==> The other side of dog shedding and dog hair loss
Dog hair life cycle and GSD differences
German Shepherd Dog Hair Growth
By the way, the current generation of mobile devices cannot show hover text notes ('title tag'), so if you're visiting our Periodicals via any phone or tablet or whatever, unfortunately you miss out on quite a bit of background information. However for the photos on the left, in short:
Short Coat German Shepherd
Long Stock Coat German Shepherd
Long Coat German Shepherd
"That is obvious!" - I know but it's rare to find pics with such clarity in coat types, hence why I find it helpful to share these.
After all the recent lengthy Periodicals, this one will be shorter as it does not directly aim to solve a problem (like dog shedding and dog hair loss), but we need this topic to round off the subject dog coat/ dog hair, as obviously all three topics are related.
Thinking about it: This Periodical too may very well solve a problem, and more than a problem of your dog!
Actually, the plan was to further have a picture story Periodical on different GSD coats (with close-up photos showing certain things that I feel need clarification), but the invite to our subscribers (you) to send in something like a macro shot of your GSD's coat unfortunately didn't yield results! If I were as unresponsive as our free subscribers are, no one would ever have received an answer.
You are still more than welcome to send such a macro shot: simply hit reply in one of the countless Periodical emails that you have received. Then I will produce for you a specific Periodical on the topic that I have in mind.
So now, in this Periodical:
- Dog skin versus human skin
- Dog hair - what is it after all?
- Functions of hair
- Dog hair life cycle
- Excursus: human hair loss!
- German Shepherd Dog specialties
Dog skin versus human skin
- to prevent penetration of foreign objects and parasites into the body
- to prevent vital moisture and nutrients from leaving the body
- for people, to regulate body temperature (for dogs, this function is minor)
- and to provide sensation to stimuli in the environment
Indeed, for dogs thermoregulation is a minor function of the skin, you will see below why.
Severely damaged skin will try to heal itself, which may result in scar tissue. Like with people, on dogs too, hair does not grow back on scarred skin, simply because scar tissue is not connected to the blood vessels below, and hair follicles obviously require to be nourished! - If the scar is not too wide, hair from neighboring intact skin cells may grow over the scar though.
The skin sheds too, through a continuous hardening process called keratinization. This is the dander you may see on your dog's resting places if you rarely shake them out (but probably you do, so you won't see much).
Own additions to source image from the excellent
Dog Owner's Veterinary Handbook
Not all but most dog breeds (including most GSDs) have on most parts of their body the type of skin shown in this simplified image, namely with Primary hair and Secondary hair (more on hair types further below). Only the Long Coat German Shepherd - not Long Stock Coat - has (almost) no Secondary hair (undercoat).
Note from the image that hair doesn't grow through the skin (like in body piercing), but rather from within the skin through an orifice (hair canal). Or, in Harry Potter language: a portal.
Also note that dog skin has no sweat glands and sweat pores (no eccrine glands and no apocrine glands) - the core function of which is: thermoregulation, yes!
You can find tons of descriptions and images online that portray dog skin with sweat glands, but those all result from thoughtless copying from human skin, they are wrong. On dog skin, sweat glands are only found in the thick scaly skin of the foot pads - and the foot pads are very much unrepresentative of dog skin.
Dog skin is thickest on back and neck, thinning towards the abdomen, and thinnest in the groin area. Dog hair typically grows quickest in the shoulder region, followed by the flank and the forehead regions.
Regarding canine skin pH (and human skin pH) I can refer to our equally helpful Periodical GSD - Bath or Shower?
Understanding canine skin pH helps you to avoid dangerously stupid "advice" like that which I found on dailypuppy.com: "Kill growth-hindering bacteria on your dog's skin by spraying a mixture of 1/2 cup of white vinegar and 1/2 gallon of water on him after each bath while he is still wet".
You may indeed need a daily puppy, a new puppy every day, because if you follow such dumb "advice" you may outright kill your puppy!
