Those kind are fine. The first thing I do is take a pair of pliers and pull the bit off that's supposed to stop you cutting too much off - it just ,means you can't see what you are doing!
Chuck them away when they become blunt otherwise they squeeze the nail before cutting and the dog will resent it.
Get a caustic/shaving pencil then if you cut too much off you can stop the blood!
CAUSTIC SILVER NITRATE PENCIL stop bleeding nails claws | eBay