Crusty Scab on Dog? What You Should Do

Crusty Scab on Dog?  What You Should Do

You’re petting your dog and enjoying a moment of special bonding. But all of a sudden your hand swipes against something hard.  You look beneath the fur and notice a crusty scab on dog.  If you’ve been in this situation before, you know how quickly your emotions can change to worry and confusion. 

What caused the scab on your dog?  What can you do to make sure your dog is OK?  If you’re feeling this way, you’re not alone!  We’re here to help you understand more about some of the possible causes for crusty scabs on dogs.  We’ll also share some ways you can treat the scabs on your dog, as well as a few strategies for preventing them from coming back in the future.

scab on dog

What Causes Crusty Scabs?

There are actually a number of different possible causes for crusty scabs on dogs.  Finding the scab on your dog is the first step. However, identifying the underlying cause will be necessary to find the right treatment plan.  

Below, we’ll share some of the more common causes that can lead to dogs developing scabs.  Reading through this list may help you identify the underlying cause for your dog. However, a visit to the veterinarian may also be in order. This will help to ensure the diagnosis and treatment are accurate and most beneficial for your pup.


There are different types of allergies that can cause you to find scabs all over dog skin.  When you think of allergies and dogs, you may think about food allergies.  While dogs are less likely to have allergies to food than humans are, there are still many dogs who have or develop allergies to food. 

Like humans, it is possible for dogs to be allergic to any food.  However, some foods, such as chicken, beef, soy, wheat, and eggs, are more common allergens.

Some dogs may also be allergic to pollen.  In fact, pollen allergies are one of the most prevalent among dogs.  Dogs with a pollen allergy may sneeze or cough more. They may also develop allergic dermatitis, which could lead to itchiness, redness, sores, and scabs.

Pollen is just one environmental allergen that could irritate a dog’s skin and cause redness, scabs, bumps, or other problems.  Other possible environmental allergens that could be behind your dog’s crusty scabs include sensitivity to shampoos and detergents or chemicals used on the lawns.

Bacterial Infections

That black crusty scab on dog may also be caused by a bacterial infection.  In most cases, a bacterial infection is a symptom of another underlying skin issue.  Most bacterial infections are caused by dogs licking, biting, or scratching their skin due to the irritation caused by the primary issue.  When the dog bites and scratches at their skin, it causes tiny cracks and cuts.  These openings in the skin allow bacteria to enter their system, which can cause an infection.  

Bacterial infections often look similar to acne pimples.  As the dog continues to scratch and lick at these bumps, it can cause crusty scabs to form.

Fungal Infections

Fungal infections may also cause a big scab on dog skin.  Ringworm, one type of fungal infection, is more common in dogs, particularly puppies.  A fungus found in some soils can cause ringworm and make a dog’s skin very irritating, scaly, or bumpy. 

Ringworm can also cause hair loss. So, if you notice that your dog has lost hair, it may mean they have ringworm.  Another way to distinguish ringworm from other causes of crusty scabs is that the area of irritated skin is often circular in shape, or shaped like a ring.

Yeast Infections

All dogs have some yeast on their skin.  However, if the yeast builds up too much, it can irritate the skin.  Yeast is more likely to grow in moist and warm places. So, you may be more likely to find yeast infections in or around a dog’s ears, in the folds of their skin, or between the pads on their paws. 

Yeast infections irritate the skin and can make it very itchy.  As the dog scratches their skin to find some relief from the itch, it can cause crusty scabs to form.

scabs all over dog


External parasites are a common cause for scabs on puppy or dog skin.  Parasites irritate a dog’s skin. They can lead them to try to lick, bite, or scratch at their skin to find relief from the itch.  As the dog scratches or bites their skin, it can irritate the skin even further. This may result in the crusty scabs you’re noticing.

A few common parasites that could be irritating your dog include:

  • Fleas:  It is certainly not uncommon for a dog to deal with a flea infestation.  Fleas are very tiny and can stay hidden on our pets, carpets, and bedding for a long time.  No dog likes having fleas. However, some are more sensitive to them and may scratch or lick at their skin incessantly.  
  • Ticks:  Ticks can also irritate a dog’s skin or cause them to scratch themselves so much that they develop scabs.  Compared to fleas, ticks are much easier to spot.  Work carefully to remove the tick, and be careful to try to get the entire tick out.  There are special tick removal tools you can try to help you with this goal.
  • Mites:  A mite infestation can be very serious for a dog.  Like fleas, mites can irritate a dog’s skin. They can cause them to scratch and bite at their skin looking for relief.  However, mites can also cause mange. Mange is a serious condition where a dog loses all of his or her fur and develops numerous crusty scabs.  There are two different types of mites that can cause mange:  scabies mites and Demodex mites.  Scabies mites are contagious to humans and other animals, while Demodex mites are not.

Immune Disorders

In some cases, an immune disorder can cause a crusty scab on dog skin or multiple scabs.  Immune disorders can limit a dog’s ability to protect themselves against bacteria and infection.  In some cases, when a dog’s immune system is working so hard, it can end up attacking itself.  Scabs caused by immune disorders can be very serious and life-threatening.

