Nasal Discharge: What the Research Says
Evidence from 20 peer-reviewed studies
What Professionals Should Know
- •Tracheal lavage cytological analysis combined with bacterial culture can help identify beta-hemolytic streptococcal infections in horses with respiratory signs; use this to confirm strangles diagnosis and guide treatment decisions
- •Understanding the inflammatory cell patterns associated with different respiratory symptoms may help differentiate between beta-hemolytic streptococcal infections and other upper respiratory conditions in your practice
- •Early identification of horses with clinical signs (coughing, lymph node swelling, nasal discharge) through these diagnostic methods enables faster isolation protocols and reduces disease spread in riding clubs and boarding facilities
- •Mouth corner lesions appear to be a breed/discipline-specific welfare indicator worth monitoring, particularly in Flat racehorses—consider bit fit and contact practices as potential intervention points
- •Training intensity measurably affects horse behavior and stress indicators (grimace scores, reactivity); monitor these signs seasonally and adjust workload or management if negative changes are detected
- •Simple stable design changes like windows improve welfare by enabling environmental engagement; combine with adequate feeding time (target ~34% of daytime) and rest periods to support both physical and mental health
- •Ensure unbroken horses receive proper fitness-for-transport assessment before long journeys; the low injury/disease rates here reflect good baseline selection and handling by experienced staff
- •Maintain adequate temperature control, space allowance (loose housing in small groups), and water/feed access during transport—these directly impact arrival condition in unhandled animals
- •Plan regular breaks during long transits (average 34 hours here included resting stops); experienced drivers with well-maintained, ventilated vehicles are essential for welfare outcomes in unbroken stock
- •Transport duration, frequency of stops, vehicle changes, and handler expertise directly impact whether horses arrive at destination injured or distressed—minimize journey time and ensure experienced handlers
- •Environmental factors like temperature and seasonal conditions significantly affect transport outcomes, suggesting need for climate-controlled transport or adjusted scheduling during extreme weather
- •High prevalence of discharge and reluctance to unload indicates systemic welfare concerns in current horse transport practices that require attention to handler technique and vehicle design
- •S. equi appears to be endemic in Ethiopian working horse populations and may be a primary driver of respiratory disease in this region—biosecurity and vaccination strategies should be prioritized
- •Working horses in Ethiopia lack immunity to equine influenza and would be highly vulnerable to an outbreak; vaccination protocols should be considered if trade or movement increases
- •Respiratory signs in working horses cannot be attributed primarily to viral causes in this population; investigate non-infectious causes (dust, poor ventilation, work intensity) and management factors
- •New racehorses entering training should be monitored closely for visible tracheal mucus as a key indicator of airway inflammation; this is more clinically useful than neutrophil counts in tracheal wash samples
- •Airway inflammation improves with time in training environment rather than chronological age—ensure adequate acclimatization period for horses new to racing
- •Current diagnostic criteria for inflammatory airway disease may overweight neutrophil counts; practitioners should focus on visible mucus and clinical signs when making management decisions
- •Routine endoscopic examination of 2-year-old racehorses may enable early diagnosis and intervention for the common condition of IAD
- •Environmental and management factors between training yards influence respiratory disease rates, suggesting that stable conditions and group dynamics warrant attention
- •Younger horses are at higher risk of respiratory disease and associated bacterial/viral infections, requiring age-appropriate monitoring protocols
- •Glanders remains endemic in central Iran with a prevalence of 1.35%; regular serological surveillance is essential for detecting infected horses in affected regions
- •Serological tests alone (CFT, iELISA, Mallein) should be confirmed with bacterial culture and PCR, as culture success was only 42.85% despite seropositivity
- •Horses showing fever, nasal/ocular discharge, subcutaneous abscesses, and lymphadenopathy warrant immediate glanders investigation and quarantine to prevent spread to other horses
- •Sinonasal myxomas are rare in horses but should be considered in cases of unilateral nasal discharge, facial swelling, and decreased airflow; endoscopic and imaging evaluation are essential for diagnosis
- •Surgical excision alone is unlikely to prevent recurrence due to myxoma's infiltrative nature; combining surgery with transendoscopic laser ablation may improve long-term outcomes
- •This combined technique offers an alternative approach for managing benign sinonasal masses that may reduce need for repeated interventions
- •Management factors including water source quality, flooring type, and work intensity are modifiable risk factors for respiratory disease in working horses—prioritize clean water access and appropriate housing
- •S. zooepidemicus plays a clinical role in respiratory disease in this population; monitor for this pathogen and consider management interventions alongside antimicrobial therapy
- •Young and old working horses are at elevated risk and may require additional monitoring and careful management during respiratory challenges
- •Glanders remains a serious infectious disease in equine populations; horses with persistent nasal discharge and cutaneous nodules in hindlimbs/abdomen should be tested immediately using complement fixation, Rose Bengal agglutination, and mallein tests
