Frostbite is an injury to skin and underlying tissues caused by freezing, often in windy and damp conditions. The skin becomes very cold and red, then numb, hard and pale. In people, it most commonly affects our extremities: fingers, toes, nose, ears, cheeks and chin. Unlike people, chickens can’t wear winter apparel like hats and boots so their exposed combs, wattles, fleshy parts of the face, legs and feet are vulnerable.
How It Works
In conditions of prolonged cold exposure, the body signals blood vessels in the extremities (the areas farthest from the heart) to narrow. Slowing blood flow to the skin means more blood is sent to the vital organs, supplying them with critical nutrients and oxygen. It also prevents a further decrease in internal body temperature by exposing less blood to the outside cold.
As the extremities become colder, blood vessels are dilated (widened), then constricted again. This process of rotating constriction and dilation allows the extremities to function for as long as possible. When the body is threatened by hypothermia (in chickens: when their temperature drops significantly below 41c/105f), the blood vessels permanently constrict in order to prevent them from returning cold blood to the internal organs. That signals the beginning of frostbite.
In the first stage, ice crystals form around the outside of cell walls. Water is lost from the cell’s interior and dehydration causes cell death.
Upon rewarming, the blood flows through veins also injured by the cold. Holes appear in vessel walls and blood leaks out into the tissues. Blood flow is impeded and small clots form in the tiny vessels of the extremities. Complications due to issues with blood flow create inflammation and further tissue damage.
Cell death happens both at the time of exposure and later due to a lack of oxygen.
Stages of Frostbite
- Frostnip: is the mildest form of frostbite which can be treated by warming the skin. Frostnip left unchecked will result in superficial frostbite, which, if reversed, will likely result in painful fluid blisters, but a full recovery in the chicken is probable.
- Superficial frostbite: appears as reddened skin that turns white or pale. If skin is rewarmed at this stage, the surface of may appear mottled. Fluid-filled blisters may appear 12 to 36 hours later.
- Deep frostbite: affects all layers of the skin, including deeper tissues that lie below the surface. They may turn white or bluish gray and be accompanied by numbness and loss of sensation of cold, pain or discomfort in the affected area. Joints or muscles may no longer work. Large blisters form 24 to 48 hours after rewarming. Afterward, the area turns black and hard as the tissue dies.
I’m not sure why some folks think that chickens ‘don’t feel pain’ like mammals. Of course they do, but as prey animals they have evolved the ability to hide it and appear stoical. These are the symptoms of frostbite in people, and I have no doubt that it affects birds similarly: prickling, numbness, blisters, joint and muscle stiffness.
Long term damage includes: increased susceptibility to the cold, decreased circulation, nerve damage, arthritis, changes to wattle and comb colour, loss of comb, toes and feet.
- Have a well-stocked first aid kit with antiseptics and pain medications.
- The affected areas should be warmed slowly. Don’t use direct heat (i.e. a hair dryer).
- Lay a warm washcloth against the area, without rubbing or massaging.
- Feet can be soaked in 40-42c/104-108f water for 20 minutes to rewarm, then daily in warm water with a Chlorhexadine 2% solution.
- Put the patient in a dog crate in a warm area with soft bedding, like a towel, while they are recuperating. It’s important that they aren’t exposed to the cold again until they have healed. Thawing and refreezing of exposed tissues will cause further damage.
- If feet are involved wrap them and restrict the bird’s movements to avoid pain and to promote healing.
- Monitor the damaged areas for infection: swelling, increased redness, discharge from the wound, or unpleasant odour.
- They may require antibiotics or medications (i.e. Metacam) for pain and inflammation.
- Ensure your bird is eating and drinking normally.
- Clean the affected areas daily with Chlorhexadine 2% solution.
- If blisters appear, leave them alone. Breaking the blisters exposes the area to infection.
- In extreme frostbite situations, it’s possible that major portions of the combs or feet will freeze. In that case, there isn’t much that you can do to save the tissue, which may take three to six weeks to fall off.
- Don’t trim the blackened area unless it becomes infected because it serves to protect the remaining comb.
- If possible, keep the patient separated from the flock so they don’t peck at frostbitten areas.
- Certain traits make some birds more vulnerable to cold: large combs and wattles, feathered feet, Naked Necks, Silkies, frizzles and bantams.
- Coop design is paramount. Frostbite can occur at any time, but often happens at night when temperatures dip and chickens are confined to the coop creating condensation and moisture. If you can see water droplets on your ceiling or inside your windows you need more ventilation.
- Roost bars should be wide enough that their breast can cover their feet.
- Make sure gaps are sealed and windows are placed to avoid drafts.
- I live in an area with a mild climate, but my coop is still insulated and has good ventilation (opening windows, roofline vents).
- I keep my water containers outside. If yours are in the coop ensure there is no spillage which would contribute to additional moisture inside.
- Add lots of extra bedding in the coop and nest boxes and clean regularly to avoid excess moisture and ammonia build up. Some people use the deep litter method which generates some heat as the litter is composting.
- Extreme cold can be reduced by using a supplementary heat source, but not a heat lamp, which can be fire hazards. I hesitate to recommend the use of heaters because chickens can become dependent on them and are more vulnerable when they are outside or if there is a power outage.
- Monitor your birds if it rains, then freezes.
- Shovel paths from the coop door around the run or outside to prevent your flock from having to contend with deep snow.
- For mild freezing, petroleum jelly helps, but is not recommended for hard frosts because it’s an occlusive moisturizer. As it absorbs, moisture sits on the skin, actually increasing frostbite risk.
- For temperatures between -10c/15°f and 0c/32°f, a product that contains wax and/or lanolin, like Musher’s Secret or Bag Balm, can help create a breathable barrier while protecting the skin. Reapply throughout the day. In temperatures below -10c/15°f most products are vulnerable to freezing themselves.
Credits: Dr Jacquie Jacob; Mayo Clinic, Poultry DVM. Featured Image: Meyer Hatchery