Hi again Larry,
Sorry for the long delay - my husband and I went out for dinner.
Hmmm... was any blood work done to find out WHY she is getting constipated?
In terms of castor oil, this is not something I would recommend. I have heard of people giving 1 to 2 tsp of castor oil by mouth per day to help relieve constipation in cats. However, I have seen cats that have vomited castor oil and aspirated it into the lungs. This is generally fatal. Because vomiting is common and thus this is a risk with this treatment, I would recommend against it.
I have some suggestions to help your cat to have a bowel movement. These are:
1. Probably the fastest way to help her would be to use Pediatric rectal suppositories made for human infants.
They should be available at any pharmacy. They include dioctyl sodium sulfosuccinate (DSS, ColaceTM), glycerin or bisacodyl (DulcolaxTM). I usually suggest the glycerin suppository. It comes as a little cone about 1inch long. For a cat, you would GENTLY insert this into the rectum. It usually helps within an hour.
2. Offer her some milk - about 2 tablespoons every 2 to 4 hours. This has a natural laxative effect and may help to move things along.
3. Switch to all canned diet, if she'll eat it.
The first ingredient is WATER which is going to help with the dehydration and thus the constipation. You could stay with your current brand but but use the canned (soft) type.
4. Add fibre by adding to her diet some canned pumpkin (a couple of teaspoons twice daily), bran cereal (1 teaspoon twice daily), or Metamucil, Konsil, Siblin or similar product (1/2 teaspoon a day).
5. Try a hairball remedy like laxatone, tonic-lax or petromalt.
All of these are essentially vaseline with flavouring added. Many cats love them! You could start at 1/2 teaspoon daily and see how she does.
6. Really encourage your cat to drink water. Good hydration helps to prevent constipation.
Offer her water in a large, flat bowl since cats don't like to have their whiskers touch the edge when they drink (which is why lots of cats like the toilet bowl). If she likes dripping water, leave a tap dripping for her. Offer her the water from a can of tuna, diluted with tap water 50:50. Offer bottled water and see if she prefers it. Offer chicken broth, diluted 50:50. Try a few drops of clam juice in water. See if she likes water with an ice cube in it. See if she likes it out of a cup or martini glass.
7. Exercise can help relieve constipation. Try get her to chase a string around the house for a few minutes 2 or 3 times a day.
8. Polyethylene Glycol (Miralax or Glycolax are trade names) is another medication that your vet could prescribe. It is reported to have excellent results. Also, it's easy to use - just mix the powder (1/4 - 1/2 tsp twice daily) into the food. Start at the lower dose and adjust based on feces 1 to 2 days later (after giving it time to work).
Polyethlyene glycol is what all the veterinary gastrointestinal specialists seem to be recommending these days. So, you might want to talk with your vet about that.
9. Consider adding another litter box in another location. The idea with this is that if your girl needs to defecate, she has a litter box nearby and doesn't just decide to "hold it" until later.
10.Encourage your cat to eat!
The idea is that the more she eats, the more this will encourage things to move through her system.
You could try getting some human baby food in meat flavours (check that there are no onions or garlic in the ingredients) and mix that with warm water and offer that, or syringe it in little bits into your cat's mouth. Beech Nut makes a line of baby food that has nothing but meat (beef, chicken, turkey or veal) in it.
If you cannot find this, you could find another meat baby food - just read the label carefully to be sure there are no onions, onion powder, garlic, or garlic powder in it. Offer her some canned cat food, and mix it with water to make a slurry if she won't eat it.
Boil a chicken breast and then put it in the blender with water to make a baby-food consistency gruel to offer. Here is another link to ways to encourage cats to eat: http://cats.about.com/cs/healthissues/a/fatty_liver_2.htm It has some good suggestions.
I hope that these ideas help you to help your cat and that she feels better soon!
If you have found this helpful, please push the green "Accept" button. I will back in the morning to answer further questions! It is 10:30 pm here now and I need to get to bed.
The above is given for information only. Although I am a licensed veterinarian, I cannot legally prescribe medicines or diagnose your pet's condition without performing a physical exam. If you have concerns about your pet I would strongly advise contacting your regular veterinarian.