Granted. A pack would be a headache. One, or two max.

As far as dogs in the wild, you don't have to wait until the SHTF. When I lived in Clark County, Nevada in an extremely rural area with a lot of mining communities (eg. high turnover) people would routinely let there dogs loose when the moved. Packs of feral dogs were a problem. In the two years I lived there, I recall three cases of people being attacked. On the other hand, when I lived in the middle of nowhere in Arizona for 20 years, I would routinely see packs of coyotes while hunting and camping. Never had a problem and never talked to anyone who did. Maybe familiarity breeds contempt.

On a related note, I recall a study a while back (can't find the link) by a biolgist in Calcutta, India. He studied the stray dogs in the city and concluded that the little ones die off because they can't defend themselves or reach food (garbage cans and dumpsters I assume). The biggest ones died off because they could not find enough food to support themselves. The medium size (collie, golden retriever size) thrived.

So, if there is an EOTWAWKI situation, being attacked by a pack of killer Chihuahuas is not going to be one of our problems.