Why does my dog growl at the others?

I have 4 dogs. 2 male adults and a male & female puppies (5 mo). One of the older dogs growls at the other older dog every time they get close to one another. This just started happening the last month or so.

it could be a dominance issue.

being protective

let's look at this as a family-dynamics Q: PLEASE - forget the CM//DW one-trick pony of 'dominance' as BAD, and 'submission' as Good with a little gold-halo over it!... jeepers, not only is that a huge over-simplification, but it is such a narrow POV that it is like trying to see constellations thru a needle's eye. broaden that perspective, pretty-please? sorry - <calmer now>okay - family dynamics: U have TWO pubertal-pups, one boy/one girl. that's a problem right there. siblings do not generally stay in the same-group by choice - Ms leave first, dad bumps 'em out. Fs may hang-about a bit longer, but post-estrus they tend to split, if not before. Mom does not like sharing-turf with a young-adult daughter. teen-siblings tend to ** fight! ** quite a lot. this leads to tension - not only in the teens, but any other dogs in the household. so altho Mom-dog is not here, there are 2 adult Ms affected by the onset of teen-hood. this is a developmental-stage, just like it is in ppl. if these two are not literal-siblings, they are step-children in the same home - reared as sis + bro. the same tensions will arise, but luckily they will be less-intense - siblings are the pits. if these are REALLY sis + bro, i would sugg re-homing the M. and de-sex the F - particularly as U never mentioned 'neutered', which usually indicates everybody is intact - Whoops! bad idea. U do not mention the Ages or Breeds of the dogs + pups - all 4 same-breed? all-4 same-type - all herders, perhaps? are they all 4 different breeds/mixes altogether? this has bearing, too - 4 dogs of similar-breeds/mixes will share some common-traits, like play-styles + a tendency to get possessive or to share toys easily. so U need to look at this a bit more-deeply. what sort of dogs are they? WHO is the most-confrontational dog? who's the peace-maker? who's the clown? THEN - look at the growling-events. growling is a GOOD Thing - it is valuable + should be treasured. the dog is expressing an emotion - usually fear, sometimes anger. anxiety in one form or another is the root of it. * when does it happen? * who is doing what? * what is going on Before the event? * what happens DURING the event - besides growling? * what happens After the growling? if the *only* thing happening is the growling, i do not see that per se as a 'problem'. ppl grumble and bi#ch at one another quite often - so long as they also talk, laugh, and smile, it's OK. for pity's sake, DO NOT punish growling! (prayer hands) growling is a DoG-sent grace - 'i am getting really upset here...'with growling punished out of existence, a dog who feels truly threatened will have no options left but BITE. (ouch) good luck! (-: