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Discovering crusty scabs on your dog’s back, especially if you do not know what caused them, or how to treat them, can be upsetting. There is a wide variety of conditions that can cause crusty scabs on a dog's skin, and I'll cover eight most common ones that could be the culprits behind crusty scabs on a dog's back and what to do about them.

1. Allergies

Environmental allergies.

They are abundant and can be caused by nearly anything that you can think of. While pollen is the number one environmental allergy that can cause visible signs of irritation on a dog’s skin, there are countless other environmental compounds that can and do cause skin irritation in a dog due to the dog being allergic to it, such as laundry detergents, shampoos and soaps, cleaning products, lawn chemicals and treatments, any kind of chemicals, and even objects like plastic bowls can cause skin irritation in dogs, just like they can in humans.

Food allergies.

Food allergies are less common in dogs than they are in humans, and also less common than environmental allergies but they do happen, and can also result in the same types of side-effects appearing on a dog’s skin. Crusty scabs is one of the visible signs your pooch may be dealing with a food allergy.

Pollen.

As mentioned above, pollen is the most common allergen that impacts a dog’s skin, which happens when the pollen has direct contact with the skin or is inhaled through the dog’s nose. Although it is unknown why pollen-allergies are among the most common allergy in dogs, it is known that this allergy results in allergic dermatitis, which causes skin irritation, itchiness, rashes, redness, bumps, blisters, moist skin, abnormal odors, sores, and crusty scabs.

2. Bacterial Infection

Superficial bacterial folliculitis is a type of bacterial infection that often results in irritation, bumps, sores, and scabs on a dog’s skin, and commonly is co-occurs in dog’s that are suffering from another type of skin disorder such as allergies, mange, fleas, or injury.

Bacterial infections usually develop because a dog is constantly scratching, licking, and/or chewing on their skin due to the primary condition that they are suffering from, but by scratching and breaking their skin open, the dog opens up their system for bacteria to get in and attack.

Puss-filled sores that look like human acne can develop due to bacteria getting into a dog’s system through the compromised skin, and the resulting sores and other skin-lesions caused by the constant scratching, chewing, and licking of irritated skin can end up leaving crusty scabs on the dog’s body.

3. External Parasites

Fleas.

They are the external parasites that most commonly irritate a dog’s skin causing the dog to excessively lick, scratch, and/or chew at their skin, which results in sore hot-spots, and crusty scabs. Some dogs are much more sensitive to fleas than others. You may not be able to see a single flea on your dog, but that in no way means that they aren’t hiding on your dog, in their bedding, on your carpets and rugs, and/or in your yard.

Severe cases of flea infestation can cause excessive blood loss resulting in anemia, and can also lead to other parasites in a dog, such as tapeworms. Proper flea prevention and control is imperative with all dogs, see the “What to Do” section of this article, below, for more about flea prevention and control.

See the following informational handouts for further information about all things related to fleas, published by DVM360 in a convenient PDF format.

Mites.

They are also a very common kind of external parasite that cause a disorder called mange in dogs that produced the same skin conditions that fleas do, and sometimes to a much more severe extent, in which a dog can lose all or most of their hair and be covered in large amounts of crusty scabs.

Demodex mites survive and thrive in a dog’s hair follicles, causing a disorder name demodectic mange in dogs that results in redness, sores, scabbing, and hair loss, but not always a ton of itchiness, and is not contagious to other animals or humans.

Scabies mites are less common but are contagious to other animals and humans, and cause a disorder known as sarcoptic mange (or scabies), which results in severe itching along with red, inflamed skin, sores, scabs, and hair loss.

See the following informational handout for further information about demodex mites and mange, published by DVM360 in, again, a PDF format.

Ticks.

Just like fleas and mites, ticks are external parasites that attach to a dog’s skin and feed on their blood, causing skin irritation, itchiness, sores, and scabs. Dog owners can commonly see a tick feeding on their dog with a naked eye, and can remove it themselves by grasping the tick with tweezers positioned as close as possible to the dog’s skin, and gently pulling the tick straight out of their skin (pulling too hard, or twisting the tick can cause its head to become stuck in your dog, which can lead to an infection, so be sure to always remove ticks slowly, carefully, and gently.)

4. Fungal Infection

Ringworm, also called dermatophytosis, is a disorder that is caused by a fungus frequently found in soil, and can result in scabs, red and irritated skin, bumps, scaly skin, itchiness, and hair loss. Puppies under a year of age are especially vulnerable to being infected with ringworm and it is highly contagious among animals and humans. The reference to “ring” in the disorder’s name is due to the circular, ring-like patches of irritated skin that develop in animals and humans who contract ringworm.

