If you ask any veterinarian or human general practitioner what is one of the most common reasons for a visit, the answer is sure to be some type of skin problem. Think about it. The skin is the largest organ in both the human and dog body, and it is designed to protect the body against all sorts of intruders, including germs or minor injuries.
Skin ailments also lead to a sense of frustration as there are hundreds of causes in both pets and humans. Something such as canine acne or human acne can be the result of an underlying disease, or something as simple as oils from the skin becoming trapped. The more visible the problem, the more likely we are to rush for medical care.
All of us, human and pet alike, have skin the is structured the same way. There is an outer layer, called the epidermis the next layer, called simply the dermis, and an under layer of fat and muscle which is called the punniculus. Together, the two top layers form the cutis, with the panniculus called for obvious reasons the subcutis.
Even thought the epidermis is charged with protecting us from disease, it is relatively thin. It is comprised of building blocks called keratinocytes. Knowing this you can now appreciate that when your skin is scraped or a wound is formed, it leaves the body open to those things that are normally blocked by the outer skin layer. These mechanisms are the same in pets and humans. This is probably why nature saw to it that this skin layer quickly repairs itself. If an area is constantly injured, the repair thickens to provide extra protection for the area.
When infection does try and take hold, a type of cell called a langerhan cell calls in reinforcements from the white blood cells to kill off any bacteria fungus or viral infection. Skin reactions often occur when these cells work too well, and begin to react to every day things in the environment such as plants, shampoo, fabric etc. This immune response results in an allergy to these items, cause some type of skin reaction.
Last, is the issue of sunburn. The mechanism for this is called the photoprotective barrier. In nature, dogs and cats developed coats to limit the amount of sun exposure, particularly since they lived outdoors in the wild. In humans we've adapted though sunscreens, hats, clothing and by staying out of the sun. Our pets can get sunburned just like humans, with the same amount of risk.
Skin tumors in humans and pets are the result of basal cells, the layer of cells between the dermis and epidermis receiving too much sun exposure. This causes these cells to rapidly divide, resulting in a neoplasm or dog skin tumor.
One major difference between humans and our dogs are the hair follicles, as you could have guessed. Interestingly, while humans have one hair per follicle per pore opening, dogs and cats have multiple hairs. These hairs also act to spread pheromones, which help to drive sexual attraction. The hair is also a window into the underlying health of the pet or person, with hair loss in dogs often indicating some type of endocrine related disease (hormonal disease).
Our skin is unique because it is so visible. It is also difficult to diagnose because of the many causes of dog skin and human skin disease. It's also a unique organ in that dog owners and humans alike demand that it be maintained in perfect condition, a high bar for any natural organ. What's wonderful, is that our understanding of skin structure in humans, and treatment approaches, directly applies to with way we address skin problems in dogs and cats.
Dog Skin Conditions, Dog Health Guide