Owners Best at Assessing Own Horse's Airway Disease Changes

In study that could have been dubbed "Who's smarter than a veterinarian?" Michigan State University researchers concluded that when it comes to assessing chronic respiratory disease changes in horses, the answer is … owners.

"Owners are astute observers of their horses and are able to accurately differentiate the improvement in respiratory signs in horses treated with dexamethasone from the lack of improvement in placebo-treated horses," said Ed Robinson, MRCVS, PhD, Matilda R. Wilson Professor of Large Animal Clinical Sciences, who led the research team.

Inflammatory airway disease (IAD) and recurrent airway obstruction (RAO, heaves) are noninfectious conditions characterized by airway inflammation and obstruction, excess mucus accumulation, and alterations in airway structure of affected horses (i.e., remodeling). Corticosteroids such as dexamethasone and bronchodilators like clenbuterol are the most commonly used drugs to relieve airway obstruction in affected horses.

"The best way to assess the efficacy of these drugs is by lung function tests," explained Robinson, but he notes these test are technically challenging and do not detect small changes in obstruction severity. Robinson noted another challenge for veterinary assessment: While owners often assess their horses daily, practitioners examine clients' horses infrequently and might not see these horses at their worst (e.g., after exercise).

In a double-blind randomized study, owners assessed their horses before and after administering dexamethasone or a placebo once daily for three weeks. Using a 10-point scale, owners assessed performance, breathing effort, and coughing and nasal discharge. Veterinarians on the other hand measured vital parameters (heart and respiratory rates), auscultating the lungs with a stethoscope, assigning an endoscopic airway mucus score, examining bronchoalveolar lavage fluid (BALF, lung wash), and measuring oxygen and carbon dioxide in an arterial blood sample.

"The owners of the dexamethasone-treated horses were able to detect changes in their horse's condition and owners of placebo-treated horses did not detect any changes in respiratory function," explained Robinson.

In contrast, veterinarians were unable to differentiate between dexamethasone- and placebo-treated horses based on clinical observations, BALF, or mucus scores.

Only respiratory rate and arterial oxygen levels improved in the dexamethasone-treated horses as compared to the placebo group.

"These study results suggest that future studies that evaluate the clinical efficacy of airway disease treatments should include an owner-assessment of their horse's condition," relayed Robinson. "Not only will this provide more data but a larger number of subjects will be included in these studies, which will provide a more representative sample of the population of horses seen by veterinarians."

The study, "Owner assessment in judging the efficacy of airway disease treatment" will be published in an upcoming edition of the Equine Veterinary Journal. The abstract is currently available online. Co-authors on this study were Vincent Gerber PhD, DVM, currently of the University of Bern and Harold Schott II, MS, DVM, PhD, Dipl. ACVIM, of Michigan State.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.

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