WELCOME and CONGRATS on your new sweet baby! And bless your heart for taking her in. She sounds like she's had quite a tough journey, but I know you'll get her to trust and open up
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As for food, what are you feeding her now and does she like it? Is there a reason you want to change it? I feed raw frozen, but think there are some awesome kibbles out there too. Are you looking for grain free, or anything in particular? A couple dense calories treats you could give her would be little blobs of peanut butter and bits of cheese.
I'm not surprised she was spooked at the groomers, I think if I were a dog I'd find the groomer pretty terrifying too. This is why we groom our 3 at home...I just don't ever want them to be alone in stranger's hands unless it's a must like at the vet. Also, my Wylie had such traumatic experiences at the groomer's when he was a pup, that we then vowed no more groomers for our kiddos. You could easily do it yourself...just brush a few times a week, trim areas that prove troublesome, and bathing is easy (or, will get easier, in your kiddo's sake). And yes, it's a great idea to turn the clippers on and just leave it, paying it no attention...do that every once in a while; eventually bring it closer to her and just sit it there so she gets used to it being close...and keep progressing from there.
Anyway, - CONGRATS again
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