What Are These Crusty Scabs on My Dog’s Back?

Picture of scabs on a dog's back

Scabbing of the skin in dogs is a common issue with many potential causes. Scabs may be a few millimeters to inches in size, appear hard and red or yellow and crusty, and may be associated with reddened skin, hair loss, pus, or an unpleasant smell. Dogs with scabs are often excessively itchy. Read on to find out what causes skin scabbing in dogs, and what you can do if you notice this.

Common Causes of Skin Scabbing

1. Parasites Including Fleas or Mites

Fleas are an extremely common cause of skin scabbing in dogs. Fleas are small insects that can be seen with the naked eye; they live on the skin surface and feed on a dog’s blood through biting. Flea bites are itchy and bothersome, causing dogs to scratch at themselves and create skin irritation.1 In addition to itchiness from the bites themselves, some dogs are also allergic to flea saliva, which causes extremely severe itchiness. Scabs due to fleas are commonly located on a dog’s lower back around the tail base, but can be anywhere.2

Some types of skin mites can also cause itchiness and scabbing, such as the mite that causes sarcoptic mange. Dogs with sarcoptic mange often have hair loss and red, crusty, itchy skin on the ears, legs, or underbelly. Mites are microscopic and must be diagnosed by a veterinarian.3

2. Allergies

Dogs can have multiple types of allergies, including environmental allergies, food allergies, contact dermatitis, and flea allergies, as previously mentioned. Allergies in dogs are becoming increasingly common, and certain breeds may be more prone to them. Environmental allergies may develop in response to allergens such as pollens, dust, or grass, among many others. Dogs with food allergies are most often allergic to a protein source; the most common of these are chicken and beef. Itchiness and skin irritation are the main signs of both environmental and food allergies, but environmental allergies may flare up seasonally depending on the allergen, while food allergies are usually present year-round.4

Contact dermatitis is skin irritation that occurs when a dog touches an allergen or substance that causes skin damage. It may manifest as skin itchiness, redness, and/or hives. Many things can cause contact dermatitis depending on what the dog is allergic to; potential triggers include grasses, synthetic materials, cleaning products, and pesticides, among others.5

3. Skin Infections

Skin infections develop when there is pre-existing skin damage, often due to underlying allergies. When the normal skin barrier is compromised, bacteria and/or yeast can migrate from the skin surface into the deeper skin layers to cause infection. Skin infections are associated with swollen, red, itchy skin, often with overlying scabbing, brown discharge, or pus, and often having a bad odor.6

4. Seborrhea

Seborrhea is a condition in which the sebaceous glands, a type of oil gland in the skin, produce too much sebum, a waxy, oily substance that normally coats the skin to protect it. Sebum overproduction causes a dog’s skin to become red, itchy, and flaky, especially along the back. The skin and fur may feel oily or dry, and may have an unpleasant odor. Seborrhea can be genetically inherited, or develop due to underlying disorders such as Cushing’s disease or allergies, among others.7

Ways You May Help Your Dog if You Notice Skin Scabbing

1. Check for Fleas and Ensure Your Dog Is Up-to-Date on Flea Prevention

Fleas are most easily detected with a flea comb; run the comb through your dog’s fur, especially around the tail base, and look for any live fleas (small brown insects) or flea dirt (flea poop, black specks resembling coffee grounds) caught in the comb.8 Rubbing suspect debris on a wet paper towel can help to differentiate flea dirt from normal dirt: flea dirt is digested blood and will leave red marks when wet.9 Also make sure your dog is up-to-date on flea prevention; this should be taken year-round. Not all flea products are the same, so talk to your vet about which is best for your dog.

2. Bathe Your Dog

Bathing your dog with a hypoallergenic or oatmeal-based shampoo can help to remove allergens or irritants on the skin surface; oatmeal shampoo may also soothe itchiness.10 However, dogs should not be fully bathed more frequently than once every 2 weeks to avoid drying out the skin.

3. Consider Fish Oil Supplements

Fish oil is high in omega-3 fatty acids, which have anti-inflammatory effects to help maintain skin health.1112 Fish-based dog foods are often high in omega-3 fatty acids, but dogs not eating a fish-based diet may take a daily fish oil supplement. This comes in liquid or capsule form and is often given with food. Fish oil is generally very safe, but you should still talk to your veterinarian to determine if fish oil is right for your dog, and at what dosage.

4. Talk to Your Veterinarian About Trying an Antihistamine

Antihistamines like Benadryl® and Zyrtec® can be taken by most dogs and are available over-the-counter. These medications may help with mild to moderate itchiness due to allergies, but are not effective in all dogs, and are often not sufficient to control severe itchiness.1314 Before giving this (or any) medication to your dog, you must first consult your veterinarian to ensure this is safe for your pup, and to determine the appropriate dosage.

5. Schedule an Appointment With Your Veterinarian

Dogs with underlying health conditions, severe itchiness, or significant skin lesions should be evaluated by a veterinarian. The vet will examine your dog, perform diagnostic tests to determine the cause of the skin scabbing, and prescribe the appropriate treatment to get your pup feeling better.

Article Sources

Pet News Daily uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

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  3. Dryden MW. Mange in dogs and cats. Merckvetmanual.com. Updated June 2016. Accessed April 11, 2022.
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  8. American Society for the Prevention of Cruelty to Animals. Fleas and ticks. Aspca.org. Accessed April 11, 2022.
  9. FleaScience. What is flea dirt? Fleascience.com. Accessed April 11, 2022.
  10. Zabel S. Shampoo use in veterinary medicine. Vin.com. Accessed April 11, 2022.
  11. Lenox C. Role of dietary fatty acids in dogs & cats. Todaysveterinarypractice.com. Published August 19, 2016. Accessed April 11, 2022.
  12. Popa I, Pin D, Remoué N, et al. Analysis of epidermal lipids in normal and atopic dogs, before and after administration of an oral omega-6/omega-3 fatty acid feed supplement. A pilot study. Vet Res Commun. 2011;35:501–509. doi:10.1007/s11259-011-9493-7
  13. Weir M, Buzhardt L. Over-the-counter (OTC) medications that can be safe for dogs. Vcahospitals.com. Accessed April 11, 2022.
  14. Shipstone M. Antihistamines for integumentary disease. Merckvetmanual.com. Updated June 2016. Accessed April 11, 2022.
Dr. Jennifer Masucci
Dr. Jennifer Masucci, VMD is a graduate of the University of Pennsylvania School of Veterinary Medicine. Through multiple years of working as a small animal general practitioner, Dr. Masucci is particularly well-versed in canine and feline medicine. Dr. Masucci is passionate about educating pet owners, so that they can offer the best care to their furry companions.