I have a rather accident prone labrador.  6 weeks of dressing a front paw at the start of the year and 6 weeks ago he was hopping lame and ended up getting a cast on.
I'm sure you can all sympathise and know how difficult it is to keep dressings and casts dry I'm sure.
As soon as the cast was on I trawled the net for something as I knew what a job I had with a dressing earlier in the year.  Plenty of neoprene pull on boots (wore out a pair in 4 days)  and plenty of the hiking boot style which are great if its just a dressing.
Well I found a company in the USA who makes cast cover boots and a company in Ireland.  I contacted them straight away and gave all the measurement and for £40 delivered in about 3 days I had a great pair of boots with leather patches to stop them wearing out and water proof too.

Should anyone be in this situation or just for future reference this is the website.  http://www.dogbootsactive.com

I used the company in Ireland about 5 years ago. Unfortunately I found the boot useless It was very difficult to put it on tightly enough - not a good idea to make it very tight when my dog's badly damaged paw/leg had been caused in the first place by an overtight bandage . The 'boot' came off far too easily and I gave up using it

Daisy

Thats a shame.  I was so impressed after struggling with various other kinds.
The cast did more damage than anything else and Callan was left with awful pressure sores and will probably have a bald hock for a long time if not life now.