EHD in Wisconsin Cows: What Producers Need to Know

Reports of epizootic hemorrhagic disease (EHD) in Wisconsin cattle require careful verification. The supplied material does not provide a verified case count, confirmation date, affected county, herd information, laboratory result, or official statement. Its references concern unrelated sports and search listings and cannot support claims about EHD in Wisconsin cattle.

Producers should verify current information through the Wisconsin Department of Agriculture, Trade and Consumer Protection, the USDA Animal and Plant Health Inspection Service, their herd veterinarian, and an accredited veterinary diagnostic laboratory.

What Is EHD?

EHD stands for epizootic hemorrhagic disease. It is caused by epizootic hemorrhagic disease virus, a member of the Orbivirus group. The disease primarily affects wild ruminants, especially white-tailed deer, and can cause sudden illness and death during periods of active biting-midge populations.

Cattle can become infected, but infection does not necessarily cause severe clinical disease. Effects vary according to the animal, virus type, exposure level, and other health conditions. A confirmed infection in one cow does not establish widespread transmission within a herd or across Wisconsin.

EHD is related to bluetongue, another vector-borne viral disease. The diseases can cause similar signs, so clinical symptoms alone cannot distinguish them. Laboratory testing is required.

What Has Been Confirmed in Wisconsin?

No verified Wisconsin case count can be stated from the supplied information. Before publication or operational decisions, verify the following through an official source:

• Number of laboratory-confirmed cattle cases
• Number of affected herds and farms
• Affected counties
• First confirmation date
• Most recent update date
• Testing laboratory and method
• Reporting agency
• Definitions for confirmed, probable, suspected, and negative cases

Reports should clarify whether a number refers to individual animals, herds, farms, laboratory submissions, or positive test results. Every numerical claim should include an inline source and reporting date.

No Wisconsin county, farm, herd, or cattle type should be identified without an official source. Farm names should not be published unless released by the owner or an authorized public agency, particularly during an active investigation.

Official statements should address four questions:

1. Is the infection laboratory-confirmed?
2. How many animals or herds are involved?
3. What action should producers take?
4. Are testing, movement, or reporting requirements in effect?

Social media posts, unattributed screenshots, and search-result numbers are not evidence of confirmed EHD in Wisconsin cattle.

How EHD Spreads

EHD viruses are primarily transmitted by infected biting midges, including insects in the Culicoides group. A midge can acquire the virus while feeding on an infected animal and later transmit it to another susceptible animal.

Midge activity is influenced by temperature, humidity, rainfall, soil moisture, standing water, vegetation, season, and local habitat. Warm conditions can support activity, while cold weather and frost can reduce or end seasonal activity.

White-tailed deer are important to EHD ecology. Cattle near deer habitat may share environments where infected midges are present, including wet pastures, low-lying ground, wooded edges, wildlife travel routes, and shared water sources. Risk varies with vector presence, weather, virus circulation, animal location, and other factors.

Ordinary contact between cows is not automatically evidence of EHD transmission. Producers should not assume that direct cow-to-cow spread is the primary route. Veterinary authorities should assess suspected herd transmission and determine whether testing or movement precautions are appropriate.

Signs of EHD in Cattle

Possible clinical signs include:

• Fever
• Reduced appetite
• Depression or weakness
• Excessive salivation
• Nasal or oral discharge
• Swelling
• Lameness
• Breathing difficulty
• Reduced milk production
• General decline in condition

These signs are not specific to EHD. They can occur with respiratory disease, toxic exposure, heat stress, injury, hoof disease, metabolic disorders, and other viral or bacterial infections.

A sudden cluster of sick animals requires prompt veterinary attention, especially when several animals become ill within a short period or when illness follows unusual wildlife deaths or heavy insect activity.

Diagnosis

A veterinarian may evaluate the clinical history, animal age and production type, weather and insect exposure, nearby wildlife illness, blood or tissue samples, postmortem findings, and molecular or serologic laboratory tests. The appropriate approach depends on the animal’s condition, timing, sample quality, and differential diagnosis.

A positive result in one cow should not automatically be described as infection throughout the farm or herd.

When to Contact a Veterinarian

Contact the herd veterinarian promptly when cattle show sudden illness, unexplained deaths, multiple cases, severe weakness, breathing difficulty, or a sharp decline in milk production.

Producers should:

1. Record animal identification numbers.
2. Note when signs began and how they progressed.
3. Count affected and unaffected animals.
4. Record recent animal movements and treatments.
5. Document nearby deer illness or deaths.
6. Follow veterinary instructions for sample collection.
7. Avoid moving visibly sick animals without professional advice.

