Conservation For You

By: G.R. Miller     Missouri Department of Conservation

White-tailed deer are susceptible to a variety of diseases, parasites and injuries. Although these conditions do not account for a large percentage of annual statewide deer mortality (typically less than 5 percent), in some situations disease or parasite outbreaks can impact a deer herd locally or regionally.

Infectious diseases of deer can be caused by pathogens that include viruses, bacteria, parasites and abnormal proteins known as prions. In rare instances, these pathogens are the cause of disease epidemics that result in significant mortality in a local population. These outbreaks are most common in herds with high deer density, which can increase the spread of the disease.

One such disease that is of concern with the drought conditions this year is Hemorrhagic disease (HD). HD is an infectious disease of white-tailed deer, with outbreaks occurring sporadically in Missouri. HD includes both epizootic hemorrhagic disease (EHD) and bluetongue viruses (BTV). These diseases are very closely related and produce similar symptoms in deer. Domestic ruminants such as cattle and goats show no signs of illness or only mild signs when infected. In contrast, domestic sheep may develop severe illness when infected with BTV.

HD is transmitted by biting midge flies, thus the disease outbreaks tend to occur from August to October, when midge flies are most abundant. The disease may go unnoticed in the wild because deer carcasses quickly decompose and are consumed by scavengers. Some infected deer may not show obvious symptoms; others may die in one to three days. Typical signs include fever; excessive salivation; swollen neck, tongue or eyelids; sloughed or interrupted growth of hooves; reduced activity; and emaciation (significant weight loss). Because sick deer are feverish, they are often found near water.

Incidence of the disease has ranged from a few scattered mild cases to dramatic outbreaks. Mortality rates during these outbreaks are usually below 20 percent; however, losses of up to 50 percent have been documented. Scotland County experienced HD in the summer of 2007, but very few deer were reported. As stated earlier, with the drought conditions and extreme heat white-tailed deer will congregate around water which could in turn increase the spread of this devastating disease. If you find a dead deer and the cause of death is not apparent, please report it to the Missouri Department of Conservation at (660) 785-2420. (Portions of this article were taken from a jointly composed deer conservation guide developed by MU Extension and the Missouri Department of Conservation).