posted at 6/3/2011 2:57 PM EDT
There's not a dog out there that doesn't NEED it's nails trimmed regularly.
Like Robin says, they get too long and either curl under or otherwise are putting too much pressure on the nailbed when they walk. That is painful in and of itself and makes them prone to split nails.
Also, the longer the nail gets, the longer the quick gets! So, if you don't cut them often enough, the quick gets longer and you can't simply cut them back to where they should be without hitting the quick. If that happens, you'll have to cut them back as far as possible (just up to the quick) and then recut every two weeks until the quick recedes back to where it's supposed to be so the nail can be as short as it's supposed to be. I know because I made that mistake with Gracie. It was a BIG MISTAKE, but it's corrected, now, and we are back to once a month trims.
It took me about a year and a half to be comfortable cutting Gracie's nails and for her to allow me to do it. It took persistance, patience, and lots of treats and praise. And, at first, my husband had to help; he held her, and I cut her nails.
I've hit the quick twice. It happens, but everyone gets over it. Not that I didn't feel terrible (I cried, actually), but the mistake can be overcome, and I learned from it. I feel pretty confident now that I won't let that happen again - I know what I'm doing and what I'm looking for, finally, and she doesn't squirm and pull away as much.
I recommend the scissor type (not the guillotine), but do NOT use the quick guard on the scissors; it allows you to go too far and, ironically, is what caused me to get her quick once. Push the quick guard out of the way so you can see what you're doing.
I wish I had good advice about making her happy about it, but I don't have anything other than enlist the help of someone she trusts as much as you to hold, comfort, and feed her treats while you do a couple of nails a day until they are all trimmed (it might take a week per month to get them all). Don't try to do all the nails in one sitting. I was happy to get ONE in one session when I first started with Gracie. It took about 6 months before we could even attempt (as a husband wife team) to do all her nails at once.
ETA: Oh, yeah, I would manipulate the scissors near her nails because it made a bit of a noise. I'd praise her and give her a treat as if I'd actually made a cut. She learned to associate the scissor noise with something good. She still doesn't LOVE the process, but she tolerates it.