One of the most interesting findings about the data was that it shows a potential link between cancer and whether or not the dog was spayed or neutered, and furthermore, that the age of spay/neuter might have an effect on both the type of cancer and the length of the dog’s life.
The survey results also show that cancer, and osteosarcoma in general, should be of great concern to mastiff breeders and owners. I believe that larger surveys should be done on osteosarcoma in mastiffs, specifically ones that focus on the ages of spaying and neutering and the incidences of cancer. The data also suggests that incidences of cruciate ligament injury and age of spay/neuter should be studied further.
The average lifespan: 8.2 years
Average weight: 184 lbs and average height: 30.7 inches (note – this is combined, males and females)
Number one cause of death: Cancer at 38%
Number two cause of death: Old age at 20%
When broken down into intact vs fixed, cancer was the #1 cause of death in fixed dogs at 48% and old age was the #2 cause of death in fixed dogs at 16%. In intact dogs, old age was the #1 cause of death at 26% and cancer was the #2 cause of death at 22%.
In all dogs – osteosarcoma was the #1 type of cancer at 49%, with lymphoma the #2 type of cancer at 14%.
Since a higher percentage of fixed mastiffs died of cancer, that data was analyzed further. There was a moderately significant relationship between age of spay/neuter and age of death from cancer. There is a chart in this album for the data. There is another chart showing that there is relationship between age of spay/neuter and age of death due to all causes. The same dogs were analyzed comparing body weight to death due to all causes, and there was no relationship found.
Since osteosarcoma was the most prevalent type of cancer, the data was analyzed further.
15 fixed dogs who listed osteosarcoma as cause of death also listed age of spay/neuter, and 9 of them were fixed under 12 months of age. 60%.
Out of 14 total dogs that were fixed under 12 months of age, 9 of them died of osteosarcoma as previously stated, and 7 of them had cruciate ligament injury.
So, for the dogs listed who were fixed under 12 months of age, the percentage incidence of death due to osteosarcoma is 64% and the percentage incidence of cruciate ligament injury is 50%. Quite high, and further surveys/studies in the breed should be done on this subject.