Please can someone explain to me why/ when you would use teu instead of seu.
For example Seu gato, Teu cachorro.
Why is one teu and the other seu?
Portuguese has two words for singular "you" which are "tu" and "você" and each has its own set of words for "your". The set is "teu/tua/teus/tuas" for "tu" and "seu/sua/seus/suas" for "você"respectively (four words are required because the word for "your" must agree in gender and number with the thing possessed).
Which style you use is a personal preference and is nothing to do with the difference between a cat and a dog - you can say "seu/teu gato/cachorro". Taking a bit of licence, in most dialects of Brazilian Portuguese where "tu" is not used on a day-to-day basis, "seu gato" says "your cat" (and in different contexts "his/her/their cat"), but "teu cachorro" is a teensy bit more like saying "thy dog".
For more discussion, and an alternative to "seu/teu", see my comment here: https://www.duolingo.com/comment/2080019
The only thing I'm not sure here is how old fashioned thy dog would sound.
The comparison is true, but perhaps not that much. Tu is less used, but it doesn't sound weird.
I know it is not really the same, but on the face of it the connections between "you-thou" and "your-thy/thine" are similar to the connections between "você-tu", and "seu/sua-teu/tua". The difference is that English is much further down the road of excising the older system from the language. Even so, words like "thou/thee/thy/thine" have not vanished completely and "thy dog" would sound perfectly normal in some regions of the UK (parts of Lancashire, for example).
It's true, though, that most of us would only come across the older system in the Bible and Shakespeare's plays. In that respect the connections are probably closer to those between "vocês-vós" and "seu/sua-vosso/vossa" and "thy dog" would be as weird as "vosso cachorro" (I guess).
Yes, vós and vosso are weird indeed. These ones are less common than tu-teu.
THANK YOU SO MUCH DAVU. YOU HAVE HELPED ME SO MUCH WITH THIS. TAKE 5 LINGOTS AND MY UPVOTE. YOU DESERVE IT. THANK YOU SO MUCH.
teu/tua is for tu (just you alone, no one else)
While seu/sua can be used for você, ele, ela, eles, elas, vocês (single object being refered to)
- e.g. Eles olham para sua casa (they look to their house)
in brazillian portuguese it seems more common to just use você when you talk directly to someone and therefore you use seu when refering to someones object, thing whatever
if I understand well your explanations, it would be easier to explain that grammar with the French way: tua/teu = ta/ton in French and sua/seu= votre. Like Tu= tu and você= vous (the polite way to speak to people!) am I wrong?