These are only my own thoughts on the above products, when I have considered them in the past. Not to be taken as gospel, by any stretch of the imagination.
Boots:
Pros:
- protect against cuts and abrasions - the best at avoiding these issues
- maybe a little insulation against cold with socks
Cons:
- can cause abrasions if not socked and taped properly
- reduces traction (I don't think even the rubber ones provide as much traction as dog nails)
- because of lack of traction and dog feet moving differently than normal, could lead to strain on muscles and connective tissue. Our dogs are running all directions, not just in a straight line, at a mostly consistent speed, like sled dogs.
- pain in the rear end to put on and take off
Pad toughening sprays:
Pros:
- easy to apply
- may provide some moderate protection
Cons:
- messy (I think they use iodine in some of these products, so can stain until dry)
- possible concern for serious paw lickers
- recommend applying for 2 or 3 weeks before you need it. I am guessing you'd get some gradual protection earlier, but not get maximum until later.
Wax based balms:
Pros:
- reduce snow sticking
- provide a layer to protect a little against heat and cold
- that layer might reduce abrasion risk a little (not from sharp things, but from constant rubbing)
- reduces pads drying out and cracking, making them more soft and pliable
Cons:
- I don't think they will do much for sharp crusty ice, other than making pads more pliable and maybe less likely to tear
- might have to reapply throughout the day regarding snow not sticking/balling in fur (but not needed regarding softening pads) -- better approach might be to trim fur between toes, with the downside that fur protects against rubbing abrasions, so don't want to trim too short
I wish there was a perfect solution for all issues, but they all have pros and cons, in my opinion. I am guessing some people out west, dealing with hot ground and cactus spines, would take the pros over the cons and use boots. On slippery ground, I haven't personally decided to do it. If there was a really bad tear or rubbed raw spot in a critical area, that is when I would probably do it. Not sure if I would do both feet at that end of the body, only the hurt one, or all of them. I would probably only do the hurt one, to minimize the cons working against the other 3 feet.
So far, I've been able to get by on dog specific antiseptic gel, and healing powers of the dog, and used the wax stuff from time to time. I also started a skin and hair supplement this year (well before season) to see if that would reduce broken nails in January. I suppose that could help pad health too. I have nail covers for if/when that does happen, and have used those in the past (you cut to fit and super glue them over the broken nail).