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DOG HAIR

Dog hair is made of a hard substance called keratin, an insoluble protein that counts high amounts of sulphur (as the amino acid cysteine) and lesser amounts of the amino acids tyrosine and leucine. Hair emerges from follicles, just below the outermost layer of skin.

In humans each hair grows from a single follicle. Dogs have single and compound hair follicles; a central follicle that produces the primary hair or guard hair may have two or more lateral follicles that produce 5 to 25 secondary hairs each.

Dog hair varies considerable in its coarseness or thickness. Fine dog hairs measure about 75 microns; coarser hair may excess 200 microns.

Healthy hair relies on the balance of the diet: proteins (and especially the sulphur-rich amino acids such as cysteine (converted to cysteine during metabolism), as well as tyrosine and methionine), essential fatty acids, copper, and B vitamins. Up to 30 percent of the daily protein requirements of an adult dog can be used for the renewal of the skin and the hair.

Hormonal factors can also interfere with proper hair growth; thyroid and growth hormone stimulate the activity of the hair follicles, whereas corticoids and sexual hormones slow it down. When prolactin (a hormone produced by lactating females) levels stay high in the blood, the coat looks like the summer one, rather thing and sparse.

Changes in the texture or appearance of a dog's coat are an indicator of something going amiss within, but hair coat changes are not specific for any one disease or condition. Dull or brittle hair can be caused by dietary imbalance, or it may be due to diseases of digestive, hepatic, rental, thyroidal, immune, or parasitic origin. Alterations of hair typically appear rather late in the course of the disease progress before changes are noticeable in the hair. And it typically takes four or more weeks before dietary supplements will have any effects on the quality of the hair.

The shine attributed to a healthy dog's coat is largely due to a complex group of fat secreted through glands in the skin known as sebaceous glands, which function as a natural dispenser of hair conditioners.

Contrary to popular belief, there is no such thing as a dog who does not shed; there are only dogs who shed a lot less. Each hair shaft produced by a hair follicle will eventually die and become dislodged from the skin (shed) and be replaced by a new hair shaft produced by that hair follicle. However, there are some breeds whose hair grows for a much longer period before it dies and is shed.

There are several phases in the activity of a hair follicle:

  • In the first, called the "anagen" or growing phase, the hair is produced by the follicle.
  • The "catagen" phase is a short interlude between the growth and the resting ("telogen") phase.
  • In the "telogen" phase, the hair follicle is basically dormant. 

The growth of the new hair pushes the old hair out of the skin. Even through spring and winter bring on prolific hair growth; the dog's hair follicles are not all in the same phase at the same time, so thankfully he never becomes totally bald!

In humans, the hair follicles on our heads spend most of the time growing (anagen phase).  This phase can last years, depending on the ultimate length of your hair (as determined by your genes). In contrast, the resting phase for each follicle is generally only weeks. Poodles have a predominantly anagen cycle like ours; their hair grows for so long, that is needs cutting (perhaps several times) before it falls out.

Most dogs, though, have a telogen (resting) predominant cycle. In these dogs the anagen phase is short, only long enough to achieve the genetically desired length of coat...anywhere from one month, to a year or more. The hair then cycles into the telogen phase and remains there for a prolonged period of time. This hair is tightly bound within the follicle and will not readily fall out or be pulled out. In the Nordic breeds, it is thought that the telogen phase may last for years.

Finally, any stress such as anaesthesia, disease, pregnancy or administration of certain drugs is likely to put most of the follicles in a resting phase. About two to three months after the stressful event, when the follicles start to be active again, abnormal shedding will often occur.

 

 

 


Contact Details

Taryn Jones
Rockhampton,
Central Queensland, 4702
Facebook:  https://www.facebook.com/pages/Tooshay-Pomeranians/503745683040651
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