My long-haired cat brings up a hairball almost every week — is that really normal?

Once a week is not normal, and your friend is right to push back. A healthy cat vomits rarely — a few times a year — and a cat bringing up hairballs most weeks is telling you something. The hairball is the evidence, not the illness.

A cat swallows that much fur for two broad reasons. Either she is over-grooming — itch, fleas, allergy or pain will all make a cat lick one area raw — or the gut is no longer moving the fur along as it should, which happens with inflammatory bowel disease and, in older cats, with intestinal cancer. "It's just hairballs" is one of the most expensive assumptions in feline medicine, because chronic vomiting can hide both of those for years while everyone reaches for the paste.

So bring your vet data, not an impression. Keep a vomit diary for a few weeks: date, time, how long after eating, and what came up — a cigar of fur? undigested food? clear or yellow fluid, or bile? Photograph it. Weigh her weekly on a kitchen scale in grams and write the numbers down; slow weight loss under a long coat is invisible to the eye and obvious on a scale. Your vet will weigh that history against the physical exam and will likely want bloods, and possibly an ultrasound — the tests decide this, not a guess from a distance.

Go to a vet now, not later, if she is vomiting repeatedly and can't keep water down, if she is retching and producing nothing, if she is lethargic, or if there is any chance she swallowed string, thread or tinsel. A thread anchored under the tongue and running down into the gut is a surgical emergency and it does not wait.