Hormonal Imbalances

Hormonal imbalances in the thyroid, adrenal glands, pituitary glands, testicles, or ovaries may also be the reason a dog has scabs all over body.  These imbalances are generally attributed to a dog’s inherited genes. They can sometimes result in skin irritation, hair loss, and crusty scabs.

Nutritional Deficiencies 

If your dog isn’t getting the right nutrients in their diet, it can have a negative effect on their skin and coat.  Nutritional deficiencies may cause rashes, irritates skin, and itchiness. These conditions can result in a crusty black scab on dog skin when your pup tries to bite or lick their skin to find relief.

Additionally, when a dog is getting all the nutrients they need, their skin will have a more balanced layer of moisture and protection against parasites or other environmental threats.

crusty scab on dog

What Does a Dog Scab Look Like and Where are Scabs Most Commonly Found?

What does a scab look like on a dog?  Well, just as you may have noticed that the scabs that form on your skin can vary in appearance and size, the same is true for scabs on a dog’s skin.  Scabs may be large or small depending on the cause.  Some may be more raised, while others may appear flatter.  The color of a scab can also vary slightly and may appear reddish, brownish, or blackish.  In many cases, scabs on a dog will look rather dry, flaky, scaly or crusty in appearance.

Your dog’s coat will impact how easy it is to see their scabs.  If they have a short-haired coat, the scabs may be quite obvious whenever you look at them.  However, if their coat is longer, you may not even be able to see the scabs at all without pushing their fur out of the way.

It is possible for a dog to have a scab on pretty much any area of their body.  However, there are certainly areas where they are more likely to be found than others, specifically the neck or back.  Some dogs may also develop scabs within the creases on their skin due to rubbing and irritation.  In these cases, you may be more likely to find scabs along the belly or upper portions of your dog’s legs.  

How to Diagnose Your Dog’s Crusty Scabs

If you see a crusty or raised scab on dog, you should bring your dog into the vet.  Your vet will be able to perform various tests and gather important information from you. This will help them diagnose the exact cause for your dog’s scabs.  They have a more trained eye, obviously. Depending on the appearance of the scab and the other information you share about your dog’s history or behavior, they may choose to perform one or more of the following tests or examinations below.

big scab on dog

Tests to Diagnose Crusty Scabs

  • Cytology:  For this test, your dog’s vet will take a small sample of the scab and skin lesion using tape.  They’ll place the sample beneath a microscope to get a close up look. This will allow them to determine whether any yeast or bacteria is present in the sample.
  • Allergy testing:  Your dog’s vet may also conduct an allergy test or blood test if they believe allergies are the cause of your dog’s scab.  Allergy testing for dogs consists of injecting small amounts of common allergens under different areas of the skin. Then, the area surrounding the injections are observed for any signs of a reaction.
  • Bacterial culture:  If your vet has already prescribed a treatment for your dog’s scabs that doesn’t seem to be making a difference, they may do a bacterial culture of the site.  Since some bacteria are resistant to certain medications, a culture can provide your vet with additional guidance about the best medication to prescribe.
  • Skin biopsy:  If the vet believes that a scab could be cancerous due to an unusual appearance, they may take a skin biopsy to remove a piece of the lesion.  For this procedure, your dog will be put under anesthesia. Once removed, the piece of the lesion will be sent to a pathologist for further testing.

Treatment Options

The right treatment for crusty scabs on dog will vary based on the underlying cause that is found by the veterinarian.  Your vet will share your dog’s diagnosis along with their recommended course of action to clear up the scabs and keep your dog healthy.  

Some possible treatment options that your veterinarian may recommend include:

Dietary Modifications

As we shared above, allergies are one possible cause for scabs on dogs back or other areas.  If your vet suspects that your dog is allergic to one of the ingredients in his food, he may recommend switching to a different food or a more limited ingredient diet.  

Treatment for Parasites

If your dog’s crusty scabs are being caused by fleas or another parasite, you won’t see an improvement until you clear up their infestation.  Choose a flea shampoo for dogs or talk to your veterinarian about other recommended treatment options depending on the severity and type of infestation.  You should also thoroughly clean your home and any linens or bedding to make sure no fleas remain that could jump back on your dog and start a new infestation.  Starting your dog on a monthly flea and tick preventative is also an important step to take.

Antibacterial or Antifungal Shampoos or Ointments

When crusty scabs are caused by bacterial or fungal infections, your veterinarian may recommend bathing your dog with a special shampoo.  These shampoos can work to treat and clear up the underlying cause of the infection, which will allow the scabs to heal and stop new ones from forming.  

Prescription Medications

Depending on the underlying cause for your dog’s scabs, your veterinarian may also decide to prescribe a medication.  The exact prescription will vary based on what is causing the scab, but may include oral antibiotics, medicated shampoos, or ointments.  If your dog is dealing with seasonal allergies, for example, your dog may recommend using an antihistamine.

If you’ve been asking, “can you put Vaseline on dog scabs,” you probably shouldn’t.  While petroleum jelly isn’t dangerous to dogs, it likely won’t help heal the scab.  The Vaseline can cause the scab to become too dry, which can make it more uncomfortable for your dog and may prevent it from healing properly.  Rather than trying Vaseline, it would be a good idea to ask your veterinarian if there is a cream, ointment, or balm that would be more appropriate to use.

