public function createSlug($slug) {
        // Remove anything but letters, numbers, spaces, hypens
        // Remove spaces and duplicate dypens
        // Trim the left and right, removing any left over hypens

        $lettersNumbersSpacesHypens = '/[^-spNpL]+/u';
        $spacesDuplicateHypens = '/[-s]+/';

        $slug = preg_replace($lettersNumbersSpacesHypens, '', mb_strtolower($slug, 'UTF-8'));
        $slug = preg_replace($spacesDuplicateHypens, '-', $slug);
        $slug = trim($slug, '-');

        return $slug;
    }

http://www.mywebsite.com?category_id=1&category_name=hot & dogs

http://www.mywebsite.com?category_id=1&category_name=hot-amp-dogs

function createSlug($slug) {
// Remove anything but letters, numbers, spaces, hypens
// Remove spaces and duplicate dypens
// Trim the left and right, removing any left over hypens
$slug   =   htmlspecialchars_decode($slug);

$lettersNumbersSpacesHypens = '/[^-spNpL]+/u';
$spacesDuplicateHypens = '/[-s]+/';

$slug = preg_replace($lettersNumbersSpacesHypens, '', mb_strtolower($slug, 'UTF-8'));
$slug = preg_replace($spacesDuplicateHypens, '-', $slug);
$slug = trim($slug, '-');

return $slug;
}