I understand the concern.  I was attacked by a pack of pit-bulls late last year and it is a real danger and great concern.  Previously, I carried a legal stun gun, but it became too cumbersome on longer runs and there may be no adequate protection if one is ambushed from behind.  Still, I would say look into the various models of tasers available and consider a military/law enforcement issue type.  I had one that strapped to the waist and upper leg that was very powerful.  (Usually, the sound alone was enough to cause most dogs to retreat). 

In the complete other direction, my sister (Humane Society Director) recommended that I carry along some dog treats.  I did this and it also worked (to distract non-aggressive dogs).  Then again, it was too much trouble to always bring along a baggie of milkbones and so on, but I still do it from time to time, if I know I am going a route likely to encounter the wandering, harmless types. 

Overall, it is ridiculous that we have to deal with irresponsible pet owners, so I would say take whatever measures necessary to protect yourself. 

I feel ya...I carried pepper spray and also used it a few times.  Once, right in front of the owner's 10 year old. I kid you not, but this little brat then DELIBERATELY let it out when she saw me coming until I had a cop talk to her.  Now I carry a 22 loaded with bird shot and bullets once I hit the third round. What is so darn infuriating is that the owners are right there, frequently, and just do absolutely nothing to stop their unleashed and unfenced dogs, growling, hackles up and charging toward me!  I am gonna start drawing (I always bring my carry permit and ID too). It's a real issue - as a health care provider, I know if it bites and it's unvaccinated, at my weight, 140 lbs, i'll be getting about five shots in the ER and a 1000.00 bill.  These yokels don't have a pot to pi$$ in so suing would not be a real deterrent.  While my gun literally folds in half, it is about 8 or 9 oz and takes up most of the space in my waist amphipod. The bird shot is my boyfriend's latest idea and I may end up shooting right in front of these country bumpkins watching their dog attack. Also, honestly, the adrenaline this crap uses up kills me for a mile or two.  I am at a loss as to wht else to do.  Their is no animal control option where I am at.

Surprise dogs are hard to deal plan for.  So, either you carry something to nail them with like pepperspray, or you just have to wing it.

Repeat visits are easier to plan for.  I'll just look for a rock leading up to the PITA and just nail them if necessary.  Premeditated it may be, but this is the way the animal kingdom operates.

Odd timing, but I actually had to try to kick a neighbor's German Shepard to sleep yesterday. I was about 1/4 mi from home with my 9 month old Boxer (thank God I denied my 6 yr old daughter's request to run with me & left the 3 yr old with her & Daddy).  Neighbor's kid opened her front door for her Mom when 2 120+ lb Shepards shot out like a bullet. Thankfully the larger one obeyed the owner & retreated. However, I had to repeatedly kick the other one as it attacked my 56 lb furbaby. My advise?  Pepperspray is ok but what if it's a windy day & you could end up spraying yourself. Running with a gun is a very personal decision. I personally intend to order a collapsable steel baton from Amazon. They're cheap, easy to carry affective. FYI: for those who opt to carry a gun be aware of criminal liability. I've had to defend a client who shot a pitbull in the leg to prevent a 2nd attack on his dog & person. He shot the dog before it got a chance to bite & faced felony charges. There were no witnesses to the "near attack," to support "self-defense.".  It was a real battle to save his record.

Check out this one:

http://www.amazon.com/Dog-Dazer-II-Ultrasonic-Deterrent/dp/B001E0L5YA

It always amazes me how any mention of carrying a gun ends up generating "guns are bad, don't do it, yada yada, so on". No one is advocating that anyone carry a gun. It is simply what I do and I was simply answering the OP. Do or don't, I don't care what YOU do, but I will carry. As the original poster says, he encounters cougars, etc.  In NE Georgia, we are currently having a huge outbreak in rabid foxes. I, and he, run on "country" roads.  I run on on one not dissimilar to the one where a couple was mauled to death by a pack of wild dogs not too long ago.  Ironically, they were animal rescuers and I ended up rescuing two of their cats post mortem.  I would rather be judged by twelve than carried by six.  And as I tried to make clear, animal control doesn't exist where I live.  The sherriff's dept "covers" for them and as a mandated reporter of animal bites, I can tell you they are not proactive but reactive law enforcement personnel when it comes to animals of the four legged variety.

I am trained, I shoot regularly, I own several and feel more than adequate to pull and shoot within ten seconds even with it in the amphi pod all folded up.  This is why i don't encourage people to do it as everyone may not be as willing to stay prepared.  As a single female in a fairly isolated area it serves many purposes and makes sense for me to own a gun and have a carry permit.  Believe me, if you knew how agonizing it is to find safe routes to run and how difficult it was to get my half training in without doing it on a treadmill, I'd win the most resourceful runner of the year award.  Fortunately, that ten seconds is plenty of time as danger, in all forms, usually gives good warning.

There are idiots everywhere but in the rural south, runners are not common place at all.  There is little regard for leashes and keeping dogs in fenced yards simply because only a few people may pass a house during the day that are not in cars.  Cars don't look like chew toys to these dogs....but my legs sure seem to.  I make it sound horrible but I live on four acres of heaven and my lab likes it too.  So while idiots may sometimes abound, it is my lot and I have to find ways to run without driving fifteen to twenty minutes and then trade the dogs for the traffic.

Add rabid foxes, and I have seen a few foxes coming out of the chicken houses where I run, I have to say no to just carrying dog treats or something as unpredictable as pepper spray.  Guns are predictable, they go bang when you pull the trigger.  I have the utmost respect for that concept and just wish dogs didn't have to pay the price for the idiot master.