There are always a few unexpected challenges when you own a giant breed dog like an Old English Mastiff. No matter how carefully you prepare for the giant ball of fluff that's part of your family, you can overlook a potential problem simply because it's hard to anticipate everything that can wrong when you have a dog that's tipping the scales at more than 200 pounds. One of the things that owners often fail to anticipate is a problem with their new home security system. Here are some things you need to know.

1.) Pet-friendly motion sensors aren't friendly to big dogs.

A lot of home security systems have indoor motion sensors that will set off the alarm if movement is detected inside the house when nobody is supposed to be home. To avoid being set off by the family dog or cat, there are systems that can be set to different sensitivities. That usually means that you can make sure that your typical cat or dog doesn't set the alarm off every time you are gone by setting it to only look for human-sized objects in motion.

Unfortunately, that's not something that always works if you have a giant dog. A typical male English Mastiff, for example, can weigh in at 150-250 pounds—easily the size of a human! 

2.) Glass-break sensors can be set off from across the room by these dogs.

Another thing that most owners come to learn (and laugh about) is the incredibly loud snoring that your big, lazy mastiff can do on a regular basis. While it can be a source of amusement when your dog rattles the floorboards with his snoring, you also have to remember that he's also going to rattle the glass of your windows—and it can easily be hard enough to set off the security sensor in the middle of the night. 

You also know that your dog is a drooler—those big jowls don't give him much choice. However, if he shakes his head after taking a drink when you aren't around to wipe his face (and he will), he's going to fling drool pretty hard at the walls and windows. Depending on how close to your window his water dish is, the impact could easily set off the alarm.

Fortunately, security companies train their technicians to help customers overcome even the most complicated security problems. Talk to your security system company about your exact concerns and discuss what options you have. If you are using the security system as a supplement to keep an eye on your dog when you aren't home, for example, you could consider turning off the motion sensors except at night. Your technician can also adjust the sensitivity of the glass-break sensors to make sure that they can tolerate a little more shaking than would normally be acceptable.