Re: how to handle marking
Mine literally was alternating between squatting and lifting his leg for several months to primarily lifting his leg, but not marking after another dog, then started to go after other dogs, and finally lifting his leg everywhere that he smells urine. This last phase seems to have developed in the last week. For the most part, you'll know when it's there and when you have to watch his every move. The one thing I would advise (that I did totally wrong) is if you're going to have other unfamiliar dogs in your place with yours, try to get them to meet on neutral territory first. I didn't do this and mine peed on a friend's shoes. That's the only incident we've had inside and I haven't had any other unfamiliar dogs over since. The neighbor's dog is over all the time without any problems (so far). Beyond that, I'm not really sure what to do.
How sad about the strangulation. I had never thought of that, but the way vizslas romp, I can see how you need to worry about something around their necks.
I had considered using training around marking, so I'm glad you brought that up. My dog seems to out of it when he marks that I sometimes wonder if he knows that he's dribbling in places that I don't care for. If it is something that can be trained, for instance, if I can reinforce him when he marks in appropriate places, that may be the way to go.