In today's world where far too many people already defer spaying/neutering of pets, we have an article that provides another rationalization for those people.  Apparently, we should be concerned about our pets experiencing increased anxiety levels and even depression as a result.

I suppose we can ignore the fact that animals that are not spayed/neutered will experience higher risks for ovarian and testicular cancers. Equally, we can ignore the problems that are often accompanied by having sexually intact members of such species and the higher attendant behavioral risks that this often entails.  One can just imagine the fun and games of people keeping only stallions instead of geldings.

We also have countless cases of bonafide animal abuse and neglect, but we can safely ignore those contributions to an animal's mental health.  Instead, let's focus on critiquing one of the most important things one can do for their pet, because it might promote an increase in separation anxiety or a phobia for loud noises.

However, if one wants to experience real depression, perhaps a stint at an animal shelter where you can enjoy the privilege of euthanizing a litter of 6 week old kittens because the owners couldn't be bothered to spay their cat.  

In general, this kind of reporting is one of the most irresponsible pieces I've seen in a while, because its sole purpose is to undermine one of the most important problems facing pet populations, and yet offers little or nothing in return.  Instead, we find insult added to injury by a closing paragraph that seeks to promote psychiatric medications for pets.  No matter what, someone's always looking to make a buck.

http://www.slate.com/articles/arts_and_life/science/2011/10/spaying_and_neutering_does_it_cause_depression_in_cats_and_dogs_.single.html

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NOTE:  This kind of statement should also not go unchallenged:
Already millions of strays are euthanized every year ...
Let's be clear.  Most of these are NOT strays, but simply the result of unwanted pregnancies or abandonment.  In other words, these are fully preventable deaths that could be avoided by human owners simply becoming more responsible.