Dogs evolved from an extinct wolf-like creature in Eurasia 40,000 years ago. Male dogs are called dogs, female dogs are called bitches and young dogs are called puppys. Some studies believe that dogs started to be domesticated 33,000 years ago. Dogs belong to a biological family called the Canidae, a member of this family is called a canid. This is the origin of the adjective “canine” which means “of or like a dog, relating to or characteristic of dogs”.
Dogs have a very good sense of smell. The part of a dogs brain that analyses smell is 40 times larger than a human’s and they can smell 1,000 to 10,000 times better than us. About one-third of a dog’s brain is dedicated to smell. The breed of dog with the best sense of smell is the bloodhound. A dog could detect a teaspoon of sugar if you added it to an Olympic-sized swimming pool full of water. Dogs can be trained to detect cancer in humans. Some dogs can tell if a human is about to have an epileptic fit. About 12 percent of the air that a dog breathes goes into a special area in the back of the nose that is dedicated to smelling. A dog can both sniff and breathe at the same time. Dogs know from which nostril a smell has entered. Dogs can use their sense of smell to gauge our emotions, they can smell fear, anxiety, even sadness this is due to the fact that they can smell hormones such as adrenaline. Police dogs can smell human bodies even when they are buried up to 3 metres in the ground.
Dogs see in colors of various shades of blue and yellow. If you want a dog to see things in a green background the best colour is blue. Humans generally see better than dogs but dogs see much better when there is low-light. Dogs cannot distinguish between red and green and these colours would appear as shades of grey to a dog.
Dogs like to chew bones but cooked bones and bones that can splinter such as cooked chicken bones should not be given to dogs. When dogs were evolving , bone marrow could sometimes form an important part of their diet. Dogs often bury bones so that they can dig them up at some moment in the future when they are hungry.
Chocolate is poisonous to dogs because it contains theobromine. A Labrador (around 30kg bodyweight) would probably die if it consumed more than ½kg of dark chocolate.
Dogs have a ligament in the neck which allows them to conserve energy while running long distances following scent trails with their nose to the ground. Many other species have a similar ligament and it is called a Paddywhack.
Although dogs have some sweat glands in their feet, their principal way of losing heat when they are too hot is by panting. When dogs have been doing a lot of exercise, they pant, it is not because they are out of breath like a human would be. Dogs have developed the method of losing heat by panting because sweating would not be very efficient due to all the fur. The normal body temperature of a dog is 38.3 to 39.2 degrees Celsius whereas human normal body temperature 37 degrees Celsius.
Female dogs can get pregnant when their bodies undergo changes which make them receptive to male dogs. This is called being on heat or in estrus. Male dogs know the female is on heat due to a smell emitted from the female dog. If the female is receptive, she will stand still and hold her tail to the side, a stance referred to as “flagging”. Most dogs go on heat every 6 months and estrus lasts between 7 and 18 days. When dogs copulate it is very normal for them to get stuck together and it may last for up to 45 minutes. Most vets recommend that bitches don’t get pregnant until the third estrus. Pregnancy can be prevented by spaying the female dog, this involves removing both the ovaries and the uterus. Dogs don’t go into the menopause and will continue to go on heat indefinitely unless they are spayed. Small and medium-sized dogs mostly have a gestation period of fifty to sixty days while larger breeds average sixty to sixty-five days. Dogs normally have between one to sixteen or even more puppies. It is not possible to know how many puppies a bitch will have just by looking at the pregnant bitch, the appearance can be very deceptive. Puppies are born deaf and cannot hear until they are about 21 days old. The young are born small, blind and helpless and require a long period of parental care.
Most dogs have 42 teeth. Corgi is Welsh for “dwarf dog.” Greyhounds can reach a speed of up to 45 miles per hour. Male dogs have a bone in their penis. The most popular bree of domestic dog in the US and the UK is the Labrador Retriever. The border collie or sheep dog is often considered to be the most intelligent breed of dog some of them have been trained to recognise the words for up to 1,000 objects and retrieved them by verbal command. Dogs can discriminate the emotional expressions of human faces.The largest breed of dog is the Irish Wolfhound. Dogs do not have an appendix. Dogs are all direct descendants of wolves. Wolves and dogs can mate to produce fertile offspring. A dog’s heart beats up to 120 times per minute, or 50% faster than the average human heartbeat of 80 times per minute.