Some dogs respond well to Omega-3 fatty acids as a treatment for allergies. This might sound unusual, but theyve been found to reduce the effects of chemicals, such as histamines, that a dogs body releases in response to allergies. Make sure that you consult your veterinarian before using Omega-3s to treat allergies, as they will be able to recommend a suitable therapeutic dose. Related: Top 10 Dog Breeds With Allergies. Cortisone