One of the skin’s most important functions is to maintain the body’s internal environment, protecting various body constituents, preventing the loss of moisture, and providing a dog or cat with the sense of pressure and touch.
There are often significant differences in the skin of different species. Notable differences between canine and human skin are as follows:
| Canine | Human | |
| Epidermal Layers | 3-5 | 10-15 |
| Epidermal cell turnover | Every 20 Days | Every 28 Days |
| Sweat glands | Foot Pads | Whole Body |
| pH of the skin | 7.5 Neutral | 5.5 Acidic |
Another major difference is that our canine friends produce multiple hairs out of a single follicle while humans and cats only produce a single hair shaft.
Human shampoos should not be used on our dogs and cats. The acid pH of their hair products will dry and damage their neutral pH skin.
A Dog’s Coat
The primary function of the hair coat is to protect the skin from physical and ultraviolet light damage. It is also helpful in the regulation of body temperature. It conserves heat by trapping dead air space between secondary hairs, which requires that the hairs be dry and waterproof. The cold-weather coat of many dogs is longer and finer to facilitate heat conservation. To facilitate cooling, the warm-weather coat has shorter, thicker hairs and fewer secondary hairs that allow air to move more easily through the coat. Scientifically, hair and fur are made of exactly the same material, a protein called keratin.
Puppies are born with simple hair follicles (one hair per follicle). They are covered by a short, soft furry-like hair. Puppies have all the hair follicles it will ever have at birth. By six to eight months the hair follicles become compound (a central hair surrounded by 3 – 15 smaller secondary hairs, all in the same follicle). At this time the hair coat becomes a coarser, longer, and usually darker hair coat. Breeds and individuals have different rates of coat development. Factors such as day length, hormones, average outdoor temperature, and nutrition all influence coat development.
Hair growth occurs in cycles or phases. Phase I is called Anagen. This is when hair is produced. The new hair grows alongside the old, which is subsequently lost. Phase II is an intermediate stage called Catagen which signals the end of the growing phase. Phase III or Telogen is the resting phase where the follicle is considered dormant. The size, shape, and length of hair are controlled by genetics and hormones. Disease, drugs, nutrition, and environment can affect the health and growth cycles of hair.
Dogs have two types of hair. There are short fluffy hairs called secondary hairs, underfur or undercoat. The second type of hair is the longer and stiffer outer hairs called primary hairs, outer coat or guard hairs. The ratio of primary and secondary hair differs by breed and age.
There is no such thing as a non-shedding canine breed. The extent to which an individual dog sheds is governed by such factors as age, amount of sunlight, outside temperature, breed, sex, hormones, allergies and nutrition. Indoor dogs tend to shed in a more or less continuous fashion because of artificial heat and more importantly light. Outdoor dogs and cats tend to shed for several weeks during major seasonal changes, most notably in spring and fall. They tend to grow more secondary hairs or underfur in the fall for warmth. In the spring they lose the underfur and replace much of it with the longer primary or guard hairs. The hair coat changes in appearance and texture but the absolute numbers of hair follicles and hair does not.
Oil & Sweat Glands
Oil glands (also called sebaceous glands) secrete an oily substance called sebum into the hair follicles and onto the skin. Oil glands are present in large numbers near the paws, back of the neck, rump, chin, and tail area. Sebum, a mixture of fatty acids, is important for keeping the skin soft, moist, and pliable. Sebum also gives the hair coat sheen and has antibiotic properties.
Dogs have sweat glands on the feet that may play a minor role in cooling of the body. Dogs primarily release excess body heat through panting and drooling.
Types of Coats
Hairless
Continuously Growing Coats
Most dogs grow their coat to a specific length and then the hair growth stops. In other breeds, the hair keeps growing. They may not appear to shed as much, but all dogs except for the hairless breeds shed. Breeds with continuously growing hair coats include:
- Afghan Hound
- Bedlington Terrier
- Bichon Frise
- Irish Water Spaniel
- Kerry Blue Terrier
- Maltese Terrier
- Poodle
- Portuguese Water Dog
- Schnauzer
- Soft Coated Wheaton Terrier
Wire-haired Coats
Wire-haired dogs have coarser textured hair that is more bristly than smooth. Many wire-haired dogs also have a characteristic beard. Most of the Terriers have this type of coat.
Curly Coats
Some breeds have curly coats based on their genotype. Straight hair is dominant over curly.
Breeds noted for their curly coats include:
- Airedale
- Irish Water Spaniel
- Curly Coated Retriever
- Poodle
- Welsh Terrier
- Wirehaired Fox Terrier
- Bichon Frise
The following breeds can have either curly or straight hair based on their genotype:
- Havanese
- Kerry Blue Terrier
- Kuvasz
- Portuguese Water Dog
- Soft Coated Wheaten Terrier
Corded Coats
Corded coats are both curly and continuously growing. The Puli and Komondor are examples of a breed with corded coats. This type of coat protected these herding breeds from wolves since the coat is so thick even wolf teeth couldn’t penetrate it.
Hairless Breeds
A few breeds do not grow any hair at all like the Mexican hairless and American Hairless Terrier. One variety of the Chinese Crested grows hair on its extremities while another the Powder Puff has long hair covering its entire body.
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