Ultrasound can provide fast, easy information on lung status in horses – study

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Study team in Italy used data from 303 asthmatic horses hospitalized at the Veterinary Teaching Hospital of the University of Milan. 
Photo by Fernanda Greppe

Ultrasound is a useful and non-invasive diagnostic tool for horses affected by equine asthma and exercise-induced bleeding from the lungs, researchers in Italy report.

Chiara Maria Lo Feudo and her fellow researchers, writing in the journal Veterinary Sciences, said ultrasonographic examination can provide fast and easy information on the inflammatory status of the lungs.

The University of Milan study team found that horses affected by severe equine asthma or a combination of mild-moderate asthma and exercise-induced pulmonary hemorrhage – bleeding from the lungs – had significantly higher ultrasonographic scores compared to horses affected by mild asthma only.

The study team said asthma and exercise-induced lung bleeding are common respiratory issues in horses. They set out to evaluate the role of ultrasonography and endoscopy in the diagnosis of these conditions.

They used data previously obtained on 303 horses, all affected by asthma and hospitalized at the Equine Unit of the Veterinary Teaching Hospital of the University of Milan at various times between 2001 and 2020.

The horses were divided into three groups based on their history, clinical examination and results of analysis of bronchoalveolar lavage fluid (BALf) – fluid wash samples taken from the lungs. They were classified as either severely asthmatic, affected by mild-moderate asthma, or affected by mild-moderate asthma together with exercise-induced lung bleeding.

Scores were assigned to lung ultrasonography, pharyngeal lymphoid hyperplasia, tracheal mucus and tracheal bifurcation edema.

These scores were compared between groups, and their associations with age, lavage test results, and tracheal wash microbiology. The relationship between endoscopic and ultrasonographic scores was statistically analyzed.

The researchers found that ultrasonographic scores were higher in the horses with severe asthma, as well as those with mild-moderate asthma together with lung bleeding.

The horses affected by a combination of mild-moderate asthma and lung bleeding had more neutrophils and hemosiderophages in their lung lavage fluid than the other horses.

The pharyngeal lymphoid hyperplasia score was higher in younger horses affected by mild asthma and lung bleeding, and associated with increased eosinophils and hemosiderophages in lavage fluid.

Tracheal mucus and tracheal bifurcation edema scores were greater in older horses affected by severe asthma, and were associated with increased neutrophils but fewer hemosiderophages.

Thoracic ultrasonography and airway endoscopy can provide useful information about the inflammatory status of upper and lower airways in the horse, they said.

Ultrasonographic changes proved to be associated with increased lavage counts of neutrophils and hemosiderophages, and with increased tracheal mucus accumulation.

“However, the diagnostic limit of thoracic ultrasonography is represented by its low specificity, not allowing to distinguish the nature of the lesions,” the researchers said.

“Therefore, airway endoscopic and bronchoalveolar lavage fluid collection remain essential in the diagnostic protocol of these respiratory conditions.

“Thoracic ultrasonography should be considered when selecting the bronchus from which to collect the bronchoalveolar lavage fluid as it provides further information on the morphology of the lung, the localization and the extent of the sites of inflammation.

“Moreover, in young, moderately asthmatic racehorses, lung ultrasonography could represent a reliable indicator to distinguish between EIPH-affected and non-affected patients.”

The study team comprised Lo Feudo, Luca Stucchi, Elena Alberti, Giovanni Stancari, Bianca Conturba, Enrica Zucca and Francesco Ferrucci, all with the University of Milan.

Lo Feudo, C.M.; Stucchi, L.; Alberti, E.; Stancari, G.; Conturba, B.; Zucca, E.; Ferrucci, F. The Role of Thoracic Ultrasonography and Airway Endoscopy in the Diagnosis of Equine Asthma and Exercise-Induced Pulmonary Hemorrhage. Vet. Sci. 2021, 8, 276. https://doi.org/10.3390/vetsci8110276

The study, published under a Creative Commons License, can be read here.

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