Disease, Parasites & Virus | Deer Hunting & Management

CWD in Texas?

Chronic wasting disease (CWD) is basically the “mad cow disease” of elk, mule deer and white-tailed deer. CWD is not new; the deer disease has been on the radar of state wildlife departments for decades. CWD was first diagnosed in 1967 in a captive herd of mule deer in Colorado and not long after was found naturally occurring in that state as well as Wyoming. It was not until 1996 that the deer disease was found outside of that area. It was at that time when many states started monitoring for the highly contagious CWD.

Hunters are always concerned about wildlife diseases, especially the highly infectious ones such as CWD, that impact game animals. It is also the responsibility of state and federal wildlife agencies to reduce the transmission of all wildlife diseases while attempting to learn more about the problem. Wildlife management – deer management specifically – is about taking the steps necessary to react to an ever-changing environment to reach certain objectives. One of the biggest variables for whitetail deer is food availability, but most hunters control for this factor through deer harvest, food plots and supplemental feeding.

CWD in Whitetail Deer: The Disease May be Found in Texas Soon

More variables = more unknowns. A higher number of variables makes it increasingly difficult to manage for a desired result. CWD has not shown to be the end all of whitetail populations in any area, but it is another variable that does negatively impact deer populations in areas where the disease is found. CWD can drastically reduce a local deer population, but not all animals necessarily die from the disease. In Texas, CWD monitoring has taken place for over a decade, but no positive samples have ever been found. That may be about to change.

Source: “The New Mexico Department of Game and Fish (NMDGF) has informed Texas officials that three mule deer harvested a few miles from the Texas border last hunting season have tested positive for Chronic Wasting Disease (CWD).

The deer were harvested in the Hueco Mountains, which extend into Texas northeast of El Paso in Hudspeth County. New Mexico has been monitoring annually for CWD since it was first discovered 10 years ago and this event is the closest to Texas that the disease has been detected. Texas also has had an active CWD surveillance program for the past decade, and CWD has not yet been detected in the state. However, state wildlife officials have been preparing for the possibility since 2002.

“While this finding is not a big surprise, we’re not going to ignore it,” said Mitch Lockwood, Big Game Program Director for the Texas Parks and Wildlife Department. “We are working with TPWD’s Wildlife Health Working Group to develop a more intensive strategy for sampling, and to determine the geographical extent of the disease if it is detected in Texas.”

The Wildlife Health Working Group is comprised of wildlife biologists, veterinarians and other animal-health experts from TPWD, Texas Animal Health Commission, Department of State Health Services, Texas A&M College of Veterinary Medicine, and USDA. The New Mexico Department of Game and Fish is also involved in the discussion.

While several thousand deer have been tested for CWD in Texas, wildlife officials express concern that the Trans Pecos region is underrepresented because of the very low number of deer and the relatively low deer harvest in that region. Samples are obtained from hunter-harvested deer, deer found dead on public roadways, and deer showing clinical symptoms. TPWD is determining how many more deer need to be sampled and deer hunters in the region could be asked for their assistance during the next hunting season.

“We are using disease models to determine the intensity of sampling that would be required to detect CWD in that deer population if it is present with a prevalence of at least two percent,” said Ryan Schoeneberg, Big Game Program Specialist with TPWD.

CWD was first recognized in 1967 in captive mule deer in Colorado and has also been documented in captive and/or free-ranging deer in nearly two dozen states and Canadian provinces, including New Mexico. Although fatal in deer, there is no evidence that CWD poses a risk to humans or livestock in the natural environment.

“It would be almost impossible to eradicate the disease once it becomes established in a population,” said Lockwood. “But, what we can do is manage the disease and minimize the risk of it spreading.”

CWD is a member of the group of diseases called transmissible spongiform encephalopathies (TSEs). Other diseases in this group include scrapie in sheep and goats, bovine spongiform encephalopathy (BSE or mad cow disease) in cattle, and Cruetzfeldt-Jakob disease in people. CWD is a progressive, fatal disease that affects deer, elk, moose, and other cervid species and there is no vaccine or other biological method that prevents it.”

