Epizootic hemorrhagic disease (EHD) reared its ugly head in several states this year and took many producers and veterinarians by surprise. EHD can cause severe die-offs in white-tailed deer, and can also be a concern in cattle herds.
Transmitted by the Culicoides family flies (biting midges), signs of EHD in cattle, though rare, include fever, ulcers in the mouth and gums, swollen tongue, excessive salivation, and lameness or stiffness when walking. This has caused some concern as it can initially be suspected as being a foreign animal disease.
South Dakota State University has been tracking EHD in South Dakota cattle. Veterinarians have reported that affected cattle in the state had excessive salivation, erosions in the mouth cavity, crusty muzzles and udders, and coronary band lesions with lameness.
The SDSU Animal Disease Research and Diagnostic Laboratory (ADRDL) has had 80 submissions from 35 different veterinarians for EHD diagnostics, the submissions from bison, deer, sheep and cattle. Of the 66 cattle cases, EHD was confirmed in 44, and the three cases from bison were all positive.
SDSU reports that most producers reported only one or two affected animals within a herd, and most of the cattle recovered without long-term effects.
Questions needing answers
Because EHD outbreaks are seasonal and inconsistent, the South Dakota ADRDL taking the opportunity to study and characterize the 2012 outbreak in cattle, but there are still questions that remain to be answered.
Some of the ongoing projects SDSU Veterinary and Biomedical Sciences Department personnel are undertaking hope to answer questions such as:
- How long do cattle stay positive for EHD antibodies? SDSU is working with a dairy herd in Hutchinson County to sequentially test older animals as well as new calves to get a feel for the persistence of these antibodies in an affected herd.
- What was the actual within-herd incidence of EHD in affected cattle herds? Follow-up calls will be made to producers and veterinarians to gain a sense of incidence now that new cases are not being reported.
- Are there any medium- to long-term effects of EHD infection in cattle? A cow-calf herd in Yankton County as well as the Hutchinson County dairy herd will be monitored for longer-term effects, especially on reproduction.
- How can the histopathology of the lesions caused by EHD in cattle be better characterized? For future cases, veterinarians are encouraged to contact the ADRDL and consider sending punch biopsies of any lesions noted.
Read more about EHD in cattle from South Dakota State University and Russ Daly, DVM, Dipl. ACVPM, here.
For more information, contact the South Dakota State University Animal Disease Research and Diagnostic Laboratory at 605-688-5171 or visit www.sdstate.edu/vs.