Let’s talk about canned food. First, if it isn’t already abundantly clear – I think dry cat food is a very bad idea. I don’t think anyone thinks the semi-moist foods (those little pieces that aren’t hard as kibble, but chewy, like Tender Vittles) are a good idea. (If you do – well, they’re not for the same reasons dry/kibble is bad and more.)
So, where does that leave us? Options remaining are a freeze-dried raw food, a frozen raw food, or a canned food. (Or, I suppose there’s the options of a freshly made raw food or whole prey or homemade cooked diet – I won’t go there for the time being.) I realize there are MANY caregivers out there that are reluctant to feed raw for many reasons, and I do not fault them for that! I think commercial canned food is a perfectly acceptable option! While the majority of my cats’ diet is a frozen raw food, I do feed canned food to them on occasion and I feed my foster cats canned food. Why don’t I feed my own cats’ canned food more often? Well, a few reasons including cost (yes, homemade raw is less expensive), palability (if some of my cats get canned, they start clamouring for it and refusing to eat their raw), and a couple cats that had IBD so long before their diet was changed that even most canned foods cause them stomach upset…. among other reasons.
However, I’ve seen some people argue against canned food – and I’d like to discuss some of the “reasons” why.
Hyperthyroidism: Some people think the lining of pop-top cans causes hyperthyroidism. I don’t believe it. Take a really close look at one of the studies that concerned people, and keep in mind – the researchers that performed these studies set out to prove the lining was the cause (and when you set out with a result in mind, it often taints your view of the results).
RESULTS: Multivariate analysis revealed that affected cats were more likely to be female (odds ratio (OR)=3.3; 95% confidence interval (CI)=1.2-9.0) and older than unaffected random control cats. Purebred cats were at a much lower risk of being diagnosed as hyperthyroid than were domestic short- and long-haired cats (OR=0.01; 95% CI=0.001-0.20). If more than one cat was present in a household, hyperthyroidism was less likely to be identified (OR=0.15; 95% CI=0.05-0.44) compared with single-cat households. Hyperthyroid cats were 6.6 times more likely (95% CI=1.8-23.9) to be reported to sleep predominantly on the floor than control cats. Cats whose bedding was regularly treated with anti-flea products appeared to be at a considerably higher risk for hyperthyroidism (OR=57.6; 95% CI=3.8–>200); and, to a lesser extent, so were cats living in households where fly sprays were reported to be used regularly (OR=3.3; 95% CI=1.2-9.3). The interaction between drinking water from puddles and regular use of organic garden fertilisers, such as compost or animal manure, was associated with a 5.3-fold (95% CI=1.1-25.6) increase in the risk of cats being diagnosed with the disease. Hyperthyroid cats were twice as likely (95% CI=0.3-12.9) to have eaten at least half of their daily food requirements as canned commercial cat food compared with unaffected cats. Cats exposed to a variety of flavours of canned cat food were more likely to be diagnosed with hyperthyroidism than were those fed only one flavour (OR=3.8; 95% CI=1.5-9.6). The presence of dental disorders was associated with a 5.5-fold increase in the risk of being diagnosed as hyperthyroid and this association was independent of the cat’s age (95% CI=1.7-17.5).
Source: Multivariate analysis of risk factors for feline hyperthyroidism in New Zealand.
So, looking at the results – they do say that cats eating canned food seemed twice as likely to develop hyperthyroidism than cats fed dry food. However, they also said that cats that slept on the floor were more than six times as likely to become hyperthyroid, and cats drinking from puddles were more than five times as likely, and cats with dental disease were more than five times as likely. So, why the focus on pop-top cans, which weren’t even remotely the biggest link? Well, in my opinion, because other studies looked only at pop-top cans and no other factors because again, researchers set out to show this was the cause. Also, diet is well within the caregivers’ control, where their cat chooses to sleep? Not so much. Trust me, I know plenty of cats that never consumed canned food ever and became hyperthyroid.
