Yes, Shih Tzu has an undercoat.
You can clean and reapply more undercoat.
Dark Undercoat was created on 2007-11-22.
The Burmese has a single, satin coat with no undercoat and no major shedding concerns.
If you choose to undercoat, which is always good, go with something that is liquid and stays liquid. A rubberized undercoat gets hard and cracks, trapping water and grime on the frame causing rust and rot.
American short hairs do not have much of an undercoat to speak of and does not need a lot of grooming or brushing.
No
The American Curl breed of cat has an undercoat but it is very thin and the cat does not shed much at all.
If it's an old car you would have to clean all the crud off the underside and fix any rust and then undercoat it.
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The polar bears have and insulating undercoat as the covering of their skin. This is the topped up by hairs which will protect the undercoat.
Yes, it should be. The required undercoat/primer is available in Home Depot,less than $20 last time I used it.