Hello,
I have some ideas for you to try:
First, believe it or not, a lot of cats like plain old Vaseline much better than the commercial products. My cats will lick it right off my finger. You can use vaseline the same way you would the Petromalt.
Butter is acceptable, but I would not want to use it long term- too much extra fat and calories. For short term, try 1/2 tsp to start once a day for a few days. Vegetable oil may also be helpful, but the same caveat applies.
Grooming is the best way of all to avoid furballs. Use a soft slicker brush and a steel comb. Use a moist washcloth to wipe them down after grooming. If there are any fleas, they must be treated to keep the cats from over-grooming themselves.
You can also try using an oral medication syringe to give the laxatone directly.
Finally, I would just note that if your cats are losing weight, they may have more than a furball issue, and a vet visit might be in order.
I hope this was helpful. Please feel free to ask any other questions your have!
Regards,
Artemis
Veterinary Technician
Feline Veterinary Technician, over 14 years experience
You are welcome! I hope one of those will solve your cats' problem.