Was this your vet who told you this? I'd be wary of trying anything without consulting a vet first, especially with a kitten. Frankly, you may want to look into mama's diet as well, since your kitten is getting most of it's nutrients from nursing (hopefully!).
If mineral oil doesn't work for your cat, try unflavoured, unsweetened Metamucil (available at pharmacies), an 1/8 of a teaspoon mixed in with his (wet) food every day (or adminsitered by dropper if kitten isn't eating solids yet).
The minute he's regular again, stop. The more his own system is left to function 'normally', the better.
Wet food is best for kitties with bowel issues. Make sure he drinks plenty of water.
Keep in mind mineral oil is VERY dangerous, especially if used incorrectly. If aspirated into the lungs, it can do serious neuroligical damage. I'd go with the metimucil, frankly.
Do check with your vet, though. Treating kittens is VERY precarious when it comes to any med.
Just to be clear; if you use an eye dropper with the mineral oil, the kitten will almost guaranteed choke due to the taste and aspirate. So...do go the other rote, as once it gets in the lungs, it's there for life, and will cause paralysis or brain damage at the worst.
I was originally told to use the mineral oil by the people at our local shelter. I was very hesitant to try it. When I finally got a vet to respond I was told the same thing. Since earlier in their life I had to hand feed several of the seven kittens in the litter. They know how to drink from a dropper and it went very well, no choking or gagging, he licked it and swallowed with no problem. I was also told by this vet that it was exteremely rare for a kitten this age to be so constipated that something genetic or physical was wrong with him and to put him down. AARRRGGHHH!!! I am so angry and frustrated because the vet seemed to think so little of one kittens life. I am basically fostering these babies until they are old enough to be fixed and adopted through the Humane Society. The momma cat was a stray last fall, along with a litter mate and a cat that was left behind by a former tenant in my complex and they had no room at the shelter so I brought in all three strays. I have been waiting for the V-SNIP program to get more funding to spay and neuter at low cost.
The kittens and Momma eat Purina kitten chow, nurturing formula and friskies wet food, they go through at least 4 bowls of water a day. They have been litter trained since 3 1/2 weeks old. They are all active and curious, even my constipated kitty.
My biggest problem with the vet is probably my lack of funding because I am disabled and on a fixed income. I know he is only one kitty out of millions that are in need of homes, but I can't just not try to help him.
Thanks for your advice., mamashu_
Yeah...the sad thing is kittens have a very high mortality rate. The average litter I see, if we get a 50% survival rate, I'm fairly happy (of course, I'm not dealing with the healthiest of cats here).
I think they may have been being a little cavalier in telling you to use mineral oil. Most vets won't bother with under 6 week kittens. They do so easily...they don't want to take the risk of a negative result and owner negative feedback.
Yes, it's generally safe, but when there's another option, it is best to avoid it. If it was even an adult, but kittens are fragile and the chance of something going wrong is fairly high.
Good luck trying to nurse it. If you're careful and diligent, there's a good chance kitten will survive to become an energetic, lovable, pain in the *ss. :)