- •Immunohistochemical analysis using anti-BpaB antibodies provides a reliable diagnostic tool for confirming B. mallei infection in tissue samples when clinical diagnosis is uncertain
- •This is a reportable disease in most countries; any confirmed or suspected cases require immediate notification to regulatory authorities and stringent biosecurity measures
- •Paranasal sinus cysts carry a good prognosis when treated early via surgical osteotomy, with nearly 80% achieving full resolution in this series
- •Older horses (>10 years) are at substantially higher risk for pressure-induced complications affecting facial bones, teeth, and nerves; early intervention is critical in these cases
- •Plan for post-operative management of SSI and nasofrontal suture periostitis, which together occurred in 40% of surgical cases; recurrence monitoring is warranted as cysts return in approximately 1 in 5 horses
- •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
- •Conservative management is a reasonable alternative for foals with congenital soft palate defects, particularly given published high morbidity and mortality rates associated with surgical correction
- •Many horses with this defect can perform functional work including ridden activities and racing without surgical intervention
- •Prioritize monitoring for severe pneumonia or ill-thrift as indicators for intervention rather than assuming surgery is necessary in all cases
- •This single bone flap technique offers an efficient surgical option for treating bilateral paranasal sinus disease in horses, potentially reducing operative time and tissue trauma compared to separate approaches
- •The procedure can be performed in standing sedation, which may reduce anesthetic risk in compromised patients
- •Consider referral for this technique if managing bilateral sinus mucoceles refractory to conservative treatment
- •Unilateral malodorous nasal discharge in horses should raise suspicion for conchal necrosis and warrants endoscopic examination
- •Transendoscopic debridement under standing sedation is an effective and safe treatment option with excellent prognosis when all necrotic tissue is removed
- •Local disinfectant application post-treatment may not be necessary for successful healing in all cases
- •Traveller and Gypsy owned horses in this study showed better overall welfare than commonly perceived, suggesting culturally sensitive education on hoof care and water management could address the primary welfare gaps
- •Hoof care should be a focus area for farriery intervention in these communities, as hoof neglect (27%) and structural hoof issues (19%) represent the most prevalent problems identified
- •Environmental factors like water availability directly correlate with horses' emotional states—ensuring adequate water resources is a simple, high-impact welfare improvement
- •Owner perception of disease priorities differs significantly between horse and donkey populations; intervention programs should be species-specific and informed by local stakeholder input rather than assumption
- •Participatory assessment methods are valuable for identifying working equid health concerns in resource-limited settings and can reveal previously undocumented conditions and regional disease priorities
- •Educational and veterinary programs targeting working equid populations should prioritize the conditions owners identify as most impactful on animal function and productivity
- •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
Key Research Findings
Beta-hemolytic streptococci were isolated from tracheal lavage samples in horses with various respiratory symptoms
Cytological profiles including neutrophils, eosinophils, macrophages, lymphocytes, and mast cells were quantified across five clinical symptom groups
Correlation between inflammatory cell populations and presence of beta-hemolytic streptococcal species was assessed across symptom severity levels
Clinical respiratory symptoms were categorized from asymptomatic controls through single symptoms to multi-symptom presentation including coughing, lymph node swelling, and nasal discharge
94% of racehorses maintained ideal body condition score with no hoof neglect observed across 353 horses in 13 training yards
Mouth corner lesions occurred in 12.9% of horses overall but were significantly more prevalent in Flat racing compared to Jump racing horses
Training season significantly affected human reactivity tests, grimace scale scores, and time spent resting and feeding, with 14.5% of horses displaying stereotypic behavior on at least two occasions
67.5% of horses showed positive human interactions; horses with stable windows spent more time surveying surroundings, spending approximately one-third of daytime feeding and 22.6% standing resting
Unbroken horses transported from Spain via France to Italy had average journey duration of 34±14 hours with 24±4 hours transit time, traveling loose in small groups (≤4 horses) in well-equipped trucks
Injury prevalence was 1.52%, diarrhea/abnormal feces 6.58%, and nasal discharge 4.30% on arrival, with minimal behavioral or health problems observed
Cold temperatures, restricted space allowance, and lack of feeding during transport were significant hazards associated with welfare problems (p<0.05)
Experienced drivers, proper truck equipment (forced ventilation, drinkers), appropriate fitness assessment, and journey breaks were critical factors in maintaining welfare during transport
22.2% of horses showed reluctance to unload, 24.6% had injuries, and 11.6% had nasal discharge on arrival at slaughter
Journey duration, unloading duration, vehicle changes, long stops, handler/driver skills, temperature, and season were significantly associated with welfare and health outcomes (p < 0.05)
Horses traveled in single bays perpendicular to direction of travel for average 26.5 ± 14 hours with mostly compliant vehicle and driver standards per EC 1/2005
Evidence Base
Analysis of the presence of Beta-hemolytic streptococci and cytological profiles in horse tracheal lavage samples with diverse clinical respiratory symptoms.