Animals with collapse, severe breathing problems, or rapid deterioration require urgent veterinary attention. Do not rely on self-diagnosis or unapproved treatments.

Human Health and Food Safety

EHD is primarily an animal disease associated with wild and domestic ruminants. Producers should follow current guidance from Wisconsin DATCP, the Wisconsin State Veterinarian, and relevant federal agencies because a sick animal may have another condition requiring different precautions.

Do not make broad claims about milk, beef, slaughter, carcass disposal, or product restrictions without official instructions. Producers should ask their veterinarian and state animal-health authorities whether restrictions apply to affected animals or premises. Consumers should follow official food-safety guidance rather than social media claims.

What Wisconsin Producers Should Do

Monitor cattle

Record animal ID, location, temperature when directed, appetite, milk production, lameness, swelling, respiratory signs, treatment history, symptom onset, and the number of affected animals. Also record recent weather, standing water, insect activity, wildlife deaths, and animal movements.

Reduce midge exposure

Where practical, producers can improve drainage, reduce standing water, review cattle access to wet areas, maintain facilities and screens where appropriate, and use approved insect-control measures. Chemical products must be used according to the label and veterinary guidance. Products approved for one species or purpose may not be suitable for another.

Report suspected cases

Unless Wisconsin authorities provide another route, contact the herd veterinarian first. Prepare the farm location, owner and veterinarian contact details, numbers of affected animals and deaths, clinical signs, onset dates, movement history, recent treatments, wildlife observations, and available samples.

Maintain biosecurity

Avoid moving visibly sick cattle without veterinary advice. Separate sick animals when practical and safe, clean and disinfect equipment according to veterinary instructions, limit unnecessary visitors and equipment sharing, coordinate testing before making herd-level decisions, and follow official carcass-handling guidance.

EHD Compared With Other Diseases

EHD and bluetongue are related viral diseases transmitted primarily by biting midges. Both can affect ruminants and produce overlapping signs, but their epidemiology, virus types, host effects, and surveillance requirements differ. Laboratory testing is necessary.

Suspected EHD signs can also occur with bovine respiratory disease, toxic exposure, heat stress, injury, hoof disease, other infections, metabolic disorders, and foreign-animal-disease concerns. A veterinarian should evaluate sudden or unusual disease, particularly when multiple animals are affected.

What a Confirmed Case Would Mean

The implications depend on the verified report. Officials may recommend monitoring, testing, vector control, wildlife surveillance, movement precautions, or no special action beyond routine veterinary care.

A confirmed case does not mean every nearby herd is infected or establish a statewide outbreak. Producers should wait for current agency guidance before changing animal movements, treatment plans, or marketing decisions.

Case counts may not represent all infections because testing can be limited by the number of animals examined, sample timing and quality, clinical severity, veterinary access, surveillance priorities, and laboratory capacity. Reports should distinguish laboratory-confirmed cases from suspected or probable cases and identify whether the count covers animals, herds, farms, or samples.

Monitor official updates about new county confirmations, affected herds, midge activity, testing instructions, movement or biosecurity recommendations, wildlife surveillance, and veterinary laboratory guidance.

Reliable Sources

Recommended primary sources include:

• Wisconsin Department of Agriculture, Trade and Consumer Protection
• Wisconsin State Veterinarian
• USDA Animal and Plant Health Inspection Service
• USDA National Veterinary Services Laboratories
• University of Wisconsin–Madison School of Veterinary Medicine
• University of Wisconsin–Madison Division of Extension

FAQ

What does EHD mean in cows?

EHD means epizootic hemorrhagic disease, a viral disease primarily associated with wild ruminants. Cattle can become infected, but a veterinarian and laboratory must confirm the diagnosis.

How many Wisconsin cows have tested positive?

The supplied material does not provide a verified number. Check a current Wisconsin DATCP, USDA, veterinary laboratory, or official veterinarian report and confirm what the number represents.

Can EHD spread from cow to cow?

EHD is generally associated with infected biting midges rather than ordinary direct contact between cattle. Follow veterinary guidance on testing, movement, separation, and biosecurity.

What are the signs of EHD in cattle?

Possible signs include fever, weakness, reduced appetite, excessive salivation, swelling, lameness, breathing problems, and reduced milk production. These signs are not diagnostic.

Is EHD dangerous to people?

Follow current guidance from Wisconsin and federal health authorities. EHD is an animal disease, but sick cattle may have other conditions requiring different precautions.

How can producers reduce EHD risk?

Monitor cattle, contact a veterinarian promptly, reduce exposure to biting-midge habitat where practical, use approved vector-control products, maintain biosecurity, document unusual illness, and report suspected cases through the appropriate veterinary channel.