Can Dogs Get Rain Rot? What That Crusty Patch Usually Is

What rain rot actually is

The name describes the weather, not the germ. Rain rot is dermatophilosis, a bacterial skin infection. It is not a fungus, even though some pages online mix it up with ringworm. The Merck Veterinary Manual’s professional chapter lists cattle, sheep, goats and horses as the animals most often affected, with “pigs, dogs, and cats rarely” affected.

The bacteria can sit on the skin without causing trouble. What lets them take hold is skin that has lost its normal barrier, and the main thing that does that is water. Iowa State University’s Center for Food Security and Public Health names “prolonged wetting by rain, high humidity, and high temperature” as the factors that let the bacteria spread. Merck’s owner page adds that outbreaks “often occur during rainy seasons,” because wetness helps the bacteria grow and release the spores that spread the infection.

The spread itself is mostly by contact. Merck says dermatophilosis is believed to be spread by direct contact between animals, and also lists contaminated surroundings and possibly biting insects. The Iowa State sheet names flies and ticks.

Why dogs so rarely get it

Look at the animals who do get it: livestock and horses that spend days and nights outside in the rain, often in herds that touch each other, often bitten by flies and ticks, and often standing in wet pens. The Iowa State sheet notes that horses and cattle can develop it on the lower legs “from standing in water or wet pens.”

A pet dog who goes out for walks in the rain and then comes inside to a dry house does not have that kind of exposure. The skin gets wet, then has a chance to dry. That is the main reason the condition is a footnote in dogs. The sources above don’t give a number for how often it happens in dogs. They only say it is rare, so we won’t guess at one either.

The situations that come closest for a dog are the ones that look like a farm animal’s life. A dog kept outdoors in wet weather, a dog with a thick coat that rarely dries out, or a dog that lives or works around horses or cattle with the condition.

What a crusty patch on a wet dog usually is instead

Hot spots. This is the one most people mean when they say their dog “got something from the rain.” VCA Animal Hospitals describes hot spots as red, inflamed skin lesions that appear quickly, ooze, and may contain pus. Its explanation of the wet-weather link is specific: matted fur prevents air from reaching the skin and retains water after a dog swims or gets caught in the rain, which keeps the skin wet. The American Kennel Club says dogs that are frequently wet “from swimming, bathing, or inclement weather are more prone” to them, and names thick-coated breeds such as Golden Retrievers, German Shepherd Dogs, Labrador Retrievers, St. Bernards and Rottweilers as predisposed.

Ringworm. Despite the name, it’s a fungus. The Merck owner page on ringworm in dogs describes bald, scaly patches with broken hairs, notes that people can easily be infected, and says fungal culture of hairs and skin scrapings is the most accurate way to diagnose it. Ringworm is the condition most often confused with rain rot online, and the two are treated differently.

Other bacterial skin infections. Merck lists other skin fungus infections among the conditions vets have to rule out when they suspect dermatophilosis. In practice, your vet will also be thinking about allergies, parasites and everyday bacterial infections, because those are common in dogs and rain rot is not.

Why “rain rot in dogs treatment at home” is the wrong search

That phrase is one of the most common things people type after “rain rot in dogs,” and it is understandable. But the hard part isn’t the treatment. It’s knowing which condition you’re dealing with. Merck says dermatophilosis is diagnosed with laboratory tests on samples taken from the skin, and that the most practical test is looking at fresh crusts under a microscope. Ringworm needs a fungal culture. A hot spot needs its own approach. Treating a guess can mean treating the wrong thing while the real one spreads.

There is some reassuring news if your vet does confirm rain rot. Merck’s owner page says that in most short-term infections the skin heals on its own in 2 to 3 weeks, usually without scarring, and that “treatment is often not required,” though antibiotics can be used in painful or severe cases. That decision belongs to your vet. Keeping the animal dry is part of every version of the plan; Merck’s professional chapter says that keeping animals dry is important.

We won’t list creams, washes or medicines here. Products made for people can be harmful to dogs, and VCA specifically advises asking your vet before using any human medication on a hot spot.

Can you catch it from your dog?

It is possible, but uncommon. Merck notes that the few reported human cases have usually been linked to handling diseased animals, and advises wearing gloves and washing your hands after contact. The Iowa State sheet describes the human form as small, painless pustules on the hands and arms after direct contact with an infected animal, and says to see your own doctor if you’re concerned. Ringworm, the common look-alike, spreads to people more readily, which is one more reason to get the patch identified rather than assume.

What actually reduces the risk on wet days

None of this means a rainy walk is dangerous. Most dogs get wet, shake off, dry and never have a skin problem. The goal is just to keep skin from staying soaked for long stretches, because that is the condition every source above points at.

• Dry the coat down to the skin on thick-coated dogs. The AKC’s advice for dogs that are often wet is to make sure the coat is thoroughly dry each time. Our guide to whether it’s OK to let your dog air dry covers which coats need help and which spots stay damp longest.
• Brush out tangles. VCA explains that matted fur keeps water against the skin. Brushing after the coat is dry stops small tangles from turning into wet pockets.
• Take off wet harnesses and collars. A soaked strap holds water against one strip of skin for hours.
• Don’t leave a dog outdoors in the rain for long stretches. Long exposure to wet weather is exactly what the livestock pattern looks like.
• Keep your dog away from livestock with skin sores. Merck and Iowa State both describe direct animal contact as the main route of spread.
• Look at the skin, not just the coat. Part the fur over the back, rump and legs once in a while in wet seasons. Crusts and mats are easy to miss under a thick coat.

A raincoat can shorten the drying job on a thick-coated dog because less of the coat gets soaked, and the AKC’s view is that keeping thick coats dry matters. It is not a treatment or a guarantee against any skin disease. If your dog wears one, take it off once you’re home so the coat underneath can breathe. See whether double-coated dogs need raincoats for the case for and against.

When to see the vet

Book a visit if you notice any of these, and ask your vet rather than relying on photos online:

• Crusts, scabs or tufts of matted hair that peel off and leave raw or pink skin underneath
• A red, wet or oozing patch, especially one that is growing
• Bald or scaly patches, or patches on more than one dog or person in the house
• Your dog licking, chewing or scratching one spot over and over
• Any sore that smells, hurts when touched, or comes with your dog being quieter or off their food

Your vet will take it from there. The specific diagnosis and treatment are their decision, not ours or the internet’s.