Respiratory Transport Risk

Hello Summarians!

Four percent of brachycephalic dogs undergoing airway surgery don't make it home. That number should probably come up in the informed consent conversation more often than it does.

Also this week: long-distance shipping triggers measurable lung inflammation and microbiome shifts in healthy horses, even when well managed.

And researchers in Switzerland have now developed the first validated scoring system for insect bite hypersensitivity in horses.

Three studies. The first one has a number worth knowing.

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Respiratory Transport Risk In Horses

This study investigated how long-distance transportation affects the respiratory microbiota and airway health of healthy performance horses. Shipping fever, a common transport-associated pneumonia, is a major cause of illness, lost athletic performance, and economic loss in the equine industry. Because disruption of the respiratory microbiome has been linked to respiratory disease in other species, the researchers examined whether similar microbial changes occur in horses during long-distance travel and whether those changes are associated with inflammation.  

Seventeen healthy performance horses were transported approximately 1,200 to 1,300 miles from New England to Florida under carefully managed travel conditions. Clinical examinations, blood testing, thoracic ultrasonography, endoscopy, and sampling of the upper and lower airways were performed before transport and at 24 and 72 hours after arrival. Respiratory bacterial populations were analyzed using 16S rRNA gene sequencing and compared with samples from non-transported control horses.  

Although none of the horses developed clinical pneumonia, transportation produced measurable physiologic changes. Serum amyloid A concentrations, respiratory rate, and thoracic ultrasound scores increased after travel, indicating mild systemic and pulmonary inflammation. Three horses showed particularly pronounced inflammatory responses, although bacterial cultures remained negative and all abnormalities resolved without treatment. Interestingly, cortisol concentrations declined following transport, suggesting a more complex stress response than previously reported.  

The respiratory microbiota also changed significantly after transport. Distinct bacterial communities were found in the upper and lower airways, with the lower airway microbiota demonstrating greater instability over time. Transport accounted for a modest but statistically significant portion of microbial variation, while increasing ultrasound scores correlated with shifts in bacterial composition. Many environmental and plant-associated bacteria, particularly members of the Alphaproteobacteria, decreased following transport, whereas only a few bacterial groups increased. These microbial changes were more pronounced than those observed in stationary horses sampled over a similar time period.  

The authors concluded that even well-managed long-distance transportation alters the respiratory microbiota and induces mild pulmonary inflammation in healthy athletic horses. Although the study cannot determine whether these microbial changes directly contribute to shipping fever, it demonstrates a clear association between respiratory dysbiosis and ultrasonographic evidence of lung inflammation. Future research evaluating fungal communities, immune responses, and interactions between the gut and lung microbiomes may improve understanding of transport-associated respiratory disease and lead to more effective preventive strategies.

Ananya Mahalingam-Dhingra, Daniela Bedenice, Debora Regina Romualdo da Silva, Melissa Mazan, Tiffany Hall, Wade Tenney, Giovanni Widmer, Clinical and microbiota alterations in performance horses undergoing long-distance transport, Journal of Veterinary Internal Medicine, Volume 40, Issue 4, July-August 2026, aalag137, https://doi.org/10.1093/jvimsj/aalag137

Bottom line — It does affect them.

Airway Surgery Risk Score For Dogs

This retrospective study evaluated 297 brachycephalic dogs that underwent surgery for brachycephalic obstructive airway syndrome (BOAS) at a veterinary teaching hospital between 2012 and 2023. The primary goal was to identify factors associated with postoperative death and complications and to develop a predictive model that could estimate an individual dog's surgical risk. Researchers reviewed medical records for patient characteristics, clinical history, airway abnormalities, surgical procedures, and postoperative outcomes, then used logistic regression to identify significant predictors of adverse events.  

