Cows and people might have more in common than it seems when it comes to weather changes and temperature extremes causing sickness.

"Any kind of stress you put animals or humans under can affect their immune system," said Dave Griswold, extension veterinarian and field investigator in the department of veterinary science.

"Weather changes probably make animals sick for the same reasons they make people sick."

The comfort zone for dairy cows is between 45 and 75 degrees Fahrenheit. Temperatures outside of this zone could cause sickness, mainly in the form of respiratory infections and mastitis, a bacterial infection in the udder.

"Dairy cows will experience lower milk production at high temperatures," said Michael O'Connor, professor of animal science. "At high humidity, they can have as much as a 10 percent reduction in milk production."

The low milk production is due to a depression in feed intake that occurs when animals are stressed due to weather extremes.

"Most farm animals can tolerate low temperatures," O'Connor said. "However, severe wind chills can cause frostbite because teats (projections of the udders) are exposed after milking."

Thick hides, hair, wool or a layer of fat on the body can protect animals from these winds. Farmers or dairy producers can also provide wind breaks for their animals in the form of a line of trees where animals can congregate or a fence is built as a wall for animals to seek shelter. In addition, animals can seek shelter in barns.

"In damp, drafty conditions, even in the comfort zone, animals can succumb to respiratory diseases just like humans," O'Connor said.

Both O'Connor and Griswold agree that heat is a worse cause of stress than cold. In Pennsylvania, specifically, dairy farmers are more concerned with hot weather extremes.

"You're not going to get the perfect environment for animals. We don't have the extremes for long periods of time of hot and cold weather," O'Connor said. "(State College) is a good place to raise livestock."

Griswold agreed.

"We're somewhere in the middle, we have our good and bad weather — if you average it out, we probably have more good where animals are concerned," he said.

Vaccinations can be given to the animals to provide some defense against diseases. However, as O'Connor pointed out, just because animals or humans are vaccinated, it doesn't mean they are 100 percent protected.

Respiratory infections start as viral infections that will make animals sick, but won't kill them, Griswold said. If they have bacteria in their system, the respiratory infection will break down their immune system and the bacteria can get into their tissues. This can result in bacterial pneumonia, which can be lethal.

If an animal does become ill, they are first moved away from the environment that induced the sickness and isolated from the other members of the herd so as not to spread the disease. They are then administered antibiotics and electrolytes, if the animal is dehydrated. Often these antibiotics are the same for animals and humans.

"A lot of the antibiotics are similar, except in price," Griswold said. "If you walk on two feet, you'll pay a lot more."

There is some controversy surrounding the use of the same drugs in both veterinary and human medicine. Some people in the human medicine community think the use of human antibiotics in food animals can lead to antibiotic resistance.

"It's an on-going battle," Griswold said.