After looking at your code I noticed a few things:
1) You should be using the method loadHTMLFile() not loadHTML(). The former method loads HTML from a FILE, the method you were using thought "test.html" was literally the HTML. 2) Turn on error reporting when you are debugging. 3) You should be declaring your namespace, in this case it's xmlns.
// Report all PHP errors
$husdjur = new DOMDocument();
$xpath = new DOMXPath($husdjur);
$tableRows = $xpath->query('/html/body/table/tbody/tr/td');
foreach($tableRows as $result)
Take a step back and read the comments you made about each paradigm:
OOP - powerful - very clean and well organized - neat result
Procedural - Easier
Given the description of the components & features of your website, it doesn't seem like a trivial task and most likely you will be updating & adding to it. I think you can figure out which one suits your situation.