Man, sorry to hear about your dog, that beyond sucks.
I have two dogs who sleep up by the house about 80 yards from the grow and it was a windy night... they didn't hear squat, besides, they bark so often I can't get out of bed every time....

As far as a motion detector, doesn't it go off when the wind moves the plants? What about rodents like ground squirrels? I'm not sure that would work. Can anyone chime in on this?

So far I have set up personal alarms, small gizmos of the type where you pull a pin which causes a high pitched 120db sound until the pin is replaced. I tie an improvised 'trip line' to the pin and tie it across the areas where the thief would have to traverse to get to the plants... hell I can even tie it to the plant... who wants to run off with a screaming plant? Anyway, I bought over a hundred of these alarms at a local auction, way more than I need but that was the size of the Lot. You can buy them individually on Ebay for $4-$8 a piece... Or buy them from me since I got way too many now, LOL.

I think my next step will be motion lights outside the grow. Looking at a possible car battery with solar 2 or 5 watt trickle charger. A normal battery should run 500-1000 watts for about 30 minutes.
I'm so damn low on funds though, not sure when I can do this. Looking to see what else I can do NOW that's $50 or less....
Thanks to all who have replied, I love it, I'm getting all kinds of good ideas from your input.

Lastly some good news. The thieves left two immature Sour Diesel plants which are now in full bloom and looking out-freakin-standing!!!!

Later all.....