Rabies

This is an article that was found in the June issue of the Angus Journal. The article is by Troy Smith.

Who didn’t cry when Old Yeller died? Come on. Surely you shared the sorrow when the classic Disney film’s canine hero met his fate. You remember how Old Yeller defended the family against a wolf gone mad with rabies. Then he was locked in a corn crib until they could be sure he hadn’t contracted the disease. And just as the quarantine was about to end; just when we thought he was in the clear, the symptoms appeared. Snarling and frothing at the mouth, the dog turned on his young master. Dangerous, suffering and doomed to die a painful death, Old Yeller had to be destroyed.
The movie was set on the western frontier, in the 19th century, when rabies was a fearsome disease. It was sometimes called “hydrophobia” because victims often seemed to display a fear or aversion to water along with other symptoms of strange, often aggressive behavior. Folks didn’t fully understand the mechanisms of microbial infections in those days, but they knew that rabies could be spread through the bite of an infected animal. They knew it could be transmitted from wild critters to domestic livestock. Old Yeller’s fans will remember how the family’s cantankerous milk cow also succumbed to rabies. Folks also knew that humans were susceptible and contracting rabies meant you were going to die.
Even today, the same reasons make rabies a threat to livestock and their caretakers. Rabies is a zoonotic disease – one caused by an infectious agent that is transmittable between animals and humans. In the case of rabies, the infectious agent is a virus to which virtually all mammals are susceptible. Though exposure to humans is reduced through widespread vaccination of pet dogs and cats, rabies remains common among wild animals – particularly flesh-eating species. According to Angela Dement, Texas A&M University (TAMU) Extension Assistant for Veterinary Medicine, skunks, raccoons, coyotes and bats rank among the most common carrier species.
Dement says the threat of infection to domestic animals and humans is sufficient to warrant an effort, by TAMU extension personnel, to heighten awareness among livestock producers. In addition to foreign and emerging animal diseases, rabies has been added to the agendas for county meetings held across the state.
“Awareness is the best defense,” states Dement, “so our goal to educate producers about the disease and how to recognize the different behaviors associated with rabies.”
Not all animals afflicted with rabies exhibit the “slobbering fits” described in the Old Yeller movie. Dement says the virus always attacks the central nervous system, but symptomatic behavior may be either of two different types. That which most people consider typical is “furious rabies” where the animal displays restless, but aimless behavior and becomes aggressive, sometimes to the point that it will bite anything that happens to be in its way. Even gentle family pets, if infected, can become vicious.
However, an animal with rabies may never show aggression or become violent. With the other type of behavior, sometimes called “dumb rabies”, the affected animal becomes withdrawn and shy. In any case, rabid animals suffer progressive paralysis. Early signs may include difficulty swallowing. Eventually, even though they are hungry and thirsty, animals are unable to eat or drink - hence the perceived fear of water. After the onset of symptoms, the disease is always fatal.
According to Dement, the virus is present in the saliva of an infected animal. If it bites another animal, or a human, the virus may spread through the wound. However, the virus may also spread when virus-laden saliva comes in contact with scratches or breaks in the skin due to another type of injury. The incubation period for rabies varies by specie, and ranges from 3 to 8 weeks in humans.
“Treatment is available for humans that may be exposed through contact with animals suspected of having rabies. But the only way to be sure if the animal really was infected is to test tissue from its brain. So, while a suspect animal should be destroyed, don’t shoot it in the head,” warns Dement. “If you think you may have been exposed, quickly seek advice from your primary care physician.”
Dement says cases where humans were exposed to rabies through contact with infected cattle or other domestic livestock have been rare in Texas, but it can and does happen. In June, officials with the South Carolina Department of Health and Environmental Control reported that two men were undergoing post-exposure treatment after handling a calf that later tested positive for rabies. The men apparently came in contact with its saliva while assisting the calf found staggering around in a field. Reportedly, the calf was one of a handful of domestic livestock, in South Carolina, that tested positive during the last 20 years.
However, according to Veterinarian W. Dee Whittier, of Virginia-Maryland Regional College of Veterinary Medicine, the incidence of rabies among cattle varies by region. The opportunity for exposure increases with prevalence of rabies among wild animal carriers. In Virginia, says the bovine specialist, cattle often are the most frequently diagnosed domestic animal.
“Due to their curious nature, cattle will approach an infected wild animal, like a skunk or raccoon, and be bitten on the nose, or feet and legs,” Whittier explains.
In cattle, rabies symptoms can include restlessness, aggression, repeated bellowing and slobbering, or cattle may act depressed or sleepy. They may show weakness, particularly in their hind legs, and appear to be choking.
“Any animal with symptoms of a neurological disease ought to be investigated until and answer is found,” warns Whittier. “And producers ought not to be poking their hands in the mouths of animals to see if something is stuck in their throats. Producers and veterinarians put themselves at risk of infection when conducting oral examinations of salivating cattle.”