If your dog has ever scratched excessively or been injured, you may have noticed a scab forming on their skin. Are scabs on dogs something to worry about, or just a normal process of healing? When should you be concerned if you notice a scab present? Learn more about scabs, how they aid in wound healing, and when you should visit your vet.
What Are Scabs on Dogs?
A scab is tissue made up of many cells. This includes red and white blood cells, proteins, skin cells, collagens, and more. Together, these tissues make up granulation tissue (the new tissue forming) and a scab. A scab is the crusty, protective layer over a wound. It helps by protecting the break in the skin barrier by providing a natural “band-aid”. It also works to pull the healthy edges of the skin back together, much like stitches do in larger wounds. Once the skin underneath has healed, the scab then dries up and flakes off.
How Are Scabs on Dogs Formed
Wound healing occurs in stages: clotting of blood, formation of the scab, tissue rebuilding, and sometimes scarring. Each stage is an important part of the healing process.
When a wound first occurs, the body sends clotting factors via the bloodstream to prevent extra loss of blood. This movement of cells to the wound also brings with it scab-building materials such as white blood cells and proteins. These cells may appear as a slightly yellow-tinged or clear fluid that oozes from the wound as the scab is forming.
From there, the scab forms. This causes local inflammation to encourage the body to send more cells and healing factors to the site of the wound, and to also fight any pathogens such as bacteria that may enter the open wound. Once the scab seal is formed, the tissue begins to heal underneath.
Scabs get smaller from an outward to inward pattern. As the wound heals, the sides of the skin will move inward toward each other. They continue shrinking until finally the remaining scab in the middle is sloughed off.
General Signs to Watch Out For
It is normal for a scab to itch due to the local inflammation and cells moving to the wound. The area may also be slightly red and inflamed. The skin underneath may be red or shiny if the scab is removed too early. Scars are also normal and will fade over time, however, It can take a while for the tissue in the area to return to the same “normal” as the surrounding skin. For deeper wounds, the scar may last for several months or years. Smaller nicks and scratches may not have a scar at all.
However, there are signs that a scab is not healing normally. Repeated loss of scabs without the tissue underneath healing is a sign of concern. Scabs that don’t seem to heal or constantly reform is also worrisome. Frequent scabbing is also a sign that you should visit your vet. If your dog has many scabs forming in an area, along with other signs such as hair loss, itching, or systemic symptoms, it’s a sign of something more ongoing.
Scabs — Causes and Comparisons
Here are some of the most common reasons why you might find a scab on your dog’s skin:
Trauma and Minor Wounds
Rips, tears, and wounds caused by trauma are the most common causes of scabs. As it heals, a scab forms over the wound — a sign that the body is reacting normally.
However, if the wound is more than a few centimeters in length, or larger than the size of a dime, it may be too large for a scab to properly heal. In this case, the wound may become infected, leading to further inflammation, swelling, and pain at the site of the wound. If your dog has a very large wound, it’s best to seek veterinary care to have the wound closed with sutures, so that a scab can form in the reduced surface area.
With a normal scab, or a sutured site, treatment involves keeping the area clean and dry, and free of debris. If the area is very red or inflamed, a hot compress can be placed on the wound twice daily for 10-15 minutes to help reduce swelling. Antibiotics or pain medications may also be provided by your vet to prevent bacterial infections and to reduce pain symptoms that may cause your dog to scratch or paw at the wound.
An Elizabethan (cone) collar or a T-shirt covering the wound is also beneficial in helping it heal. By preventing your dog from licking or chewing, the scab will not be accidentally removed, and the area can heal with less irritation.
Scabbing with Hair Loss
Hair loss, in addition to excessive scabbing of your dog’s skin, can be a sign for concern. If the affected area is very itchy, your dog may scratch or lick, which can cause the hair to fall out. Some parasites may also cause hair loss, along with systemic changes such as metabolic illnesses.
Diagnosis of general hair loss and scabbing involves a thorough exam. Your vet may take a skin scraping, a non-invasive procedure that involves gently scraping a layer of cells from the skin and placing them in a growth medium. This is then monitored over time, or looked at under a microscope, to determine the cause of the skin irritation.
