Most LED lights will last approximately 8-10,000 hours of use. Equates to about 1 years continuous use. If for Christmas e.g. about 8 hrs per day = 1000 days. Assume 30 days in use per year = about 33 years! Thats the maths anyway!
Not very long if the dog eats them, but have been told some LEDs last up to 100,000 hours, which is over 12 years solid use. So they should see you out at this rate. Not sure what quality these lights are though.
LED lights can have a life span of around 25,000 to 50,000 hours. It can last for about 13 years and 7 months if you use the LED lights for a normal of 10 hours a day. The life time is the main advantage of the LED lights because the traditional bulbs such as the incandescent bulbs give only about 1000 hours of lifetime. Visit http://www.myledlightsource.com/types-of-led-lights/led-tube-lights/ to know more about the different kind of LED lights.