Mange typically shows up as patchy hair loss, red or inflamed skin, and crusty or scaly lesions. The exact appearance depends on which type of mange is involved, but the combination of bald spots, irritated skin, and intense scratching is the hallmark. Here’s how to recognize the different forms and where they tend to appear on the body.
Sarcoptic Mange (Scabies)
Sarcoptic mange is caused by a burrowing mite and produces some of the most dramatic skin changes. The skin turns red, develops thick yellowish crusts, and hair falls out in the affected areas. Dogs with sarcoptic mange scratch relentlessly, and the constant scratching and biting creates raw, abraded skin that can look worse than the mange itself.
The earliest signs tend to appear in predictable spots: the edges of the ears, the elbows, the hocks (ankles), the chest, and the lower abdomen. These are areas where fur is thinner and mites gain a foothold more easily. If left untreated, the crusty, hairless patches spread outward and can eventually cover most of the body. In advanced cases, the skin thickens and darkens from chronic inflammation.
One useful clue that sets sarcoptic mange apart: if you rub the edge of a dog’s ear and the dog reflexively tries to scratch with a hind leg, that strongly suggests scabies. This response, called the pinnal-pedal reflex, shows up in roughly 80% of scabies cases. It’s not a definitive test on its own, but combined with the telltale crusty ear margins and elbow lesions, it paints a clear picture.
Demodectic Mange
Demodectic mange looks quite different from scabies and comes in two distinct forms. The mites involved live in hair follicles rather than burrowing into the skin, so the visual pattern is more about hair loss and scaling than raw, crusty wounds.
Localized Demodicosis
The localized form appears as isolated, scaly bald patches, usually on a dog’s face, giving what’s often described as a “polka-dot” appearance. The patches are typically small, well-defined circles of thinning or missing fur with mild flaking. By definition, localized demodicosis involves no more than four spots total and doesn’t affect more than two body regions. The most common locations are around the lips, around the eyes, and on the front legs. Many cases of localized demodicosis resolve on their own, especially in young dogs.
Generalized Demodicosis
When more than four spots are present or when large areas of skin are affected, the condition is classified as generalized. This is a much more serious situation. Large patches of hair loss spread across the body, and the exposed skin often becomes infected with bacteria, leading to pus-filled bumps, swelling, and a foul smell. The paws are frequently involved, becoming swollen and tender. In severe cases, the entire body surface can be affected, and the dog may look almost completely bald with thickened, discolored skin.
Mange in Cats
Cats get their own form of mange, most commonly caused by a mite that targets the head and face. The first signs appear on the inner edge of the ear, then spread rapidly to the rest of the ear, the face, the eyelids, and the neck. The skin develops a dry, crusty, thickened texture, and affected cats scratch intensely. In advanced cases, the crusting can extend down the legs and across the body.
Cats can also develop ear mites, a related but distinct condition. Ear mites live in the ear canals and produce a dark, crumbly discharge that looks like coffee grounds. You’ll notice the cat shaking its head and scratching at its ears, but the skin changes stay mostly inside and around the ears rather than spreading across the face.
How Mange Differs From Allergies
Mange and allergies can look surprisingly similar at first glance, since both cause redness, itching, and hair loss. A few visual differences help tell them apart.
- Location of hair loss: Sarcoptic mange strongly favors ear margins, elbows, and hocks. Allergies more commonly affect the paws, armpits, groin, and the area around the eyes and muzzle. If the ear edges are crusty and thickened, mange is more likely.
- Crusting pattern: Mange produces thick, yellow-gray crusts that build up in layers. Allergic skin tends to be red and inflamed but without that heavy crusting, unless the dog has scratched enough to create wounds.
- Intensity of itching: Sarcoptic mange causes some of the most severe itching in veterinary medicine. Dogs with scabies often cannot stop scratching even briefly. Allergies cause itching too, but it tends to wax and wane with seasons or exposure to triggers.
- Speed of onset: Mange lesions spread steadily over days to weeks. Allergic flare-ups often follow a pattern tied to seasons, new foods, or environmental changes.
Veterinarians often need to rule out mange before diagnosing allergies, since there’s no single definitive test for environmental allergies. A skin scraping under the microscope can confirm demodectic mange, though sarcoptic mites are harder to find and sometimes require treatment trials to confirm the diagnosis.
Other Forms Worth Recognizing
A less common type called cheyletiellosis, sometimes nicknamed “walking dandruff,” looks distinctly different from other mange types. Instead of bald, crusty patches, it produces heavy flaking along the back and shoulders. The scales are large and visible, and if you look closely, you can sometimes see them moving slightly as the tiny mites crawl beneath them.
Chiggers, or harvest mites, create yet another pattern. Their orange-red larvae cluster in specific spots, usually around the head, ears, feet, or belly. They feed for a few days and drop off, leaving behind small red bumps that itch intensely. Unlike other forms of mange, chigger infestations are seasonal and self-limiting.
What Progressive Mange Looks Like
In its earliest stages, mange can be easy to miss. You might notice a dog scratching more than usual, or spot a small patch where the fur looks thinner. The skin underneath may be slightly pink. At this point, it’s easy to write off as a minor irritation.
Within a week or two, the affected areas become more obvious. Hair loss expands, the skin reddens noticeably, and crusts begin forming. The dog’s scratching intensifies, and you may see raw spots where the skin has been broken open. Secondary bacterial infections are common at this stage, adding pus, swelling, and odor to the picture.
Advanced, untreated mange is unmistakable. Large areas of the body are hairless, the skin is thickened and wrinkled with heavy crusting, and the dog may appear dramatically underweight from the metabolic stress of chronic skin infection. The skin can take on a gray or darkened appearance from prolonged inflammation. At this stage, recovery is still possible with treatment, but it takes significantly longer, and some skin changes may be permanent.