Spring is right around the corner, and many horses have seasonal allergies. Seasonal allergies can make horses uncomfortable and cause owners a lot of worry, ranging from pollen in the air to biting insects.
Allergies to pollen typically present as airway issues, coughing during work, and breathing problems, which may be diagnosed as equine asthma. Reactions to biting insects result in skin sensitivity, itchiness, and rubbing of manes and tails, sometimes leading to hives.
You can support your allergy-prone horse through targeted supplementation. But first, let’s understand why allergic reactions happen.
Why do allergic reactions happen?
An allergic reaction results from how the horse’s body reacts to a foreign protein (allergen). It is an overreaction to an otherwise harmless substance. The first time this allergen is encountered, the body responds by creating immunoglobulin E (IgE). These antibodies can bind to allergy cells called mast cells that are found in the skin, airway and digestive tract. When the IgE comes into contact with the allergen in the future, it binds it and takes it to the mast cell for removal. In response to being brought an allergen, the mast cells release histamine, which is one of the mediators of allergic reactions. It is the primary cause of mucus secretion, sneezing, and hives.
Histamine’s role is to help keep allergens out of the body. It stimulates inflammation, mucus production, sneezing, coughing, and airway constriction, reducing the likelihood of allergens reaching the lung lining and triggering a response. However, it also hinders the transfer of oxygen and carbon dioxide across lung tissue, leading to breathing difficulties, commonly associated with asthma. In the skin, histamine release causes swelling and itchiness.
Evidence that omega fatty acids help reduce the severity of allergies
Research indicates that omega-3 fatty acids have a beneficial effect on chronic inflammatory diseases like asthma, inflammatory bowel disease, and rheumatoid arthritis. Eicosapentaenoic acid (EPA) and docosapentaenoic acid (DHA), the omega-3 fatty acids, serve as precursors to specialized pro-resolving mediators (SPM) called resolvins and protectins, which mediate inflammation.
Studies suggest a protective effect and a potential causal relationship between decreased fish oil intake and an increasing number of individuals with asthma or other allergic diseases. Impaired SPM synthesis in severe asthma patients prevents the resolution of inflammation in the lungs. Furthermore, a high intake of omega-3 fatty acids, particularly DHA, has been found to prevent asthma onset in young adults.
Omega-3 fatty acids have shown promise in managing airway inflammation and other allergic responses in horses too. Supplementing with polyunsaturated fatty acids increased plasma levels and improved clinical symptoms of inflammatory airway disease (IAD) and recurrent airway obstruction (RAO) in horses. Feeding horses a DHA-containing supplement resulted in a peak in plasma DHA levels, improved cough scores by 60%, and reduced respiratory effort by 48%.
Omega-3 fatty acids may also benefit horses prone to biting insect sensitivity. Owners reported improvements when horses were diagnosed with Culicoides spp. hypersensitivity were supplemented with linseed oil, which is rich in omega-3 alpha-linolenic acid (ALA). However, EPA and DHA, available only from marine sources like marine algae and cold-water fish, are more potent forms of omega-3 fatty acids.
Fish oil: benefits for horses and humans alike
The benefit of omega-3 fatty acids in managing airway inflammation and other allergic responses is not limited to human research. Work by Nogradi et al. (3) looked at whether the addition of polyunsaturated fatty acids in the diet of horses could increase plasma levels and, in turn improve clinical symptoms of inflammatory airway disease (IAD) and recurrent airway obstruction (RAO). Using horses diagnosed with these conditions, they fed a complete pelleted low dust diet and either 30 or 60 grams of a DHA supplement or 30 grams of placebo.
They found that feeding the DHA-containing supplement for 2 months resulted in a peak in plasma DHA at 4 weeks and a 60 percent improvement in cough score, and a decrease in the respiratory effort of 48 percent compared to an improved cough score of 33 percent and decreased respiratory effort of 27 percent in the control group. The researchers noted that the results with the DHA supplement were similar to those seen with a 3-week course of dexamethasone steroid without diet modification.
Omega-3 fatty acids may also aid horses prone to biting insect sensitivity. In horses that were diagnosed with Culicoides spp. hypersensitivity and fed 200 ml of linseed or corn oil for 18 weeks, owners reported an improvement when supplemented with the linseed oil (4). Linseed oil is rich in omega-3 alpha-linolenic acid (ALA) but is not as potent as EPA and DHA.
While several plant-based omega-3 options provide ALA, EPA and DHA are only available from marine sources such as marine algae and cold-water fish. ALA must be converted to DHA and EPA since these are the active forms of omega-3 in the horse’s body. While the horse is capable of this conversion process, it is not very efficient. Therefore, a far better approach to promoting a healthy inflammatory response is directly supplementing the EPA and DHA.
Marine-derived DHA and EPA
Equine Omega Complete® provides marine-derived DHA and EPA mixed with organic cold-pressed soybean oil, offering a palatable source of essential fatty acids. For horses needing additional vitamin E support, Equine Omega Vitamin E® is also available.
To achieve maximal plasma concentrations of DHA, supplementation should start well in advance of allergen exposure. With spring approaching, it’s crucial to start supplementing your allergy-prone horse right away for a healthy and allergy-free season.
Sources
- Serhan CN, and Levy BD.Resolvins in inflammation: emergence of the pro-resolving superfamily of mediators. J Clin Invest. 2018;128(7):2657-2669. https://doi.org/10.1172/JCI97943.
- Miyata J, Arita M. Role of omega-3 fatty acids and their metabolites in asthma and allergic diseases. Allergol Int. 2015 Jan;64(1):27-34. doi: 10.1016/j.alit.2014.08.003. Epub 2014 Oct 27. PMID: 25572556.
- Nogradi N, Couetil LL, Messick J, Stochelski MA, Burgess JR. Omega-3 fatty acid supplementation provides an additional benefit to a low-dust diet in the management of horses with chronic lower airway inflammatory disease. J Vet Intern Med. 2015 Jan;29(1):299-306. doi: 10.1111/jvim.12488. Epub 2014 Oct 10. PMID: 25307169; PMCID: PMC4858086.
- Friberg, Logas. Treatment of Culicoides hypersensitive horses with high-dose n-3 fatty acids: a double-blinded crossover study. Vet Dermatol. 1999 Jun;10(2):117-122. doi: 10.1046/j.1365-3164.1999.00147.x. PMID: 34644932.
