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Viral Diseases In White-tail Deer
by James L. Cummins
Not all species have fur or scales, or are even visible to the naked eye. In this “Species Profile” we will look at the smallest of species, the virus, specifically those that occur in white-tail deer.
White-tail deer live for an average of 8 years. However, many do not live beyond 4 or 5 years of age. Although hunting is a major cause of mortality in managed deer populations, other forces cause mortality. Some of these include nutrition, predation and diseases. Here we will discuss the viral disease component of the mortality equation.
Many infectious diseases affect white-tail deer. In deer management programs, the presence and impacts of diseases must be significantly considered. The most common means of deer diseases are protozoa, bacteria and viruses. Here, we will discuss the highly fatal epizootic hemorrhagic disease (EHD), or blue tongue, as it is commonly called.
About 2 years ago I received a call from a friend of mine, Martin Walker, who hunts near Panther Burn; it is located approximately 30 miles southeast of Greenville. He had shot a seven-point with approximately a 15-inch spread. This gentleman normally shoots deer with larger antlers; however, this one was running with a limp. After approaching the animal, there were no signs of the deer being wounded. After bringing the deer to his farm shop, where I joined him, we noticed that there was much hair from the under side of the chest cavity missing. His hooves showed no signs of sloughing, although there was hemorrhaging in the lower intestines. These were sure signs of EHD.
EHD was first reported in 1955 in New Jersey where approximately 700 deer died. Since that outbreak, others have occurred throughout the United States in varying intensities. In 1971 scattered outbreaks of EHD occurred throughout the Southeast. In 1976, an EHD outbreak killed several thousand white-tail deer in Kansas, Nebraska, North Dakota, South Dakota and Wyoming. Although white-tail deer are the major species that are impacted by EHD, antelope, mule deer and pronghorn are also affected.
EHD usually occurs from late summer to early fall. It is transmitted through blood-sucking gnats. One characteristic of this disease is its sudden attack. White-tail deer that are infected initially loose their fear of humans. Next, they loose their appetite and, of course, grow weaker. They also salivate much more than normal and show signs of fever (136 degrees Fahrenheit). Their heart rate increases, as well as breathing, before the animal is finally comatose.
As evidenced by another buck I observed this past January, signs of EHD are characterized by extensive hemorrhaging of organs and tissues. Often, as a result, the feces, urine and saliva will contain blood. Although all organs are susceptible to hemorrhaging, those organs that are affected most often are the heart, liver, spleen, lungs, and as we have indicated, the intestines.
Other viral diseases include skin tumors. If you spend much time in pursuit of the white-tail deer, you will probably come in contact with a skin tumor, which are often called warts or fibromas. Tumors can be found on any part of the body. The carrier can be other deer, insects or even contaminated foliage. There are no threats to humans from these tumors.
Arboviruses are another form of viral infections in white-tail deer. One of the most common arboviruses in Mississippi is viral encephalitis. Arthropods carry this disease and can infect almost any vertebrate.
The exotic foot and mouth disease was discovered in the United States in 1924. In California, where it was found, over 22,000 deer and many livestock were exterminated. This extermination program successfully eliminated the disease from the United States. However, should it reoccur, it could have serious implications on our white-tail deer herd.
Other viral diseases, such as rabies, have been found in white-tail deer populations
in the United States; however, have not caused significant problems to populations.
James L. Cummins, a fisheries/wildlife biologist by training, is Executive Director of the Mississippi Fish and Wildlife Foundation.