My dog has sudden poop accidents and panics before going out. Why?

I am so sorry to hear about Nickel (what a cutie pie!). I wonder if your dog has inflammation or irritation in the distal color or rectal/anal area that causes her pain/irritation when it is time to have a bowel movement and this is why she becomes irritated/frantic. It is worthwhile to have her anal sacs examined by a vet if she hasn't already. You may also talk to them about putting her on a diet trial of a hypoallergenic diet in case she is having some mild inflammatory bowel symptoms causing the urgency or inflammation. There are diets that are made of hydrolyzed protein (where the protein has been broken down so it isn't recognized as an allergen) or novel protein diets, where the protein and carbohydrate sources are ones your dog hasn't eaten before (for example fish and potato or kangaroo and oats). The vet should also do a full neurological examination of your pup to be sure there aren't any abnormalities in the nerve pathways of the rectal area. An x-ray or ultrasound of the abdomen may also be helpful. If your vet hasn't been able to find a cause, you may request a referral to a specialist such as an internal medicine specialist. Another option you may try at home would be to add some fiber to his Nickel's diet to see if the bulking up of the feces helps Nickel identify a bowel movement is coming earlier. You can achieve this by adding a few teaspoons of canned pumpkin to Nickel's food.