Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you with your wee one today.
Now just like people, dogs can be sensitive to certain proteins in their diet and this can trigger dietary allergies. When this happens, we can see food allergies cause GI disease or skin based issues (usually manifesting as itchiness all over the body since the protein in their food is distributed all over the body).
In situations where a food allergy is suspect, these animals often benefit when we can find the allergen that is settling them off. Ruling out food allergies can take time and patience but can be done at home (your vet can be a good adviser on proceeding with this) via an elimination diet with one protein source. Ideally this should be one she hasn’t had before (so likely won’t be allergic to; ie duck, fish or lamb based foods) or a hypoallergenic diet like Hill’s Z/D (More Info) or Chappie wet food diet (as this is a fish based diet with little else to trigger allergies). So, if you suspect or want to rule out food allergies for Dolly, this would be your best course of action (perhaps using the hypoallergenic diets to quickly determine if food as opposed to environmental issues are triggering her signs).
In regards ***** ***** to go about an elimination diet, be aware that this should be done for a 4-6 week period (unless adverse effects or she refuses the diet) to give time for the previous diet’s allergens to pass out of her system. As well, you want to make sure she is getting no treats or other bits, because these little tid bits (if they harbour the trigger allergen) can undo all your hard work of these trials. Again food trials are something you can do at home but do require patience and perseverance, because it does take time to figure out what the dietary trigger is (and there can be more then one). It can often be helpful to keep a diary to keep track of what you have tried. And while food trials take patience and tough love (as you avoid giving anything else), once you find what works, that is the biggest challenge and management can be much easier.
Overall, if you are suspicious that Dolly has a food allergy, do consider starting a diet trial for the next 6 weeks on either of those aforementioned hypoallergenic diets (you can use any diets you wish but these low allergen foods will answer your suspicions quickest, since you may need to try a few different alternative protein diets otherwise to get to the root of her signs). If she settles, then your suspicions will be confirmed and you can continue the diet you use or slowly work out (based on the current diet's recipe and her reaction to diets) what she is sensitive to and what agrees with her. But if she doesn't settle, then one would have to consider other allergens (ie pollens, environmental ones like dust mites, etc) and potentially consider speaking to her vet about allergy testing to pinpoint what is to blame so that you can address it properly for her.
I hope this information is helpful.
If you need any additional information, do not hesitate to ask!
All the best,