Any underlying causes should be treated as the scabs and hair loss will continue otherwise. If there is no apparent cause of the hair loss, your vet may recommend a few different treatment options for your dog. The first line of defense is an Elizabethan collar or cover over the scabs to prevent excessive scratching and hair loss. Allergy medications such as Zyrtec or Benadryl can also be useful in reducing itching around the affected area. Pain and anti-inflammatory medications can also help reduce irritation and prevent further hair loss.
Mange in dogs is caused by the parasite Demodex, and can also be called Demodectic Mange. Scabies mites can also affect dogs, and is referred to as Sarcoptic Mange. These microscopic mites live in the follicles and glands of your dog’s skin, feeding on the cells there.
Mites, like other parasites such as fleas and lice, cause excessive itching, and their feeding on the skin can lead to damage to the skin cells. As a result, your dog may scratch excessively, causing scabs to form in areas where the mites live. In more severe cases, the damage inflicted by scratching and parasites feeding can lead to hair loss and crusting of the skin as dirt, debris, and infection take hold.
Demodex mites are microscopic and can’t be seen by the naked eye. If your vet suspects mange, they’ll take a skin scraping and place the sample under a microscope, where the mites can then be observed. Microscopic mites can be treated with topical medications like Frontline and Advantage, as well as medicated dips or shampoos that are used daily. Some oral medications used for heartworm and parasite prevention such as NexGard and Bravecto can be used to treat mange, however, this is considered “off-label” use. If there is a secondary infection, your vet may also recommend antibiotics.
In many cases, mange is a result of a dog being a stray or left in unhygienic conditions, so it is often rarer to see with family pets. Since some types of mange infect humans, it is important to take care when treating your dog. Be sure to wash all bedding and clothing that comes into contact during treatment. Keeping your dog’s environment clean through regular bleaching, vacuuming, and scrubbing of surfaces can also prevent spread.
Other Skin Parasites
Large parasites, such as fleas, ticks, and lice, can lead to excessive itching and eventual scabbing. Parasites themselves may also resemble oddly shaped scabs, but aren’t. They often hang out on the hair shaft where it meets your dog’s skin. Fleas may be easier to spot on thinner-haired parts of the body such as the belly.
You may also notice flaking of black scab-like specks or other debris. You can perform the “paper towel” test by placing a moistened paper towel u
nder your dog. Then, give them a scratch in areas where fleas frequent, such as the base of the tail. If you notice black specks that turn red landing on the paper towel, it is a sign of a flea infestation.
As with mites that cause mange, most parasites are treated with flea and tick preventives to kill any parasites on the body and stop the life cycle of feeding, egg-laying, hatching, and so on. The most common topicals used include Advantage and Frontline that treat fleas, ticks, and lice. However, oral flea treatments like Capstar, and collar-based treatments like Seresto can also be used on fleas.
For puppies under 8 weeks, plain dish soap can be used to bathe your puppy (and suffocate the live fleas) and then a flea comb to remove them as they are too young for most medications.
Fleas are most active in warmer months and will come out of hibernation to hatch when the weather is right. Ticks and biting lice can hide in the environment, as well as brushy wooded areas. Keeping baseboards vacuumed, regularly washing bedding, and removing brush from near your house can reduce the number of parasites. Visually inspecting your dog for any signs of parasites when coming back inside can also help prevent an infestation.
Bacterial infections are another common cause of scab formations on your dog’s skin. They are often opportunists, using open wounds from cuts and scratches to infiltrate. These microorganisms can cause intense itching and inflammation as they take hold under the layer of the skin, leading to your dog scratching and chewing and worsening symptoms. As the body tries to heal, it will form scabs over the wounds made by both the irritation and itching. If the wound gets large enough, it may turn into an abscess (pus-filled wound under the skin) or hot spot (open wound).