5. Hormonal Imbalance

Caused by inherited abnormalities in a dog’s testicles, ovaries, adrenal glands, thyroid glands, and/or pituitary glands, and will generally cause a dog to lose all of their hair, which can cause skin irritation and crusty scabs on their skin.

Endocrine (hormone) abnormalities can cause skin irritation and scabs in dogs that can be the initial stages and signs of Cushing’s Disease, hypothyroidism, and tumors, which is why it is very important to always address any skin issues your dog is experiencing and have further tests performed by a licensed veterinarian in order to determine what is causing skin irritation in a dog.

6. Immune Disorders

If a dog is suffering from any type of auto-immune or immune-suppressing syndromes or disorders, they can develop skin conditions that lead to sores and scabs on their skin.

These skin disorders appear as a side effect of the fact that the dog’s immune system is either compromised and unable to fight off the skin irritants, or because the immune system is working extra-hard and as a result, is attacking itself.

These types of skin conditions are among the most serious kind and can result in death.

7. Nutritional Issue

Lacking proper minerals and vitamins in their diet can cause a dog to develop skin irritation, rashes, and itchiness that leads to sores and scabs on a dog’s skin. This is because dogs need specific nutrients, in certain amounts in order to keep their skin properly hydrated which keeps it moist, moisturized, and glossy.

When a dog’s skin is properly balanced and moisturized, this provides an extra layer of defense against parasites being able to easily attack and latch onto a dog’s skin, and also protects the skin from being scratched or torn open by environmental elements, which happens much more easily when the skin is dry and flaky.

Parasites seek and attach to host’s that are unhealthy, so when a dog is not being fed a well-balanced, high-quality diet that includes all of the vitamins and minerals they need for proper and balanced nutrition, they become unhealthy and parasites will often first target dogs that are suffering from nutritional deficiencies.

8. Yeast Infection

This is a fairly common type of skin infection in dogs. Some yeast being present on a dog’s skin is normal and even necessary, the problem occurs when the dog develops an excessive amount of yeast, and it beings to build up in warm, moist places on the dogs body, causing outbreaks of irritated, itchy, and discolored skin that can result in scabs on a dog’s body due to the dog licking, chewing, and scratching their skin incessantly to try to relive their discomfort.  

Further complication can arise when the scratching and chewing causes open wounds on the dog’s skin that bacteria then enters, and creates a whole host of new and serious side effects that must be treated.

RELATED: 9 Common Skin Problems in Dogs (How to Prevent and Treat Them)

What to Do About Crusty Scabs on Dog's Back

What to Do About Crusty Scabs on Dog's Back

1. Use Anti-bacterial/fungal Dog Shampoos, Ointments

There are many different over-the-counter (OTC) strength (versus veterinarian prescribed) anti-bacterial and anti-fungal creams and shampoos that are manufactured and sold commercially by many different companies, and can easily be found and purchased at most large retail chains, pet stores, and online retailers.

Ask your veterinarian, and/or complete research to determine which shampoo and/or ointment has been shown to work best for the specific skin condition your dog is suffering from, and wash your dog with the shampoo and/or apply the ointment, carefully following the included directions. You can find OTC medicated shampoos to treat a wide-variety of skin disorders in dogs that are caused by fleas, mites, lice, general allergies, and more.

2. Keep Your Dog, Home and Yard Clean

Keeping these three things clean, and pest-infestation free, is one of the most important things that pet owners can do to prevent their dogs from developing painful, and potentially dangerous skin disorders. Especially disorders that are caused by external parasites and bacterial infections, both of which can be controlled and prevented by simply making sure to always keep your dog, home, and yard clean.

Doing so effectively includes behaviors such as the following:

a) pick up and properly dispose of feces in your yard, and anywhere your dog plays, multiple times each day, once at the bare minimum;
b) bathe your dog as often as needed, but at least once every couple of weeks or once a month, at minimum, and always bathe your dog if they get into something exceptionally stinky, dirty, or have been anywhere known to commonly be frequented by ticks, fleas, mites, lice, or any other type of parasite or a sick animal (which should always be avoided, if possible);
c) wash all of your dog’s bedding at least once a week, and more often as needed;
d) wash your bedding and clean all furniture, carpets, rugs, and flooring in your home at least once a week, and more often as needed.

