Cynologist

Receptors for the sense of smell occur in the upper, innermost part of each nasal cavity. Minute particles of odoriferous substances are deposited on these receptors, particularly when sniffing, and in some manner not yet understood cause the cells to initiate impulses in the olfactory nerves which are interpreted by the brain as being due to a particular 'smell'. The dog, like most animals but unlike apes and their relatives, has an acute sense of smell. This is at least partly due to the fact that the lining of the nasal cavity, being folded, has a large surface area where numerous receptors can be accommodated. The sense of smell allows the dog not only to find acceptable food, but also to reject unsuitable material. It is also concerned with socially important odours, which may be individually identifiable, and aids identification of the opposite sex. The odour that arises from an animal is complex in origin, but clearly comes from body secretions, including those of skin glands and the specialized glands near the anus of dogs. The forked tongue of a snake is used to sample the air by flicking it in and out of the mouth. When withdrawn into the mouth the animal inserts the forked tips into two openings in the roof Read more [...]

The Ear on the outside of the dog's head is in reality a sound-collecting funnel known as the pinna and forms part of the external ear. The deeper part of the funnel is not easily seen, though it can be felt, and is attached to the bony skull low down at the back of the head. The external ear leads down to the middle ear, a cavity in one of the skull bones and closed off from the external ear by a thin, semi-transparent tympanic membrane or eardrum. The cavity is also connected to the pharynx, at the back of the nose, by a narrow auditory tube which is normally closed but can be opened by swallowing in order to equalize pressure on each side of the tympanic membrane. Within the cavity is a chain of small bones (ossicles), named malleus, incus and stapes from their shapes of hammer, anvil and stirrup. On the inside wall of the cavity, nearer to the brain, are two openings leading into a system of fluid-filled bony tubes forming the inner ear. Part of the system, the cochlea, is coiled like a snail shell; it starts at the vestibule, a large chamber, which in the opposite direction leads into three bony semi-circular canals, associated with the balance mechanism. Mammals generally rely on the sense of smell more than on Read more [...]

The Dog is very aware of its environment through its senses of sight, hearing, smell and taste. The more general senses of touch, temperature, pain and hunger, among others, are also important sources of external and internal awareness. Some sensations probably do not reach consciousness though they play an important part in the functions of the dog. Some senses are of value in appreciating distant stimuli. Both man and dog can normally see movements at the end of the garden, or hear a dog barking in the next street, but appreciation of other stimuli must involve direct physical contact: food cannot be tasted unless it is in contact with the tongue and other parts of the mouth. The different types of sensation have been arranged in three categories as those associated with body surface, internal organs, and with muscles and joints. Skin Sensations Receptors for thermal stimuli (warmth and cold) are present throughout the skin, but are not as well-developed in the dog as in the human. Receptors sense changes in the environmental temperature and allow the animal to seek an equable situation or to lower or raise its body temperature as necessary either by panting or shivering, or by erecting its hair coat or taking exercise. Touch Read more [...]

The dog's skin A dog's skin consists of two basic layers - The epidermis (outer layer) The dermis (inner layer). The epidermis is not nearly so thick in a dog as in humans. The dog's coat performs the protective function for which man needs his thick skin. The dermis contains blood vessels, skin glands (including the sebaceous glands, see below) and hair follicles, from which the hair grows up through the epidermis. In man, the dermis and epidermis are linked by interlocking ridges to give flexibility to the skin. The dog has very few of these ridges except on the thick skin of its nose and foot pads. Obviously a dog has far more hair follicles than a man, and.these help fuse the two layers. The dog's coat Nearly all dogs (except some "hairless" breeds) are covered with a thick coat, made up of a mass of individual hairs, each of which grows from within a follicle. At the base of the follicle, a small papilla produces keratin - the substance of hair. Hairs grow from follicle complexes of several hairs, including one primary, or "guard" hair belonging to the coarser outer coat and several secondary hairs constituting the softer undercoat. Most of the follicles have a small muscle attached. Because of the acute angle Read more [...]

