Orf (Sore Mouth) in Sheep
- Orf, also called sore mouth or contagious ecthyma, is a contagious parapoxvirus infection that usually causes crusted, painful sores on the lips, gums, and muzzle of lambs and sheep.
- Many mild cases improve over 1-4 weeks with supportive care, but nursing lambs can become weak or dehydrated if mouth lesions make nursing painful.
- See your vet promptly if lesions spread to the udder, feet, or eyes, if sheep stop eating, or if you notice fever, foul odor, pus, lameness, or rapid weight loss.
- Orf is zoonotic, so pet parents and handlers should wear gloves and avoid direct contact with sores, scabs, and live vaccine sites.
- Typical U.S. cost range for a farm call and exam is about $150-$350 for straightforward cases, with added costs if testing, wound care, antibiotics for secondary infection, or hospitalization are needed.
What Is Orf (Sore Mouth) in Sheep?
Orf, also called sore mouth, scabby mouth, or contagious ecthyma, is a viral skin disease of sheep caused by a parapoxvirus. It most often affects lambs, especially around the lips and mouth, where it creates raised bumps that turn into pustules and then thick crusts. Adult sheep can also be affected, particularly on the teats, udder, face, or feet.
The disease is highly contagious within a flock. Sheep usually become infected when the virus enters through small breaks in the skin, such as abrasions from rough feed, thistles, or nursing. Dried scabs are especially important because the virus can survive in the environment for years, which helps explain why outbreaks can recur on the same premises.
Most cases are self-limiting, but that does not mean they are harmless. Painful mouth lesions can reduce nursing and feed intake, and lesions on the udder can make ewes reluctant to let lambs nurse. Secondary bacterial infection can make cases more serious.
Orf is also zoonotic, meaning people can catch it from infected sheep, contaminated equipment, or live vaccine material. If anyone handling the flock develops a skin lesion after contact, they should contact a human healthcare professional.
Symptoms of Orf (Sore Mouth) in Sheep
- Crusted sores on the lips or corners of the mouth
- Pain when nursing or eating
- Lesions on gums, tongue, or inside the mouth
- Sores on teats or udder in ewes
- Lesions around the nostrils, eyelids, ears, or face
- Lesions at the coronary band or between the claws
- Weight loss, weakness, or dehydration
- Pus, foul odor, swelling, or fever
Mild orf often stays limited to the lips and heals over a few weeks. The bigger concern is where the lesions are and how much they interfere with eating, nursing, or walking. Young lambs can decline quickly if painful sores keep them from nursing.
See your vet sooner if multiple sheep are affected, if lesions involve the udder or feet, or if any sheep seem weak, dehydrated, lame, or unable to eat normally. Because other serious diseases can also cause mouth lesions, a flock-level outbreak should not be assumed to be orf without veterinary guidance.
What Causes Orf (Sore Mouth) in Sheep?
Orf is caused by the orf virus, a member of the parapoxvirus group. Infection usually happens when the virus enters through tiny skin injuries. Common entry points include abrasions from coarse hay, brush, thistles, erupting teeth in lambs, docking or tagging wounds, and irritated teat skin in nursing ewes.
The virus spreads by direct contact with infected sheep and by indirect contact with contaminated scabs, bedding, feeders, fences, halters, and handling equipment. Dried scabs are especially important in transmission because they can remain infectious in the environment for years.
Outbreaks are often seen in young lambs, newly mixed groups, or flocks under stress. Sheep that have had orf may develop some resistance, but immunity is not always complete or lifelong at every body site. That means repeat cases can still happen.
Live orf vaccines are available for some flocks, but they intentionally create a controlled local infection and can seed the environment with virus. That is why vaccine decisions should be made with your vet, especially if your premises has never had orf before.
How Is Orf (Sore Mouth) in Sheep Diagnosed?
Your vet will often start with the appearance and location of the lesions, the age of the sheep, and the flock history. Classic crusted lesions around the lips of lambs are strongly suggestive of orf, especially if several animals are affected at once.
Even so, diagnosis is not always based on appearance alone. Your vet may recommend testing if lesions are severe, unusual, widespread, or if there is concern for another disease. PCR testing on scabs or a lesion sample is commonly used to confirm orf.
This step matters because other conditions can look similar, including trauma, photosensitization, dermatophilosis, bluetongue, ulcerative dermatoses, and in some situations foreign animal diseases that require rapid reporting. If lesions are extensive or the flock is systemically ill, your vet may also check for dehydration, poor body condition, mastitis, or secondary bacterial infection.
A clear diagnosis helps guide practical next steps, including isolation, nursing support, wound care, and whether vaccination makes sense for the rest of the flock.
Treatment Options for Orf (Sore Mouth) in Sheep
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Farm call or basic exam
- Visual assessment of lesions and hydration status
- Isolation of affected sheep from high-risk groups when practical
- Supportive care such as softer feed access, close nursing observation, and clean water
- Glove use and handling precautions because orf is zoonotic
- Monitoring for weight loss, dehydration, udder lesions, and secondary infection
Recommended Standard Treatment
- Farm call and full veterinary exam
- Targeted lesion sampling or PCR when diagnosis is uncertain or outbreak management matters
- Assessment of lamb nursing success and ewe udder health
- Wound-care guidance and flock biosecurity plan
- Treatment for secondary bacterial infection when your vet finds evidence of it
- Pain-control or anti-inflammatory planning when appropriate and legal for the production class
- Short-term nutrition and hydration support recommendations
Advanced / Critical Care
- Urgent veterinary reassessment or referral-level support
- More extensive diagnostics to rule out other infectious or reportable diseases
- Fluid therapy or assisted feeding for weak lambs
- Intensive treatment of severe secondary infection, mastitis, or foot lesions
- Hospitalization or repeated farm visits for compromised animals
- Detailed flock outbreak planning, segregation strategy, and vaccine discussion with your vet
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Orf (Sore Mouth) in Sheep
Bring these questions to your vet appointment to get the most out of your visit.
- Do these lesions look typical for orf, or do we need testing to rule out other diseases?
- Which sheep should be isolated, and for how long should we treat scabs and contaminated areas as infectious?
- Are any lambs dehydrated or failing to nurse, and what signs should I monitor twice daily?
- Do any ewes have teat or udder lesions that could interfere with nursing or raise mastitis risk?
- Is there evidence of secondary bacterial infection that needs treatment?
- What handling precautions should my family or staff use to reduce zoonotic spread?
- Should we consider an orf vaccine for this flock, or would that create more risk on our premises?
- What cleaning, bedding, and equipment changes will help reduce spread during this outbreak?
How to Prevent Orf (Sore Mouth) in Sheep
Prevention starts with biosecurity and skin protection. Quarantine new arrivals, avoid mixing unfamiliar groups without a plan, and check lambs and ewes regularly during lambing and nursing season. Reduce mouth and skin trauma when possible by managing rough forage, thorny browse, and abrasive feeders or fencing.
Because the virus survives well in dried scabs, outbreak control should focus on limiting contact with contaminated bedding, pens, feeders, and handling tools. Wear gloves when examining lesions, and wash hands well after handling sheep or equipment. People with cuts or compromised skin should be especially careful.
If your flock has a history of recurring orf, your vet may discuss a live orf vaccine. This can help reduce clinical disease in some settings, but it does not provide complete protection and it deliberately introduces live virus to the vaccination site and environment. For that reason, vaccination is generally a strategic flock decision, not a routine step for every premises.
Work with your vet on a flock-specific plan that balances disease history, lambing schedule, labor, and human safety. Good records, early lesion recognition, and prompt separation of affected sheep can make a meaningful difference.