You are correct.  When deciding whether to sue, one of the most important considerations is whether you have any actual damages that you can recover from the potential defendant.  If not, it's not worth the time or expense (and attorneys will not take the case).

However, with a dog bite I think it is always worth while to talk to a personal injury attorney who has experience in this area of law, just to make sure you have considered all of your potential damages.  One interesting fact to consider is that if, before the dog attacked you, the authorities in your town had designated the dog as a "vicious" animal, something that often happens with dogs that have a history of biting, you may be able to collect triple damages.  (See Massachusetts General Laws Chapter 140, Section 159.)

This triple damages provision also applies to damages to property.  So, for example, if the vicious animal destroys clothing or even harms another animal, the owner of the dog may have to pay triple damages.  For more information about the law of dog bites, see Massachusetts General Laws Chapter 140, Section 155. Good luck.