From an external point of view, dogs are totally different in appearance from humans, but they have body features similar to ours. Their bodies transport blood using a heart and circulatory system; they inhale oxygen and exhale carbon via their lungs, and take in nutrients from food via a digestive system. On the other hand, it is their characteristic differences from people that make them remarkable and special members of the family.
There are a variety of shapes and sizes when it comes to dog breeds. We have the Toy Poodle, Papillon, Chihuahua, and Shih Tzu, which are some of the tiniest breeds you will find. These miniature varieties weigh between 2.3 to 4.5 kilograms (5 to 10 pounds), sometimes even less. In the medium-sized range we have terriers and spaniels, weighing between 4.5 to 23 kilograms (10 – 50 pounds). The large breeds are setters, retrievers, and shepherds which weigh an average of 30 to 45 kilos (65 – 100 pounds). Then there are the giants of the dog kingdom; Mastiff, Saint Bernard and Komondor breeds can weigh up to 91 kilograms (200 pounds). It is common to find size variations within breeds, with females weighing less than males. The mixed breeds also have varied sizes.
Metabolism Of Dogs
The metabolic rate of dogs tends to be higher than that of people. Dogs breathe, pump blood and mature at a faster rate. Their body temperature is also greater than ours. Compared to children, puppies seem to have even more energy. It is important to note that this elevated metabolic rate brings about a shorter life span. It is generally considered that 1 dog year is equivalent to 10-12 human years for the first 2 years, and then 4 human years after that. A dog’s real life span is dependent on its state of health and size, with smaller breeds having longer lives than larger ones.
Dogs find it easier to keep warm than cool their bodies. In extremely cold environments, sled dogs survive by using their fur for insulation, thus maintaining the heat produced by its high metabolic rate. On the other hand, hot and humid climates pose a problem. Sweating is a key method of cooling the body, but unfortunately dogs cannot sweat. They will pant instead, rapidly breathing in order to lose excess heat. This happens at a rate 10 times faster than normal, and achieved by moving hot, wet air in and out of their mouths. Panting has to be done intermittently, as it reduces oxygen intake into the lungs, forcing the dog to stop and breathe adequately. Drinking water is also a way of cooling down, and their coat of hair also provides cover from direct sunlight.
Due to this inefficient cooling system, summer tends to bring with it dangerous and deadly situations. A large number of dogs die of heat stroke annually, with the most common cause being locked in a parked vehicle. Although the car windows might be open, temperatures can still go past 66°C (150°F), causing heat stroke and fatality in minutes. Tying or enclosing them out in the sun, or shutting them inside a poorly aerated travel crate can also cause such deadly conditions to occur.
Keeping dogs cool and hydrated during hot seasons is important. Use of air conditioning, shade, spray misters, dipping pools and spraying them with a hose are all useful ways of doing this. There should always be fresh and cool water for drinking for dogs.