Routing URLs and trailing slashes

Hello,

I have a little problem with codeigniter because I want to have urls like that http://site.com/dogs/ or http://site.com/cats/ etc.

So see my routes.php file :

PHP Code:

$route['([0-9a-zA-Z-_+]+)'] = "site/categorie/$1"; 


My htaccess file :

Code:

RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*)$ index.php?/$1 [L]

My urls are working but I can access with this url http://site.com/dogs/ and this url http://site.com/dogs
But it's a big problem for duplicate content in SEO.

I already tried :

PHP Code:

$route['([0-9a-zA-Z-_+]+)/'] = "site/categorie/$1"; 


But it's doesn't work...

I am looking for a solution to for using trailing slashes for my urls.

Thank you for you help.