Some dogs, due to age or illness, tend to drag their legs; a sort of boot made in synthetic material can help avoiding the continous rubbing on the skin. It can also be used in comination with some types of trolleys.
It's found in commerce in various animal shops and in the following sites: Doggon' Wheels (UK and USA) Doggon' Wheels (USA), Wheelchairs for dogs, K9Carts.
If someone wants something more solid and specific you can always go to a shoemaker having him produce a real leather boot with laces.

Incontinence pads

To limit incontinence problems (often back paralysis involve also the bladder, or more simply age) one can recur to a do-it-yourself using apt baby pads.
Personally I have found slip pads (without lateral openings and with the stickers that are applied on skin) very useful; they must be cut so to leave space to insert it through the legs and leaving the anus, testicles and tail free (only anus and tail for females). Be careful to close up all openings with any sticker type to prevent undesired discharges.

The pad should be chosen according to the size of the dog; take into account that a 9/13 Kg (20/28 pounds) baby pad works for a 25Kg (55 pounds) dog. If the dog is particularly big you can use adult pads.
For females you can use normal menstrual pads too with the appropriate sanitary towel.

Keep in mind that urine irritates the skin, which means you should frequently change the pads and clean the dog!
After cleaning you can smear a zinc cream (the same for baby) to protect the zone from the urine.

I suggest you to visit this website at the page "Incontinence": http://www.srdogs.com/Pages/care.fr.html

You can buy similar products also online. K9Carts uses, for females, a similar pad to the menstrual one but specific for incontinence; you must add and absorbing padding. For males, instead, they use a sort of bandage round the abdomen at the height of the penis; also here you must add an absorbing padding. You can also apply it along with a cart made by the same company, produced with a special sling to which sanitary towels can be applied. America's Doggon's Wheels instead uses a similar pad for both males and females.

The Slee-Pee Time Bed sells special beds for incontinent pets.

Protections for the posterior part, matresses and other

Always in the site K9Carts you can also find protections in cloth for all the back body part (for paralyzed dogs perhaps, when they are not on the trolley they could wound themselves dragging their limbs) and even thermos covers, water mattresses for arthritic problems, ecc.