Find out more: Click to save vet cost, training cost, and your nerves!
Conversely, human skin (much simplified) looks like this:
All people (unless they have a defect) have on most parts of their body the type of skin shown in this simplified image, namely with thin, short, and soft vellus hair only - and with sweat glands and sweat pores.
Human vellus hair corresponds in some regards to canine secondary hair, but in other regards to canine primary hair (more on canine hair types further below). I don't like the classification of human hair into primary, secondary and tertiary hair anyway, because this leads to the contradictory classifications that abound in literature. So, let's stick to vellus hair.
Vellus hair is light-colored or transluscent, and normally two millimeters long MAX! On most body parts you can only see it on the human skin when you look really close (well, I can only, I can't know how good your eyesight is).
Terminal hair like that on the scalp, beard, pubic and armpit hair (and on hirsute people on lots of other body parts) tends to further obscure vellus hair. Considering the entire body, human skin harbors an average of about 5 million hair follicles (according to the anthropologist Adolph Schultz), and between 1.6 mio to 25 mio sweat ducts (pores/orifices/portals) - yes, this figure varies widely as sweat ducts are exceedingly difficult to count!
Note that changes in hormone levels can transform some hair follicles from producing vellus hair to producing terminal hair - and back from producing terminal hair to producing vellus hair (namely the hair follicles that are responsive to androgens, which is genetically determined). This may happen through hormones or hormonal stimulants administered with medicaments, or through metabolic hormonal changes like puberty and pregnancy, or through disease or defect (like Hypothyroidism, Cushing syndrome, or Androgenetic alopecia - see the prior Periodical Hair Loss in Dogs).
In the absence of defects, the only human skin where absolutely no hair grows: lips, eyelids, nipples, palms, foot soles, and right on the genitals. - Although they have no hair follicles, our palms do have sweat ducts (as you will certainly have experienced during some handshakes) - and the foot soles have sweat ducts too.
Very much related, just to serve curiosity, on the right you see an awesome whole body sweat map.
How a corresponding map for a dog would look?
Everything would be white, except the foot pads would be yellow.
In some places you can read that "there is no vellus hair growth at the area behind the ears, at the forehead, nose, ..." - but all of this is wrong: You just need to look really close at a healthy person.
The arrector pili muscle in the human skin image further above - that I highlighted so well facilitating my limitless artistic skill (yeah right!) - also exists in canine skin (the Dog Owner's Veterinary Handbook seemingly just didn't find space for it). Arrector pili or pilomotor muscle is a microscopic band of muscle tissue which connects each follicle of human vellus hair and each follicle of canine primary hair through the dermis with the epidermis.
Now, when at rest, the arrector pili muscle has its normal length, and thus the hair shaft emerges from the skin at a shallow angle. But when this muscle contracts - see my ingenious Picasso-styled arrows! - it pulls the hair shaft into vertical position. Can you see how it pulls?
It is this effect that makes our skin hair (and dog primary hair) stand up! And, hopefully you can see it, this piloerection also results in a slight elevation of the skin around each hair shaft - which gives these millions of orifices/portals in the body some cover (like with our eye sockets). This is what people call "goosebumps"! And it happens when the body is under some form of stress, eg:
- when we - or the dog - are in fear
- when we - or the dog - are upset
- or when the skin experiences cold temperature
From my notes in the image further above you can also see that (in both canine and human skin):
- the hair shaft is the part above the skin, and the hair root is in the epidermis, the top skin layer (the part below the hair root, ie in the dermis, is called the dermal root sheath)
- the sebaceous gland disseminates an oily substance (sebum) all across the epidermis (the top skin layer)
- fat cells actually are below the dermis
- elastic fibers hold the skin together
- hair can only grow as long as the dermal papilla is nourished with nutrients through blood circulation!
This leads us back to dog hair.
Dog hair - what is it after all?
