Epizootic Hemorrhagic Disease (EHD) is an acute, infectious, often fatal viral disease in white-tailed deer. EHD is less common in cattle and is rarely fatal. EHD is characterized by sudden death, especially in white-tailed deer with carcasses showing extensive hemorrhages of many organs. EHD is closely related to bluetongue virus and the clinical signs are indistinguishable. Laboratory testing can determine the type. Neither EHD nor bluetongue is spread among animals by direct contact. Both are transmitted by tiny flies commonly known as biting midges.
These diseases characteristically occur from mid-August through October, warns the Indiana Board of Animal Health. Freezing temperatures, which stops the biting midges, bring a sudden end to new cases.
No curative treatment is available once an animal becomes ill. An infected animal may be treated with supportive therapy including anti-inflammatory treatment. Control of the insect population is one form of prevention. Vaccines have been available; however, they have not proven to be effective in preventing EHD. Currently, research is ongoing to develop a more effective vaccine to the many strains of EHD and bluetongue.
Humans are not at risk by handling infected deer, eating venison, or being bitten by infected vectors. Deer that develop bacterial infections or abscesses secondary to hemorrhagic disease may not be suitable for consumption.
Clinical signs in white tailed deer:
- Sudden death
- Swollen jaws/neck/tongue
- Swollen periorbital region
- Conjunctival hyperemia
- Blood from the nose, mouth, eyes, rectum
- Severe dyspnea
- Depression
- Anorexia S - loughing hooves
- Necropsy findings include: red, heavy, lungs; blood in the intestines; hemorrhages in various tissues
Deer may be found dead with no previous clinical signs; may be ill for 2 to 3 days and then die; or may be ill for a few weeks and either succumb or survive. Supportive care and use of anti-inflammatories may be beneficial. Drugs may be off-label so appropriate measures should be taken to follow veterinarian guidelines.
Sampling & Testing
Clinical signs of EHD may mimic foreign animal diseases including foot-and-mouth disease and vesicular stomatitis. Currently, any EHD-suspect case in cattle is investigated as a possible foreign animal disease outbreak.
When the state veterinarian determines that animals died from a mass casualty/mortality event such as a natural disaster or an infectious disease outbreak (such as EHD) not all animals are required to be sampled. Animals at a higher risk for CWD including older animals, males preferentially over females, or those in poor body condition should be sampled. Purchased animals should also be sampled to prevent a possible quarantine should the origin herd have an animal test positive for CWD.
The following criteria must be met for an exception to sampling all animals that die on the farm in a mass casualty event:
- An official diagnosis of EHD from an approved laboratory, such as the Animal Disease Diagnostic Laboratory (ADDL) at Purdue. The whole carcass may be submitted or lung, liver, and spleen.
- At least 15% of deer older than 1 year of age at last inspection count must be sampled. These should include all purchased additions and higher-risk animals.
- All purchased deer that die should be sampled for CWD, even if it is more than 15% of the herd.
- A final count of all cervids older than 1 year of age that died and were not sampled due to EHD must be submitted to your field veterinarian at the next inspection.
- Approval must be given by the Board of Animal Health CWD Program Director, Dr. Shelly Chavis.
Categories: Indiana, General