I have 2 cats that are about 4 years old. Last year, one got constipated and had to be hospitalized for several days. I has to force feed her through a tube that was surgically placed in her neck. It took several months to get her back to normal...now, over 1 year later, her sister is having the same problem...the vet is trying to get me to feed Science Diet...I have been feeding Iams, which I know is icky, but better than the Purina brands available here in my area. I have been ordering Orijen Senior for my dogs. I am wondering if I can avoid a recurrence of these problems by swithing the cats to a better quality kibble like I did the dogs...any suggestions for cats prone to constipation?