Painful Truth: What Causes Ulcers on a Dog’s Skin and How to Help

Have you ever noticed your dog scratching a little too much or suddenly developing weird sores that seem to pop up out of nowhere? I get asked this all the time at the clinic: what causes ulcers on a dog’s skin? As a veterinary assistant with a special focus on pet nutrition, I’ve seen my fair share of dogs with skin issues—from minor irritations to full-blown ulcerated wounds. It’s frustrating for pet parents, and even more uncomfortable for the pups. Let’s dig into why these pesky skin ulcers happen, how to recognize them early, and what we can do about them.

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Common Culprits Behind Canine Skin Ulcers

1. Allergies Gone Wild

This is probably one of the top reasons I see dogs come in with skin ulcers. Allergies—whether environmental, food-related, or even from flea bites—can lead to severe itching, scratching, and chewing. When your pup keeps going at one spot, it can eventually break the skin and turn into an open sore. I remember this sweet Golden Retriever named Bella who had a chicken allergy. Her mom had no idea and kept feeding her chicken-based kibble. Poor girl ended up with ulcers near her tail because she wouldn’t stop chewing. Once we switched her diet, things cleared up fast.

2. Pressure Sores (Especially in Larger or Senior Dogs)

These show up in dogs who spend a lot of time lying down, especially on hard surfaces. We see it a lot in elderly pups or big breeds like Great Danes. The constant pressure on elbows, hips, or hocks wears away at the skin, which eventually forms an ulcer. It’s kind of like bedsores in people. Adding soft bedding and rotating their position regularly can do wonders.

3. Bacterial or Fungal Infections

Sometimes, what starts as a minor scratch or bite can get infected. Moisture, dirt, and bacteria are a bad combo. Infections can quickly spiral into full-blown ulcers. A little Shih Tzu I saw recently had a tiny cut on her leg that went unnoticed. After a weekend of licking and scratching, it turned into a nasty ulcer. We had to shave the area, clean it out, and put her on antibiotics. The good news? She healed up beautifully!

Underlying Health Issues That Can Cause Skin Ulcers

1. Autoimmune Diseases

This one’s a bit more complex. Conditions like lupus or pemphigus cause the immune system to attack the body’s own skin cells, leading to ulcers and lesions. These cases are rarer but can be serious. If you notice ulcers on your dog that don’t seem to respond to basic treatment or keep coming back, your vet might want to run some bloodwork or skin biopsies.

2. Nutritional Deficiencies

Yep—what your dog eats absolutely affects their skin health. Diets lacking in essential fatty acids, zinc, or certain B vitamins can make skin thin, brittle, and more prone to ulceration. I always stress this with clients: Don’t skimp on quality food. A balanced, complete diet can prevent a lot of problems down the road.

3. Tumors or Skin Cancers

It’s scary, but some ulcers are actually the result of underlying tumors. If you see an ulcer that seems raised, oddly shaped, bleeds often, or just doesn’t heal, it’s best to get it checked ASAP. These cases aren’t super common, but they do happen, especially in older dogs. I once helped care for a senior Boxer with a mast cell tumor that ulcerated—it was a tough situation, but catching it early made a huge difference.

Other Contributing Factors to Consider

Environmental Triggers

Hot pavement, harsh chemicals, even certain grooming products can irritate your dog’s skin and contribute to ulcers. One time, a client used a new flea shampoo that was way too strong for her pup’s sensitive skin. Boom—red, inflamed patches and ulcers within 24 hours. Always patch-test new products or ask your vet before trying something new.

Parasites and Bug Bites

Fleas, ticks, mites—oh my. These pests do more than just annoy your dog. Their bites can lead to intense scratching and localized infections. Some dogs also have flea allergy dermatitis, where even a single bite can cause a chain reaction. A good parasite prevention plan isn’t just about comfort—it can literally prevent skin ulcers.

Trauma or Injury

Dogs are curious little adventurers. They run through bushes, dig in dirt, and squeeze under fences. Minor scrapes can go unnoticed and quickly turn into something more serious if they get dirty or infected. Keeping a close eye on any scratches or scabs is key to avoiding bigger issues later.