Which hair? There are at least three types of hair, and thus three types of hair follicle:
- Guard hair or Primary hair or Top hair gives the outer coat or top coat. It is thick, long and stiff hair that normally grows at one hair per primary follicle. This primary hair is most abundant on the neck and back of the dog, to protect the skin cells from rain and sunrays.
- Secondary hair or Insulating hair or Under hair obviously gives the undercoat. It is thin, short and soft hair that grows at up to 15 hairs per secondary follicle. This hair is similar to the silky soft hair that newborn puppies have (only), and some adult dogs have so little Under hair that they are simply said to have "no undercoat". Long coat German Shepherds are like that.
While dogs that appear hairless, like the American Hairless Terrier, actually do have this thin, short and soft Secondary hair. There is no such thing as a bald dog - unless the dog suffers a severe defect (see the prior Periodical Hair Loss in Dogs).
- Tactile hair or Sinus hair is the thickest and stiffest hair. It is even thicker than Guard hair, however contrary to the other two hair types it is rooted in a blood filled sinus surrounded by sensory cells which amplifies the motion of the hair and thus increases sensitivity to its movements (makes sense for tactile hair)! Most Tactile hair grows on the head: as whiskers, eyebrows/eyelashes, and chin hair. Tactile hair too sheds, but much slower than the other hair types.
New live hair cells grow from the dermal papilla and literally push the older cells up the dermal root sheath (see the skin images further above). Once the older cells are cut off from nutrient supply in the papilla, they die - and while moving up the dermal root sheath they are compressed to form a protein called keratin.
The hair shaft that we see is a compressed compound of keratin, small amounts of water and a binding agent, which holds the keratin and water together. The scales that are clearly visible in the macro shot are what makes the hair flexible.
Functions of hair
The main functions of hair are:
- to prevent foreign objects from reaching the skin (the last barrier of the body!)
- for dogs, to regulate body temperature
- to provide sensation to stimuli in the environment
- for dogs, to serve as signal in social interactions
- for dogs, to provide camouflage in the environment
Compare these functions of hair with the functions of skin further above.
Indeed, for people, thermoregulation is a minor function of the hair - which is a distinct difference not only compared to dogs but also compared to our hirsute ape ancestors, who have about the same number of hair follicles (just that they are all the thick, long, stiff, and thus highly visible guard hair/ terminal hair), but who have only about a fifth of the sweat glands and sweat ducts that we have!
It is the high number of sweat glands and sweat ducts on the human skin that allows our sweat to evaporate between the vellus hairs directly on the skin, and thus to regulate our body temperature. As you can see in the image on the left, even on our scalp - where hair density is highest - there are relatively few hair follicles compared to skin surface area! I have highlighted for you the hair follicles in a section of that same scalp in the image on the right.
The development of hair follicles primarily happens during fetal and perinatal skin development. After birth, new hair follicle formation is rare, both in human skin and in canine skin alike. However, hair follicles periodically regenerate by undergoing repetitive cycles of growth, cessation, and secretion based on genes and hormone balance in the body. This is the hair life cycle.
Dog hair life cycle
If you look through the literature, you will read everywhere that the hair life cycle consists of an anagen, catagen, and telogen phase - and in some sources this is even complemented by a fourth phase: exogen. Like here: "The hair follicle undergoes cycles of growth (anagen), apoptosis-mediated regression (catagen) and relative quiescence (telogen). In each cycle, a new hair shaft is formed, and the old hair is eventually shed, mostly in an actively regulated process termed exogen."
Or here: "Catagen: The brief portion in the hair cycle in which growth (anagen) stops and resting (telogen) starts". - No! When growth stops, nothing but resting (cessation) or regression (secretion) can follow, not a "catagen" phase before resting!
Thus, at best such descriptions are irritating - but personally I find them plain nonsense: Nowhere in biology you have growth, then regression, and then quiescence. You have growth, then quiescence, and then regression. Besides, the above definitions of the hair life cycle people copied from studying mice in the laboratory.