In dog and bitch, the urinary system consists of a pair of kidneys and ureters, the bladder, and the urethra. Urine is manufactured in the kidneys, passes through the ureters to the bladder and is eventually evacuated through the urethra. Each kidney is a bean-shaped organ. Dark reddish-blue in colour and situated on the roof of the abdomen either side of the aorta. It consists of millions of pinpoint-sized filtering units through which the circulating blood passes. Waste products and excess salts and water in the blood pass through these into long, microscopically narrow tubules which convey the fluid to the point on the kidney where the ureter arises. During its passage the fluid is altered until it enters the ureters as urine, the production of which is a continuous process. The ureters are muscular tubes which convey the urine into the dorsal surface of the bladder, a highly distensible. muscular, balloon-shaped sac which narrows to a neck in the pelvis and is continued as the urethra. In the male dog, the urethra is narrow and curves round the near edge of the pelvic floor, passing forward into the penis. The urethra of the bitch is short and wider and opens into the floor of the vagina. The kidneys play a large Read more [...]

Information about the external and internal environment of the body is continously received, analysed and processed by the brain and spinal cord, known collectively as The Central Nervous System. The nerves, which enter and leave the brain, and the spinal cord throughout its length are the routes along which messages, in the form of electrical impulses, travel. Sense organs throughout the body collect information about the environment, such as outside temperature, mechanical pressure, blood levels of oxygen and carbon-di-oxide; they code this information and send it via sensory nerves to the spinal cord and brain where motor nerves convey instructions to an organ or tissue.
Twelve pairs of major nerves in the head arise from the brain and emerge through holes in the skull to reach their target organs such as muzzle, eyeball, teeth or tongue. Nervous to the rest of the body arise in pairs from the spinal cord, and exit from the vertebral column through spaces between one vertebra and the next.

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The simplest way to consider the dog's own complex "food processor" is via the component parts of the gut, each of which is a food-processing chamber with a specific job. These parts often have their own gland producing enzymes related to their job. The order of stages is: 1. Mouth and salivary glands 2. Oesophagus (gullet) 3. Stomach 4. Duodenum, small intestine and pancreas 5. Liver 6. Large intestine and rectum. The mouth Once a dog is aware that food is available or that it soon will be, the guts swings into action. Saliva is produced in the mouth by the salivary glands to begin digestion of the impending meal. In many dog homes, the opening of a particular cupboard or the sound of the can opener is enough to trigger salivary secretion. The Functions of the Saliva Saliva acts as a binder to help hold together a bolus of food, and lubricates the oesophagus to ease its passage. Saliva contains an enzyme which begins digesting starch in the mouth - this is secreted into the food and continues acting in the stomach. Saliva also "cleans" the tongue. The sense of taste is partly dependent on the action of saliva, which washes substances out of foods into the dog's taste buds. Evaporation of saliva from the tongue is part Read more [...]

The function of the respiratory system is to provide the body with a constant supply of oxygen from the atmosphere, and to eliminate from the body waste carbon dioxide gas. It consists of the nose, mouth, larynx, the trachea, the bronchi and the lungs. In the head, the air passage (the nose) lies dorsal to the food passage (the mouth), but in the neck the air passage (larynx and trachea) lies ventral to the food passage (oesophagus or gullet), so that at the back of the throat, the region called the pharynx, the directions that food and air must take cross each other. Swallowing without food or fluid falling into the larynx is made possible by movements of the soft palate and the larynx, as is the continuous channel for air during uninterrupted breathing. Nose and mouth are separated by the hard palate and its continuation, the soft palate, a movable muscular shelf which merges on either side into the walls of the pharynx. The soft palate is so long that its edge cannot normally be viewed; there is no uvula and mouth and nose cavities can communicate freely. The palate can be raised up to block off the rear exit from the nasal chambers during swallowing and lowered to close the back of the mouth cavity during nose-breathing; Read more [...]