Moderate

Mallenders

Mallenders is hyperkeratosis — cracked, scaly, crusted skin behind the knee (front-limb flexor surface). It is not rain-rot (Dermatophilus), not cellulitis (sudden hot limb swell), not proud flesh (exuberant granulation), not lice, and not sweet-itch (Culicoides). A photograph cannot diagnose mallenders. A still cannot tell mallenders from scratches (pastern dermatitis), rain rot, or proud flesh. Diagnosis is a vet exam. The skin scan is a first look at the skin behind the knee to share with a vet, not a mallenders test, and there is no mallenders scanner.

Symptoms to watch for

Cracked, scaly, or crusted skin behind the knee — the look is a clue, not a still-photo verdict

Thickened, hyperkeratotic skin on the front-limb flexor surface (behind the knee) — location is a clue, not a diagnosis

Skin that can look like scratches (pastern dermatitis), rain rot, or proud flesh — a still cannot tell them apart

Crusts or scales that persist or crack — a reason to book a vet, not a photo verdict

A change in thickness, cracking, or crust is a reason to book a vet, not a photo verdict

The same cracked, scaly pattern can appear at the hock — that is a different site and a vet exam, not a photograph

Common causes

Hyperkeratosis of the skin behind the knee (front-limb flexor surface) — cracked, scaly, crusted skin; the site and the scale are clues, not a diagnosis
Not rain-rot (Dermatophilus congolensis), not cellulitis (sudden hot limb swell), not proud flesh (exuberant granulation), not lice, and not sweet-itch (Culicoides insect-bite hypersensitivity)
The same cracked, scaly pattern can appear at the hock — a different site, a vet exam, not a second page
A still cannot tell mallenders from scratches (pastern dermatitis), rain rot, or proud flesh — those need a vet

Prevention

Watch the skin behind the knee for new cracking, scale, or crust, and book a vet rather than waiting on a photo
Do not pick crusts or apply a caustic or home protocol from a photo hoping it will settle — that is a vet visit, not a photo
Note whether the change is behind the knee or at the hock, whether the skin is hot or swollen, and whether the horse is sore, so you can tell the vet
Do not treat a photo, a crusted patch, or a scan result as a diagnosis
Skin photos can help you and the vet look at the skin behind the knee — they do not confirm or rule out mallenders, and they cannot tell it from scratches (pastern dermatitis), rain rot, or proud flesh

What to do

1
Book a vet visit if you find cracked, scaly, or crusted skin behind the knee. Diagnosis is a vet exam — not a photograph.
2
Do not pick crusts or apply a caustic or home protocol from a photo. A still cannot tell mallenders from scratches (pastern dermatitis), rain rot, or proud flesh.
3
Photograph the skin behind the knee in good light, close and from the side, and keep the photos on the horse's record so you and the vet can see change over time — a first look to share, not a diagnosis.
4
Use a skin scan only as a first look at the skin behind the knee to share, not as a mallenders test. There is no mallenders scanner.
5
If mallenders is confirmed, follow the plan your vet prescribes. Do not start a treatment protocol from a photo.
6
Keep the vet on the same page. Share what you see; do not treat a photo as a verdict.

When to call the vet

Pick up the phone if…

Schedule a vet visit if you find cracked, scaly, or crusted skin behind the knee. Call sooner if the skin is hot, swelling, or the horse is lame, dull, or off feed — that can be cellulitis (emergency), not mallenders, and is a vet call, not a photo diagnosis. A photograph cannot diagnose mallenders. A still cannot tell mallenders from scratches (pastern dermatitis), rain rot, or proud flesh. Diagnosis is a vet exam. The skin scan is a first look at the skin behind the knee, not a mallenders test, and there is no mallenders scanner.

Get a first look at the skin behind the knee

Scan the skin in HorseCare. 5 free scans this month, then Pro.

Scan the skin

5 free scans this month, then Pro. Scans run in the HorseCare app.

Educational content only. Not a substitute for veterinary advice.