The Washington State Department of Agriculture has confirmed diagnosis of epizootic hemorrhagic disease (EHD) in four cows in eastern Washington. EHD primarily affects wild deer, but the vector-borne virus can cross over to cattle.
“Although EHD is seldom prevalent in cattle, we must show an abundance of caution and investigate each case due to the similarity of symptoms this disease has with the highly contagious and economically disastrous foot-and-mouth disease,” says Washington State Veterinarian Dr. Brian Joseph.
Epizootic hemorrhagic disease virus (EHDV) belongs to the genus Orbivirus, family Reoviridae, according to a fact sheet from the Center for Food Safety and Public Health, Iowa State University (CFSPH). At least seven recognized serotypes of EHDV circulate among cervids worldwide.
EHD Outbreaks in cattle generally are milder than in deer, but can result in reduced productivity, lower milk yield and occasional deaths.
Several species of midges from the Culicoides genus serve as biological vectors for the EHD virus, and with no vaccines available in the United States, insect control remains the best preventive measure against the disease. Supportive care is the only treatment for infected cows.
According to the CFSPH, signs of EHD can include:
- Weakness, stiffness/ lameness
- Respiratory distress
- Severe and rapid edema of the head and neck
- Swelling of the mucous membranes of the oral cavity
- Swelling and hyperemia of the conjunctiva
- Ulcers and erosions in the oral cavity resulting in excessive salivation and nasal discharge, sometimes blood-tinged
- Diarrhea and dehydration
- Progressive abnormalities in blood clotting, with extensive hemorrhages in many tissues including the skin and gastrointestinal tract
- Deaths are common during the acute stage of the disease
- Surviving animals may have ulcers, erosions, scars and other damage to the lining of the rumen and omasum, resulting in prolonged lethargy, inappetence and emaciation
- Breaks or rings in the hooves caused by growth interruptions, resulting in lameness, and in some cases, sloughing of the hoof wall or toe
The Washington State Department of Agriculture reminds producers that signs in cattle such as excessive drooling, lethargy, lameness or oral and nasal lesions with ulceration, can resemble those for the more virulent and economically devastating foot-and-mouth disease.
For more on EHD and similar diseases in cattle, see these articles from BovineVetOnline.com: