Dogs - Physical traits and functions - General characteristics - Teeth - Digestive machine - Skeletal structure

 Physical traits and functions

General characteristics

Dogs come in a wide range of shapes and sizes. It is difficult to imagine that a large Great Dane and a tiny poodle are of the same species, but they are genetically identical with the same anatomic features. All dogs have 78 chromosomes, or 39 pairs of chromosomes (humans have 23 pairs), and one member of each pair comes from each parent. The normal temperature (rectal) of an adult dog is 100–102.5 °F.

Teeth

Dogs have  units of tooth. Twenty-8 deciduous tooth erupt through six to 8 weeks of age, and by the time puppies are six to seven months antique these deciduous tooth are all replaced by means of 42 adult tooth. The permanent tooth encompass incisors, that are used to nip and bite; canine, which tear and shred flesh; and premolars and molars, which shear and overwhelm. In brief, a dog’s teeth function guns and as equipment for reducing or tearing food. The dogs are the top and decrease fangs for which the dog circle of relatives became named. As in most carnivores, the enamel are excessive-topped and pointed, unlike the vast, grinding teeth of many herbivorous animals.

The teething procedure can be tough for dogs. Their gums harm and emerge as swollen, they may lose their appetites, and they may have mild intermittent diarrhea.

Digestive machine

Dogs rarely chew their food. Once the meals is taken into the mouth, it is gulped or swallowed and handed thru the esophagus into the belly, wherein digestive enzymes begin to interrupt it down. Most of the digestion and absorption of meals takes area in the small intestines with the resource of the pancreas and the liver. The pancreas secretes enzymes wanted for regulating the digestive manner. As in human beings, the pancreas produces insulin and glucagon, both of which can be essential for the law of glucose. The liver is the biggest internal organ inside the body. It has six lobes (whereas the human liver has most effective two). The liver is chargeable for many crucial life-retaining capabilities. It facilitates digestion by way of generating bile, which aids in the absorption of fats. The liver additionally metabolizes protein and carbohydrates, and it excretes toxins from the bloodstream. In addition, it manufactures most important blood-clotting marketers. Because the liver plays all these vital functions, liver ailment may be a first-rate trouble in puppies.

Skeletal structure

Dogs are running animals, with the exception of these bred specially for one of a kind functions. For instance, the bulldog, with its huge head and short, “bowed” legs, cannot be called a creature born to chase recreation. Most dogs, however, are properly prepared to run or lope over long distances, supplied that they may be physically conditioned for such activities. The creation of the shoulder and pelvic bones and the manner they articulate with the leg bones and the backbone allow most breeds to trot, run, or gallop without difficulty. Certain breeds have wonderful gaits which have been genetically selected via humans. The German shepherd canine is thought for its “flying trot.” The severe extension of the the front and rear legs causes the canine to appear as if it had been soaring, even though one foot always remains at the floor. Another unique gait is that of the greyhound. This dog become bred for superb bursts of velocity, and its maximum secure gait is the gallop. The spine is unusually flexible, permitting the dog to contract and extend its four legs in unison, wherein all 4 feet are off the ground on the identical time.

Other breeds also have particular functions. The Afghan hound become bred to chase sport over lengthy distances in rocky terrain. Its structure lets in incredible flexibility via the hip joints and decrease lower back, permitting the canine to turn speedy in a small region. The dachshund, through comparison, is lengthy and occasional with quick legs. This dog turned into bred to seek badgers underground, and its shape allows it to enter subterranean tunnels on the lookout for its prey.

Although most breeds no longer follow the pursuits for which they were originally bred, their instincts remain strong, and their structure still allows them to perform their specific tasks.

Dogs - Senses - Coats

 Senses

Dogs have the identical five senses as humans. However, some are extra fantastically developed, and others are poor compared with those of human beings. Dogs’ feel of scent is by means of some distance the most acute and is immeasurably higher than that of humans. Dogs are used for such responsibilities as monitoring lacking individuals, digging underground, and tracing toxic materials, along with gases, which can be undetectable through human beings. Dogs can stumble on tablets, explosives, and the scents in their masters. Not all dog noses are the same, but. Some breeds, which includes the German shepherd and the bloodhound, have a lot greater keenly evolved olfactory senses than others. One would no longer pick a quick-nosed breed, which includes the pug, to have interaction in tracking.

Even in short-nosed breeds, however, the olfactory centre is highly pretty evolved. It is organized in folds with a view to clear out smells from the incoming air. Some rescue dogs are trained to comply with a scent at the floor, and others are trained to fragrance the air. Both are in a position to differentiate one character from another even after a significant passage of time. Hunting puppies—inclusive of suggestions, retrievers, and spaniels—are trained to heady scent birds and may distinguish one variety of bird from every other.

The dog’s sense of taste is poorly developed compared with that of humans. If forced to live on their own, dogs will eat almost anything without much discrimination.

Dogs own an acute feel of listening to. Aboriginal breeds had large, erect and really mobile ears that enabled them to listen sounds from a high-quality distance in any direction. Some modern-day breeds have better listening to than others, but all of them can locate noises properly past the range of the human ear. Dogs are able to check in sounds of 35,000 vibrations in keeping with second (in comparison with 20,000 consistent with second in human beings), and that they also can close off their inner ear if you want to clear out distracting sounds.

The eyesight of a canine isn't always as eager as its sense of odor, and it is usually thought that dogs have bad shade belief. Some breeds, which includes the Saluki and the Afghan Hound, were developed to chase sport by sight over long distances, and those dogs can see well enough to stumble on any movement a ways on the horizon. Dogs can typically see higher in bad light than people however now not as properly in vivid mild. They have a much wider subject of imaginative and prescient than humans because their eyes are set further towards the edges in their heads, however they may be now not as adept at focusing on objects at close variety or at judging distances. Dogs have a third eyelid, a membrane that protects the eyeball from irritants and is every so often seen in the front of the attention.

Dogs are sensitive to touch, the fifth sense, and use this sense to communicate with one another and with their human counterparts. Learning where to touch a dog is an important part in either stimulating or relaxing it and is useful in training a puppy or bonding with an adult dog.

Coats

There are three basic types of hair: short (as on a pointer or Doberman pinscher), medium (as on an Irish setter or Siberian husky), and long (as on a chow chow or Maltese). Within these categories there are also coarse and fine types of hair. Dogs come in a wide variety of colours, but in many breeds colour selection is an important consideration, as is the colour distribution on the dog.

Most dogs shed their coats seasonally. This is a natural occurrence that depends in large measure on the amount of available daylight. In the fall as days become shorter, a dog’s coat will grow thicker and longer. In the spring the dog will begin to shed its coat, and it will take longer for the coat to grow in over the summer. Temperature influences the amount of body coat a dog grows. Dogs living in warm climates all year long rarely grow hair coats as thick as those living in colder areas, although this will affect the body coat and the amount of protective undercoat more than the topcoat or the length of furnishings on the belly, ears, and tail.

Grooming is an important part of touch to a dog and can be a pleasurable and relaxing means of relating to it. The dog’s coat forms a barrier between the environment and the skin. Grooming the coat enhances the dog’s beauty and well-being and gives the owner the chance to evaluate the general health of the dog.

Dogs - Reproduction - Sexual maturity - Reproductive cycle - Gestation and whelping - Reproductive capacity

 

Reproduction

Sexual maturity

There is some variation in the age at which dogs reach sexual maturity. Small breeds appear to mature faster than large ones, which usually cycle later. It is not uncommon for large-breed females to come into heat for the first time at more than 1 year of age, although 8 to 9 months is the norm. Dogs are sexually mature between 6 months and 1 year but are not socially mature until they are about 2 years of age. Females first cycle anywhere from 6 to 18 months of age and approximately twice a year thereafter. The only exception is the African basenji, which cycles annually, bearing one litter a year.

Reproductive cycle

The heat cycle of the female lasts from 18 to 21 days. The first stage is called proestrus. It begins with mild swelling of the vulva and a bloody discharge. This lasts for about 9 days, although it may vary by 2 or 3 days. During this phase the bitch may attract males, but she is not ready to be bred and will reject all advances. The next phase is the estrus. Usually the discharge decreases and becomes lighter, almost pink, in colour. The vulva becomes very enlarged and soft, and the bitch will be receptive to the male. This stage may last 3 or 4 days or as long as 7 to 11 days. The female may be receptive a day or two past the time when she would still be fertile. In order to be sure that the breeding is taking place at the optimum time, vaginal smears and blood tests can be done by a veterinarian beginning before estrus and through the estral phase.

At about the 14th day, or whenever estrus ends, the final, or luteal, stage of the cycle begins; this stage is called diestrus. The discharge becomes redder, the vulva returns to its normal size, and the bitch will no longer accept the male for mating. When all signs of discharge and swelling are absent, the heat is complete. The diestrus stage lasts 60 to 90 days (if no pregnancy has occurred) or until the bitch gives birth. She then enters anestrus, which is the time frame between the end of the last cycle and the beginning of the next proestrus.

Canine males are always fertile from the onset of their sexual adolescence, usually after six months of age. Larger-breed males may take a few months longer to become sexually mature. Males are usually promiscuous and are willing to mate with any available female.

Males produce far more sperm than is needed to impregnate the ova that are released during estrus. Small-breed bitches usually produce small litters. Two or 3 puppies in a breed such as a Yorkshire terrier is considered the norm. Large-breed litters can have as many as 10 or 12 puppies, although the normal bitch can suckle up to 8 at a time.

Gestation and whelping

The normal gestation period is 63 days from the time of conception. This may vary if the bitch has been bred two or three times or if the eggs are fertilized a day or two after the mating has taken place. Eggs remain fertile for about 48 hours. Sperm can live in the vaginal tract for several days. In order to determine if a bitch is pregnant, a veterinarian can manually palpate her abdomen at about 25 days after breeding. Ultrasound also can be done at that time. At about 40 days X rays will confirm pregnancy.

Most bitches whelp normally. However, the large-headed, short-bodied breeds and the toy breeds often must undergo cesarean sections in order to deliver live puppies.

Reproductive capacity

Both males and females are fertile well into their advanced age. It is generally considered best for the bitch to be bred for the first time upon maturity but not before her second or third heat cycle, depending on her age at the first. Because small breeds mature more quickly, they can be bred at an earlier age than large breeds. A bitch will have less difficulty in conceiving and carrying a litter if she is bred before the age of five. As she becomes older, litter size generally decreases. After the age of seven, bitches are likely to have small litters and experience problems in delivering the puppies. Veterinarians feel that bitches generally should not be bred after that age. Males can be bred as long as they are fertile, although with age the motility and quantity of sperm decrease.