Dogs can eat celery in moderation as a low-calorie snack. While celery is generally safe for dogs to eat, consuming large amounts can lead to vomiting and diarrhea. In small portions, celery provides dogs a crunchy vegetable that is safe as part of a balanced diet.

1. CAN DOGS EAT CELERY
Vegetables are great for us, but what about our loved dogs? Dogs
can safely eat some vegetables, including broccoli and cabbage,
but what about celery? Can dogs eat celery? Celery is a crunchy
vegetable that could be fed to dogs as a low-calorie snack. In
moderation celery is safe for dogs, however, consumption in huge
amounts can cause vomiting and diarrhea.
https://thedogcare.org/can-dogs-eat-celery/