I am so sorry to hear that Sita and you are going through this!
Glad the tests have come back clean yet it is very frustrating - if there is a wholistic vet in your area maybe you could go for a second opinion there.
The only article I can up with in an online search was this: http://www.justanswe...-just-poop.html
It speaks about purple slime in dog's poop and a vet tells tests and what he would do.
Here is my thoughts - just thoughts - not medical advice:
I agree with the bland diet for a little while (5 -12 days? depending how fast she heals - give it at least a day or two after no more purple in poop). If her poop isn't firm or it still may be good for her tummy & GI tract: maybe canned pumpkin (not pumpkin pie mix) with the chicken and rice and some goats milk or kefir maybe a little diluted with spring water?.
The article I linked spoke about adding fiber, pumpkin has fiber.
I feed Taste of the Wild, the High Prairie formula. (I've heard Orijen and Fromm are both really good foods too).
I don't add canned food but cook organic chickens in a crock pot and boil sweet potatoes (and drain the water), I add boil the organs and chop them up and add that broth plus the regular chicken broth (about 2 cups) to the deboned chicken & sweet potatoes and have over a months worth of nutritious moisture to add to the dry kibble. I have been experimenting with adding chopped carrots last month and apples chunks (not the seeds) this time to the new batch made. The apples were raw and I blanched the carrots so they would still have some crunch and be easier to digest.
I agree with Sherab's? statement, don't make switches too soon or too fast. It upsets the apple cart and you don't want more of that.
Tayamni just went to the Vet for abdominal pain but no blood from stool. She got stepped on at the dog park and it stressed her to the point of not eating. After being listened to, poked, prodded and tested and negative for worms and Giardia, the Vet put her on Famotidine and bland diet for 5 days. After one dose of Famotidine she is eating her mix I mentioned above and has had a lot of intestinal gurgles - her poop is firm so I think the gurlges are good in this case - since she had none before when she stopped eating, and that is not like her at all - the hoover vacuum. Also, she would lay curled up and didn't want her tummy rubbed - which is her go to place for rubs.
Taste of the Wild is supposed to be made in the south-east USA. I don't know if all the ingredients are sourced from USA or not.
This video just says "trusted Vendors" https://www.youtube....h?v=A0iP8y0wnb0 but it is a nice video to let you know how the food is made.
Look up to see if there have been any recalls on the food you use, just to be safe. I don't believe Taste of the Wild has recalls but their parent company Diamond has had a good amount in the past.
Hopefully you will be able to control this issue with food & supplements - and take a look at treats you give, too - or others give your dog.
Oh I did try to switch my AI Dogs over to the adult version of the High Prairie formula but it didn't have enough fiber and Tayamni seemed allergic to an ingredient in the adult formula (maybe that was another flavor with the garbanzo beans) there's so much to watch for ....
I used to feed Tayamni raw chicken once a week as a treat but it got to be a pain when Coffey was a puppy. I know people that make human grade balanced cooked meals for their dogs.
I've heard that pureed Raw vegetables are great!!!!!! Just know what is good for dogs and then what Sita tolerates! Tayamni has sensitivities to certain herbs and vegetables.
BEST OF LUCK and HOPE YOU FIND OUT WHAT HEALS HER SOON!