I'll stick my nose in here and relate the saga of Assumpta, the hairball queen.
When she arrived here, she was terribly matted and had some nasty hairballs (and a lot of fear and aggression about throwing up because someone had apparently punished her harshly for it in the past). They got better for a time on a high-fat dry food, but she also got quite fat (mostly from being free-fed). So she got switched to measured meals of dry prescription R/D (a diet food, extremely low-fat) and she did lose weight, but developed terrible
dandruff, shedding and back to lots of hairball problems (perhaps once/twice a month, depending on the season). When I put her on a high quality all canned diet, hairballs went down to one every 4 months or so (if that), and always
during seasonal coat blows (early spring shed, for example...we run two woodstoves, which tends to cause somewhat greater shed because she likes to lie right in front of it). Corn seems to be a big sensitivity for her, and when I removed it from her diet, her skin and coat problems pretty much went away.
Fast forward to a couple of months ago, and her initial signs of pancreatitis...lethargy and vomiting in a very un-hairball-like manner (perhaps once every couple of weeks); she was placed on a temporary bland prescription diet of canned i/d (which contains corn
), and within a couple of weeks, she had bad dandruff, shedding, and a hairball. Over the last couple of weeks, I've switched her over to canned Innova Light, and the skin/coat problems are gone again. Her hairballs have definitely been linked to shedding and coat problems.
Regarding senior foods, I tend to agree that in many cases, they are gimmicks unless you have a valid medical reason for feeding a special-needs diet. My cat has pancreatitis, and seems to have had an unpredictable response to high-fat foods that I'd normally feed, so I'm trying something more moderate (the light food). Also, when she had her abdominal ultrasound, they noticed some mild kidney changes consistent with very early stages of CRF, so I am now also thinking of phosphorous content, as high-protein foods often (or usually) come with higher levels of phosphorous. Granted, she's not symptomatic yet, and it'll probably be some time before she has serious renal problems, but since I have
that info, I intend to consider it as a factor when making health choices (like food and vaccinations). When Assumpta turned 7 (or so), I asked my vet if I should start looking for senior foods, and she said to hold off on it until we had some kind of reason to be cutting back on fat, protein, or other ingredients, that it wasn't necessary for a healthy cat. Well, now we have a reason. In my travels, I have found VERY few light/senior/hairball foods that I wouldn't mind feeding (many of them just aren't much good); I went with the Innova because I knew Assumpta liked their regular formula, because I've had good luck with their food in the past, and because it was moderate, with a low phosphorous content (somewhat similar to the i/d, but with better ingredients for Assumpta). However, I tend to believe that a healthy older cat on healthy food shouldn't need a "special" formula unless their medical status indicates using one. Use your best judgement with that one, it's just my own perspective that light/senior/hairball/special formulas are generally not entirely necessary, but can be very useful if the cat has certain dietary needs.
A hairball every six weeks in a long-haired cat isn't completely outside the range of "normalcy" (not all cats are the same in this respect, and I think I see more hairballs in general with dry food cats); my concern would be if this is a new thing, an increase in frequency, if the hairballs accompanied a food change, or if you notice anything else unusual, especially in older cats (and you're absolutely positive that it's not one cat doing all the vomiting?). Any
change in habits is cause for careful examination in older cats. My own experience was that canned food and no corn largely resolved the issue; when she was on the R/D, I tried every kind of EFA skin sprays, oils, and supplements to try to fix her skin and coat, but it never helped. The other thing that helps is grooming several times a day during heavy shed; I always tackle her for combing at least once, but when she's shedding heavily (like when she was on the i/d), I did her several times a day.
The short answer is no, you can't train cats to vomit outside...they're just going to do what they need to, when they need to, and they don't care a fig about carpeting. My cat always gets down onto the floor to bring up hairballs (then goes off and plays quite happily)...but with the pancreatitis, it was full-out power-vomit that came wherever she was sitting (couch, bed, dining room table, my lap). It wasn't at all normal for her, and even though it was only happening every 2 weeks (or less) it was so abnormal as to really freak me out.