Main cause of death associated with 24 most common dog BREEDS
The researchers found that "the effect of sterilization was relatively consistent among size classes within any of the 24 breeds analysed". REF1 That is, the biggest or smallest breed dogs had similar probabilities of death (either an increase or decrease amount the most common and the two least common PP causes of death for sterilised dogs.) across the four categories.
That means that sterilisation V intact dogs had the major influence of dog death type NOT the breed, and not the dog breed size !
BREED SIZES by colour:
red-small [up to 10 kg],
blue-medium [10.1–25 kg],
green-large [25.1–40 kg],
yellow-giant [>40 kg]).
Breed abbreviations are shown:
(LA: Lhasa Apso, SCT: Scottish Terrier, SHT: Shih Tzu, YT: Yorkshire Terrier, TP: Toy Poodle, DACH: Dachshund, MS: Miniature Schnauzer, MP: Miniature Poodle, BH: Basset Hound, BEA: Beagle, ESS: English Springer Spaniel, COLL: Collie, ACS: American Cocker Spaniel, SH: Siberian Husky, IS: Irish Setter, SP: Standard Poodle, BOX: Boxer, SS: Shetland Sheepdog, DP: Doberman Pinscher, GS: German Shepherd, LR: Labrador Retriever, GR: Golden Retriever, GD: Great Dane, ROT: Rottweiler).
The majority of sterilised dogs die from neoplastic causes (cancers). Sterilised dogs die more from these than intact dogs (which die more often from trauma and infectious diseases).
Sterilised dogs die on average at 9.4 years Versus 7.9 for intact dogs.
Curiously of the EIGHT main cancers that the sterilised dogs die from five of them are among the top ten human cancer diagnoses in Northern America.
It may be that its not a coincidence that " No other species (than the domestic dog) is similarly able to mirror the human experience of the impacts of environment, lifestyle choices, and medical care on health." REF 1
"The increased risk of death due to cancer observed in sterilized dogs could be due to the fact that in both sexes, dogs sterilized before the onset of puberty grow taller than their intact counterparts as a result of reduced estrogen signaling . Recent studies in humans suggest that growth is a risk factor for a number of different cancers"
It is further speculated that "The relationship between sterilization and infectious disease could arise due to increased levels of progesterone and testosterone in intact dogs, both of which can be immunosuppressive" REF 1
The following theory by the authors of the analysis is what I find dog owners should be aware of in off lead dog parks.
We see many dog fights and aggressive behaviour by intact dogs and dogs towards intact dogs because they are intact and either show more dominant behaviour or give off hormone scents that sterilised dogs pick up on and feel they have to challenge the intact dog (even if the intact dog is not showing any form of dominant behaviour).
" Additionally, sterilization and disease risk might both be correlated with specific canine behaviours. Given the opportunity, intact male dogs are more likely than sterilized dogs to roam, and to fight with other dogs, and intact female dogs show more dominance aggression than spayed females. These behaviours might increase the risks of both infectious and traumatic causes of death among intact dogs."
The obvious take away is that sterilising your dog will definitely have it have a more peaceful and social time in off lead dog parks, AND steriisation might also increase any specific dog's lifespan.