Sore mouth, or orf is the contagious viral skin disease affecting sheep and goats caused by a Parapoxvirus. This causes painful skin lesions around the muzzle, lips, and mouth, starting as blisters and pimple-like pustules before crusting into thick scabs. ORF disease hit goats harder than sheep, and while any breed can be affected.
Sore mouth is also a zoonotic disease, meaning it can spread from sheep to humans. Farmers, veterinarians, and handlers are at risk of infection through direct contact with affected animals or those recently vaccinated. The disease is widespread, with surveys showing a large share of U.S. sheep operations reporting cases, which makes early recognition and proper herd management essential for protecting both flock productivity and human safety.
Cause of Sore Mouth Disease
The Orf virus causes sore mouth disease in sheep and goats. It belongs to Parapoxvirus, a genus within the Poxviridae family known for large, double-stranded DNA viruses. Under a microscope, Parapoxviruses stand out for their oval shape and a distinctive crisscross or spiral surface pattern unlike other poxviruses. Orf virus is the group’s most significant member, and it’s remarkably tough: dried scabs can harbor infectious virus for months, sometimes years, which is why it keeps resurfacing on the same farms season after season.
Parapoxviruses cause sore mouth disease by entering the body through 
Sore Mouth Treatment in sheep and goat
There is no spacific treatment of sore mouth in goat and sheep. Treatment may not needed for mild cases, as it is a viral, not a bacterial, infection. Lambs and kids, require careful management that may include tube feeding to ensure they receive enough nutrition and hydration. With proper care and attention to the lesions, animals can recover fully.
However, a veterinarian should always be consulted for proper treatment and to help prevent the virus from spreading.
Antibiotics for Sore Mouth in Goats and Sheep
Antibiotics cannot treat sore mouth disease itself, since it’s viral, but they can treat secondary bacterial infections that develop from the lesions. Antibiotic sprays are commonly used to prevent these secondary infections and to clean the wounds. Many first-aid sprays are available on the market, but choose one containing antibacterial ingredients specifically — there’s no effective topical antiviral for the Orf virus, so an “antiviral” claim on a product label won’t actually treat the underlying infection.
Sour Mouth Disease Transmission
Sore mouth is transmitable virus can spread in many ways, such as through direct contact or by touching effective equipment or objects. The virus can also survive on the skin or body of an uninfected animal and enter through the mouth or small cuts in the skin, causing infection.
Outbreaks are common among young animals, especially bottle-fed lambs and kids that share nipples. The virus can survive on surfaces and spread at shows or fairs through close contact. Animals that recover usually develop some resistance, but reinfection can occur because there are different strains of the virus. Fortunately, repeat infections are usually milder and shorter.
Prevention of Sour Mouth in Goat and Sheep
Preventing sheep from Sore mouth virus (parapoxvirus) is very difficult. it spread quickly when it enters a herd. If any animal shows symptoms of sore mouth, follow these steps quickly to protect the rest of the herd.
Healthy animals should be protected from the infected ones. The virus often enters the herd through new animals brought from outside. When buying new animals, always quarantine them for at least 21 days before mixing them with the herd.
Once a herd becomes infected, it is hard to eliminate the disease because the virus can survive in scabs. When scabs fall off infected animals, they can spread the virus to others months or even years later. This virus is very tough—it has special proteins that help it block the animal’s immune system.
The sore mouth virus can survive for months or even years outside the animal. Scabs left on pasture usually don’t last through winter, but the virus can survive in barns, pens, troughs, feeders, gates, and walls. Dried scabs can remain infectious for years if kept in a cool, dry place.
Cleaning is very important to control sore mouth. Regular cleaning removes infected material and reduces the risk of spreading the virus. All pens, feeders, and tools should be washed with soap and hot water, then disinfected with an effective disinfectant such as iodine or chlorine. Surfaces should be allowed to dry completely, and contaminated bedding or scabs should be burned or safely disposed of. Good cleaning and vaccination help protect healthy animals and prevent future outbreaks.
Sore Mouth Vaccine for Sheep and Goat
Ovine Ecthyma is a vaccine used to protect sheep and goats from sore mouth disease. It should only be used on healthy animals that are not already infected, as it helps control and reduce the spread of the disease. Pregnant animals should be vaccinated at least 7 weeks before lambing. Lambs can be vaccinated after the first day of birth.
The vaccine is made from a live virus taken from scabs of a mild form of sore mouth. The virus is modified so it doesn’t cause serious illness but produces a mild infection that helps animals build some immunity. However, the vaccine does not provide strong or long-lasting protection. It may not completely prevent animals from getting sore mouth, but it can make the disease less severe and shorter in duration.
Conclusion: Sour Mouth Disease in Goat and Sheep
Sore mouth disease, also known as orf, contagious ecthyma, or scabby mouth, remains one of the most common and economically significant viral infections in sheep and goats. Caused by the Parapoxvirus, this disease leads to painful sores around the mouth, udder, and other parts of the body, affecting feeding, growth, and milk production. Although sore mouth is typically self-limiting. Severe cases require proper veterinary care, good hygiene, and supportive treatment to prevent secondary infections.
To reduce the risk of outbreaks, farmers should regularly disinfect barns and equipment, quarantine new animals, and use the Ovine Ecthyma vaccine under veterinary guidance. Early detection, isolation of affected animals, and continuous monitoring can help control the spread of the virus within herds.
By following proper management, vaccination, and hygiene practices, farmers can effectively protect their flocks from sore mouth disease, ensuring healthier animals, improved productivity, and a safer working environment.
Because sore mouth is a zoonotic disease, it can also spread to humans through direct contact with infected or recently vaccinated animals. Therefore, wearing gloves, practicing biosecurity, and maintaining strict hygiene standards are essential for both animal and human safety.
