No. Custard is not safe for dogs, as it's high in sugar, fats, and lactose which can host numerous health issues in dogs, such as dental and gastric issues. Some custard brands also contain xylitol, a sweetener that is extremely poisonous to canines.
Risks
Custard is a mix of cream, sugar, salt, eggs, and flavoring, which are too much for a dog’s stomach to handle. Allowing dogs to eat custard makes digestive upset inevitable.
Since custard is loaded with sugar and fats, dental problems and obesity may occur if eaten regularly or in large quantities.
Some brands use xylitol as a sweetener and chocolate as a flavoring. Both are extremely poisonous to dogs.
Custard typically contains high levels of lactose. Stomach problems, along with other side effects, may occur if a lactose-intolerant dog consumes custard.