This is a hard no for canine diets.
Quick call
No. Onions can cause oxidative damage to red blood cells and serious anemia.
What matters most
Avoid raw, cooked, powdered, and dehydrated onion in all forms.
When to call your vet
If your dog has vomiting, diarrhea, unusual fatigue, or belly pain after eating onions, call your vet the same day.
Urgent: If your dog already ate this food, call your veterinarian or ASPCA Animal Poison Control (888-426-4435) now.
Source check: ASPCA identifies onion as toxic to dogs in any form. Source