Mange in Dogs - Types, Symptoms, Contagion, and Treatment

Mange is a skin disease caused by a mite infestation — external parasites that are one of the main causes of itching in our dogs.

There are several types of canine mange: demodectic, sarcoptic, otodectic, and Cheyletiella mange. Depending on which species attacks the dog, the presentation of the condition will vary.

The itching that some of these mites can trigger, along with the possibility of transmission to humans, make it essential to see a vet and start urgent treatment. Let's take a detailed look at everything related to canine mange.

What is mange?

The term mange refers to several diseases caused by mites. They differ in terms of the causative agent, symptoms, affected areas, the age of the animals, or their zoonotic potential. What they all have in common is that they need to be treated to stop the mites from multiplying.

Symptoms of mange

Each type of mange produces a different clinical picture in our dog. Although we'll cover them in detail in the sections dedicated to each one, here's a list of symptoms that should make us suspect the presence of mites:

• Pruritus (itching).
• Skin wounds.
• Flaking.
• Alopecia (hair loss).
• Erythema (redness and inflammation) of the affected areas.
• Hyperkeratosis (thickening of the skin).
• Hyperpigmentation (darkening of the skin).
• Ear discharge.
• Possible secondary infections caused by bacteria or yeast, as complications of the wounds.

Types of mange and their characteristics

Since there are several types of mites that can cause mange, it's important to know how to tell them apart in order to apply the right treatment in each case. These are the types of mange we can find in a dog.

Sarcoptic mange

Also known as scabies, the typical symptom is intense itching. On the skin of the ears, elbows, hocks, lower chest, and face, you may see red spots resembling insect bites, papules, crusts, and hair loss. It's caused by the itch mite, Sarcoptes scabiei.

This mite is a histophage, meaning it feeds on skin tissue. Its entire life cycle, lasting between 17 and 21 days, takes place on the dog's body. After mating, the females of these parasites burrow, creating tunnels or galleries, in the top layer of our dogs' skin to lay their eggs — hence the intense itching they cause. These hatch a few days later and, once they reach adulthood, continue laying eggs.

It's highly contagious and can be transmitted through direct contact or via contaminated objects or surfaces.

Humans can also catch it, with a rash as the symptom, especially on the arms. It's worth knowing that they can't reproduce on human skin, so the condition should clear up once the dog — the source of infection — is treated.

Demodectic mange

This type of mange is caused mainly by Demodex canis, which lives on the skin of nearly all our dogs, since they receive it from their mother in the first days of life. These mites are considered a normal part of the skin's fauna, but they become a problem if their population gets out of control. This generally happens in puppies or adult dogs with a compromised immune system.

This type of mange can be localized or generalized. The localized form appears in puppies under a year old, especially those aged 3-6 months, with hair loss (alopecia) around the eyes, mouth, and sometimes the legs and feet. It usually clears up on its own, without treatment, within 6-8 weeks, but sometimes the skin can become red and infected.

It can even progress into the generalized form. This appears as large bald patches that end up merging on the head, legs, and trunk. Sores, crusts, and even fistulas appear. It can affect both older animals and young ones between 3-18 months old.

In the latter, it's usually linked to underlying diseases that compromise the animal's immune status. This is why demodectic mange is sometimes called "hereditary mange," but that's a completely mistaken name, because even when the immune deficiency has a hereditary basis, the mite itself is the true cause of the disease. What is true is that certain breeds tend to develop this type of mange more often: English and French Bulldogs, Shar Pei, Beagle, Pug, American Staffordshire, Boxer, and Pit Bull, among others.

Other Demodex mites

Although Demodex canis is the mite most likely to be behind a dog's demodectic mange, there are other species that can also cause disease. They're much less common.

One example is Demodex cornei, notable for being contagious. It causes flaking and itching. Another of these mites is Demodex injai. It's found in the sebaceous glands and causes oily seborrhea.

Notoedric mange

This type of mange is caused by Notoedres cati, a mite similar to Sarcoptes. Although it affects cats, it can occasionally be found in dogs and even in humans, in whom it causes dermatitis.

It's mostly confined to the head, where the skin can be seen to thicken. It causes itching of variable intensity, hair loss, redness, and crusting. It's spread by direct and indirect contact and affects young or weakened animals more. If left untreated, it can be fatal.

