Could she be in heat or pregnant? I even had a dachshund act like this as she started false pregnancy twice. She actually rounded up small plush toys and eventually took them toa closet. She too wanted to nest away from everyone. She acted just as you explained until she took to the closet herself for a week. My yorkie female, Sadie, had a little diarrhea before she went into heat and again when she was ready to have the puppies. So, I am wondering if it is something like that with your girl, heat, false or true pregnancy.
As for the tuna -- I would not feed that -- even the packed in water because of the high mercury levels. They have a warning on the can for pregnant humans not to eat it -- that tells me small dogs should probably not either. We have not had tuna in the house for years, since the mercury levels went up so high. |