Dogs nails, unlike human nails, are more often than not, not clear. This means that you cannot see the "quik" of their nail, which is connected to major blood vessels. When a dog's nails are clipped, if clipped to close the 'quik', the nail will bleed profusely; it quite painful to the dog, who can't tell you when you are too close to accidentally trimming too close to the 'quik'.
Most dogs do not like have their nails clipped partially because it is instinctive defense because it is just as painful and dangerous to not clip a dog's nails. Un-clipped dog nails grow into the paw pads or catch on everything (forcing the nail to pull off, often damaging the paw pad and can result in even worse bleeding and other damage to the paw pad) and can literally pull the nail with paw pad off(!!) Although it is rare, dogs seem to know their nails can be particularly vulnerable and have to be trained to sit still while groomed.
Walking, with or without un-groomed nails, is painful to dogs. If your dog need his nails clipped, he is already in pain so the area is sensitive. When you try to clip a dogs' nails and he/she won't let you, it is usually because of combination of defensive anxiety because the dog is already in pain and/or the instinctive fear that the trimming will rupture the blood vessels located within the base of nail. This occurs even in dogs with light/'see through' nails.
There is a product that electronically files dogs nails, specifically to minimize both the risk and potential for harming any dog that is making regular clippers obsolete, called "pedi-paws", that costs $20. Ingrown nails need to be clipped by a vet, however, to begin a regular schedule to clip your dog's nails and protect the paw pad. If your dog has not has his nails clipped on a monthly schedule, it is worth taking him to a vet; vets understand the potential for damage and also can make referrals to an experienced groomer. Groomer's fees for nail trims are under $20, although in severe instances, where the dog's nail is embedded in the paw pad or one or more nails has been caught on something and ripped away from the nail bed, they often will refuse to clip nails because it can be a risk to damaging the dog's paw pad or cause infection. In that case a vet would examine the dog's paws and if necessary, prescribe an anti-biotic and/or anti-inflammatory and clip the dog's nails (vs use the Pedi-Paws or similar trimmer). Whether or not the dog's nails are at a risk for other complications, a vet can also use a mild sedative to calm the dog for routine clippings to help him get used to having routine nail trims.
If you decide to to keep trying this at home, you might want to use the Pedi-Paws product because it gives you more control than clippers. As soon as you notice even a small pinkish color anywhere near the tip of the dog's nail, stop trimming, even if the nail seems slightly too long. Keeping a dish of cold, dry baking soda close by and holding the dog's paw in it, in case you hit the quik of the nail, which will cause it to bleed will stop the bleeding, along with applying mild pressure and will sooth the nail area. (The baking soda should cake onto the nail that has been cut and stop bleeding within 30 seconds. There are also professional powder products used that do the same thing that are less messy.)
None of this, other than having a groomer help your dog adjust to regular nail trims, will stop your dog from 'freaking out' however, not clipping his nails every month, can cause serious damage both to his nails and paw pads. It's not an area where you want to save money because the consequences will end up costing more both to the dog and your pocketbook. Skipping bows, perfumes and similar grooming extras, will help you cover the cost of a good trimmer. (I would stop using the clipper type and taking frequent breaks might also help keeping your dog calm)
Generally, that is why many dogs are afraid of nail clippings, especially, if the quik of their nail has been cut by accident they become afraid of the clippers(just getting too close to it can severely upset many dogs). If they haven't been accustomed to holding still, their moving around can cause clippers to slip into a position closer to the quik of their nail.
Again, to help them overcome their fear, you might need to let a professional do their nails several times until they get used to a different type of trimmer and ask to be close enough to watch the way the groomer helps the dog stay in one position (with your own or other dogs) so you can train them to do the same thing at home, in the long run.
