There is a volunteer search and rescue organization in my area. I've been considering getting involved. Has anyone seen a English Mastiff get involved in this work? My main concern is lack of endurance and overheating. Any info. is appreciated. I presently have a four month old Mastiff. She's easy to train and great to live with.

I have a feeling that you will not find anyone out there using english mastiffs for this type of work. One of the general requirments of any SAR dog reguardless of breed is that the team must be able to work 3 consecutive 8 hr days without affecting performance. I think the same reasons you have already stated would put you outside of that requirement.

Scott, those are valid concerns. Some things to consider are what kind of SAR are you thinking of getting involved in? Are you talking disaster work or wilderness SAR? If wilderness, what type of terrain would you be working in? Also, understand that becoming a SAR dog handler is not just about working the dog, it is also about working you. You will need to become certified in first aid, CPR, and a host of other areas of training in which you will have to demonstrate your abilities through written exams and participation in real missions, without the dog. Certifying yourself will take a year or more, depending upon how your local group handles such things. And then there is certifying your dog, which is a separate thing.
Basically, any dog with the drive and ability to do the work and with the stamina to work long hours, can succeed in SAR. This dog might not be right for the work, but training him or her to do so could be an invaluable experience for you, to determine whether or not you have what it takes. If you do, then you might consider getting a more appropriate breed for the work later down the road. If you don't, then you will have had some great experiences with a great bunch of people, and hopefully will not have wasted their time. One way to ensure that you do not waste their time, is to volunteer first to help them by hiding from their dogs, so that at least you can serve a function in that way. Understand that they will not train your dog for you, but they can certainly help you train your dog if they think you and your dog have what it takes. In other words, ask your local group how/whether you can get involved, and see what they say.

Thanks for the feedback. The Mastiff Club Of America is trying to re-establish this breed as a "working dog". They mention among other things search and rescue work. Aside from being a great companion dog and possibly a good therapy dog, I don't see alot of work in the future.
The group that I was talking about is always open to new people. They encourage new people to come WITHOUT THIER DOGS to watch, learn and hide from thier dogs. They say to bring an article of clothing in a ziplock bag or new paper grocery bag. I realize it's a huge undertaking to commit to this volunteer position. They say it's a three year process that turns into a reserve position on the Los Angeles Sheriffs Dept. Volunteers carry a pager and radio. They train for cadaver, underwater and quite abit more. My interest lies in dog training. This type of group could really teach me alot and at the same time I could be giving something back to the community. That's it for now. Scott