How to Identify a Skin Ulcer on Your Dog Early

1. Signs to Watch Out For

In the clinic, I always tell pet parents that catching things early is half the battle. If you’re wondering what causes ulcers on a dog’s skin?, it’s just as important to know how to spot them before they get nasty. Usually, you’ll notice redness, hair loss in a patch, maybe some scabbing or even a bit of oozing. If your pup keeps licking or scratching a certain spot over and over, that’s your cue to take a closer look. Trust your gut—if something seems off, it probably is.

2. Touch and Smell Can Tell You a Lot

I know it sounds weird, but give that spot a little sniff. Infected ulcers often have a funky, sweet-ish smell. It’s not pleasant, but it’s one of those unmistakable signs. Also, if the skin feels warm to the touch, swollen, or moist, it’s likely an ulcer or something brewing under the surface. I once had a client bring in her Labrador thinking he had a bug bite. Turned out it was an infected ulcer that needed flushing. She caught it early though, and he healed up in no time.

3. Behavioral Clues

Dogs can’t exactly say, “Hey, my skin hurts,” but they’ll show you in their own way. Limping, flinching when touched, or avoiding being petted in certain spots can all be signs of discomfort. One of my regulars, a tiny Chihuahua named Max, got unusually snappy one week. Turns out, he had an ulcer forming behind his ear from a matted area trapping moisture. Once we cleaned him up, his sweet personality came right back.

What To Do If You Spot a Skin Ulcer

1. Don’t Panic—but Don’t Ignore It

First things first—take a breath. Most skin ulcers are treatable, especially if caught early. But ignoring it can lead to serious infections or deeper wounds. Clean the area gently with saline solution or warm water, but avoid using harsh products like hydrogen peroxide unless your vet tells you to. That stuff can damage healthy tissue and slow healing. If the ulcer is open, bleeding, or looks infected (pus, swelling, heat), it’s time to book that vet visit.

2. The Role of the Vet (and What to Expect)

At the clinic, we’ll usually start by shaving the area to get a better look, clean it out thoroughly, and maybe do a culture to see if bacteria or yeast are involved. In some cases, we’ll prescribe antibiotics or antifungals, and if it’s really deep, your dog might need pain meds or even minor surgery. I remember treating a bulldog named Rocky who had an ulcer on his neck that we didn’t want to stitch—too much tension on the skin. Instead, we managed it with daily cleanings and bandage changes. It took a few weeks, but he pulled through beautifully.

3. Home Care Tips from My Daily Routine

Keep the area dry: Moisture slows healing. Use a clean towel to gently pat the area if it gets damp.
Use a cone (Elizabethan collar): I know, your dog will hate it. But trust me—it’s a lifesaver for preventing licking and chewing.
Follow up: Healing can be slow, so keep up with vet rechecks and be patient. A little progress each day is normal.

Prevention is Better Than Treatment—Here’s How

1. Nutrition: The Underrated Skin Saver

Since I specialize in nutrition, I always harp on the importance of a balanced diet. Skin is the body’s largest organ—and it needs the right building blocks to stay strong. Look for dog food rich in omega-3 fatty acids, zinc, and vitamin E. If you’re not sure, ask your vet or someone trained in pet nutrition. I’ve had so many cases where just upgrading a dog’s food made chronic skin issues vanish. No joke. The difference is night and day.

2. Keep Their Environment Skin-Friendly

Soft bedding, clean living spaces, and regular grooming all help prevent skin breakdown. If your dog’s a swimmer or loves the outdoors (muddy hikes, anyone?), make sure to rinse and dry them off afterward. Dirt and moisture trapped in the coat can create the perfect storm for ulcers. Regular brushing also helps you catch potential trouble spots before they become serious.

3. Stay on Top of Parasite Prevention

Monthly flea and tick preventatives aren’t just for bug control—they’re also your first line of defense against ulcers caused by bites and allergic reactions. I’ve seen dogs chew themselves raw from one flea bite. Keeping those pests away is worth every penny.

4. Know Your Dog’s Risk Factors

Is your dog a senior or has mobility issues? Watch for pressure sores.
Does your pup have known allergies? Stick to hypoallergenic food and grooming products.
Does your dog have thick fur? Check for mats, especially after baths or rain.

Knowing your dog’s unique needs makes you a more proactive pet parent. I always tell folks—you know your dog better than anyone else. When something feels off, follow that gut feeling. It’s usually right.

