Newborns (wet and more readily chilled) and sick calves are most vulnerable to freezing, according to Katharina Lohmann, Western College of Veterinary Medicine, Saskatoon, Saskatchewan.
Adult cattle sometimes suffer frostbitten ears, scrotums or teats in severely cold weather if they have no windbreaks or if they get wet and then temperatures plummet.
Sick or dehydrated animals with compromised circulation are at risk for frostbite due to poor blood supply to extremities. “Any animal with severe diarrhea, for instance, is more vulnerable to freezing ears, tail and feet. Frostbite kills tissues when ice crystals form inside the cell membranes and the cells rupture,” she says.
If it’s just the superficial skin layers, those outer layers may slough away (like a superficial burn), but the skin eventually heals if deeper tissues are still alive. Damage to deeper layers and small blood vessels leads to more extensive tissue death. Frozen tissue generally sloughs away and can only heal by scarring if there is no viable skin left.
Frozen tissue treatment
Regarding treatment, there’s not much you can do once tissue cells actually die. If you suspect frostbite, and it’s not too severe, treatment is aimed at warming the calf. “We sometimes see calves that people bring in because legs and ears are swollen. We suspect they had frostbite that didn’t quite kill the tissues,” says Lohmann. As blood returns to those areas, it creates edema, redness and inflammation.
There may be subcutaneous hemorrhage due to damaged tissues. “A study of frostbite injuries in calves (1982-1991), published in the Canadian Veterinary Journal in 1993, with reference to other studies, stated that edema after frostbite injury seems to result from changes in vascular permeability and impairment of fluid movement from the tissues. There seems to be direct injury to blood vessels during freezing,” Lohmann says.
Affected areas can be checked for sensation (response to touch) to see if tissues are still alive and for blood supply. “Often we check the feet for sensation at the coronary band, sometimes sticking it with needles to see if it bleeds and whether the calf feels it. If it doesn’t, that’s usually an indication the tissue is dead. If they do feel it, the best treatment is getting them warm and keeping them inside, out of the cold, until the swelling has resolved,” she says.
Steve Hendrick (Coaldale Veterinarians in Coaldale, Alberta) says during cold weather, calving cows need windbreaks and lots of bedding to help keep a newborn calf from freezing as mom licks it dry. “If you find a calf that’s already chilled, taking it inside is imperative. The fastest way to warm a cold calf is with warm (not hot) water, initially. This direct contact is quicker than warm air. A hot box is great – a small heated area where you can put a chilled calf – but works best for mild cases when a newborn is simply chilled and needs to dry out,” says Hendrick.
A calf that is already freezing, however, presents more of an emergency. “Warm water will be quicker, whether it’s the bathtub or some other method,” he says.
Warming the calf
Dr. John Campbell, head of the Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, says a digital thermometer is a great tool when calving in cold weather. “These are a better indicator of body temperature than just feeling inside the calf’s mouth. If his temperature is about 100 degrees, you still might need to worry about ears freezing, but he’s not at risk for severe cold stress,” Campbell says.
“If his temperature is between 95 and 100, this is borderline hypothermia. If the temperature is less than 95, you’ve got to quickly warm that calf. For the ones between 95 and 100 degrees, you can probably put them in a warm room, a hot box, the cab of your truck – anyplace warm – and tube them with warm colostrum, and they will be fine.” The warm colostrum helps warm them from the inside, and high fat content provides energy to create body heat. You don’t want the colostrum too hot, but it should be cow body temperature.
“If the calf’s temperature is much below 95, the hot box or warm room won’t help enough, especially if he’s already dry. Hair coat works as insulation. I’ve put some of these calves (with temperatures of 80 degrees or less) in a hot box and left them there for hours, and they don’t warm up much. Their interior body temperature is so cold that a hot box won’t help as much as you’d expect,” he explains.
“The advantage of a hot box is: Calves are breathing warm air. The lung is actually their biggest body surface, so circulating warm air in a hot box is helpful. But the most success I’ve had with really cold calves is a warm-water bath. The only way I’ve been able to save some is to tube them with warm colostrum and put them in a laundry tub with water temperature close to body temperature – about 100 degrees, feeling warm to your touch,” says Campbell.
It takes some effort to warm them, changing water frequently. “You’ve put this giant ice cube in the water, and it cools quickly. Water must be warmer than the calf, so you have to keep changing it. Someone needs to be there in case the calf can’t hold its head up; you don’t want to drown the calf. A big laundry tub works nicely because you can fold the calf in there with his head upright,” he explains.
“If you find a near-frozen calf, don’t overdo it with too much heat at once,” says Lohmann. “Rapid thaw at moderate temperatures (100 to 105 degrees Fahrenheit) is best. We generally use hot water bottles and heat lamps and closely monitor rectal temperature so the calf doesn’t overheat – which could be harmful,” she explains. Getting damaged skin too hot can add to frostbite damage. Don’t rub frostbitten areas too vigorously (trying to help restore circulation), as this may further damage compromised skin tissues. Gentle massage with warm wet towels may be more beneficial.
Warming an animal too much or too quickly, such as putting a very cold calf into hot water (such as a hot tub), may cause heat injury and may be life threatening in cases of severe hypothermia, according to Lohmann. In a cold animal, blood is shunted away from extremities and into the body core to try to keep internal organs warm enough to keep functioning. If you suddenly put the cold animal in hot water, this can drive cold from body surfaces into the body core.
If the heart is chilled too much (cold shock), it stops, and the calf will suddenly die. It’s better to start with lukewarm water, then gradually warm it to body temperature (101 degrees). Humans whose temperature is drastically lowered for surgery are always brought back to normal temperature slowly.
A good way to warm a severely cold calf is to use warm IV fluids, warm colostrum tubed into the stomach and warm air (to warm the air it’s breathing). You need to warm the innermost part of the body as swiftly as you warm the outside.
You don’t want frozen feet, ears, and tails. Hendrick says even after you’ve thawed and dried the calf and it’s back with mom, watch for any swelling, lameness, etc. Calves with frozen feet may not be able to function.
“How quickly a calf’s feet might freeze depends on temperature. If it’s down to minus 30 or lower, they can freeze fairly quickly, especially if there’s wind,” he says. If a calf gets too cold before it nurses, the calf gets even colder. Colostrum contains twice the fat of regular milk and provides energy to keep warm. You need to get colostrum into a calf fast if it’s already cold, says Hendrick.
“If calves are dry and had adequate colostrum, they can handle cold weather. Some people use calf earmuffs to keep ears from freezing. No one wants frozen ears; those calves get docked in the market without good reason. The best way to avoid this is to get them dry immediately.” 
PHOTO 1: This calf was born at minus 25ºF in February and lost her ears in spite of careful thawing. She was also very lame with swollen feet, but they recovered.
PHOTO 2: The same calf, 3 months old with the ears gone.
PHOTO 3 & 4: These women are warming and thawing a calf with warm water and a hair dryer, with extra attention on the extremities.
PHOTO 5: The cold calf then receives warm colostrum via a nasogastric tube. Photos by Heather Thomas.
Heather Thomas is a freelance writer based in Idaho.
