The concluding numbers on this page are based on the following estimates and the figures are rounded for ease of calculations and because you will never get a truly accurate figure because we don’t know how many cats and dogs there are in the world or the USA. We guess but we don’t have very accurate figures. Please excuse the blizzard of numbers.
If there are glaring faults in the calculations and/or presumptions please tell me in a comment and I will make corrections.
There are approximately 80 million domestic cats and 80 million domestic dogs. There are 80 million feral cats in the USA. I’ll estimate 10 million feral dogs (a wild guess because I don’t have figures)
There are 500 million cats (domestic and feral) in the world. I’ll presume that there are a similar number of dogs.
Cats live for 15 years. Dogs live for 12 years.
Killed at shelters and by disease or injury
Around 3 million die premature deaths annually in the USA (this is a big guess). The same figure for dogs.
Percentage deaths by old age
6.67% of the total for cats and 8.33% for dogs. These figures are based on the following: For cats – if there were 15 cats in the world and they were born each year for 15 years, one would die of old age per year or one out of the total of fifteen. One-fifteenth is 6.67%. For dogs the lifespan is shorter so more die per year (see below).
For domestic cats: 6.67% of 80m is 5,333,333 per year or 14,612 per day. For dogs 8.33% of 80m is 6,664,000.
For domestic cats add in premature deaths of 3m for a total of 8,333,333 per year or 22,831 per day. For domestic dogs add in 3m premature deaths for a total of 9,664,000 per year or 26,476 per day.
Add domestic cats and dogs together for a yearly figure of 17,997,333 per year or 49,307 per day.
Feral cats live shorter lives, say an average of around 5 years. This means 20% die per year. This makes 16m dye annually. This figure combines dying of old age and through disease and injury.
Combined domestic and feral cats dying per year in the USA is 24,333,333 or rounded down to 24 million.
If there are 1 billion cats and dogs in the world then 33,350,000 cats die of old age and 41,650,000 dogs die of old age annually making 75 million dying per year but this excludes premature deaths. I think you’d have to add in around 25m or more making 100+ million cats and dogs dying per year in the world.
Associated: click for top ten reasons for cat deaths.