[thedoc (OP)]

Anand asked the Naked Scientists:
   I have seen few hundred times dogs urinating on streets, roads when I was in India. But now, today, a dog in my street made me to wet my brain. Okay, here my question, why dogs (only male) always urinates on something.. say...lamp post, tyres, bin bags and even on wall. What's the science behind that? I remember that male dogs (most often) smells the place before urination and why the female dogs doesn't do that?

I really thank you all The Naked Scientists for such an informative talk-radio program.

What do you think?

[evan_au]

It has to do with marking territory.

Male dogs urinate as high as possible on vertical surfaces to show their height. Female dogs tend to urinate on the ground, but this also gives a scent signal to other dogs.

I would be surprised if female dogs did not pay attention to such signals. But neutered dogs may be less interested than whole dogs.

Dog droppings also provide a chemical signal, in conjunction with their anal glands.

See: https://en.wikipedia.org/wiki/Dog_behavior#Scent

[alancalverd]

For the same reason that they lick their genitals: because they can.

And as far as I can tell from several neutered bitches, they mark territory, signal to others, and read the signals, to pretty much the same extent. The problem is that whilst dogs tend to pee on trees, which are fairly resilient, bitches like to pee on a well-manicured lawn and  discolor the grass. But in the street or a park, bitches still have a good sniff first and like to pee where others have been.

"Have one on me" said a friendly old tree
To a dog going home to his spouse
"No thank you" said he "for as you can see
I've just had one on the house."