Hoof rot starts as red, inflamed skin between the toes and progresses to separation of the hoof wall from the underlying tissue, with a distinctive foul smell that’s hard to miss. It affects sheep, goats, and cattle most commonly, though horses get a related condition called thrush. Knowing what each stage looks like helps you catch it early, when treatment is simplest.
Early Signs: Redness Between the Toes
The first visible change is inflammation of the skin between the two halves of the hoof, called the interdigital space. This skin turns pink or red, looks moist, and may appear slightly swollen. At this stage, veterinarians call it “scald” or interdigital dermatitis. It can be caused by a single type of bacteria working alone and doesn’t always progress further.
You might not notice anything wrong by looking at the animal from a distance. The only early clue is often mild lameness or a slight favoring of one leg. To spot scald, you need to lift the foot and spread the toes apart. The skin between them will look raw and irritated compared to a healthy foot, which has dry, pale skin with no lesions.
Moderate Infection: Horn Starts to Separate
Once a second type of bacteria joins in, the infection becomes true contagious foot rot and begins attacking the hoof itself. At this point, two bacteria work together to break down the tissue where the soft skin meets the hard hoof horn. You’ll see a slight detachment of the hoof wall right at the junction between the interdigital skin and the hoof.
If you run your thumb along this area, the wall may peel away from the heel and sole more easily than it should. Underneath, you’ll find a white, slightly moist substance that carries a strong, unmistakable rotten smell. This isn’t pus. It’s necrotic tissue, meaning the cells have died. The smell is one of the most reliable indicators at this stage, and experienced farmers often identify foot rot by odor before they even see the damage.
The separation spreads from the interdigital space toward the heel and then under the sole. The hoof horn in these areas feels soft or spongy rather than firm. The animal will be noticeably lame by now, and in cattle, you’ll typically see symmetrical swelling of the lower leg just above the hoof.
Severe Infection: Hoof Wall Detaches
In advanced cases, the separation extends from the sole to the outer wall of the hoof. The infection destroys the network of tiny blood vessels that anchor the hoof wall to the tissue underneath. Without that blood supply, the horn loses its connection and peels away in large sections. In the worst cases, the hoof may only remain attached at the toe and along the outer edge near the top of the hoof.
At this stage, the exposed tissue underneath is raw, grey or greenish, and extremely tender. The smell intensifies. Animals with severe foot rot in multiple feet may be reluctant to stand at all. Cattle will try to shift their weight toward the heel to avoid pressure on damaged areas, and sheep may drop to their knees to graze rather than bear weight on their front feet.
How Scoring Systems Grade Severity
Veterinarians use a standardized 0 to 4 (or sometimes 0 to 5) scoring system called the Modified Egerton Scoring System to describe how far the disease has progressed. A score of 0 means a completely normal foot with no lesions. A score in the low range indicates mild interdigital inflammation, the scald stage described above. A score of 3 represents moderate interdigital dermatitis. By score 4, the horn of the heel and sole is being undermined and the separation has spread to the walls of the hoof.
This scoring system matters practically because it determines treatment decisions. Low scores often respond to topical treatment and keeping feet dry, while high scores may require more aggressive intervention and a longer recovery period.
Cattle vs. Sheep: Key Differences
In cattle, foot rot tends to appear suddenly. One day the animal walks fine, the next it’s noticeably lame with a swollen lower leg. The swelling above the hoof is often the first thing you notice, even before you pick up the foot to look. The interdigital skin will be cracked, necrotic, and foul-smelling when you examine it closely.
In sheep and goats, the disease is more commonly chronic and contagious within a flock. It spreads through contaminated pasture, especially in warm, wet conditions. Sheep foot rot tends to progress through the stages more gradually, making it easier to catch at moderate severity if you’re checking hooves regularly. The visual appearance is similar, but sheep hooves are smaller, so separation of the horn can affect a larger proportion of the hoof more quickly.
Cattle can also develop a related but distinct condition called digital dermatitis, which looks different from classic foot rot. Digital dermatitis typically appears as an ulcerative or raised, wart-like lesion on the skin at the back of the hoof, between the heel bulbs. It’s classified on its own M0 to M4 scale based on visual appearance and is caused by a different group of bacteria.
What Hoof Rot Looks Like in Horses
Horses don’t get foot rot in the same way ruminants do, but they develop a condition called thrush that shares some visual similarities. Thrush produces a runny, black, foul-smelling discharge concentrated around the frog, the triangular pad on the sole of the hoof. The discharge collects in the grooves on either side of the frog and in the cleft between the heel bulbs.
In severe cases, thrush creates a deep gash running down the center of the frog. The tissue becomes soft, dark, and crumbly rather than firm and rubbery. If you’re a horse owner, the combination of black discharge and a rotten smell when you clean the hoof with a pick is the classic sign. Unlike ruminant foot rot, thrush doesn’t cause the hoof wall to separate, but left untreated, it can eat deep enough into the frog to reach sensitive tissue and cause significant pain.
Environmental Conditions That Make It Worse
Foot rot thrives in wet, muddy environments. The bacteria that cause it can survive in soil and on pasture for a limited time, but they need moisture to stay active and penetrate the skin. Prolonged standing in mud, wet bedding, or waterlogged pasture softens the interdigital skin and creates entry points for infection.
If you’re seeing signs that match the descriptions above, check your other animals as well. In sheep and goats especially, foot rot spreads rapidly through a group once one animal is infected. Early-stage scald in several animals at the same time is a strong signal that conditions are right for an outbreak, and acting at that point is far easier than dealing with advanced hoof separation across an entire flock.