What is a brain-freeze?

A cold-stimulus headache, colloquially known as an ice-cream headache or brain freeze, is a form of brief pain or headache commonly associated with consumption of cold beverages or foods such as ice cream and ice pops. It is caused by having something cold touch the roof of the mouth, and is believed to result from a nerve response causing rapid constriction and swelling of blood vessels or a "referring" of pain from the roof of the mouth to the head. The rate of intake for cold foods has been studied as a contributing factor. A cold-stimulus headache is distinct from dentin hypersensitivity, a type of dental pain that can occur under similar circumstances.

Explanation:

Googled it

if you think your dog may have been exposed to a toxin, the best thing to do is to check the label of the item you think your pet ingested. read the information about toxicity. often, but not always, the information on packaging regarding children is relevant to dogs and some manufacturers even discuss dog toxicity. if there is an 800 number on the package – call them! it’s also recommended that you call your veterinarian to confirm the recommendations. if you go to your veterinarian, take all packaging and any information you have on the product.

answer apply a dressing and apply pressure,then get to the hospital;