Otodectic mange

Also called ear mite infestation, it's caused by the mite Otodectes cynotis. It's highly contagious by contact and mainly affects younger animals, especially those under six months old.

It irritates the external ear canal and produces a foul-smelling, dark brown discharge similar to coffee grounds. Looking at a sample of this discharge under a magnifying glass, you can see the mites, which look like tiny white specks about the size of a pinhead, and they move.

It causes intense itching due to the mite's activity, as it feeds on earwax and exudates. From scratching, animals can lose hair around the ears. In some, though uncommon, cases the mites spread over the whole body. It doesn't affect humans.

Cheyletiella mange

Also called cheyletiellosis or "walking dandruff," it affects the youngest puppies, from 2 to 12 weeks old. It's characterized by a red skin rash and large amounts of flaky skin, like dandruff, on the neck and back.

It's highly contagious, which is why it's more common in kennels or breeding facilities with poor hygiene conditions. These mites are large enough to be seen with just a magnifying glass.

Itching may or may not appear. Humans can also be affected, with a rash mainly on the arms, torso, and buttocks. But since they can't reproduce on human skin, treating the animals will also resolve the condition in people.

How is mange diagnosed?

The vet will take skin and/or hair samples from the animal via a skin scraping and/or with a comb. Looking at these under a microscope, it's possible to see the mite and identify it, although this isn't always easy and is sometimes impossible given how tiny these parasites are.

If the symptoms match mange but no mites are found, the diagnosis will be presumptive — that is, based on the symptoms and the response to treatment. In fact, false negatives are common, meaning the mite isn't seen even though it's present.

The number of mites and the severity of the damage to the dog aren't related. There can be a small number of mites with a very intense clinical picture, or the opposite — a huge infestation with a dog showing almost no symptoms.

Treating mange in dogs

Treatment starts with determining which type of mange the dog has. Baths used to be prescribed, but nowadays there are oral tablets and topical spot-on treatments available that easily eliminate the mites. Spot-on treatments make it easier for owners to stick to the treatment, and they're also much more comfortable for the dog.

One of the active ingredients used against mange was ivermectin, but it's being replaced by safer products, including for breeds such as the Collie or Old English Sheepdog, for which ivermectin is toxic. In some cases the vet will indeed prescribe baths or ointments. We should only ever use medication prescribed by this professional.

Anti-itch medication can also be given during the first few days, and if any lesion becomes infected, antibiotics will be needed. Cheyletiella mange is treated with flea-control products. Trimming or shaving the coat makes treatment easier. For Otodectes, parasite treatments can be applied directly in the ear.

Mange and humans

We've seen that some mange mites have zoonotic potential, meaning they can infect humans. Although this might sound alarming, transmission from dogs to people isn't actually that common.

A normal immune system will prevent the mites from causing symptoms. What's more, in humans the process is self-limiting, since the mites can't reproduce on human skin. Cleaning the house and washing our hands after handling the sick animal are protective measures that are usually enough.

If children, elderly people, or sick individuals live in the household, this cleaning and hygiene needs to be scrupulous. For extra peace of mind, we can keep the dog in a single room to prevent contact with people in at-risk groups. So mange is, in the end, easy to control and treat.

How to prevent mange in dogs

If we suspect our dog has mange, or the vet has already diagnosed it, it's important to keep the following measures in mind, especially if the mite is highly contagious or zoonotic. The goal is to prevent new infections or recurrences:

1. See the vet at the first symptom to stop the mites from multiplying and spreading.
2. Thoroughly clean the environment, including bedding and accessories, or get rid of them.
3. In some cases all animals living together will need to be treated.
4. In certain circumstances, dogs with sarcoptic mange may need to be isolated.
5. In Otodectes cases, the ears need to be cleaned in addition to applying treatment.
6. If we need to use a shampoo, it's essential to let it sit on the skin, strictly following the instructions before rinsing. Otherwise it may not be effective.
7. Keep animals in optimal hygiene conditions.
8. A dog that's well cared for, well fed, and properly vaccinated and dewormed will have a strong immune system, able to resist or fight off mites.