Do House-Elves Guard Houses?

[Caius Marcius]

No: HPFGUIDX 19891

In chapter 35 of GoF, during Barty Crouch's "Veritaserum" confession, 
he states how, after Winky was discharged, he lived alone at home 
with his father. 

"'Now it was just Father and I, alone in the house.  And then . . . 
and then . . ." Crouch's head rolled on his neck, and an insane grin 
spread across his face.  "My master came for me.  He arrived at our 
house late one night in the arms of his servant Wormtail
."

Is there an implication here that by casting Winky aside, Crouch Sr. 
forfeited protection which might have secured him against Voldemort?  
We know that house-elves get pushed around a lot, but primarily by 
their masters; we've also seen that they have a command of magic 
which often seems more powerful than the magic of human wizards.  In 
addition to their house-keeping chores, do house-elves also serve 
a "watchdog" function? Logically, it would seem that a house-elf 
would make guarding the house a high priority. Would Winky have been 
able to successfully defend the Crouch household against Voldy's 
intrusion had she still been around? 

That would make Crouch's dismissal of Winky an even more poignant 
episode if it left him exposed to Voldemort's intrusion.

 - CMC