If you mean the lamp itself, decades. If you mean the bulb or element, those may need to be replaced rather frequently based on usage.
You can usually find them amazon. I bought one at Wal-Mart last year though
Acat's heat can can last anywhere between several days and two weeks.
Usually heat cycles last for around two weeks. Every dog is different so it may be longer.
Usually between 14 and 21 days.
They are not exposed to as much heat.
Floor lamps are very durable. This will depend though on the manufacturer and where you buy the product. They are made to last. If it does not cost a lot, then it is not as durable.
HID or high intensity DISCHARGE lamps are lamps without filaments. They work as a gas discharge system which means that they work similar to a flourescent tube, in that they have a ballast system which provides a start-up voltage and then settles down to a running voltage once the lamp is ignited.. The lamp itself usually consists of a quartz shell, filled with some type of gas such as argon, zenon, etc. As a result, they are capable of putting out some serious lumens. The big drawback is that they usually don't last as long as regular incandescent lamps or LED's, and are more expensive to replace.
Most dogs will come into heat twice a year. This can be altered by stress such as being relocated etc. They will sometimes skip a heat. The heat cycle usually last about three weeks from beginning to end.
When was the last time you went to the bathroom??
The filaments inside the lamp get old and burn out one at a time. It is usually the speed you never use is the one that is last to go out... Some lamps are not equipped with 3-way bulb sockets... and a 3-way bulb may not appear to work on all but one brightness.
Heat (or seasons) usually last for around 10-14 days, but can last up to 21 days.
A Yorkshire terrier are usually in heat for 6 weeks, the 2 week, is the best to breed because she is fertilized. And the discharges have gone through allot already!