A complete guide to contact dermatitis in dogs

Contact dermatitis is the least common type of allergy in dogs. Flea allergy dermatitis (FAD) is the most common, with canine atopic dermatitis coming in close second. Allergies are typically caused by repeated exposure to an allergen, which causes immune system hypersensitivity over time. But, some dogs can develop an allergy to a substance after their first exposure. These substances are generally harmless, but the immune system decides to overreact to their presence. See how frustrating allergies can be for pets, pet owners, and veterinarians?

Contact dermatitis results from direct contact with an allergen. Dogs can develop contact allergies to virtually any substance at any age. However, once the cause of the irritation is removed and the associated illness treated, your pooch’s health will improve. Keeping your pup away from the trigger of their allergies will eliminate future flare-ups.

Contact dermatitis is further divided into two categories: allergic contact dermatitis and irritant contact dermatitis.

Allergic contact dermatitis occurs when your dog has an allergic reaction to a substance, like a fabric, metal, or fragrance. It can take several days after exposure for an itchy, red rash to develop.

Irritant contact dermatitis tends to come on quickly in response to an irritating substance. Common irritants include detergents, soap, cleaning chemicals, and acid.

Contact and atopic dermatitis are often confused. Although they can cause similar symptoms, the source of the exposure is different. Contact dermatitis develops because of direct contact with an allergen, like a cleaning chemical or flea collar. Atopic dermatitis, also known as inhalant dermatitis, or atopy, is caused when your pup breathes in an allergen. If your dog has inhalant allergies, they can suffer during ragweed season alongside you.

Further differences include the time of year these allergies appear. Contact dermatitis can pop up at any time, while atopic dermatitis often flares up during spring and fall. These two seasons have the most pollen, mold, and dust in the air, which can trigger inhalant allergies. However, your dog can also develop a contact allergy to the pollen in the grass, causing their feet to become inflamed and itchy.

👉 Your vet needs to diagnose the cause of your dog’s allergies. Without knowing the root of the problem, your pooch may continue to suffer from allergic dermatitis. 

While atopic dermatitis is widespread and affects most of the body, contact dermatitis is localized to the point of contact. A skin rash, red bumps, inflammation, and hair loss are common signs of both types of allergic reactions.

Any substance can trigger contact dermatitis in your dog. Yet, some substances cause more reactions than others. These irritating allergens include:

• Pesticides and insecticides. Sprays used to kill or ward against spiders, roaches, ants, mice, and other pests can irritate your dog’s skin.
• Gardening supplies and chemicals. Fertilizers and herbicides are common chemical allergens found outside. Be wary of the oils found in cedar chips and mulch, because they can also lead to an allergic reaction.
• Cleaning products. Any sort of cleaning chemical can linger on surfaces, exposing your dog to a potential contact allergen.
• Fabric. Leather, wool, carpet, and rugs can inflame your dog’s skin if they lie down on these fabrics.
• Plants. Certain plants, like poison ivy, poison oak, and peppers, can cause an allergic reaction in dogs that come into contact with them.
• Synthetic materials. Your dog may be allergic to plastic, rubber, and metal in items like their collar or toys.
• Soaps, shampoos, and lotions. Heavily perfumed products can irritate your dog’s skin, so stick to perfume- and dye-free products.
• Medications. Topical medications applied to a wound, incision, or ear flap can cause an allergic reaction in your dog.
• Bacterial, fungal, or parasitic infections. Allergies can be triggered by infections caused by bacteria (e.g., Staphylococcus) or fungus (e.g., mold). Common parasites like fleas can also induce a reaction.
• Insect bites. A bee or wasp sting or ant bite can cause your dog’s immune system to kick into overdrive.
• Flea collars or medications. Some pets have a hypersensitivity to the chemicals found in flea preventives and may develop a reaction.

Dogs most prone to allergic dermatitis

While any breed of dog — at any age — can develop a contact allergy, certain dog breeds are more likely to develop other allergies, like atopic dermatitis. If your dog is one of the following breeds, they may be more sensitive to allergens in the environment, whether they’re inhaled or touched:

• Pit bulls
• Boxers
• Bichon frises
• Bull terriers
• Dalmatians
• West Highland white terriers
• Cocker spaniels
• German shepherds
• Beagles
• Irish and English setters
• Lhasa apsos
• Shar-peis
• Pugs
• English and French bulldogs
• Miniature schnauzers
• Fox red Labrador retriever
• English cream golden retriever

Keep in mind that atopic dermatitis generally doesn’t develop in dogs until they’re at least 6 months old, but often appears by the age of 3. Your dog’s symptoms will likely start out mild but worsen over time. In addition, atopic dermatitis typically has a genetic component to it. If purchasing a puppy from a breeder, be sure to ask about any family allergy history to help avoid atopic dermatitis in high-risk breeds.

