There is a lot you can do to help build her immune system. I think the first step and most critical is to always evaluate what assaults are being levied on her immune system. Consider everything her immune system is having to "grapple with" or "manage" because the more overworked it is, the more exhausted and compromised it will become. The greatest assaults on the immune system are chemicals, toxins, vaccines, and drugs (the latter two both contain chemicals or toxins). So this includes, pesticides, lawn chemicals, toxic cleaning chemicals used on surfaces she comes into contact like floors, mats, carpet etc., flea and tick chemicals, heartworm pesticides - you get the idea.
Drugs should be considered because if her body is trying to rid itself of toxins and expel them, this usually manifests as ear infections, eye discharge, skin eruptions and issues, etc. So not interfering in this process and suppressing it is key. Allow it all to run its course and help facilitate it.
What you feed is critical - you are feeding a good quality kibble, but she may have yeast overgrown issues - urinary and ear infections often point to yeast involvement. So consider switching her to a grain and starch free food.
Look into products that facilitate nutrient absorption and healing such as Fido Wobenzym, Seacure, Olive Leaf, Wild Salmon Oil is a source of Omega 3s and a great anti-inflammatory and immune booster. There are many more.....
I do not recommend Missing Link because while it contains many wonderful ingredients for dogs, there are a few that are particularly bad for allergy dogs and those with certain issues. It contains flaxseed oil which can clog the respiratory cells of dogs, and is a common allergen for dogs so I would avoid - stick with fish oils for this benefit. It also contains yeast and carrot which are two of the last things you want to give a dog with allergies, a yeast problem, or an ear infection that could be yeast related.
Hope that helps...
