A routine bath can turn into a veterinary visit if done incorrectly. Harsh products, rough scrubbing, or poor rinsing can cause skin irritation, infections, and weeks of treatment.

Ivan Ravera specializes in dermatology at the Veterinary Teaching Hospital. He helps pet owners understand how to keep bath time safe.

Your pet's skin barrier

Your pet's skin has a protective barrier made up of skin cells, fats, natural oils, and healthy bacteria that keep skin moisturized and protected from germs and irritants. Proper bathing won't harm this barrier, but harsh soaps, rough scrubbing, or incomplete rinsing can.

"This barrier is the skin's main defense," Ravera said. "In healthy dogs, research shows damage to the skin barrier recovers more than 50% within 24 hours and fully restores within about 72 hours. But more serious damage can take weeks to heal."

What can go wrong

Skin reactions. Some dogs develop irritation or allergic reactions to shampoo ingredients, causing redness, itching, and flaking — especially with harsh products or incomplete rinsing.

Yeast overgrowth. In dogs with underlying allergies or other health conditions, prolonged damp fur can lead to yeast infections, particularly in skin folds and between toes. Signs include itching, a musty smell, redness, greasy scales, and ear infections. 

Dry, vulnerable skin. Bathing with harsh products can damage the skin barrier, leaving skin dry, irritated, and more prone to infection.

Deep infections. Rough brushing, clipping, or scrubbing can damage hair follicles. Combined with contaminated shampoos, this can cause post-grooming furunculosis — a painful deep skin infection that can sometimes require weeks of antibiotics.

Preparation and clean supplies

Check your supplies before bathing. Old shampoo loses effectiveness and can harbor bacteria, especially if water has gotten into the bottle. Replace shampoo that's more than a year old or has been stored somewhere damp.

If you dilute shampoo for easier application, mix only what you need for each bath. 

“Studies show diluted products are contaminated far more often than undiluted ones,” said Ravera. “It is best to dilute products the same day as the bath. Never store leftover diluted shampoo.”

Reusable dilution bottles should be cleaned and dried after each use.

Brush your pet thoroughly before wetting to remove loose hair and mats that trap water and shampoo against the skin. Use gentle strokes; rough brushing creates tiny scrapes that sting when shampoo is applied. If your pet needs a lot of detangling, do it a day or two before bathing.

Use lukewarm water and apply shampoo gently with your fingertips in circular motions, working from neck to tail. Keep shampoo away from eyes, ears, and nose.

Veterinary students drying a dog with a towel

Rinsing and drying

Thorough rinsing is critical. Shampoo left on skin causes irritation that makes it easier for bacteria to take hold.

Run your hands through the coat while rinsing, feeling for slippery spots. If you feel slickness or see foam, keep rinsing. Pay special attention to armpits, groin, under the tail, between toes, and behind ears.

Trapped moisture causes problems, too. Press towels against the coat rather than rubbing. If using a blow dryer, keep it on cool or low and moving constantly; holding heat in one spot can burn skin. Make sure your pet dries completely, especially in skin folds and between toes.

Product selection and frequency

Use shampoos made for pets, not humans. 

“Dog and cat skin is less acidic than ours,” said Ravera. “Human products disrupt your pet's natural balance, creating conditions where harmful bacteria thrive.”

If your vet prescribed a medicated shampoo, follow instructions exactly. Most need to stay on the skin for 10 to 15 minutes. Rinsing too soon means the medication won't work.

Many healthy dogs do well with baths every 4 to 12 weeks, but frequency depends on coat type and lifestyle. Cats generally don't need baths unless they have a condition that makes it hard to self-groom.

Skip the bath and call your vet if your pet has inflamed skin, open sores, or seems uncomfortable when touched. 

"Bathing irritated skin with the wrong products can make inflammation worse or spread infection," Ravera said. "But medicated baths prescribed by a veterinarian are an important part of treatment for many skin conditions."

When problems keep coming back

Contact your veterinarian if your pet develops redness, bumps, excessive scratching, or unusual odor after bathing.

"There's no such thing as 'sensitive skin' in pets," Ravera said. "In my experience, these pets often have an underlying condition. And when you're facing recurrent problems — repeat ear infections, repeat skin infections, repeat itching — 100 percent of the time there's an underlying disease causing it. Most of those cases are allergies."

He recommends that pet owners dealing with recurring skin issues see a veterinary dermatologist. 

"If you don't address the underlying cause right away, it becomes more difficult to resolve the issue."

The Veterinary Teaching Hospital's Dermatology Service provides specialized care for pets with skin allergies, chronic ear infections, autoimmune skin diseases, and bacterial or yeast infections. The team works closely with pet owners and their primary care veterinarian to diagnose conditions and develop long-term management plans tailored to each animal. Appointments are made by referral through your primary care veterinarian.

Veterinary students bathe a dog in a tub