Probably the most common mistake people make is to believe  their dog  is  mutt- friendly because it lives with  other dogs.

I get calls on a daily basis from folks  insisting  their,  8 month old, male Bullterrier will be fine in puppy school  because he  lives with  his biological  mother and sister and  therefore loves dogs -  .yeh,  I bet ... guaranteed  he'd  eat a whole one on his own.

You see, dogs at home  are family  but  outsiders are a different story. They look different,  smell different and behave differently and when encountered,  a red flag pops up,  "Enemy ... destroy!",  which is a good  reason why  pups with tiny, milk teeth  should attend  school  where they will encounter  little  foreign  terrestrials,  as well as  a large,  experienced trainer who will liberate  them  from    becoming   terminators  of the Canine race.

Remember dogs are pack animals and providing there is abundance of food  they are  happiest co habiting with other  animals which could be  two-leggeds or   four-leggeds -  be they  feathered, hairy  or smooth   because everyone in their 'cave'  becomes  family'  to  defend fiercely against prevailing cats, dangerous  postmen  or  innocent 4pawed-pedestrians. And this alliance  is taken  very seriously and often  until  death do them part - also a  good reason not  to introduce a new kitten  into a tightly, knit pack  because the results could be counterproductive with  one moggy  less on our planet.

Now another interesting aspect of  doggie relationships is when  out of their territories or on  hallowed  'mutual ground',  family members, sure as hell, gang up on  innocent victims. And  what began  as a simple,  routine inspection of  little  Fluffet's body parts often  prove  a fatal attraction should she take fright and run ... and who wouldn't when impolitely examined  by two, ruddy,  great, testosterone powered   Rottweilers?

Family ties begin early because  sibling pups of  8 weeks  will  gang up  against  the enemy and    one thing is guaranteed -  when pups are off  their home turf  they become Jeckle  and Hydes,  often  shocking their doting parents  rigid with their  distasteful sexual innuendos, racialistic attitudes  and foul body  language!

And don't think  the canine-scanner ever misses an  enemy.  I recall  being alerted to danger  one full night by my   trusty pack who all insisted there was an   intruder on the premises.  Murder was on my mind by the morning .- then I remembered,  I had just  introduced one lucky  rooster into my  run of  14  hens. So you see, family is family  and the enemy is the enemy .... capisce!