👉 If your dog is genetically predisposed to atopic dermatitis, they may also be more sensitive to contact allergens. Pets often have allergies to more than one substance, making management a challenge. 

No matter what the cause, most allergies in dogs manifest similarly. In general, allergens cause skin reactions, rather than the respiratory symptoms humans can get. If your pooch has a contact allergy, you may notice the following signs:

• Excessive itching (pruritus)
• Skin inflammation
• Blisters
• Alopecia (hair loss)
• Lesions or ulcers
• Redness or changes in skin color
• Saliva staining on the paws from excessive licking
• Scaly, dry, or thickened skin
• Discharge from the affected area
• Wounds from scratching, chewing, or licking
• A secondary bacterial infection

Common spots on dogs that are affected by contact dermatitis include the abdomen and paws. These two areas touch the most surfaces, so they’re most likely to become irritated.

Your pup’s vet will conduct a physical exam and get your pup’s history. Your dog’s history is the biggest key to determining what they’re allergic to. Your vet will also try to figure out when your pup’s allergy symptoms started and ask questions to see what your pooch was exposed to.

In general, an allergic dermatitis diagnosis is reached by ruling out other potential causes, like FAD or sarcoptic mange. Your vet might do a skin scraping to check for mange mites. They might also do a skin cytology to see if bacteria or yeast are the reason for your dog’s itchy skin. Blood work may also be recommended, since hypothyroidism and other diseases can lead to skin issues in dogs.

If your vet suspects your dog has atopic dermatitis, they’ll likely also recommend allergy testing. Allergy testing lets you know which environmental allergens affect your dog. Skin testing is more accurate than blood testing, so your family vet may refer you to a veterinary dermatologist.

Treatment for contact dermatitis depends on which symptoms your dog exhibits and the severity of their condition. Treatment solutions for your pup may include the following therapies:

• Oral or injectable steroids. Medications like steroids are essential for squelching inflammation. Injectable steroids work much faster than oral steroids, so if your dog has a severe case, they may receive an injection followed by a course of oral steroids.
• Oral antihistamines. Antihistamine products, like Benadryl or Zyrtec, block the release of itch-causing chemicals in your dog’s body.

• Medicated shampoo. Shampoo with antibacterial, antifungal, and steroid properties combats all the potential causes of your dog’s itching, while stripping allergens from their skin.
• Removal of irritants. Once you know what’s triggering your dog’s contact dermatitis, get rid of it! Whether it’s your pup’s bed, your scented lotion, or even your leather sofa, you’ll need to toss it out to make your dog comfortable.
• Skin health supplements. A variety of supplements can help soothe your pooch’s itchy skin. Search for products that contain essential fatty acids, like omega-3s, for superior anti-inflammatory and skin health benefits.
• Hypoallergenic food. Dogs with allergies tend to be allergic to multiple things. Reduce potential hypersensitization by feeding your pup a hypoallergenic diet. If your vet puts your dog on a diet trial to determine if they have food allergies, don’t use omega-3 fish oils at the same time. Flavoring in treats and supplements can interfere with the trial.
• Parasite prevention. Flea and tick prevention keep itchy ectoparasites at bay and can also help treat mange. Again, if undergoing a diet trial, avoid using scented preventatives.
• Antibiotics. If your dog develops a secondary skin infection from staph or a type of yeast infection like Malassezia pachydermatis, they’ll need antibiotics or antifungals.

Contact dermatitis can be extremely painful and uncomfortable for dogs. The good news? As your vet’s treatment plan begins to kick in, there are a few things you can do at home to help. Cold baths can help soothe skin inflammation and anti-itch shampoo can combat the urge to scratch.

👉 But, don’t forget to remove the offending allergen, or your furry pal will keep reacting to the irritant in their environment.

Vet-recommended allergy supplements

Allergy supplements can help prevent a severe reaction if your pooch comes in contact with an allergen. Here’s a couple our vet recommends:

The prognosis for dogs with contact dermatitis is excellent, especially once their allergen is removed. A full recovery can take some time, depending on how severe the allergic reaction was and what symptoms it caused. If a secondary skin infection develops, recovery will take longer and more medications will be needed.