you r right navjot, now i m telling u the situation, of my problem. i have three st. bernared, two females, one male and one female labredore. all are staying in a hall on terrace( 2nd floor) but there in no saperate cages. and also they have sufisiant space to walk and play, outside the hall, the door of hall is open 24 hrs. problem is this, in day time they all are quite and play. but in the night, they start fighting( i think)... and barking, after few interwells. and when i go to see them, they stop barking. so i dont know the reason. tell me how can i manage this situation. and please tell me from where i can get anti bark coller, or any other product.