Inhaled lidocaine assessed as a treatment for asthma in horses

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Lidocaine is being investigated as a potential treatment for equine asthma.

A clinical trial is being conducted in Massachusetts at Tuft University’s Equine Center.

Equine asthma can be challenging to treat.

Bronchodilators, which relax the airways, make it easier to breath. But humans and horses can quickly develop a tolerance, so they tend to be used sparingly to preserve their effectiveness in acute attacks.

For this reason, corticosteroids, which reduce the inflammation that fuels asthma, are key planks in treating humans and horses. Most asthma sufferers inhale them using puffers.

However, inhaled steroids are a very expensive option for horses, which means owners tend to opt for oral or injectable steroids. The downsides are serious side-effects, especially in aging horses with metabolic problems.

Professor Melissa Mazan
Professor Melissa Mazan. © Tufts University

“We have learned a lot about how to diagnose equine asthma and its molecular mechanisms, but we treat this condition almost exactly like we did when I started out more than 20 years ago,” Tufts University veterinarian Melissa Mazan told TuftsNow.

“And anyone trying to treat an asthmatic horse often ends up stuck between a rock and a hard place.”

Which is why Mazan, from the university’s Cummings School of Veterinary Medicine, set out to explore the potential of lidocaine, a cheap and widely available local anesthetic.

Mazan’s interest was sparked after reading a study investigating whether lidocaine could treat people with an intractable cough. Those in the study inhaled lidocaine through a nebulizer and had a good response.

Mazan and a fellow faculty member, large-animal veterinarian Daniela Bedenice, designed a clinical trial open to interested horse owners. Plenty came forward.

The first phase involved a blind trial involving seven horses with asthma, all of whom were assessed for exercise tolerance, lung function, and levels of inflammatory cells. Each received either lidocaine or a saline placebo via a nebulizing mask twice a day for two weeks.

Those receiving lidocaine showed significant improvement. In fact, two horses struggling during the trial resulted in the study being “unblinded”. They were found to be on the saline and were changed to the lidocaine, which improved their condition.

In the latest phase, which is ongoing, enrolled horses are assigned either lidocaine or a corticosteroid, the conventional treatment for equine asthma, to see how the treatments compare.

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