Ask A Scientist© Veterinary Topics Archive

name Edie
status other
grade other
location CA

Question - i had a dog who passed away 8 yrs ago at the age of 15
1/2 yrs old. For every dog you u add 7 yrs in dog years. i.e. a
dog is one yr old its actually 7 yrs in human years. Do cats and birds
have the same type of animal to human ratio?
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Hello Edie!

Well, cat and dog years are a kind of made up way for explaining to
people what stage an animal is in it his/her life, so the owner can
relate to a stage of their own life. For instance, at 2-3 years old,
a cat or a dog is more like a teenager in terms of their
developement. What you really need to know is how old animals
generally live, and then compair their life span expectation to your
own. For instance, the reason that 1 dog year = 7 people years is
this: dogs generally live about 12 years (average - I'll explain
shortly). So when they are 12, it'd be like us being 84, which is
about the human life expectancy. BUT, this is the problem; some
breeds can live up to 18 years, others usually only make it 5 years
(aka Irish Wolf Hound), so the 7 human years per dog year doesn't
really work. But, in general, this is how you can think about ages
that animals will live:

Small dogs usually live longer than large dogs; mutts live longer than
pure breeds.
Cats generally live longer than dogs. A really old cat would be 18
years old, but most make it to about 15 or 16 if they are well taken
care of and don't have a huge medical problem. Birds can have really
long lives, for instance big parrots can live to be over 80 years
old! Some smaller birds only live to be about 8-10 years old. So in
general, it's very difficult to come up with a "dog years" type
equation for those animals!! What you can do, however, is this:

Find out what type of animal you have, and how long it generally lives
(you can do an internet search for this information)
Figure people live to be about 85 years old. Take the age you think
your animal is going to live, and divide 85 by that number. It will
give you a general "animal to human" year ratio, so you can figure out
where it his/her life your pet is compaired to people!! It's not very
scientific, but it's always fun 

Best wishes,

Susannah Sample BSBME
Vet. Student
University of Wisconsin
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Hi Edie,

Despite the old rule about 1 year being 7 dog years, we now know that it 
isn't that simple. Dogs actually age more quickly than the 1:7 rule for the 
first couple of years... a 1 year old dog is really already a "teenager". 
Then they age more slowly.

In addition, large breed dogs tend to age much more quickly than small 
dogs... the average lifespan of an Irish wolfhound is about half as long as 
a miniature poodle. Some breeds have shorter lifespans for other reasons... 
they may have a tendency to develop certain types of diseases or cancers.

Cats tend to live a little longer than dogs.

Birds represent a wide rang of genera. Some birds, especially small 
songbirds, live a relatively short time in the wild, only a year or so. On 
the other hand, in captivity, some parrots, cockatoos and others may live to 
be more than 80 years old!

Keep up the interest in animals and science!

Laura Hungerford DVM, MPH, PhD
University of Maryland
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