Overall, 4% of dogs died before discharge, while 10% experienced major complications such as aspiration pneumonia or the need for emergency airway intervention. Minor complications, particularly postoperative regurgitation or vomiting, occurred in approximately 35% of cases. Emergent presentation for respiratory distress was the strongest predictor of both death and major complications. Dogs with advanced laryngeal collapse (grade 2 or higher) were also at substantially greater risk. Female sex, English Bulldog breed, and a history of regurgitation or vomiting before surgery were associated with increased risk in some models, although not all remained stable predictors after internal validation. Conversely, dogs with a history of exercise intolerance or previous BOAS treatment appeared to have lower complication rates, possibly because earlier recognition and intervention prevented progression to severe disease.  

The resulting prediction models demonstrated good ability to distinguish between high- and low-risk patients, although the authors acknowledged some overfitting due to the relatively low number of deaths. Simplified models containing fewer variables showed improved calibration while maintaining acceptable predictive performance. The investigators emphasized that the models should currently be used only as decision-support tools because they have not yet undergone external validation in other hospitals or patient populations.  

Clinically, the study highlights the importance of identifying dogs at increased surgical risk before anesthesia. Factors such as emergency presentation, severe laryngeal collapse, and gastrointestinal signs can help veterinarians anticipate postoperative complications, improve client counseling, and determine whether referral to a specialty center or more intensive postoperative monitoring is warranted. Although preliminary, this individualized risk calculator represents a promising step toward more personalized perioperative management of dogs undergoing BOAS surgery.

Ruzics, E. A., Reynolds, P. S., Morse, Z., Shipman, J., & Ham, K. M. (2026). Development of a predictive model for estimation of postoperative risk following brachycephalic obstructive airway syndrome surgery. Journal of the American Veterinary Medical Association https://doi.org/10.2460/javma.26.01.0071 

Bottom line — Early results support this as a beneficial protocol

Scoring Allergies In Horses

The study developed and validated the Equine Insect Bite Hypersensitivity Severity Score (EqIS), a standardized clinical scoring system designed to objectively assess insect bite hypersensitivity (IBH), the most common allergic skin disease in horses. IBH is caused by an allergic reaction to Culicoides biting midges and produces intense itching, hair loss, skin damage, and chronic discomfort. Although several scoring systems have been used previously, most have not undergone formal validation to ensure consistent results between different observers, limiting their usefulness for clinical trials and long-term monitoring.  

The researchers evaluated 44 client-owned horses with IBH in Switzerland. The EqIS combines two components: a lesion severity score based on seven types of skin lesions across 32 body regions and an area score measuring the extent of skin involvement. Rather than simply adding these values, the system multiplies lesion severity by the affected area, allowing more accurate representation of disease severity. Six trained veterinarians independently scored the horses, and the study measured both intraobserver reliability, which assesses whether the same examiner produces consistent results over time, and interobserver reliability, which evaluates agreement among different examiners.  

The EqIS demonstrated outstanding reliability. Intraobserver and interobserver intraclass correlation coefficients were approximately 0.98 to 0.99, indicating excellent reproducibility. Agreement for estimating the affected skin area was also very strong. Owners completed visual analog scales evaluating itchiness and overall disease severity. These subjective assessments showed moderate correlation with the veterinarian-derived EqIS, while the two owner ratings strongly correlated with each other, demonstrating that owners primarily judge disease severity by the horse’s level of itching.  

The investigators also developed a simplified version of the EqIS for routine field use. This abbreviated score closely matched the validated system while requiring less time to perform. Overall, the study establishes the EqIS as the first extensively validated, IBH-specific clinical scoring system, providing veterinarians and researchers with a reliable, objective tool for monitoring disease progression and evaluating treatment effectiveness in horses.

Juwela Lam, Anna Eckert, Tanya Rhiner, Nina Waldern, Elio Schwarz, Katharina Birkmann, Daniel Widmer, Macsmeila Dietrich, Thomas M Kündig, Antonia Fettelschoss-Gabriel, Validation of an improved insect bite hypersensitivity severity score for allergic equine insect bite hypersensitivity in horses, Journal of Veterinary Internal Medicine, Volume 40, Issue 4, July-August 2026, aalag132, https://doi.org/10.1093/jvimsj/aalag132

Bottom line — Could be a useful tool.

Just putting things in perspective …