Hemorrhagic Disease of Whitetail Deer

Hemorrhagic disease of white-tailed deer can be caused by either epizootic hemorrhagic disease (EHD) virus or blue-tongue (BT) virus.  It was long considered to be a deer disease that was found only in southern climates. There are two types of EHD virus and three types of BT virus found in North America.  The strength of the infective virus and the length of time the deer has had the infection can vary; some deer show only mild symptoms while others go down quickly. Infected animals can exhibit lameness, swelling of the head, neck or tongue. Some individual strains show extensive internal bleeding , hence the name “hemorrhagic disease”.  Some forms result in rapid death and others can be chronic and linger for an extended period. Chronic, long term cases can also show deformed hooves. The severe cases usually show extensive hemorrhaging under the skin, in the lungs,  gut and in the mouth

None of the strains are spread by direct animal-to-animal contact.  Rather, the virus that causes the disease is spread by the bite of  “midges”, a biting,  water-associated insect that is prevalent in late summer. The severity of the occurrences can vary; in some cases only a few animals are infected.

Before anybody swears off deer hunting, you should know that none the  virus strains can be transmitted to humans. And the infective midges are usually associated with the late summer-early fall period. However the first good frost usually kills the midges and the outbreak ends as quickly as it began.

The first documented infection in NY was in Albany County in the fall of 2007. I was the Region 4 Wildlife Manager at the time and a number of deer were reported to be dying near a small pond  (where the infected midges probably came from). Several carcasses were delivered to the DEC Pathology Unit and the diagnosis was made shortly thereafter. A few other specimens were recovered from other nearby locations and as I recall we didn’t have a hard, killing frost that fall until later in October, well after the archery season began. Interestingly while doing deer checks that year during the regular season, I had several butchers report taking in early archery deer that had signs of extensive internal bleeding, not associated with the kill shot. To the best of my knowledge, there have been no subsequent outbreaks since that season.

There were also a couple of cases reported in western NY, near the PA border later that fall. Some people feel global warming may be the reason for the northward spread of hemorrhagic disease, but that’s way out of my ballpark.

However if anyone takes a deer this fall that has extensive internal bleeding in the mouth, lungs  or other places not associated with the kill shot, you might want to consider getting an “Unfit for Human Consumption” replacement tag from DEC simply because of the grossness of the infection.

Somewhere I’ve got a bunch of pictures from the 2007 outbreak in Albany County  deer; if I can find them, I’ll post them.

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