To me, the only sensible approach to defining the hair life cycle in dogs and people is what I wrote above: Hair follicles periodically regenerate by undergoing repetitive cycles of growth, cessation, and secretion based on genes and hormone balance in the body. That's it.
Hair growth you notice when your dog's hair gets longer. Then when the genetically determined hair length has been reached, the hair stops growing: it rests. And when the dermal papilla produces a new hair inside the dermis, the existing hair is shed. In case of dog hair loss, no new hair is produced but the existing dermal root sheath wears out after some time and thus the hair is shed anyway. It really is that simple - if you stick to common sense and simple wording.
So, dog hair growth and dog shedding is a continuous cycle from birth to death. And like with shedding, dog hair growth too is different from dog breed to dog breed, and even among dogs of the same breed: Because the genes, metabolism, feeding, stress levels, and living environment of the dogs are different.
For example, if you feed your dog kibble, you almost certainly need to add a quality skin and coat supplement to the food, because the skin and hair follicles are nourished last, and not much will reach them. Note that Yumega is the top remedy made in the UK (thus in the USA, for once, it incurs high delivery cost).
Now that you know of the dog hair life cycle, you see that dog shedding should not be seen as sudden hair loss in dogs, but instead as the best indicator of healthy dog skin and a well nourished dermal papilla that keeps the dog hair life cycle intact!
If despite all the causes of dog hair loss described in the prior MYGERMANSHEPHERD PERIODICAL you are facing unexplained problems with your dog's hair growth, note that the microscopic examination of the dog's hair shafts (trichography) often reveals one or more of the causes why the dog lacks hair growth.
Excursus: human hair loss!
By the way, in people, androgenetic alopecia (much more common in men than in women, hence also called "male pattern baldness", although androgenetic alopecia actually occurs in women too) is by far the most common cause of baldness (~85%), and it is a hereditary defect:
After puberty (yes, already!), the enzyme 5α-reductase does not properly synthesize DHT (5α-Dihydrotestosterone) - which allows some DHT to reach the dermal papilla (responsible for hair growth, see above). There, the DHT undermines the absorption of vital nutrients required for healthy hair follicles. Being starved to death, the hair follicles shrink beyond the size they need to produce hair!
Thus, in principle stopping hair loss - and indeed restarting hair growth! - in ~85% of people(!) is easy: You only need an effective DHT blocker, and of course balanced nutrition to provide the hair follicles with nutrients! Unfortunately however, an effective DHT blocker that doesn't have severe side effects has not yet been found. - I will not take propecia, no.
A very interesting sidenote of this is: The dermal papilla is nourished directly from the blood capillaries in the skin (the dermis, see in the human skin image above). There is NO orifice ("portal") in the skin that would allow to directly nourish the dermal papilla from the outside - like say with a shampoo, balm, or ... Minoxidil used as a topical on the scalp! This is why Minoxidil is so weak in efficacy. If you're affected by baldness, you know exactly what I am talking about.
So then affected patients try to use more Minoxidil, hoping to somehow "soak" the entire dermis with Minoxidil through sweat pores and hair canals (the only skin orifices) - and promptly they get skin rashes and eczema in the short term, and a whole array of long-term complications from having ruined their sweat glands and sweat ducts, sebaceous glands, hair canals, and the entire dermis and epidermis!
In my view, based on plain common sense following the insight imparted above, a truly effective anti hair loss remedy and/or hair growth remedy has to be systemic (like in "True beauty comes from within"): a pill or liquid to swallow, an injection, inhalation, or stem cell contribution that restarts nourishing the dermal papilla through the blood capillaries by effectively blocking DHT.
Inhalation? Yes, inhaling would be most effective because in the lungs it goes straight into the blood, and the dermal papilla is nourished from the bloodstream (see above). The advantage of inhalation of a substance over injection is that inhalation feeds the bloodstream at a much slower rate than injection does, and slower in this case is good: It gives the body time to react and adapt to the "helper" substance (of whatever kind, here blocking DHT), and thus over time hopefully rendering it unnecessary.
