Rabies in horses and cattle become a concern during summer months
This may be a bad year for rabies, according to experts. By mid-May, two dogs tested positive for rabies in northeastern Colorado – the first cases among dogs in Colorado since 2003.
In addition, there were 41 confirmed cases of rabies in wild animals, mainly skunks, in Colorado so far this year. The number of unconfirmed cases of rabies in wildlife is always many times greater than the number of confirmed cases.
Rabies can occur in all warm-blooded animals and is almost always fatal. It is caused by a virus that affects the nervous system, transmitted by saliva of an infected animal, usually via a bite or by saliva coming into contact with mucous membranes, such as the eye, or an opening in the skin.
Rabies is uncommon in horses and cattle, but there are always a few years when wildlife cases increase, because there is more chance to be bitten by a rabid animal.
Once signs of rabies appear, the animal has trouble eating or drinking because it can’t swallow. Infected animals drool because they are unable to swallow their saliva.
Colorado rancher Kit Pharo has seen an unusually high number of skunks this spring wandering around in the daytime. In mid-May, his son Tyson brought home a two-year-old heifer that was acting sick.
“She had been standing at the water tank with her head down while all the other cows and heifers were out grazing. When he unloaded the heifer, she was on the fight,” says Pharo.
“We suspected rabies. We had a veterinarian look at her, and he suspected rabies. As instructed by the vet, Tyson gave her an antibiotic. The vet said, ‘If she lives, she lives. If she dies, we’ll send her brain to the lab,’” Pharo describes.
On May 20, the sick heifer calved. The calf was up nursing the next morning, but the heifer was not eating or drinking. She charged the fence when anyone looked at her.
He continues, “Later that day, I pulled the calf under the fence and started bottle feeding it.”
Six days after bringing the heifer home, she died.
“We removed her brain and sent it to a lab,” he says. “We will know soon if she had rabies.”
John Wenzel, a veterinarian in New Mexico, says rabies is always lurking in a few “reservoir” animals, but some years there’s an increase in cases.
“In my practice in southwestern New Mexico a few years ago, we had a tremendous increase in rabies in gray foxes. The gray fox strain seems to make affected animals more aggressive than what we normally see. These foxes were coming into town, chasing people and being hit by cars,” says Wenzel.
Any horse or livestock showing neurological signs or abnormal behavior should be considered a possible rabies case, Wenzel says.
Rabid cattle may look like they are choking, because they can’t swallow or may seem blind or depressed. Initial signs of rabies in a horse may be abdominal pain and colic, excessive drooling or lameness.
If producers suspect rabies, Wenzel notes that they should wear heavy gloves and eye protection to prevent exposure during treatment or handling. These barrier protections can help keep saliva from getting on open areas of skin or eyes.
“Also keep a record of people who have been in contact with the animal and the dates of contact,” he says.
Rabies can be transmitted from a rabid animal to a human via saliva. The typical route is through a bite.
“Horses and cattle rarely bite, but if saliva enters through a break in the skin, producers are at risk,” Wenzel describes. “If the horse or cow struggles when the producer is trying to tube them – as may happen if the problem is mistaken for choke or colic – the animal may be throwing its head and slinging saliva onto the face or skin.”
There is also a risk of being bitten when trying to examine the mouth.
Wenzel notes that, for every horse or cow with rabies, there are usually several people who get exposed and need to undergo post-exposure treatment.
Hard to recognize
Signs of rabies in horses or cattle are often vague.
“When I was at Kansas State University going to veterinary school, we had 10 cases of horse rabies while I was there,” says Wenzel.
Eight of them were brought in because of lameness, he notes, adding that producers should protect themselves when examining animals.
Drought – with wild animals moving around more in attempts to find food and water and coming into closer contact with livestock and humans – often results in higher numbers of cases in cattle.
Signs and symptoms
Cattle infected with rabies may be dull and lethargic or nervous and aggressive. Rabies may be mistaken for choke, wooden tongue or respiratory disease. Sometimes the animal simply can’t eat or drink.
Rabid animals generally seek water because they are thirsty and unable to swallow. Cattle or horses often stick their muzzle in the water, trying to drink, but can’t.
“Livestock owners need to monitor their animals. Any time they act different, think about rabies. We’ve had several reports of people being chased by cows when they’ve gone out to feed and stocker calves out on pasture charging the horses when people go to check on them,” says James L. Alexander, regional zoonosis control veterinarian for the Texas Department of State Health Services.
Heather Smith Thomas is a correspondent for the Wyoming Livestock Roundup. Send comments on this article to firstname.lastname@example.org.