Epizootic Hemorrhagic Disease (EHD) & Bluetongue (BT)
Prevention and Treatment
- David W. McQuaig
With the Epizootic Hemorrhagic Disease (EHD) and Bluetongue (BT) season fast
approaching, I was more than willing to do this article when approached to help out
whoever I can that will have to face these devastating viral diseases.
I am neither a veterinarian nor a professional on this matter, but do have experience
dealing with it first hand which goes a long way.
It is most common to see outbreaks in late summer through early fall. The biting midge
most commonly responsible for transmitting the virus is the C. variipennis. It is also
reported that it could possibly be transmitted by mosquitoes and gnats as well. Once the
deer is infected with the virus, the incubation period is 5 to 10 days.
I have learned that Hemorrhagic Disease is the most important infectious disease of
whitetail deer, and outbreaks occur almost every year. Because disease features produced
by these viruses are indistinguishable, a general term, hemorrhagic disease, often is used
when the specific virus responsible is unknown. There are 2 subtypes of EHD virus and 5
subtypes of BT virus in North America. It is suspected that there is variation in ability among
these subtypes or even with strains of each subtype to cause illness in deer. Furthermore, it
is unlikely that recovery from infection with one virus subtype will protect the deer from infection
with another. Hemorrhagic disease viruses cannot survive outside the host animal or biting fly
vector. When deer die, EHD or BT virus will deteriorate rapidly in the carcass, and virus
isolations are seldom obtained beyond 24 hours after death. Therefore, a live sick
deer or a freshly dead deer is needed to make a virus isolation and determine which virus
is present.
Clinical signs are seen in three different syndromes: Peracute disease is characterized by
high fever, loss of appetite, swelling of the head and neck, troubles breathing, swelling of
the tongue and weakness. Deer with the peracute form usually die within 8-36 hours and
are found dead with no apparent reason for death. In the acute form (Classic EHD) the
above symptoms will be accompanied by extensive hemorrhages in tissues including the
skin, heart and gastrointestinal tract. You may notice excessive salivation and nasal
discharge, which could be blood-tinged. Deer may also develop ulcers or erosions of the
tongue, dental pad, rumen, etc. High mortality rates are very common in the peracute and
acute forms. The third form is the chronic form and in this form deer could be ill for
several weeks but gradually recover. Deer with the chronic form could develop ulcers and
scars of the rumen. This could cause emaciation even when there is no lack of food.
It is my opinion that the healthier my animals are, the better chance of survival. I take
great care in making sure the feeders and drinkers are always clean. I watch my deer
closely to know their usual behaviors so that when they are not acting ‘normal’, I know to
act quickly. I have noticed that PREVENTION and insect control are extremely
important. We spray our pens, outside the fence and property perimeter with Permethrin
at a rate of 30 gallons per acre. We also are sure to saturate all bedding areas as it then
transfers on to the deer during bedding times. Even though the container says that the
Permethrin is good for 28 days, I have talked with the manufacturer and they recommend
re-spraying in two weeks because of break down. We keep all vegetation mowed and
weeded down so that the gnat does not find good breeding ground. In fence rows, we
saturate the taller grass. I have heard of ranchers in TX using mosquito magnets outside
their pens to kill the gnats before they get to the deer.
When I notice a deer exhibi t ing EHD/ BT symptoms, we get them in the barn immediately.
Although many veterinarians say that there is no effective treatment, I have found that we can save
most of them by giving the following doses of meds to any of them showing signs:
Bucks Does Fawns
Tetradure – 20 cc. Tetradure – 12 cc. Tetradure – 2 cc.
Baytril – 12 cc. Baytril – 12 cc. Baytril – 1 cc.
Banamine – 3 cc. Banamine – 3 cc. Banamine – .5 cc.
When we have deer in the barn, we also spray them with Permethrin. We keep them in
the barn for as short a time as possible as it can be stressful on them. There are times we
do have to run the same deer through more than once.
So many times people have asked me whether I really ran bucks through in velvet and my
answer to that is, “Absolutely! I would rather have messed up antlers than dead deer”.
The bucks can grow new antlers next year, but not if they are dead.