A history and physical examination are your vet’s first steps in figuring out what is going on. A skin scraping and surface cytology can be done and placed in a medium to look for bacterial, fungal, and yeast growth. Samples can also be sent off to a lab for testing of the exact type of bacteria, and the right medi
cation for treating it. However, this is generally only done if the wound is not responsive to more general antibiotics or medicated shampoos.
Treatment involves cleaning and clipping the affected area. Antibiotics may be given orally, or an injection given that lasts 1-2 weeks. Elizabethan (cone) collars are also recommended to keep your dog from licking and chewing. If you suspect your dog has an infection or irritated spot, keeping the area clean and dry can help reduce the chances of a secondary infection leading to scabbing, hot spots, and abscesses. However, worsening or non-healing scabs and wounds should be seen by your vet.
Yeast and Fungal Infections
Fungal and yeast infections are also common skin conditions that can lead to inflammation and eventual scabbing and crusting of the skin. Yeast infections may have a distinct “corn chip” smell to them, however, infections that are irritated may smell off or bad even without yeast, especially if there is oozing from the scabs. Fungal infections tend to start as a small irritation that generally spreads out in size or shape over the skin.
With fungal infections, a Wood’s Lamp or other black light can be used. Fungal infections, especially ringworm, tend to glow brightly under them. Yeast infections can be tested with a skin scraping or plucked section of hair that is placed into a growth medium and observed over 7-14 days.
Yeast and fungal infections are generally treated with medicated daily shampoos, with a thorough drying of the affected area after. Oral antifungal medications such as ketoconazole can be given as well. Preventing your dog from licking and chewing is also best to avoid the spread of the infection. While a T-shirt is sometimes recommended in allergic reactions to stop scratching, it may impede the healing of yeast infections where the area needs to be kept dry and aired out.
Owners should also take care in the case of fungal infections as many are contagious to other pets and people. Thoroughly washing bedding, clothing, and hands after handling a dog that has scabbing caused by fungal infections is best.
Systemic illnesses often affect the entire body, and the skin is no exception. As your dog’s body changes due to illness, you may see skin symptoms such as hair loss, scab formation, and crusting or hardening of the skin (called plaques.) The scabs may be due to the skin attacking itself and leading to wounds, or from scratching or biting areas of the body that are painful or inflamed. Cushing’s Disease and Hypothyroidism are two common metabolic illnesses in dogs, however, Diabetes, Addison’s Disease, and more can all lead to whole-body changes. Immune-mediated diseases like Lupus can also affect the skin.
Diagnosis of systemic issues is usually done by ruling out other causes. Your vet will start with a physical exam to check for parasites or wounds on the body. They’ll also take a history to look for symptoms such as changes in eating, drinking, urination, and bowel habits which may indicate a metabolic change.
Skin scrapings can rule out parasites, bacteria, and fungal causes. Your vet will also likely order blood work, including a metabolic panel and a CBC (complete blood count) to check for anemias, organ dysfunction, and more. From there, they may order specific tests such as blood glucose or an ACTH-stim test to check for specific diseases.
Treatment depends on what the underlying cause is. If your dog is severely ill, such as with an Addisonian crisis, they may be hospitalized until stabilized. Thyroid medications can help supplement lost thyroid hormones in Hypothyroidism. Steroids can reduce the body’s response in immune-mediated illnesses, or reduce cortisol production. Hormone replacement is used to treat Addison’s, while insulin or prescription diets can regulate Diabetes.
A Lack of Scabs Forming
Sometimes, a lack of a scab is cause for concern. Open wounds or sores that don’t seem to heal, or don’t clot may be an indication of a more serious issue, such as clotting diseases, toxicity, or underlying illness. It is always best to have wounds that do not heal or do not stop bleeding examined.
Genetic blood disorders common in breeds like Doberman Pinschers, or ingestion of rat and other poisons can cause prolonged bleeding and is considered a medical emergency. In some cases, long-term injury or repeated wounds can deplete the body’s ability to form scabs and need supportive care with blood transfusions or external wound closure.
Scabs are a normal, natural part of the body’s healing process. Schedule a vet visit if you notice a scab that just doesn’t seem to heal. Your vet can help determine if your dog needs a little help in feeling better.