Thank you for contacting Drs. Foster & Smith with your questions.
Some cats with constipation issues will benefit from increased fiber in the diet. This will only help if the constipation is fiber-responsive and the cat is consuming enough water as well. There are different types of fiber as well (soluble and insoluble) and each type will affect the cat differently. For some cats, increasing the fiber can worsen the constipation and lead to fecal impaction. Fiber is usually only beneficial to cats that have not had repeated bouts or long histories of constipation and also do not have megacolon. We would suggest talking to your veterinarian about whether adding fiber to the diet would be appropriate for your cat.
Other cats may respond to a low-residue diet that is highly digestible and low in fiber. These are usually cats that have megacolon and recurrent constipation. Low residue diets are usually prescription diets and only available through your veterinarian.
In general, canned or moist diets are beneficial as well (they aid in keeping the animal hydrated). Encourage your pet to drink more by offering water in a water fountain, adding ice cubes to the water, or other options.
We also recommend trying to address other underlying diseases or factors that can lead to dehydration and constipation, such as renal disease or inflammatory bowel disease.
For animals who are difficult to medicate, there are other options available. Products such as Pill Pockets can be used to hide pills. You can also ask your veterinarian if the medication comes in a different form, such as a soft chewable or a liquid.
For your cat with hairballs and vomiting, you could try a hairball diet or a hairball remedy. But recent studies have shown that these cats likely have an underlying issue, such as inflammatory bowel disease, that is the root cause of the vomiting. We would recommend having your cat examined by your veterinarian to determine the underlying cause of the vomiting and an appropriate course of action.
We hope this information is helpful. Thanks again for contacting us.
Drs. Foster & Smith