Pınar Orhan, Çelik Doğan Cansu, Aktaran Bala Deniz et al. (2025) — BMC veterinary research
Racehorse welfare across a training season.
Annan Rachel, Trigg Leah E, Hockenhull Jo et al. (2023) — Frontiers in veterinary science
Journeys, Journey Conditions, and Welfare Assessment of Unbroken (Unhandled) Horses on Arrival at a Slaughterhouse in Italy.
Zappaterra Martina, Nanni Costa Leonardo, Felici Martina et al. (2022) — Animals : an open access journal from MDPI
Journeys, Journey Conditions, and Welfare Assessment of Broken (Handled) Horses on Arrival at Italian Slaughterhouses.
Felici Martina, Nanni Costa Leonardo, Zappaterra Martina et al. (2022) — Animals : an open access journal from MDPI
Respiratory disease and sero-epidemiology of respiratory pathogens in the working horses of Ethiopia.
Laing G, Christley R, Stringer A et al. (2018) — Equine veterinary journal
Descriptive results from a longitudinal study of airway inflammation in British National Hunt racehorses.
Cardwell J M, Wood J L N, Smith K C et al. (2011) — Equine veterinary journal
Inflammatory airway disease, nasal discharge and respiratory infections in young British racehorses.
Wood J L N, Newton J R, Chanter N et al. (2005) — Equine veterinary journal
Serological and Bacteriological Surveillance of Glanders Among Horses in Central Region of Iran.
Dehghan Rahimabadi Peyman, Nazari Alireza, Kamyabi Mostafa et al. (2023) — Journal of equine veterinary science
Surgical Debulking and TransEndoscopic Noncontact Diode Laser Application for Treating a Sinonasal Myxoma in a Horse.
Palozzo Adriana, Celani Gianluca, Varasano Vincenzo et al. (2021) — Journal of equine veterinary science
Pathology, infectious agents and horse- and management-level risk factors associated with signs of respiratory disease in Ethiopian working horses.
Laing Gabrielle, Christley Robert, Stringer Andrew et al. (2021) — Equine veterinary journal
Pathological and Immunohistochemical Analyses of Naturally Occurring Equine Glanders Using an Anti-BpaB Antibody.
Erdemsurakh Ochbayar, Purevdorj Baatarjargal, Ochirbat Khurtsbaatar et al. (2020) — Veterinary pathology
Paranasal sinus cysts in the horse: Complications related to their presence and surgical treatment in 37 cases.
Fenner M F, Verwilghen D, Townsend N et al. (2019) — Equine veterinary journal
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
Congenital defects of the soft palate in 15 mature horses.
Barakzai S Z, Fraser B S L, Dixon P M (2014) — Equine veterinary journal
A single caudally based frontonasal bone flap for treatment of bilateral mucocele in the paranasal sinuses of an American miniature horse.
Easley Jeremiah T, Freeman David E (2013) — Veterinary surgery : VS
Necrosis of the nasal conchae in 12 horses.
Cehak A, von Borstel M, Gehlen H et al. (2008) — The Veterinary record
The Welfare of Traveller and Gypsy Owned Horses in the UK and Ireland.
Rowland Marie, Hudson Neil, Connor Melanie et al. (2022) — Animals : an open access journal from MDPI
Owner reported diseases of working equids in central Ethiopia.
Stringer A P, Christley R M, Bell C E et al. (2017) — Equine veterinary journal
Guttural pouch mycosis in horses: a retrospective study of 28 cases.
Dobesova O, Schwarz B, Velde K et al. (2012) — The Veterinary record