What Herbs Can Be Given To A Cat With An Intestinal Blockage?

I am not sure what you mean by intestinal blockage.  Intestinal blockages can occur anywhere along the intestinal tract.  The location and severity of the blockage dictate which kind of signs the cat would show.

If you mean constipation, this condition will not be resolved by administering herbs.  If your cat has mild constipation, you can add fiber to the diet in the form of pumpkin and vegetables, and even metamucil.  Also, ensure there is plenty of clean fresh water available.  Consider changing their diet from dry to wet.  Also, ensure you are cleaning the litter box at least once per day.  

Cats showing other signs of more severe constipation should be examined by a veterinarian.  These signs include straining to defaecate, painful defaecation, vomiting, blood in the faeces, inappetance, and lethargy.