All things being equal, smaller dogs tend to live longer than larger dogs.
Of course, not all things are equal, and that is especially true in the dog world.
Take a look at the two graphs below, for example. Though they may look similar, they are not, as they are actually plotted on different axes.
It turns out that Cavalier King Charles Spaniels are so unhealthy their mortality cannot be graphed on the same scale as that of the Golden Retriever!
In fact, in Sweden, where this data comes from, it seems that the Golden Retriever is about as healthy as a mongrel -- and in fact may be a bit healthier.
As the Swedish longitudinal analysis of over 350,000 dogs in the Agria Insurance data base notes,
Golden retrievers were at low risk for mortality in this study – only 22% died before 10 years. Golden retrievers were significantly less likely to die of trauma and heart disease and were in the baseline (average) risk group for neurological and tumour causes of death. They were at increased risk in the first age category for locomotor problems, but this effect waned with age as demonstrated by a negative age-breed interaction.
As the Swedish study notes, breed-specific information gleaned from the insurance data can be extremely useful to people looking to acquire a dog and those trying to determine whether an investment in veterinary treatment is worth the expense.
Information on the average survival pattern for different breeds is useful clinical information. Prospective owners should understand that in getting, for example, either a Bernese mountain dogs or a golden retriever, the likelihood of the dog living past 10 years of age is very different. Most owners, once their dog becomes seriously ill or dies, are keen to know if the condition is rare or common, in general or in their breed. Many owners are especially concerned if they feel their dog has died prematurely, that is at a younger than average age. Veterinarians and their clients can also use survival statistics as part of informed decision-making regarding expensive veterinary care and for conditions in which quality of life is an issue. For example, an Irish wolfhound that has survived to eight years has a 76% chance of being dead before 10, whereas an eight-year old golden retriever has a 90% chance of surviving to 10.