Lumpy Jaw in White-tailed Deer

Lumpy Jaw

The white-tailed deer hunting season sneaks up on us each year. Most hunters are already in the woods looking for a big, mature buck. Hunters often see some strange things while in the woods. Have you ever seen lumpy jaw in deer? Sometimes, those odd things include deer afflicted with a variety of diseases and other internal and external physical issues.

One fairly common problem in whitetail is lumpy jaw. The name “lumpy jaw” says it all because deer with this problem stick out; The animal looks like it has a lump between (or under) its jawbone and the hide. The lumpy jaw many hunters witness is the result of adult arterial nematodes (Elaeophora schneideri). These worms live primarily in the whitetail’s carotid arteries. In fact, partial paralysis of the deer’s jaw muscles occurs when high arterial worm infestations reduce blood flow.

Whitetail Deer Management: Lumpy Jaw in Whitetail Deer

Impact of Lumpy Jaw

An overabundance of arterial worms is bad news for deer. As a result of jaw muscle paralysis, food becomes trapped inside the deer’s mouth. This food becomes impacted and leads to the lumpy jaw and/or swollen cheek appearance. Over time, the impaction often causes tooth loss, bone decay, and sometimes even death.

So now your thinking, how do white-tailed deer get lumpy jaw? Good question! The common horsefly passes the nematode larvae from an infected deer to an uninfected one by feeding on deer blood. The horsefly carrying larvae-infected blood is ultimately what perpetuates this lumpy jaw condition in deer.

Deer Management: Lumpy Jaw in Whitetail Deer

Lumpy Jaw & Deer Populations

Lumpy jaw in deer is widespread, but it poses little threat to deer populations. Luckily for property owners, hunters, and the deer, infection rates in are not high enough to impact white-tailed deer populations. Arterial worms, like most other deer issues, do not pose a risk to humans. Hunters can consume deer that exhibit lumpy jaw. Many deer have arterial worms and show no symptoms, so you’ve eaten deer with arterial worms.

However, as a hunter I don’t like to think it too much. Who wants to think about arterial worms, nasal bots, or any other of the many diseases, viruses, or things deer can possibly tote around?

Deer Management: Lumpy Jaw in Whitetail

More Lumpy Jaw in Deer?

Arterial worms are not the only game in town. Other creatures can give white-tailed deer that lumpy jaw appearance. A bacterium called Actinomyces bovis can also cause an infection of the jawbone. This bacterium is actually a common inhabitant of the mouths of healthy whitetail. It is only a problem when a sharp object such as a thorn punctures the inner lining of a deer’s mouth. This oral puncture allows A. bovis bacteria to invade the tissues.

Additionally, healthy deer — like all animals — can simply get large or odd-shaped food items caught in their mouth. However, food impaction in white-tailed deer is most often the result of arterial worms. This results in muscle issues that lead to food impaction and lumpy jaw syndrome. As mentioned, lumpy jaw in deer does not pose a health problem for hunters. The meat can be safely consumed.

Precautions for Processing Deer

Deer hunting is both challenging and fun, but common sense precautions while handling a processing white-tailed deer should be taken after each successful harvest. In fact, proper handling and cleaning techniques are as important as sound deer management practices. Many diseases affect deer in North America, including rabies, tularemia, plague, blue tongue and potentially even chronic wasting disease (CWD). CWD is a disease that affects white-tailed deer, black-tailed deer, mule deer, and elk and is fatal to infected animals.

Biologist believe a protein called a prion causes CWD in deer, and it’s this disease that most hunters are probably worried about. Prions concentrate in the brain, spinal cord, eyes, lymph nodes and spleen. Prions have not been found in meat or muscle tissue. According to the researchers, there is no evidence that chronic wasting disease can be transmitted to humans. Continue reading “Precautions for Processing Deer”

White-tailed Deer Warts

A deer hunter never expects to see giant warts or tumor-like growths on a white-tailed deer, but they do occur. Over the years I’ve seen many of photos of both live and harvested deer with “tumors,” although I’ve never seen one while in the field. The technical term for these growths is cutaneous fibroma and it’s caused by a virus. From a deer management perspective, there is not much you can do to keep wild deer from getting fibroma.

What are External Deer Tumors?

