Constipated Older Cat

I have a 13 year old cat who has been constipated for about 4 years now. I have tried high fiber, low fiber, psyllium, etc. acupressure, acupunture, and alot of herbs. He's also been on raw diet, moist food and dry food. At the moment I feed him moist food. I realize diet plays an important role. He has had ultra sounds done and xrays. He has secondary hepatic lipidosis; he was 30lbs and lost the weight too fast. He is now at 15lbs. When he moves his bowels with the aid of an enema, stools are dry at first then become mucousy with a tinge of blood. I feel he has weak muscles. I've heard Milk Thistle can help his liver; I'm not sure how to give to him. My main concern is the weak muscles. Do you know what herb(s) can help with the weak muscles? Historically speaking olive oil given every 5 days helps him move his bowels. If I give it every day his body becomes use to it. Maybe, with the olive oil and a specific herb we can get things moving.

You are quite right, diet is everything in chronic constipation. I understand you have tried a number of options and within those options there are useful and less-than-useful choices. I would suggest you look at homemade diets again and, if you haven't already, see the work of Richard Pitcairn, "Natural Health for Dogs and Cats", "The Complete Herbal Handbook for the Dog and Cat" and "Cats Naturally" by Juliette de Bairacli Levy and "The Barf Diet" by Ian Billinghurst for recipes and further information. It is important that he receive as close to his natural food as possible. This means not only raw muscle meat and something to take the place of bone matter (see books above), but fibre (in place of fur/skin/cartilage/etc), oils specific to cats and some kind of vegetable to replicate the stomach contents of a given prey animal. Given your cat has secondary hepatic lipidosis, it is doubly important that he receive oils he, as a obligate carnivore is able to digest and metabolise; these would be animal based oils, not vegetable-based oils. Ideally, the oils would be in his food, not given as a separate event. Again see the sources listed above. Secondary hepatic lipidosis also would have an impact on digestion and metabolism so it is importnat his liver is supported. Please see below for further information.
As you mention mucous and blood in the stools, this means your cat's intestinal tract is irritated and inflamed. It would be best for you and he to work with a qualified practitioner who has experience with animals and herbs. You may find such a person through the Veterinary Botanical Medicine Association (www.vbma.org). Herbs that may be helpful include those that soothe and coat the digestive tract: Althaea officinalis (Marshmallow root), Ulmus fulva (Slippery Elm) as well as herbs to support your cat's liver: Taraxacum officinale (Dandelion root), Carduus marianus (Milk Thistle) and Rumex crispus (Yellow Dock). The latter also has an affinity for "lazy" muscles associated with the intestine. A small amount of Foeniculum vulgare (Fennel) could also be added to relieve any associated gas or griping. I would suggest these herbs be given in glycerite form. These may be found at your local herbalist's or health food shop.