Dollar Tree

I went in to grab a shower curtain this afternoon. Something that should have taken a couple minutes at best, instead it took almost 20 minutes. I was standing in line to check out almost the entire time I was inside the store. Only one cashier was open for the first 7 minutes I was waiting (I had somewhere to be and time was a factor for me). Finally a second cashier was called and a new lane opened. I stayed in my line though as I was towards the back. In front of me was an older gentleman on a mobility scooter with a small dog. He finally reached the front of the line and apparently he knew the cashier. Even though the cashier was well aware of the lines, and I had been waiting over 16 minutes at that point, the cashier walked from behind the counter and proceeded to greet and play with the dog. The cashier continued to show love and affection to the dog (dog's name is Abby, she's only 7 months old, and she's a future support animal, all information I acquired while the cashier played with this dog), until I said "ma'am, some of us have places to be." At which the people behind me agreed vocally. The cashier was then hostile and rude to me as it was finally my turn to checkout.
I don't feel asking her to do her job deserves such hostility, and if she wants to play with dogs, she shouldn't be doing it on my time.