Dear Dr. John,

About two weeks ago, our 14-year-old cat seemed to be straining to go to the bathroom and was not producing anything. We wasted no time in having him seen. We were told that our cat was severely constipated. There had not been any change in diet for the cats in the household, so we were puzzled as to the cause. Can constipation come on suddenly for no apparent reason?

Our vet gave him some enema treatment and sent him home with us. He also gave us something called Laxatone which is usually used for hairballs and suggested that we add some Metamucil sprinkled into his food. He seemed fine for a few days and then the same problem reoccurred so this time he was given something called Lactulose. We were told that it might be needed long term but that we could also try Miralax. What do you suggest? J.S.

Dear J.S.,

Sometimes one never fully understands what causes chronic cat constipation. One needs to keep an eye out for small, dry, and hard feces which can suggest that more serious constipation is waiting to happen. Diet is of course one possible cause if it lacks enough fiber or is too dry. Changes to the physiology of the colon can also be the cause.

If constipation is found, it is important to seek quick relief and resolution to the problem because the longer it is present, the more likely it will repeat due to weakened muscle in the colon and compromised nerve function. In response to your questions, constipation can come on suddenly for no obvious reason. Cat laxatives found in hairball medications can be helpful and both Metamucil and Miralax can be purchased over-the-counter, which can work well. Lactulose is often used by veterinarians to keep stools soft. In badly constipated cats, I might use Lactulose initially and then increase fiber with products like Metamucil or switch from the Lactulose to Miralax which works similarly as an osmotic laxative. Stay observant to make sure the cat continues to defecate regularly.

Dr. John de Jong owns and operates the Boston Mobile Veterinary Clinic. He can be reached at 781-899-9994.