When Skin Ulcers Keep Coming Back

1. Chronic vs. Acute Cases

Alright, let’s be real—sometimes ulcers on a dog’s skin don’t just show up once and vanish. I’ve worked with plenty of dogs who battle recurring skin ulcers, and the root cause isn’t always obvious. That’s when we start talking about chronic issues instead of one-time events. Think: long-term allergies, autoimmune conditions, or even hidden infections that never fully clear up. If your dog’s dealing with the same sore spot over and over, don’t just slap on a cream and hope for the best—it’s time to go deeper.

2. Digging Deeper with Diagnostics

When things get persistent, your vet might suggest some advanced testing. I’ve assisted with skin scrapings, cytology (basically looking at the cells under a microscope), and even biopsies when things look suspicious. Blood panels can also check for immune system disorders or underlying disease. One case that really sticks out in my memory was a shepherd mix named Luna. Her skin ulcers just wouldn’t heal. After months of flare-ups, we finally found out she had an underlying thyroid issue. Once that was treated, her skin dramatically improved. That’s why getting to the root cause matters.

3. Specialty Care and When to Ask for a Dermatologist

If your regular vet hits a wall, don’t be shy about asking for a referral. Veterinary dermatologists have advanced training and tools that can make all the difference for tough cases. In fact, many of the chronic ulcer cases we couldn’t crack in general practice eventually found solutions through specialty care. Sometimes it’s just about having more specific diagnostic tools, or targeted therapies you won’t find over the counter.

Supporting Healing Holistically (From a Nutrition-First Perspective)

1. Supplements That Actually Help

Now, not every supplement lives up to the hype, but there are some that I personally recommend because I’ve seen them work. Omega-3 fatty acids (like fish oil) are anti-inflammatory and support skin healing. Vitamin E, probiotics, and even turmeric (in proper dog-safe doses) can also be helpful depending on what’s going on. Just always check with your vet first—some supplements interact with meds or aren’t right for every dog. One of my favorite success stories was a Frenchie named Milo who had recurring skin ulcers from food allergies. With a combo of a novel protein diet and omega-3s, he finally stopped scratching and those ulcers healed for good.

2. DIY Doesn’t Mean Do-It-All-Yourself

It’s tempting to try every homemade remedy you see online, but be careful. Natural doesn’t always mean safe. Things like tea tree oil, apple cider vinegar, and garlic often pop up in DIY skin care tips—but they can be toxic or too harsh for dogs. I always remind clients that while you should absolutely be proactive, your vet (or a knowledgeable veterinary assistant like yours truly!) should be part of your skin care team. It’s all about working together for your dog’s comfort.

Maintaining Skin Health Year-Round

1. Seasonal Flare-Ups Are Real

Just like people, dogs can have seasonal allergies that affect their skin. Spring and summer are big triggers thanks to pollen, grass, and bugs. In winter, dry indoor heat can make the skin flaky and irritated. I usually tell folks to track their dog’s flare-ups in a journal—over time, patterns can help us tailor a care plan. Even something as simple as a humidifier in winter or wiping down paws after walks in the spring can reduce the risk of ulcer-causing inflammation.

2. Grooming = Prevention

Keeping your dog’s coat clean, tangle-free, and trimmed helps you spot issues early and avoid matting (which traps moisture and leads to ulcers). Some dogs need professional grooming; others just need weekly brushing and the occasional bath with a gentle, skin-supportive shampoo. If your dog has skin sensitivities, ask your groomer to skip scented products or harsh chemicals. I’ve seen so many flare-ups just from perfumed sprays that were meant to “freshen up” the coat. Trust me—less is more.

3. Stay Consistent, Not Reactive

Managing your dog’s skin health isn’t about reacting when things go wrong—it’s about consistent care. That means regular vet checkups, a healthy diet, parasite prevention, and keeping a close eye on any changes. If you do all that, you’ll be way ahead of the game. Skin ulcers are painful and frustrating, but with the right approach, they’re totally manageable. You’ve got this—and your pup is lucky to have you on their team.

References

Disclaimer

This article is for informational purposes only and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult your veterinarian if you suspect your dog is experiencing any health issues.

Camellia W

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