Just for your information (this is not meant to be offensive in anyway shape or form)
A professor of mine is writing a book about this mountain lion problem in Northern California, where he is from. The reason your parents and their neighbors are having more instances of sightings is simple...basically, as the surrounding areas grow further and further from city centers (like Sacramento) there roaming area is shrinking. So say a mountain lion needs 50 acres to survive and sustain their life. If we get rid of 500 acres there are 10 Mountain Lions that need new homes. They can't move into habitat that other mountain lions live in because of food shortages. Well this is where your parents come in. The mountain Lions can live off of the SAME 50 acres by eating your dog

or calves etc. The problem is where does the line draw....the human population is increading and we do need homes.
This is a really big issue in conservation. Part of the problem is that MOST americans want a single family home with a parcel of land and a white picket fence (I am guilty myself) when we SHOULD live in apartments to save "wild" lands. *sigh* this is starting to should way to much like the papers I am writing.
regardless, it sucks that your parents are having problems with mountain lions. Try to not supply them food by keeping your dog safe, have the neighbors put the cows in the barn. If you limit the food supply they will need to find a new place to live...the danger with this is they might start stalking people. We really just need to STOP moving to Sacramento....

but that will hurt animals elsewhere...
Ok enough of conservation psycho babble...I am just really passionate about all this stuff....if everyone else is aware of issues like this then maybe slowly people will realize EVERY little thing you do does have a great impact on the world and to be consious of it!