Вот еще вариант
PHP:
$str = 'Origin: Brazil<br>Agency:<br>Other Name:, Abby Lee, Abby Lee Brazil,<br>Debut year: 2014<br>Debut age: 25 years old<br>Breast: Big<br>Birthday: 1989-09-08<br>Hair Color: Brown<br>Tattoos:<br>Flower on right stomach<br>Flowers on left side<br>Dinosaur on left buttock<br>Piercings: Navel, clit<br>Forum Thread';
preg_match_all('~([^<>:]+):(.+?)(?=[^<>:]+:|$)~', $str, $matches);
$matches[2] = preg_replace('~<br>~', ' ', $matches[2]);
$a = array_combine($matches[1], $matches[2]);
print_r($a);