well ... when we pray we have to pray on a clean floor surface (which is why we use a carpet)
and before we pray we wash ourselves .... basically its a complete sponge bath. we wash arms up to the elbow, legs to mid calf, feet, hands, ears, mouth, nose, back of the neck, top of the head and face.
cleanliness is extremly important in islam. specially when it comes to prayer.
it is not haram(wrong or sinful) for a muslim to own a dog, it just creates extra work for you lol as you have to clean way more.
we cant share a dish a dog has eaten from (enless its been washed 7 times) and stuff i mentioned earlier.
ive owned dogs before and ive kept them out of one room of the house ... which was my bedroom and i would pray only in my bedroom, but each time i prayed id have to shower, and change my clothing. its a huge pain.
of course there is always the option of an outdoor dog.
the prophet mohammed did himself own dogs .... so the idea that muslims hate dogs is not at all true ... not that you think that but i know many people have that misunderstanding.
in fact a woman who was extremly evil and was a prostitute stopped and drew water from a well and fed it to a dog and she was granted eternity in heaven for that one act alone.
we believe that animals will testify for or against us on the day of judgement on how we treated them.
anyway ... lol ... yes its any animal ... i cant pray on a floor a bird poops on either;) or a cat ... or any other animal ... or a floor a person walks on with dirty feet or shoes(which is why we dont wear shoes inside the house, enless they are shoes worn ONLY inside the house)
however .... oddly we are allowed to own a cat and there is no worry like with a dog .... as a cat cleans itself regularly. though one still would need to change clothes and clean the floor.
i kinda ramlbed on ... hope that explains it lol
just water is good although if you want to use soap its all good 
