Database connection

Hello everyone, I used PDO directly in a model Cakephp 3.6 to make a request a little complex and for reasons of performance, after that my Models lose the connection to my database, $this->getConnection() in my model return null, how can I reconnect my Models automatically?

How do you mean “used PDO directly in a model”?
Like you actually added another PDO connection manually in a model?

A very simplified example in model:

    public function getPets()  // params would be used in real app
        $dbh = ConnectionManager::get('default');
        $sql = "SELECT * FROM dc_pets Where `adopted` = :adpt";
        $sth = $dbh->prepare($sql);
        $params = ['adpt' => 0];
        return $sth->fetchAll(\PDO::FETCH_OBJ);

Of course if for real I’d pass in an offset and a rows per page to paginate