Chronic lower airway diseases, such as recurrent airway obstruction (RAO) and inflammatory airway disease (IAD), are all too common in horses today. Reducing dust in the diet and environment can benefit these horses, but Purdue University researchers found that omega-3 fatty acid supplementation will reduce signs even further.

For the purpose of their study, the researchers used an algae-based omega-3 supplement that also contained vitamin C, methylsulfonylmethane (MSM), and a mushroom complex.

“Algae is the richest source of DHA (docosahexaenoic acid), and this is a vegetarian and renewable source of DHA (unlike fish, which is the other common source of DHA and EPA),” said Laurent Couëtil, DVM, PhD, Dipl. ACVIM, a professor in the Purdue University Department of Veterinary Clinical Sciences, in West Lafayette, Indiana.

Specifically, the team aimed to evaluate the algae supplement’s impact on horses with RAO or IAD housed in a low-dust environment, based on changes in visual analog scores (VAS) for cough, lung function, and bronchoalveolar lavage fluid (BALF).

In order to determine an effective dosage, Couëtil and his colleagues first conducted a pilot study of four healthy horses and four RAO-affected horses from Purdue’s herd. The team fed the algae supplement at the lowest recommended dose to one group and at double the dose to the second group. After two weeks, the team doubled both treatments. They collected blood every two weeks and concluded the study when the blood plasma’s omega-3 content plateaued, which was Week 4.

The researchers then conducted a nine-month clinical trial involving 32 client-owned horses diagnosed with either RAO (14 horses) or IAD (18 horses) over a nine-month period. Horses remained the same environment they had been in prior to enrolling in the study, but they no longer had access to hay and were instead acclimated to a complete pelleted feed to reduce dust in the diet.

In addition, the team randomly assigned one of three treatments to participating horses:

The recommended dose of the algae supplement;

Two times the recommended dose of the algae supplement; or

A placebo.

Upon reviewing their results, the team determined that the VAS for cough improved significantly in all three treatment groups; however, after eight weeks of consuming the supplement, horses receiving the algae supplement had better VAS for cough compared to horses receiving the placebo. The team noted no additional benefit associated with horses receiving double the dosage.

“We were surprised by how quickly horses improved after receiving the supplement,” Couëtil said.

Additionally, after two months of algae supplementation, horses had healthier BALF and showed improved lung function compared to those in the placebo group. Further, DHA levels in blood increased tenfold in supplemented horses. The researchers noted none of these effects in horses receiving the placebo.

The team concluded that, based on this study, omega-3 supplementation “could be an additional option to help better manage both IAD and RAO horses when compared to a low-dust environment by itself.”

The study, “Omega-3 Fatty Acid Supplementation Provides an Additional Benefit to a Low-Dust Diet in the Management of Horses with Chronic Lower Airways inflammatory Disease,” was published in the Journal of Veterinary Internal Medicine.