Frostbite
Dogs who get cold have a risk of getting frostbite, especially when they've been trapped in the snow or exposed to very cold winds.
Frostbite occurs when the body diverts blood from the face, ears, and limbs and routes it to the abdomen in an attempt to keep the organs warms. The shift in circulation can save a pet's life, but it leaves the extremities unprotected from the cold. Water in the body's cells freeze and expand, causing cells to rupture. Frostbite usually occurs in the extremities such as the ear tips, tail and toes. Parts away from the center of the body get less blood, which causes them to freeze more easily.
The skin on frostbitten areas will be discolored- it's usually pale, white, blue or gray and will be extremely cold to the touch. It may become very red after thawing if the blood vessels in the area have not been badly damaged.
Frostbite can be hard to recognize because the characteristic pale white, gray or blue color of frozen skin may be invisible beneath the pet's fur. Pets with frostbitten toes will often limp, and frozen ear tips will often droop. The affected skin will be hard and nonpliable, and it will be extremely cold. Days afterward, there may be redness, blisters, and possibly a serious infection.
Male dogs, including those who have been neutered, often suffer frostbite on the thin skin of the scrotum because it's exposed to cold even when they sit or lie down.
Pets with frostbite always need immediate vet care, although they'll often recover when the frozen areas are warmed gradually. Keep in mind that pets with frostbite tend to have hypothermia as well.