3. Brush Your Dog Daily

This falls along the lines of keeping your dog clean, but unlike bathing a dog which is not recommended to be done daily, brushing your dog can and should be done every single day. By brushing your dog, you do a multitude of things that help to keep their skin and coat healthy and disease and disorder free.

The simple act of brushing a dog not only help to remove dirt, dandruff, bacteria and any foreign objects or parasites that could irritate a dog’s skin from their body, brushing a dog also helps to stimulate oil glands and equally distribute all of the dog’s natural oils that are essential to their overall skin health, and spreads these protective oils throughout the entire surface area of the dog’s skin which in their largest organ, and first line of defense against harmful and dangerous parasites, fungi, and bacteria entering their system. A good brushing doesn’t have to take a lot of time, even five minutes a day will do. Brushing a dog also detangles their coat and loosens and eliminates dead hair, ensuring that a dog’s pores do not become clogged and infected.

4. Use Fish Oil

Essential fatty acids are absolutely essential to the health of a dog’s skin and coat, and not all dogs get enough of this vital nutrient in their diet, which can lead to skin disorders. Simply give your dog fish oil capsules once per day with a meal, or add some fish oil liquid into your dog's food to remedy this issue.

You can read more about this topic in the following peer-reviewed article published in the Journal of Nutrition about a scientific study that showed clear benefits of high doses of essential fatty acids in a dog’s diet to the dog’s overall skin and coat health.

5. Flea and Tick Collars, Topical Treatments

A plethora of different companies make a wide-variety of flea and tick collars as well as topical and oral treatments that work to keep fleas and ticks off of your dog. With anything that you use on your dog, it is important to thoroughly research the product, its ingredients, effectiveness, potential side effects, and customer reviews before deciding to purchase and use it on your dog.

Make sure to seek the advice of your dog’s veterinarian, as he or she can advise you on which options are known to work best for your specific type of dog, and the area in which you live.

6. Keep Them on High-Quality, Balanced Diet

As explained in the “Nutritional Issue” section of this article, a dog’s diet greatly impacts the condition of their skin, and a diet that lacks essential vitamins and nutrients can dry out a dog’s skin, causing a dog to itch, chew, and bite themselves in response to the irritation, which in-turn can cause the dog to rip their skin, leaving compromised areas of their skin open to parasitic, bacterial, and fungal infections, and more.

Some foods (like these brands) are specifically balanced for better skin and coat condition in dogs. You can also select foods yourself, picking with high quality ingredients, including plenty of protein, vegetables, and a bit of carbs and fat. For most dogs, this is their optimal diet. Additionally, parasites are known to seek out and feed on dogs that are not in optimal health, therefore a poor diet makes a dog much more susceptible to parasite bites and infestations.

7. Use Only Safe, Good Quality Grooming Products

Sure, a two dollar dog shampoo might seem like a great deal, but there are usually reasons why a product is much less expensive than its counterparts, and that is often because it is made with cheaper, chemical-ridden, irritating, and even harmful ingredients and chemicals. To save yourself the stress and hassle of dealing with a skin condition, do your research before your purchase any grooming product for your dog. Here's a veterinarian written article on how to shop for the best shampoos and grooming products.

8. Try Some Over the Counter Medication…

Benadryl, the same allergy medication that humans take to help control their allergies can be given to a dog, for the same purpose. This medication is especially helpful to give to dogs that are having problems sleeping due to their itchiness. The general guideline for giving dogs Benadryl is to give a dog one milligram of Benadryl per each pound of their body weight. Never give a dog more than two doses of 50 mg of Benadryl in a 24-hour period.

9. …Or Veterinarian Prescribed Medication

If no other treatments work, and/or if your dog’s skin condition is exceptionally bad, and/or causing the dog discomfort and difficulty in their everyday life, doing the things that they normally do, you’ll need to take your dog to see a licensed doctor of veterinary medicine who can prescribe a wide-variety of prescription strength oral medications, such as antibiotics and can also prescribe your dog prescription strength medicated shampoos and ointments.

Additionally, a veterinarian can perform any one (or multiple) of the following diagnostic tests that can help to determine exactly what is causing your dog’s skin condition, which will in-turn allow the vet to best treat and clear it up. Here are some of the diagnostic tests that your vet can perform: a) allergy testing; b) bacterial culture; c) cytology; d) fungal culture; e) physical exam; f) skin biopsy; g) skin scraping.

READ NEXT: 9 Ways to Improve Your Dog’s Skin and Coat Health