Facial Eczema in Cows
- Facial eczema in cows is not a true skin allergy. It is a liver and bile duct injury caused by sporidesmin, a toxin made by the pasture fungus Pithomyces chartarum.
- Affected cows often develop painful photosensitization on pale or exposed skin, especially the face, ears, teats, udder, and sometimes the muzzle after 10-14 days of toxic pasture exposure.
- Early signs can include seeking shade, restlessness, reduced appetite, milk drop, weight loss, and sensitivity to sunlight before obvious skin crusting appears.
- See your vet promptly if you notice sun sensitivity, swollen ears or eyelids, peeling skin, jaundice, or multiple cows affected at once. Herd-level prevention matters.
- Typical veterinary cost range in the U.S. is about $150-$600 per cow for exam, farm call, and bloodwork, with higher herd investigation and supportive care costs if several animals are involved.
What Is Facial Eczema in Cows?
Facial eczema in cows is a toxic liver disease that leads to secondary photosensitization, not a primary skin problem. Cows develop it after eating pasture litter contaminated with spores from the fungus Pithomyces chartarum. Those spores contain sporidesmin, a mycotoxin that damages the liver and bile ducts.
Once the liver is injured, it cannot clear phylloerythrin, a chlorophyll breakdown product, normally. Phylloerythrin then builds up in the bloodstream and reacts with sunlight, especially ultraviolet light. That is why affected cows can develop painful redness, swelling, crusting, and skin sloughing on exposed or lightly pigmented areas such as the face, ears, teats, udder, and muzzle.
The condition is best known in New Zealand and Australia, but the underlying process matters anywhere cattle graze warm, moist pasture with dead plant litter. Some cows show obvious skin lesions, while others mainly have liver damage, production loss, poor thrift, or abnormal liver enzymes. Because liver injury can be long-lasting, even cows that improve outwardly may need ongoing monitoring with your vet.
Symptoms of Facial Eczema in Cows
- Seeking shade or avoiding sunlight
- Restlessness, irritability, or rubbing the face and ears
- Drop in milk production or reduced feed intake
- Red, inflamed skin on pale or exposed areas
- Swollen ears, eyelids, teats, udder, or brisket
- Crusting, oozing, peeling, or sloughing skin
- Pain when touched, photophobia, or agitation in daylight
- Jaundice or yellow discoloration of mucous membranes
- Weight loss, poor body condition, or chronic poor performance
- Eye irritation, tearing, corneal clouding, or tongue lesions from licking
Early cases may look like simple sunburn, but facial eczema can progress quickly because the skin lesions are only the visible part of a deeper liver problem. Cows may first seem uncomfortable in bright light, bunch in shade, or show a sudden production drop before crusts and peeling develop.
See your vet immediately if skin is sloughing, the cow is very painful, the udder or teats are affected, jaundice is present, or more than one animal is showing signs. Herd outbreaks need fast action because other cows may already have liver damage even if they do not yet have obvious skin lesions.
What Causes Facial Eczema in Cows?
The root cause is ingestion of sporidesmin, a toxin produced by the fungus Pithomyces chartarum. This fungus grows on dead plant material at the base of pasture, especially in warm, humid conditions and after warm rains. Risk rises when cattle graze close to the ground, where spore numbers are highest.
The toxin is absorbed from the gut and concentrated in the liver and biliary tract. There it causes cholangitis, bile duct injury, reduced bile flow, and hepatitis. As bile flow is disrupted, phylloerythrin accumulates in the blood and triggers photosensitization when sunlight hits the skin.
Pasture conditions matter a lot. Overgrazed paddocks, heavy pasture litter, and high-risk seasons all increase exposure. Ryegrass-based systems are often discussed in the veterinary literature, but the bigger issue is the presence of toxic spores in the lower pasture layer. Zinc can help reduce the toxic effect when used preventively, but it does not reverse liver damage that has already happened.
How Is Facial Eczema in Cows Diagnosed?
