Get a grip
We've got squirrels, lots and lots of squirrels. We have so many that they are driving the dogs and myself crazy. Poodles have drive; each individual varies but mine have a bucket load full. The Standard Poodle was the original water retriever so the drive to chase it high. Elsa's drive is higher than Luke's; he can sit quietly watching a squirrel for hours, standing like a statue with his tail only slightly vibrating and his nose dripping. You might occasionally hear a tiny whimper but unless they run for the glass he is very statuesque.
Elsa on the other hand comes unglued; she has taken to using the back of the couch as her runway and shrieks a good amount of the time that she is in pursuit. The good thing about poodles is that they have an off switch; even if they are in a highly stimulated zone I can talk them down by simply asking them to "stop" or "get off the couch." If I am previously occupied by writing or working on photos then it will continue, escalating to the crazy zone. Before we moved to CT my dogs had never seen a squirrel in a tree; they only knew that squirrels lived in the rocks at the marina and loved to stalk them there.
We have big families of the grey ones here and depending on the day there can be one or twelve running around. When they really get going with their squirrel squabbles it is the toughest on the dogs. They race up trees fighting the whole way, going round and round until one gives in. There is a tree only about 5 feet from the living room window, a perfect spot to squirrel watch from the back of the couch and this is where I often find Elsa.
The secret to getting a grip on this wild and often out of control chase drive is to nip in the bud. Much like any other behavior, once it starts and is at full throttle it is much more difficult to diffuse. So if I foresee a squirrel chase getting out of control I need to stop it before it gets to that point. Elsa often charges up and down the stairs after the squirrels; she runs down to the front to watch them and when they get out of sight she charges upstairs to the back of the couch. Getting a grip on these instinctive driven behaviors are tough to crack once they are full on.
Any environmental stimulus that can rev a dog into a frenzy needs to be dealt with. The dog or dogs who get themselves wound by the squirrel or whatever it may be needs to learn to get a grip. Luke has got things pretty much under control; I simply don't allow the craziness. Every once in a while Elsa will push Luke past his limit with her charging around the house, but knowing that it is now becoming a daily issue I am addressing it much sooner so that it does not get to that "crazed" point.
There is lots of training to do, new things to learn and teaching "how to get a grip."