Epizootic Hemorrhagic Disease (EHD) in Cattle
Epizootic hemorrhagic disease, or EHD, is a viral disease of cattle spread by tiny biting midges called Culicoides. It is very similar to bluetongue fever, which is caused by a virus from the same family and spread by the same midges. An in...
What is it?
Epizootic hemorrhagic disease, or EHD, is a viral disease of cattle spread by tiny biting midges called Culicoides. It is very similar to bluetongue fever, which is caused by a virus from the same family and spread by the same midges.
An infected cow has a fever, drools, has a red and damaged mouth, struggles to swallow, and produces much less milk. Several animals in the herd are often affected at the same time, in late summer and autumn.
The disease first appeared in Tunisia in 2021, then spread to many regions of the country, before being reported in several southern European countries.
Key point
A disease listed by the World Organisation for Animal Health (WOAH). It resembles bluetongue and foot-and-mouth disease, which only laboratory testing can rule out. Any suspected case must be reported promptly to your veterinarian, who will determine whether to notify the official veterinary authorities.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Fever, lethargy, and decreased appetite or refusal to eat.
Abundant drooling from the mouth.
Red mouth with erosions and sores on the gums, tongue, or palate.
Difficulty swallowing: the animal chews slowly, drops food or water from its mouth, and the tongue may be swollen.
Red and watery eyes, nasal discharge.
Swelling under the jaw or in the legs.
Sores or scabs on the teats, making milking painful.
Red and sensitive skin above the hooves, lameness; some animals remain lying down and struggle to stand.
Marked drop in milk production in dairy cows.
More rarely, blood in feces or difficult breathing: these are signs of severe disease.
EHD does not itch and does not cause bumps across the body: these signs point to a different disease.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The disease is caused by a virus from the orbivirus family, related to the bluetongue virus.
This virus damages the walls of small blood vessels. This explains the redness, swelling, mouth sores, and in severe cases, bleeding.
Wild deer are also susceptible to this virus; among farmed animals, it is mainly cattle that show signs.
Late summer and autumn, the season when midges are most abundant.
Wet areas, stagnant water, overflowing troughs, damp manure—these are where midges multiply.
Cattle spending the night outdoors, near water or manure.
Dairy cows are at higher risk; severe disease and losses occur more frequently in dairy cattle than in beef cattle.
Transmission
The virus is carried by Culicoides, tiny biting midges that feed mainly in the evening and at night. A midge that has bitten an infected animal can then infect another animal.
The disease does not pass directly from one animal to another: without midges, it does not spread.
Midges can be carried by the wind, which explains the rapid spread from one region to another.
Humans are not affected.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
Your veterinarian will examine the mouth, eyes, teats, and feet, take the temperature, and assess how many animals in the herd are affected.
The signs closely resemble those of bluetongue and initially those of foot-and-mouth disease. To the eye alone, it is impossible to tell them apart—only laboratory testing can.
Blood samples are sent to the laboratory to detect the virus.
Foot-and-mouth disease must be ruled out first, as it spreads very rapidly by contact to all cloven-hoofed animals.
Your veterinarian will determine whether to notify the official veterinary authorities and what measures to take while awaiting test results.
Treatment
No medication can destroy this virus. Treatment focuses on relieving the animal's suffering and supporting it through the illness.
Keep the animal in shade and at rest, with clean, fresh water always available.
Offer soft, palatable food that is easy to chew and swallow, since the mouth is painful.
Your veterinarian may prescribe an anti-inflammatory to reduce fever and pain, and an antibiotic if wounds become infected. The choice of product and duration depend entirely on your veterinarian's judgment.
An animal that can no longer drink becomes dehydrated quickly; your veterinarian can provide fluid therapy.
Never use leftover medication or products intended for another animal.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Control midges by eliminating stagnant water, repairing leaking troughs, and removing and drying manure.
During midge season, bring animals indoors in the evening and at night when possible, and keep them away from water sources.
Ask your veterinarian which insecticides or repellents are suitable for your animals and buildings.
Monitor the herd daily during late summer and autumn: check the mouth, drooling, appetite, milk, and lameness.
Any suspected case must be reported promptly to your veterinarian, who will determine whether to notify the official veterinary authorities.
Possible complications
Dehydration and weight loss when the animal cannot drink or eat.
Milk drop lasting several weeks after recovery.
Lameness and teat lesions that complicate milking and increase the risk of mastitis.
In severe cases, with marked tongue swelling, dehydration, or difficulty breathing, the animal may die.
When to see a veterinarian
Several cattle have fever, drooling, and a red or sore mouth at the same time.
A cow has difficulty swallowing, is dropping feed, or has a swollen tongue: call without delay.
A cow is breathing with difficulty, is dehydrating, or remains lying down and cannot get up.
Milk production drops sharply in several cows in late summer or autumn.
Lameness and sore teats appear at the same time as mouth lesions.
You see fluid-filled blisters in the mouth, between the hooves, or on the teats: call immediately, foot-and-mouth disease must be ruled out.
While waiting for veterinary advice, do not move or sell any animals in the herd.
Prognosis
Most affected cattle recover within a few weeks with good care, but milk production may take time to return.
Severe cases, with swollen tongue, dehydration, or difficult breathing, are more often fatal; dairy cows are more exposed to these forms.
Early intervention, with water and food that are easy to consume, significantly improves the chances of recovery.
Frequently asked questions
How to distinguish it from foot-and-mouth disease?
Foot-and-mouth disease causes true fluid-filled blisters in the mouth, between the hooves and on the teats, and spreads very rapidly through contact to all cloven-hoofed animals, including sheep and goats. MHE tends to cause erosions instead and is not transmitted by contact. To the naked eye, confusion is possible: call your veterinarian, only the laboratory can make a definitive diagnosis.
What is the difference with bluetongue (catarrhal fever)?
The two diseases are very similar: same virus family, same midges, same seasons and similar signs in cattle. In bluetongue, the sheep on the farm are often more severely affected, with swollen heads and bluish-purple tongues. Only laboratory analysis can determine which disease it is.
What about contagious nodular dermatitis?
Nodular dermatitis causes firm, round bumps to appear in the skin within a few days, along with enlarged lymph nodes in front of the shoulder. Lumpy skin disease does not produce bumps on the body: it primarily affects the mouth, eyes, teats, and feet.
Are milk and meat dangerous for my family?
BSE is not transmitted to humans. However, a sick cow that has been treated must not be milked for consumption or sent to slaughter without veterinary approval, respecting the withdrawal periods associated with the medications used.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
Content reviewed by the TunisieVet editorial team · Updated 16 October 2026
Comments (0)
No comments yet.
AT A GLANCE
Need a veterinarian?
Find a practitioner near you on TunisieVet, with their specialities, hours and contact details.
Find a veterinarianCategories
Affected species
This information is provided for educational purposes only and is not a substitute for a veterinary consultation. If you have any concerns about your animal's health, consult a veterinarian.
Thinking of welcoming a pet? Dogs and cats are waiting for a family in Tunisia, and adoption is completely free.
Adoption listingsTo discover
Related diseases and linked Animalia content.
Rabies
Viral · Vaccine available
Babesiosis
Parasitic
Leptospirosis
Bacterial · Vaccine available
Foot-and-mouth disease
Viral · Vaccine available
