Secure the dog before you assess the smell
Skunk spray is intensely painful in the eyes and overwhelming to a dog's nose, and fox scent rolled in or sprayed nearby can send some dogs into a similar frenzy of rubbing, bolting and shaking. In the first minute, shorten the lead, get two secure contact points if he wears both harness and collar, and move him steadily away from the spot. Talk low and slow, let him press against your legs, and do not drag him. A dog who tears free in this state runs blind, which turns a washing problem into a lost-dog problem on the spot.
Check eyes and face once he steadies
When he is standing with you rather than fighting the lead, look at his face. Red, watering or half-closed eyes and repeated pawing at the muzzle suggest spray reached his eyes, which is painful and deserves a vet call for advice, especially if the squinting does not ease. Wipe around the face gently with a damp cloth or water from your bottle if he tolerates it, working away from the eyes. Stop him grinding his face into soil or gravel, which can scratch irritated eyes and skin, by keeping the lead short and his head up while you walk.
The walk home is part of the incident
Choose the quietest, shortest route back rather than finishing the planned walk; his stress and the smell will both get worse with every new dog or startling noise. Keep him out of other dogs' way, cross roads with extra care because a panicked dog lunges unpredictably, and skip any off-lead section entirely even if it is your usual routine. If he is too distressed to walk sensibly, stop somewhere safe, let the worst of it pass, and phone for a lift rather than wrestling him along a busy route.
Washing a sprayed dog, in the right order
Wash him outside, in a garage or straight into the bath before he rubs against furniture, because skunk oil transfers to soft furnishings and lingers there for weeks. Use a dog shampoo and warm water, work it thoroughly through the worst areas, rinse, and repeat rather than expecting one pass to finish it; the face needs gentle care with a cloth rather than soaking, keeping shampoo away from already sore eyes. Fox scent is less oily but equally devoted, and the same patient double wash applies. Ventilate the room, bag any cloths you used, and expect a faint smell to return when his coat gets wet for a few washes yet.
When the incident needs more than a bath
Call your vet if eye pain, drooling, vomiting, lethargy or wounds appear, if you suspect he actually fought with the animal rather than just being sprayed, or if the panic does not settle long after you are home. Keep him off that exact spot for a few walks, since the scent and the memory both pull behaviour in the wrong direction. And because the real danger in those first seconds was flight, remember that KinsLe's Lost Pet Alert System can alert nearby members immediately if a panicked dog ever does break away from you.