Those of us with outdoor-loving pets know the downside to all that freewheeling frolic: muddy paws, tangled fur, and often much worse.

Animal behavior experts have many theories on why some dogs roll in noxious odors. Some researchers posit that getting one’s neck into a smell is an instinctive way to bring info about potential food back to the pack. Others think that rolling in rankness may simply be a dog’s version of teenagers dousing themselves with body spray.

“Perfume or aftershave is used not just to make us more attractive to others, but because we like the smell too,” says Patricia McConnell, animal behaviorist and author of “The Other End of the Leash” (Ballantine, 2002).

Alexandra Horowitz, in her book “Being a Dog: Following the Dog Into a World of Smell” (Scribner, 2016), points to a scent-oriented olfactory lobe in dogs’ brains that lights up when potent smells are nearby. Dogs, she suggests, don’t really differentiate between “good” or “bad” odors. To them, every smell — even rotten squirrel — is just more information.

Luckily, whether you’re dealing with sand, mud or something more, there’s a lot of good gear on the market to help you get Fido clean and fresh-smelling.

If wrangling your pet into the bathtub is nigh on impossible, consider Bissell’s BarkBath portable system. Sort of a wet vac for dogs, the kit comes with a low-suds shampoo. Fill the reservoir with whatever temperature water your pet prefers, and then use the handheld wand to alternately squirt on the water/shampoo mixture and to vacuum up water and residue. One touted feature: Whereas in a traditional tub you’d use about 19 gallons of water to bathe a Labrador-size dog, with the BarkBath you’ll only use 40 ounces.

It can also be used just as a vacuum to remove moisture if you’re dealing with a soggy but not sludgy pet.

McConnell advises easing balky bathers in slowly. Start by lining the tub with treats and adding some to the inside of the tub. Turn the water on gently and reward your pet with a treat. Work your way up to the washing hose using the treats, and be patient. You may need several sessions before a fearful dog is comfortable with the bathing experience.

Don’t use human shampoo on dogs; the pH level is much higher and too acidic for dogs’ skin.

Just need to wash paws? Consider this gadget from Paw Boss: a low-profile water tray equipped with nubby pads in a wash cup, into which you dip paws. City dwellers might appreciate being able to quickly rinse the street grit off their canines’ feet. Bonus feature: vinyl skins for the unit, so you can customize to suit your decor. Options include faux wood, pop-art geometrics, bubbles and metallics.

Simpler still is Pet Product Innovations’ Paw Plunger, a rugged mug with a handle and a soft membrane over the mouth, where you dip the paws. It comes with a lid so you can tote the mug on a walk and rinse off salt or dirt.

If you’re nowhere near water and need a quick cleanup, consider a gentle wet wipe like CleanWell’s , which is steeped in thyme oil instead of the usual disinfecting wipe chemicals like triclosan, benzalkonium chloride or alcohol. Babyganics is another brand made with plant-based ingredients, and no artificial fragrances or dyes.

To deal with tangles and simple hair mats, consider using any inexpensive yet sturdy wide-toothed comb; gently work your way from the back to the head, combing in the direction of the fur.

The FURminator tool, which gets under the top coat to remove loose hair, comes in both a long- and short-hair version.

For short curly coats, consider Conair’s Top Paw, with boar bristles on one side and synthetic ones on the other.