
Ligation of the ipsilateral common carotid artery and topical treatment for the prevention of epistaxis from guttural pouch mycosis in horses.
Cousty M, Tricaud C, De Beauregard T et al. (2016) — The Veterinary record
Guttural pouch mycosis in horses: a retrospective study of 28 cases.
Dobesova O, Schwarz B, Velde K et al. (2012) — The Veterinary record
Transarterial coil embolisation in 31 horses (1999-2002) with guttural pouch mycosis: a 2-year follow-up.
Lepage O M, Piccot-Crézollet C (2005) — Equine veterinary journal