Size Matters!

I was called to a case where a large dog weighing 50lbs had killed a smaller dog weighing only 10 lbs. The details of what happened were somewhat sketchy since my client was not there to witness the event. As best I could, I gathered information from third parties to try and understand what happened.

This is actually quite important because based on the facts I could give my recommendations for how to proceed with the large breed in the future presence of little dogs. It appears that the Chihuahua was a victim of Predatory drift. Predatory drift is related to predation, but is not the same.

Predation is defined as a sequence of behaviors fulfilled in order to acquire food (hunt).
The identifiable behaviors that are part of the feeding sequence are:
• Search (find prey, mainly by sense of smell)
• Stalk (sneak up as unnoticed as possible)
• Rush (move suddenly towards prey)
• Chase (run after the fleeing prey)
• Bite/hold/shake/kill the prey
• Dissect and eat the prey

All canids exhibit some or a few of these behaviors at a given time. Even our dogs that do not hunt for survival anymore can exhibit part of the predatory sequence; this is hardwired. Predatory drift, on the other hand, refers to an instinctual reaction that a dog might have when another animal, such as another (smaller) dog, is identified as
prey (food).

When a (small) dog feels scared or threatened by a larger size dog, either in play or in another type or encounter, the small dog might begin to act as prey by yelping in a high pitch tone, barking, running away from the large dog, etc. In turn, the larger dog may interpret this sort of behavior as coming from prey (another animal he might stalk, chase, grab, kill, etc.) and not a small playmate. Predatory drift happens very quickly, so quickly that preventing it is nearly impossible.

So as you can see by the definitions above, there is a different motivation (hunt/feed) than if the larger dog had injured  or in this case killed the smaller one as a result of aggression.  There are many definitions for aggression but for our purposes here, I will define aggression as:

The intent to harm as a result of protecting oneself or to protect a resource from others. Even though the definition above is very specific (again one can argue there are more “reasons” why animals can be aggressive) I think that with few exceptions they all fall within the realm of protecting oneself or protecting resources.

The situation described above with the two size-dogs had other interesting components. According to witnesses the large dog approached the small dog in a friendly manner, the small dog, which was on a leash, apparently started to move away from the large one.  I am not sure, if he yelped, cried and was even able to run since he was on a leash and the fact that the dog was mortally bitten in the stomach.


When dogs fight they normally do not bite the belly.  Most bites are delivered to extremities, the face including ears or the side of the body.  When dogs actually engage in food acquisition behaviors, they dissect their victim which it appears to be what happen in this instance.

Predatory Drift is actually more prevalent than people think it is.  When I was attending the San Francisco SPCA Academy for Dogs Trainers, I remember very clearly Jean (Donaldson) saying that everyone (in the industry) has had either direct experience with  Predatory drift or knows of someone that has. I also remember how one of our instructors at the Academy owned a Greyhound who was lovely and very well mannered. However, this gentle giant was never off leash at the dog park. Not so much because he would not come back as his recall was quite good and he was now a “retired” Greyhound, but because his owner was very aware of the chance of his Greyhound- a sight hound, engaging in Predatory behaviors towards smallish dogs.

While there are some breeds that can in a pinch exhibit predatory drift all of them as canids have the possibility. The difference (this is a real interesting part…) lies in which of the stalk & kill sequenced behaviors a particular breed will engage in more readily a consequence of the genetic make-up and the “job” or genetic bias of the breed.

Here is an example: Border collies and other sheep-herding dogs have a very “strong” stalking behavior (as a breed - of course there is always differences within individuals) but rarely will they go from the stalking all the way down the sequence to the kill.  They are not “finishers” an industry term.

What is also really interesting is that if they are engaging in a given behavior of the sequence, yes the sequence always take place in the same order… and one interrupts  the dog, it cannot move forward with the next behavior but has to go back to the beginning…  Love those Border collies!


In any event, the take home message is that we all should be aware and educate others about the real possibility of a small dog being injured as a result of Predatory Drift. In addition, it is my recommendations that we do our part in taking the necessary steps when our dogs - be it because of their size, small play companion and or breed to prevent this misfortune.

I will keep my recommendations to my client and his dog a suspense - suspense makes  life interesting, no?  At least until someone is curious enough to post on the blog asking for the answer. :)