Whitetail Deer Diseases

It’s an accepted fact that animals are, statistically speaking, highly susceptible to illnesses, both bacterial and viral.  Animals aren’t capable of thinking in terms of “prevention” and are generally at the whim of instinct when deciding what to ingest and what not to.  Complex ecosystems create myriad avenues for infection, and animals only lines of defense against this persistent onslaught are genetics and developed immunity.  In this article we’ll take a look at some common whitetail deer diseases and how they affect not only herds in the wild, but in captivity as well.

Contraction of whitetail deer diseases can be caused by anything from a bite from an infected insect, eating forbs or other foodstuffs contaminated by infected insects (usually larva), or just coming in contact with other groups of animals, domesticated or otherwise, such as goats, sheep, or cattle. While many whitetail deer diseases are severe and highly lethal, outbreaks or epidemics on a large scale are rare.  This is due to deer being basically “homebodies.”  Whitetails may travel up to three miles in any given direction but usually stay within the same area for most of their life.  This means that outbreaks are usually contained at the regional level and never spread very far beyond areas of initial infection.

One of the most common types of whitetail deer diseases is infection from parasites.  Parasites are quite resourceful when it comes to finding host bodies and can make their way into a deer’s system by simply being stepped on and working their way in.  Parasitic infections like roundword, foot worm, brain worm and tapeworm are common among whitetails.  Their effects can vary from completely benign to rapidly lethal, the worst of which seems to be tapeworm which is most common in areas of dense whitetail populations and can cause horrific fatalities in as few as two days.

Although there have been no reported cases in Texas, Chronic Wasting Disease (CWD) is probably one of the highest profile whitetail deer diseases.  CWD is a neurological affliction very similar to “mad cow disease,” attacking the brain and nervous system of its carrier with fatal results.  At this point, very little is known about CWD and how it is contracted, although physical contact and proximity are viewed as two of the most common contributing factors the spread of the disease.  There is no known cure for CWD and outbreaks of this kind are potentially devastating to both native and captive herds and are therefore highly regulated against.

Other common whitetail deer diseases are Hemorrhagic afflictions such as Blue Tongue (BT) and Epizootic Hemorrhagic Disease (EHD).  These are contracted and spread through insect gnat and are violently brutal in lethality.  EHD is endemic to Texas.  Deer which survive such ailments become immune and may spread their immunity to offspring.  Those that cannot overcome the disease are subjected to massive internal hemorrhaging before death. 

Since the gnat which spreads EHD is not native to northern states, northern deer are not immune to the disease. Therefore, having more than 25% of northern genetics in a deer substantially reduces the animal’s ability to fight off the disease. Although a number of EHD vaccines are currently in development and live testing, EHD continues to be a major killer of native and captive whitetail deer herds in Texas.

Yet another of the most lethal of whitetail deer diseases is Malignant Catarrhal Fever (MCF), a nasty viral infection that attacks the deer’s central nervous system and induces a cringe-worthy number of horrible symptoms and side effects before eventually carrying out its lethal mission.  Scientists know almost nothing about MCF as contraction and spread of the disease has been found to happen not only in dense herds but also in solitary, isolated deer with almost zero exposure to others.  MCF is not guaranteed fatal, but those deer that survive will forever be a host to the disease and are therefore a risk to healthy herds as well as any offspring that deer may produce.