for my 2penneth, i dont see much difference between unwanted dogs being pts and any other bred animal being pts...
because dogs are companions not "stock" and they:
they are our eyes if we are blind, our ears if we are deaf and assist with little jobs when we are not very mobile
they tell us if we have cancer or about to have a fit
they find us when we are lost, in an avalanche, and save us from drowning,
they fight our wars for us and lay down their lives for us
help us find prey where we cannot and when they have it in their mouths bing it back to us- even when they are hungry
they work alongside us with our sheep and cattle gathering and herding that 10 men could never do
they find our sheep when they are lost or in 6 feet of snow
they help us catch our criminals
they ARE our best friends
and no matter what we do to them they are still prepared to love us.
Don't get me wrong I agree if a dog has been baldy bred or badly treated so much that it can never safely live with humans then there is only one answer. But most of the hundreeds of thousands (no exageration) of healthy dogs pts each year in the UK are either perfectly nice pets or have nothing wrong with them that a bit of training and responsible dog ownership wouldn't put right. They aren't just as cute and fluffy as a puppy

Forgive me if this sounds bad, but as long as my a#$E points to the ground there will always be people who breed their dogs because they think it's a money spinner, regardless of whether or not a piece of paper exists saying they 'can't'. Especially the small handbag types, crossbred and unchecked and easier to sell than something big-at least that has been my observation. And as long as Joe Public is prepared to hand over the dosh for these animals, the problem will exist. Even well bred dogs who have come from parents who have had all the health checks can end up as a rescue (going through one at the moment with a litter brother to by boy) because buyers either cannot or will not understand that a small cute fluffy puppy does NOT always stay that way!
Yes Joe Public needs educating !!!