Elizabethan Collars

While you are treating the underlying cause for your dog’s crusty scabs, you may want to have them wear an Elizabethan collar.  Also called e-collars, Elizabethan collars prevent a dog from being able to lick or bite at their skin.  Since scabs are often itchy or painful for dogs, it is likely that they’ll try to find some relief by licking or biting at the affected areas of their skin.  Doing so can prevent the areas to heal or lead to an infection, so using an Elizabethan collar is important to prevent your dog access to these areas.

Preventing Crusty Scabs

Now that you have some ideas for what may be causing the black crusty spots on dogs skin and what treatments your dog’s veterinarian may recommend, let’s discuss some ways you can prevent crusty scabs in the future.

As you can probably guess, the methods to use to prevent those yucky crusty scabs from coming back will vary based on what has caused your dog to develop them in the first place.  However, there are a few general suggestions that are good for all dogs to maintain their skin health and overall hygiene.  Read through the list below and consult with your veterinarian for more specific recommendations based on your pup’s medical history.


Fish oil supplements can help keep your dog’s coat and skin healthy.  When their skin is healthier, it is less likely that they will develop a skin condition that could lead to crusty scabs.  While fish oil and other fatty acids are found in some dog foods, your dog may not be consuming enough to maintain a healthy skin or coat.  Consult with your veterinarian to determine whether they can benefit from a fish oil supplement.


Daily, or frequent, brushing can help keep your dog’s skin and coat clean and healthy.  When you brush your dog, not only does it remove loose hair, but it also gets rid of bacteria, dirt, dandruff, and other debris.  When these debris stay on the skin, you’re increasing the likelihood that something is going to irritate your dog’s skin and lead to potential problems, such as itchy skin or scabs.

Additionally, brushing your dog stimulates their oil glands.  It also works to make sure the natural oils produced by these glands are spread over all of their skin.  Since their natural oils are designed to protect their skin and internal systems, this can be quite helpful in keeping bacteria, fungi, parasites, and other threats from entering their body.


Regular bathing is also important.  While it shouldn’t be done every day, like brushing, most dogs should be bathed about once a month.  Bathing will help remove irritants and debris from the skin.  If you’re concerned that your dog has sensitive skin, it is a good idea to run the list of ingredients in the shampoo you use by the vet.  You don’t want to inadvertently cause a reaction by trying to prevent one.

Using High-Quality Grooming Shampoos and Products

As we mentioned above, some dogs are sensitive to certain ingredients, so you should always be careful when selecting shampoos or other products to use on your dog.  

It may be tempting to save money by purchasing a cheaper dog shampoo, but really cheap products are more likely to be made with ingredients that aren’t as gentle, effective, or even safe as more expensive shampoos.

Allergy Medications

If seasonal allergies are the culprit for your dog’s skin irritation and scabs, then you may want to talk with your veterinarian about giving them an allergy medication.  Just as many humans can benefit from antihistamines, the same is true for dogs.  Zyrtec and Benadryl are two popular antihistamines that your vet may recommend.  Be careful not to purchase an antihistamine with a decongestant (such as Zyrtec-D or Benadryl-D) as they are toxic for dogs.

Flea and Tick Preventatives

As we shared above, fleas and other parasites can cause crusty scabs on dogs.  If your dog’s scabs can be attributed to parasites, then you’ll want to institute measures to prevent future infestations.  Getting your dog on a flea preventative or using a flea collar is an important first step to take.  

Additionally, you’ll want to keep your home and yard clean to take away any places where fleas or ticks may live.  In the home, vacuum, sweep, and mop your floors regularly.  You should always wash all of the bedding (including your dog’s bedding) at least once a week.  In the yard, cut back tall grasses so fleas and ticks won’t have as many spaces to hide.


Final Thoughts – Crusty Scabs on Dogs

A crusty scab on your dog can look pretty disgusting and also be quite concerning.  As we shared above, there are many different possible explanations and treatment options for crusty scabs, so the best course of action is to bring your dog in to see their veterinarian.  Your dog’s vet can help determine the cause for the scab and recommend the best treatment plan to keep your dog and their skin healthy.


What causes crusty scabs on dogs?

There are many possible causes for a scab on dog skin.  Some of these causes include allergies, parasites, bacterial infections, dermatitis, yeast infections, ringworm, immune disorders, and nutritional deficiencies.

How do I treat crusty scabs on my dog?

The best treatment for a crusty raised scab on dog will vary based on the underlying cause of the scab.  Some possible treatments your veterinarian may recommend include treating your dog for fleas, ticks, or other parasites, bathing your dog with an antifungal or antibacterial shampoo, changing your dog’s diet, or giving your dog a prescription medication or topical treatment.

What does folliculitis look like on dogs?

Folliculitis often looks similar to acne when it first appears.  You might see raised red bumps filled with pus on the skin.  The area around the bumps may appear red or swollen, and in some cases your dog may have flaky or crusty scabs or areas of dark spots (hyperpigmentation) as well.

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