The definitive facts of coats. My credentials to speak of coats: I’m a retired conformation judge (which really isn’t much of a credential as far as coats are concerned). More to the point, I’ve had Giant Schnauzers since 1972 and I’ve been a high-end fibre producer for 20 years (llamas and alpacas).
A hair follicle produces a single “dominant” hair. When this hair is thick and harsh, it’s a “guard hair” which repels water and creates the “roof” of a shell which protects the animal from weather. This guard hair in its thick and harsh form will grow anywhere from a quarter of an inch to a foot or more in length depending on the genetics, nutrition, health, and living conditions of the animal it’s growing on. When the guard hair has grown as long as it can under its particular circumstances, the follicle kicks it out. It sheds.
The important part we have to know about shedding is that a “brand new baby hair” is as thick and harsh as it can be. As the hair grows longer and longer, the follicle gets tired and the hair gets thinner, weaker, and softer.
As you can see, shaving a hair doesn’t pull it out and let a new one grow in. The hair WILL fall out eventually, but if you keep shaving too long you’re going to be constantly working with the bottom weak, soft part of each hair.
Around that single dominant guard hair, each follicle will grow from 2 to 30 “undercoat” hairs. Generally, the harsher and stronger the guard hair, the fewer undercoat hairs that follicle will have.
Undercoat hairs are totally different from guard hairs. They are very short, very thin, and very soft. They don’t repel water well. They’re the animal’s thermal underwear. Some animals grow undercoat all the time, some grow undercoat in the winter and none in the summer.
You can see that no matter how many times this guard hair is cut as it grows, it will never be as thin as an undercoat hair. This is the coat that a working pack llama needs – harsh, weather-resistant, never tangles, easy to keep. Very little leg hair. Sheds out in the spring.
How close together the follicles are, how many undercoat hairs a follicle grows, and how harsh or long a guard hair it supports are inherited separately and controlled by different genes BUT each gene tends to modify genes in the same “department”, as we’re about to see.
When an animal with thinner guard hairs is selected to be bred, all sorts of interesting things start to happen. In general, the thinner the guard hair is, even when “newborn”, the more undercoat hairs that follicle will produce.
Looking at this finer guard hair, you can see that, with enough clippings, it could easily get to the point where you will feel mostly undercoat hairs even though the guard hair is still thicker than the undercoat hairs.
In the next stage, the guard hair has grown even finer. The most interesting part of this process, for me at least, is that as the guard hairs become softer and finer, the undercoat hairs become more prolific AND longer.
You’re pretty close now to the “perfect” fibre-producing animal. The guard hair no longer sheds, and the first time you cut it it’ll be buried in undercoat. From there it will be VERY difficult ever to strip it again. Stripping IS shedding, after all, and this guard hair doesn’t WANT to be stripped. Even if you DO manage to strip it, you’ll get only a minor improvement in harshness. In this animal’s coat, the long, soft undercoat hairs have completely taken over the guard hairs.
And finally, the perfect wool animal. This is the animal that a llama wool producer wants – fine, thin hairs, all the same, soft, with excellent lustre. The “best” coat for this animal will be on the main body. Neck, shoulder, and hip coat will likely be slightly harsher, with guard hairs you can feel as you examine the coat.
There IS a guard hair in there, but it’s the same thickness now as the undercoat hairs, AND the same length. You can’t tell the difference. When an animal has a coat like this, it’s called a “single coat” – Poodles, Portuguese Water Dogs, Bedlington Terriers, and all the other “single coat” breeds have this coat. As you can see, it’s NOT a single coat, but since you can’t tell the difference without a microscope, and it won’t shed, “single coat” is as good a name as any other.
In GENERAL, then, the more leg hair a dog has, the softer and thicker the body coat will be. The less leg hair the dog has, the harsher the body coat will be and the fewer undercoat hairs it will have. The aim, then, according to the Giant Schnauzer breed standard, is to produce a dog with very harsh, strong, thick guard hairs which is still able to produce enough undercoat to keep the dog warm in harsh weather.