Now, you may or may not have come across Madison Cavanaugh's bestseller The One-Minute Cure or Ed McCabe's Flood Your Body with Oxygen or William Campbell Douglass' Hydrogen Peroxide: Medical Miracle or the like, and you too may be wondering: "Could this maybe help with hair growth too?".
Before you try anything like this, note that the first two are journalists, only Douglass is a medical doctor (and promptly, his book sells as weak as my books sell...). The education of a journalist is: to learn to write in a way that sells well. The more it sells, the better the journalist (yes indeed, radio and TV journalists too first learn to write). Both Cavanaugh and McCabe sell very well, they are great journalists. But even the greatest journalists don't have the education and understanding of a medical doctor or biologist: they learn to research and think in a way that does well.
Note that I am not saying that medical doctors necessarily do the best for you or your dog (they don't). If you have read anything from me, you'll know very well that I am very critical of the conventional western medicine with the type of medical doctors who excel most in routinely writing out prescriptions for medicaments that holistically harm you or your dog more than they benefit you!
But that doesn't mean that I would outright dismiss anything a medical doctor says, and welcome everything a "natural health professional" says (remember here that "professional" means nothing other than to earn money with it!). Rather, I try to integrate the best science-based medical and non-medical therapies from all disciplines ("holistic medicine"), which is probably rather typical for a biologist than for a medical doctor.
So, could a molecular therapy maybe help with hair growth too?
Possibly, but I haven't yet found out which and how. Simply "flooding your body with oxygen" or with hydrogen peroxide as a blanket treatment promoted in book bestsellers certainly is a risky undertaking! Explaining the chemical reactions that ensue in the body would go beyond the purpose of this Periodical, but I can say: It is not as simple and safe as journalists present it in book bestsellers! Hence why I myself practice caution, and why I would suggest you practice similar caution - for hair growth as much as for anything else.
Before you buy into a therapy that presents itself in book form too, make use of the chance to read all the reviews incl. comments that others have left on Amazon. Globally, Amazon customer reviews is the largest (and funniest!) public voice on available remedies, and the more you read and think, the better you'll get at differentiating honest experiences of real users from fake reviews of interest groups!
If nothing else, you will always get a much more balanced view of the subject (which is crucial) - and oftentimes you can have loads of FUN reading them. Here, start with the reviews of McCabe's book (most hilarious), laughing is the best medicine anyway!
Why this excursus? Because I know that ~85% of men and ~40% of women among our subscribers will, at some point, consider this Periodical as extremely valuable information - namely when they (you?) are starting to see hair loss on their/your own scalp.
German Shepherd Dog specialties
One specialty of German Shepherd Dog hair growth has been called medullary trichomalacia, which is a hair shaft abnormality of middle-aged German Shepherds of either sex. The condition is characterized by the sudden onset of multiple areas of broken hairs, especially over the shoulder area. There is no pruritus, pain, or dermatitis associated with this coat abnormality, and the dogs are otherwise healthy. Affected dogs do recover completely after a period of 2 to 15 months. The cause of medullary trichomalacia is unknown, but as no other dogs are affected it must be a hereditary defect.
Another specialty of German Shepherd Dog hair growth (and more so of Nordic breeds) has been called post-clipping alopecia: After clipping (for GSDs this normally means only after surgery), the hair of affected dogs does not grow back at all for months, and total hair regrowth may take up to two years in otherwise healthy dogs. Hair color may change also. The cause is unknown, but histopathology shows a predominance of catagen hair follicles post surgery which suggests a link between trauma and dog hair life cycle.
Final mention here shall be the black hair follicular dysplasia which affects dogs with (partly) black coat - like the majority of German Shepherds: Between age 1 month and 9 months, all black hair is lost! Along with the balding dog, this genetic defect also results in scaly skin in the affected areas. Obviously, if either of the parents show this defect, the dogs should not be bred!
==> Next edition: The essential topic most neglected by dog owners! <==