Is it normal that when my dog was put to sleep she yelped and whined ?

[Chloe D]

I took my dog twist to the vets to be put asleep she was 15 and could not walk,eat or do normal things . I have had dogs put down before and everything was normal but this time twist yelped like she was in pain the vet said it was a rare reaction but i still feel unsure . Has anyone else had this expierience if so please let me no and why thank you xxoo