First, they are not tumors at all — they’re warts. Cutaneous fibromas are caused by a naturally occurring virus of the deer’s skin. The virus that causes these unsightly warts in deer is believed to be transmitted through biting insects and/or direct contact with damaged skin. Once the virus enters the skin, warts begin to form.

As the warts increase in size, the skin surrounding them is typically hairless and grayish in color. The number of warts on an infected animal can vary from one to several hundred, they can sometimes clump, and can in some cases end up covering much of the deer’s body.

Do Warts Bother Deer?

For the most part, these warts will not cause a white-tailed deer any major problems. However, sometimes the growth of the wart can indirectly cause problems by restricting the consumption of food or the deer’s breathing depending on where the growths are located.

Although death from fibromas in deer can occur, death from warts is not always imminent it seems. There have been many hunter testimonials of white-tailed deer with warts “shaking them off,” so to speak. In those cases, where they really the same deer? I can’t say for sure. I could see a situation where a deer with an isolated wart could recover, so to speak.

Deer Warts, Deer Hunting

From a deer hunter’s perspective warts are quite unsightly. Since fibromasts are a virus of the skin, they will be removed if the deer is skinned. Notice I said IF the deer is skinned. Although the meat of a deer is typically not affected, most hunters that harvest a deer with a large number of warts are hesitant to put the meat in the freezer.

This is understandable and probably the safest thing to do. Some research reported that a buck with external warts also had internal and cancerous fibromasts. Again, if an animal does not appear healthy then use your own, conservative discretion.

The take home message on warts is that they do occur naturally in white-tailed deer across their range. Fibromasts can occur on any deer, healthy or otherwise. With that said, these warts occur rather rarely and there is nothing that can be done from a deer management standpoint to manage against them. Deer are the only host for the virus, so fear not for yourself should you find yourself standing over an infected, wart-covered animal.

Nasal Bots in White-tailed Deer

Nasal Bots in Deer

Most deer hunters that have harvested white-tailed deer have, unfortunately, found nasal bots. Nasal bots in deer are very common. At first glance, what a hunter encounters looks like a large maggot. And, that’s basically what a nasal bot is. They live in the cavities of the deer’s nose and mouth.

Nasal bots are the larvae of a specific kind of fly that belongs in the genus Cephenemyia. Deer biologists actually find them in a percentage of whitetail deer, particularly when a thorough examination of the head is conducted. From my experience, white-tailed deer in Texas are more likely to have nasals bots than to not have them.

What’s Up, Nasal Bot?

These bots are specific to members of the deer family, which also includes elk and mule deer in the United States. Nasal bots begin life when the adult fly lays a group of eggs around the nose or mouth of a deer. Next, the small larvae within these eggs are then released when the deer licks the eggs.

White-tailed deer often have nasal bots

The warm, wet saliva creates an environment that permits the “hatching” of the immature bots. These larvae then migrate to the nasal passages and occasionally into the sinuses. While there, they molt into larger stages of the maturing larvae.

The mature larvae then move to the deep cavities in the deer’s mouth called the retropharyngeal pouches. The fully matured bots then exit and pupate in the ground until emerging as adult flies. Then, they begin the life cycle all over again.

Are Nasal Bots in Deer A Problem?

To a white-tailed deer, nasal bots are typically only a minor nuisance. The bots do irritate the lining of the nasal passages and move about in the retropharyngeal pouches. In fact, most sneezing and coughing of deer is assumed to be the result of nasal bots. From a clinical perspective, the bots do not cause deer any harm. No sores, infection, nor other problems have been reported, even when the parasites are present in large numbers.

Deer hunters normally encounter nasal bots after the deer they harvested has begun to cool. After the deer dies, the body temperature falls and the bots begin to leave the nasal passages and oral pouches in search of a more suitable environment. These bots then exit through either the nose or mouth. Bots can also move in the wrong direction, or down the trachea (where it is usually warmer), and may appear to be in the body cavity of the deer, even though they are not.

Lastly, nasal bots in deer pose no disease threat to deer hunters. They do not harm the venison. Remember, nasal bots are only found in nasal passages and around the mouth of deer. Deer “infected” with these harmless parasites are safe for human consumption. However, I suspect many unknowing hunters have discarded deer carcasses after observing an ugly larvae crawl out of a deer’s nose.