What the Studies Say About Equine Asthma and Omega-3
There have been a lot of studies published that support the benefits of omega-3 supplementation in animals. In this article, we are going to summarize one that relates to horses with chronic lower airway inflammatory disease.
What Is Equine Asthma?
Equine asthma cases consist of horses that have been diagnosed with either recurrent airway obstruction (RAO), previously known as heaves, and inflammatory airway disease (IAD).
RAO horses will cough, have excessive airway mucus and inflammation, have trouble breathing, and may wheeze during a flare up of the disease. Management of the disease includes removing hay from the diet, along with other methods, to reduce exposure to dust. In addition, horses may be treated with bronchodilators and glucocorticoids.
IAD is less severe and generally affects performance horses. It can cause poor performance and intermittent cough. IAD does not cause respiratory distress at rest and is hard to determine by physical examination only.
Feeding Omega-3 to Horses with RAO and IAD
In 2013, researchers at Purdue University published the results of their study examining the effects of omega-3 supplementation on horses with equine asthma.
In the study, 32 horses (18 geldings, 11 mares, and three stallions between the ages of six and 22 from a variety of breeds) were fed a complete pelleted diet without hay. Fourteen of those horses had RAO and 18 had IAD. The horses were given either 30 grams of an omega-3 algal supplement, 60 grams of the same algal supplement, or 30 grams of a placebo. The supplement was fed on top of the horse’s complete pelleted feed.
It’s important to note that algae omega-3 supplements only contain high concentrations of DHA (docosahexaenoic acid) compared to EPA (eicosapentaenoic acid). In comparison, fish oils, such as Wellpride,naturally contain both EPA and DHA, which have already been proven to have many benefits for horses, humans, and other animals for a variety of conditions. This was the first study to demonstrate a benefit for equine asthma.
Researchers at Purdue University wanted to determine if an omega-3-rich supplement and a low-dust diet could improve the clinical score, pulmonary function, and bronchoalveolar lavage fluid (BALF) cytology in horses. The BALF cytology was important, since horses with RAO have increased markers of free radical formation from oxidative stress in their BALF.
As a first step, the researchers conducted a pilot study to determine the minimum effective omega-3 dose necessary. Next, the horses were evaluated based on performance, respiratory rate, respiratory effort, nasal discharge, presence of cough and abnormal lung sounds, abdominal effort, and nostril flaring. They also had blood drawn, pulmonary (lung) function testing, and BALF collection at the beginning of the study and on Day 56 after being fed one of the three diets for 8 weeks.
All medications were withheld during the study. The horse’s performance, breathing difficulty, and cough were also evaluated weekly by their owners or caregivers.
The Study Results
All of the study horses improved regardless of diet fed; however, the horses treated with omega-3 supplements improved significantly more than their placebo-fed counterparts. Improvement was expected in all groups due to the change from a diet with hay to a pelleted feed, which resulted in less exposure to dust among all of the study participants.
The first signs of improvement showed up in the horses treated with omega-3 supplementation after two weeks of treatment and improved the most by weeks 2 and 5 for coughing, weeks 5 and 6 for respiratory effort, and weeks 3 and 5 for performance. Placebo-fed horses only improved after week 5, but the effect never reached statistical significance.
After two months of supplementation, horses fed with omega-3 had a decrease in neutrophils in the BALF from 23% to 9%. In addition, the researchers noted an improvement in lung function. The scores for cough improved by 60% and respiratory effort decreased by 48%. In comparison, the control group only saw a cough score improvement of 33% and a decrease in respiratory effort by 27%.
The study authors noted that for horses with chronic airway disease, a low-dust diet along with omega-3 supplementation for 8 weeks had “similar clinical benefits as a 3-week course of dexamethasone administration without diet modification.”
The authors did add that if a horse affected with RAO has a flare up, he still may need medications.
One of the most interesting findings was that the single dose of supplementation (30g) was as effective as the double dose (60g). “According to our findings, feeding the 2x dose did not proportionally increase plasma concentrations of DHA,” wrote the authors. “It is possible that there is a limit on how much omega-3 PUFA can be absorbed and integrated in the horse’s plasma, and higher doses of supplementation may not confer additional health benefits. Another possible explanation is that the source of the omega-3 PUFA makes a difference. The supplement used in our study was from an algae source, and we are not aware of any previous report of its use in horses.”
To read the full study, visit http://onlinelibrary.wiley.com/doi/10.1111/jvim.12488/full.
The study was done at Purdue University by staff and lead author Nora Nogradi, DVM, MS, when she was a graduate student under Laurent Couëtil, DVM, PhD, section head of Large Animal Internal Medicine at Purdue University. Additional study authors include Joanne Messick, VMD, PhD, from the Department of Comparative Pathobiology and grad student Mateusz Stochelski and John Burgess, MS, PhD, from the Department of Nutrition Science.