[Animals] Why Bigger Dogs Live Shorter

[#Steeven.™]

If you like large dogs, we have bad news for you, but luckily, things can always improve.

Whether you have a big or small dog, depending on your tastes, there is something you might need to know: in the animal kingdom it is governed by that rule that the bigger you are, the longer you live. Nobody expects a house mouse to live more than two years, but an African elephant can live 65 or more, and we're not even talking about the Antarctic blue whale, which can live up to 90.

However, there is an exception to this rule, and that is the domestic dog. Here the rule is that the smaller you are, the longer you live. For example, the tiny Yorkshire Terrier, which has an average weight of three kilos, has an average life of 15 years. Compare it to an English Mastiff that has an average life of only eight years and can weigh 104 kilos. Why is this happening?

As reported by 'Psychology Today', before tackling the question of why different breeds of dogs age at different rates, one would need to address the aging process itself. The general consensus on how we age is based on the concept of wear and tear. That explains how we age, sure, but not why we age, which could be posed as an evolutionary question: "Since some species have evolved to live longer than others, why haven't all species evolved to have greater longevity?" .

Since some species have evolved to live longer than others, why haven't all species evolved to have greater longevity?
The answer that evolutionary theorists give is that there are two different paths that any type of animal can "choose", based on the idea that each species has only a fixed amount of biological resources. Remembering Darwin and the fittest, it should be mentioned that these are the species that produce the largest number of healthy offspring. It sounds a bit cruel, and perhaps that is why there is another alternative theory; that of Self-Preservation: Here the genetic programming is for a slower growth rate, fewer offspring, and the maintenance of enough resources to build defenses against harmful mutations and conditions that will adversely affect the animal later in life.

 

Live fast, be big, leave a pretty carcass
A new study collected data on 164 dog breeds. It included information on adult body mass, birth weight, at what age breeds reach 50 percent of their adult mass, litter size, average age of death, and, of course, typical causes of death.
The first review of this data confirmed what others have shown, which is that larger dogs tend to die younger than smaller dogs. It also showed that larger dog breeds tend to have more offspring. For example, the diminutive Yorkshire Terrier has litters averaging three puppies. By comparison, the giant English Mastiff typically has litters averaging nine pups in size.

 

Larger breeds are more susceptible to physical ailments after reaching their adult size, which is typically two years of age.
The authors suggest that the development of dog breeds larger or smaller than ancestral gray wolves actually occurred through genetic mani[CENSORED]tion of the initial growth rate. The pressure to breed larger dogs has resulted in faster early growth velocity. Unfortunately, this means that instead of dedicating resources to general body maintenance and health, breeding for larger dogs emphasizes the use of bodily resources for rapid early growth, rather than using them to strengthen the immune system, repair the damaged DNA and improve resistance. The data shows that this is reflected in the fact that larger breeds are more susceptible to physical ailments after reaching their adult size, which is typically two years of age.
Furthermore, the same mutations that increase body size in dogs also lead to an increased risk of cancer. Basically, the data shows that the bigger the dog, the more likely it is to suffer from this disease. The researchers divided the causes of death into four categories: trauma or accident, infection, toxic exposure, and cancer. Their analysis revealed that deaths from trauma, infection or toxin were not related to the size of the dog. However, the chance of dying from cancer increased steadily with the dog's weight.

 

Data shows that the bigger the dog, the more likely it is to get cancer
Does that mean if you have a big dog you should start thinking about an epitaph? Not quite, actually. There is hope for them, however, in the longer term, as natural selection should allow larger dogs to develop better cancer defenses and longer lives at the expense of smaller litters.

 

https://www.elconfidencial.com/alma-corazon-vida/2023-05-19/perros-grandes-viven-menos-esperanza-vida_3630375/