The human brain is much larger than that of a dog. Even a big St Bernard of similar weight to a man has a brain which is about 15 per cent of the weight of a human brain. While both have sizeable chunks of brain involved in bodily functions and movement, most of the canine brain deals with the senses and recognition, and very little is available for the formation of ideas.
Unlike cats, dogs frequently have a sweet tooth. In their mouths are taste receptors which are linked to nerves. As with humans, these enable them to respond to salty, bitter, acid and sweet substances. Appreciating the sweet things in life is unnecessary in highly carnivorous animals such as cats, who lack this sweet receptor, but dogs are more omnivorous, so they need to be able to recognise them. My Maltese love a bit of candy floss and ice cream!
Dogs can sometimes find their way home over incredibly long distances. How do they do it? Well, they may be able to navigate by noting the position of the sun in combination with a biological clock which is situated somewhere within their bodies, and it is possible that, like birds, they have magnetic particles in their brains that act as compasses. Some scientists even surmise it may involve telepathy.
It's a sad fact that big dogs don't live as long as the smaller breeds. Unfortunately, big means briefer. Few Wolfhounds will reach 12 years of age, and Labrador Retrievers are seldom around to celebrate their 15th birthday. Some terriers, on the other hand are still bouncing along at 20! The oldest dog on record was an Australian Cattle Dog that died in 1939 at just over 29 years old - trust an Aussie to knock up a big score!
The dog's principal weapon system is his teeth. His powerful jaw muscles enable him to clamp down with considerable power. A 20kg(44lb) mongrel has been found to exert a bite of 165kg(363lb) pressure, whereas the strongest of men, even under special training, can only manage a bite of 73kg(160lb)
Dogs are excellent at hearing. They can detect noises well beyond the range of the human ear and can shut off their inner ear so as to filter out from the background din those sounds on which they wish to concentrate - they can handle cocktail parties really well! Such acute hearing also enables them to detect and give warning of imminent earthquakes and volcanic eruptions hours or even days before they occur.
While some dogs continue to be alert and lively into ripe old age, most do not. Nowadays it is recognised that our canine friends can develop brain changes in old age that are like those found in human Alzheimer Disease patients. The symptoms are many and varied; confusion, increased sleeping, difficulty in recognising familiar humans, forgetfulness, etc. As with elderly people, keeping your dogs body and mind active helps to ward off the condition.
Chocolate contains a chemical, theobromine, which we humans can handle well but its toxic, even fatally so, of eaten by dogs. The small breeds are more susceptible than the large ones, and unsweetened dark chocolate is more dangerous than milk chocolate. So take some advice and don't ever dive choccies to your pet.
When you see a dog barking up a tree, it may seem it has something important to say. As well as using their body language dogs communicate vocally. Each has his own individual voice with characteristics that come to be recognised by others of his kind. Dogs make different noises for a range of reasons; to announce their presence, to answer other dogs, or stimulate them to vocalise, to indicate they are in defensive mode, to alert their family pack, or to warn off intruders on their territory.
Round and round before lying down
Dogs usually turn round and round in a tight circle before lying down. Why? This behaviour goes back to their ancestors - the wild dogs and wolves who were very much aware of the undesirability of bedding down on top of some irascible venomous snakes or scorpion. Many of us humans do something similar, automatically and without looking, brushing a seat with our hand before sitting down.
The position of the eyes on a dog's head will determine his field of vision. Short-nosed breeds like Pugs and Bulldogs, with eyes at the fronts of the head have overlapping fields of vision and thus better stereoscopic sight than long-nosed types with obliquely placed eyes and little overlap. This explains why long-nosed dogs, like Borzois and Salukis, often trip over obstacles when they are running at speed.
The dog family has the stamina to be great marathon runners. African Wild Dog packs will chase their prey for hours over great distances and even kill lions when they are tiring. Among our domestic breeds the champion sprinters are Greyhounds, Salukis, Whippets, Afghan Hounds and Borzois. Racing Greyhounds and Salukis may approach an impressive 43mph, but this is slow compared to cheetahs who reach 80mph over short distances.
Are dogs telepathic? Well, many owners and even some scientists think so. It would explain how your pet knows that Dad's on his way home when his car is still a couple of miles away. Dogs can certainly distinguish the sound of familiar vehicles, but it isn't likely that, even with their powers of hearing, they can detect the family car so far away purely by using their ears.
You and I yawn when we are tired or bored - or both. Our dogs also yawn, but not for the same reasons. With them it is a gesture that can be an indication of anxiety or uneasiness but, most frequently, it's a reassuring display on the part of a dominant dog addressing a lesser one which means "don't worry, i mean you no harm".
We don't know muchfor certain about a dog's power of memory. Some experts believe that a dog will only remember things when there is some form of associated exterior "trigger factor". Without such a stimulus he doesn't think about past events. If you're away from your dog for over 10 hours, they say, he will no longer pine for you. I doubt that many owners would agree!
Most dogs have whistkers although they are not usually as luxuriant as those of many cats. Their purpose, as tactile sensors, is to help the animal, when in darkness, to snuffle about for food or, if necessary, bury it. One wild species, the Bush Dogs of South America, possesses especially luxurious whiskers - they probaly have to search a lot harder for their next meal than you little Maltese!
Dogs do this all the time unlike us human, who tend to regard it as unspeakably vulgar and over familiar. So what's the point of sniffing other dogs bottoms? Well, dogs possess glands just inside their anal orifice which produce a special secretion. They use this not only to leave proprietorial scent marks around their territory, but also to carry chemical messages, which are undecipherable by us but inform other dogs of the identity and sex of the bottom owner.
Although dogs eyes hardly resembles the "tiger burning bright in the forest of the night", dogs do see better in the dark than humans, although not as well as cats. Dogs' retinas contain far more rod cells - which are sensitive to low light - than ours do, and they also have a shining layer beneth them which reflects concentrated light back through them. This tapetum lucidum is not as well developed as in cats, so their eyes do not shine in the dark to the same extent.