Your vet usually diagnoses facial eczema by combining the history, pasture risk, clinical signs, and bloodwork. The pattern is often suggestive: cattle on pasture during a warm, humid risk period develop painful photosensitization on exposed skin, along with reduced production or signs of liver disease.
Blood testing is important because some cows have significant liver injury before severe skin lesions appear. Vets commonly look at GGT and other liver-related chemistry values. Markedly increased hepatic enzymes support hepatobiliary injury, and herd testing can help identify subclinical cases. In some regions, pasture spore counts or fecal spore counts are also used to assess exposure risk and guide herd decisions.
If the diagnosis is unclear, your vet may also consider other causes of photosensitization or liver disease, including toxic plants, other mycotoxins, or severe sun exposure in pale-skinned cattle. In selected cases, additional diagnostics such as ultrasound, liver biopsy, or necropsy of a deceased animal may be recommended to confirm the extent and type of liver damage.
Treatment Options for Facial Eczema in Cows
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Farm call or herd visit focused on triage
- Physical exam and assessment of skin pain, hydration, and sun sensitivity
- Immediate removal from high-risk pasture and strict shade access
- Supportive nursing care, soft forage, and reduced sun exposure
- Targeted bloodwork only for the most affected or highest-value animals
Recommended Standard Treatment
- Full veterinary exam plus farm call
- CBC/chemistry or liver-focused panel including GGT and bilirubin as indicated
- Pain control and anti-inflammatory plan chosen by your vet
- Topical wound care guidance for damaged skin and teats
- Herd-level review of pasture risk, feeding strategy, and shade access
- Preventive planning such as zinc program review and pasture monitoring
Advanced / Critical Care
- Repeat exams and serial blood chemistry monitoring
- Hospital-level or intensive on-farm supportive care for severe pain, dehydration, or udder/teat injury
- Advanced diagnostics such as ultrasound, liver biopsy, or necropsy support for herd decision-making
- Aggressive wound management and eye care if corneal injury is present
- Expanded herd screening and consultation on prevention failures
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Facial Eczema in Cows
Bring these questions to your vet appointment to get the most out of your visit.
- Do these signs fit facial eczema, or should we also rule out toxic plants, other mycotoxins, or severe sunburn?
- Which cows should we blood test first, and which liver values are most useful for this herd?
- How much shade and pasture change do affected cows need right now?
- Are the teats, udder, eyes, or tongue involved, and does that change treatment or milking management?
- Should we test pasture or fecal spore counts on this farm, and how often?
- Would a zinc prevention program make sense here, and what form and timing fit our cattle group?
- How do we monitor cows that look normal but may already have liver damage?
- At what point should we consider culling, drying off, or changing breeding and production plans for badly affected cows?
How to Prevent Facial Eczema in Cows
Prevention focuses on reducing spore exposure before liver damage happens. The biggest practical steps are to avoid forcing cattle to graze down into the pasture base, provide supplemental feed when risk is high, and move animals away from paddocks with heavy dead litter. Overgrazing increases exposure because the toxic spores concentrate near the bottom of the sward.
Monitoring matters. In regions where facial eczema is a known risk, your vet may recommend pasture spore counts, fecal spore counts, or seasonal herd blood monitoring. These tools help identify danger periods before obvious clinical cases appear. Warm, humid weather after rain is especially concerning because it favors fungal growth and sporulation.
Zinc is a preventive tool, not a cure. Veterinary sources consistently note that zinc must be given at the right dose and at the right time to be protective. Depending on the herd and region, your vet may discuss zinc oxide in feed, water-based approaches where appropriate, or slow-release boluses. Because underdosing can fail and overdosing can create other problems, zinc programs should be designed and monitored with your vet.
Some farms also use pasture management strategies such as fungicide treatment in high-risk systems. No single plan fits every herd. The best prevention program balances pasture conditions, season, production goals, labor, and cost range while protecting cows before clinical disease appears.