Two recent large studies have looked at possible environmental or dietary factors involved in the patho-genesis of hyperthyroidism. One of the studies with a case controlled design looked at 100 cats with hyper-thyroidism and 163 control cats. The cats medical records were reviewed and the owners were asked to complete a mailed questionnaire. Data included demographic variables, environmental exposures, and diet (including preferred flavors of canned cat food). In this study, housing, exposure to fertilizers, herbicides, regular use of flea products, and the presence of a smoker in the house were not associated with an increased risk, but cats that preferred fish or liver and giblets flavors of canned cat food had an increased risk. The results suggested that cats that prefer to eat certain flavors of canned cat food might have a significantly increased risk of hyperthyroidism.
In the second case controlled study owners of 379 hyperthyroid and 351 control cats were questioned about their cats’ exposure to potential risk factors including breed, demographic factors, medical history, indoor environment, chemicals applied to the cat and environment, and diet. The association between these hypothesized risk factors and outcome of disease was evaluated by conditional logistic regression. Two genetically related cat breeds (Siamese and Himalayan) were found to have diminished risk of developing hyperthyroidism. Cats that used litter had higher risk of developing hyperthyroidism than those that did not. Use of topical ectoparasite preparations was associated with increased risk of developing hyperthyroidism. Compared with cats that did not eat canned food, those that ate commercially prepared canned food had an approximate two-fold increase in risk of disease. When these four variables (breed, use of cat litter, consumption of canned cat food, and use of topical ectoparasite preparations) from the univariate analysis were selected for further study as candidate risk factors and analyzed by multivariate conditional logistic regression, a persistent protective effect of breed (Siamese or Himalayan) was found. In addition, results suggested a two- to three-fold increase in risk of developing hyperthyroidism among cats eating a diet composed mostly of canned cat food and a three-fold increase in risk among those using cat litter. In contrast, the use of commercial flea products did not retain a strong association. The results of this study indicate that further research into dietary and other potentially important environmental factors (cat litter) is warranted.
Source: Feline Hyperthyroidism, WSAVA World Congress 2001
So now we’re limiting it to certain flavors of canned food – and noting that cat litter has as much or more risk as canned food.
More recent research shows flame retardants are more likely.
Co-incident with the introduction of polybrominated diphenyl ethers (PBDEs) into household materials nearly 30 years ago, feline hyperthyroidism (FH) has increased dramatically. Risk of developing FH is associated with indoor living and consumption of canned cat food. We hypothesized that increases in FH were, in part, related to increased PBDE exposure, with key routes of exposure being diet and ingestion of house dust.
Source: Elevated PBDE Levels in Pet Cats: Sentinels for Humans?
This makes sense: Sleeping on the floor, where dust settles, linked to hyperthyroidism. Drinking from puddles, where chemicals accumulate, linked to hyperthyroidism. Cat litter (dust), linked to hyperthyroidism. Fishy foods (from waters where flame retardants may have washed), linked to hyperthyroidism. I don’t advocate feeding fishy flavors much, if at all, anyway, so simply giving up the fish flavored foods or using them sparingly isn’t an issue for me.
Conclusion: Fear of hyperthyroidism, a very treatable disease by the way, is not sufficient to deter me from feeding and recommending canned foods. If it is for you – avoid fish flavors, use pouches or cans without pop-tops, and you should still be able to feed canned without that concern.
Dental health: Another reason I’ve heard for avoiding canned food is dental health. I don’t buy this one. Most dry (kibble) foods are made in pieces so small, cats don’t chew them at all, they swallow them whole. (If you doubt that, watch the many toothless cats at a shelter gobble the dry food.) Secondly, if dry food is so good for their teeth, why is it that over two-thirds of cats have dental disease before age three despite the vast majority eating dry food? Dry food is higher in carbohydrates than canned food – carbohydrates break down to sugars, and sugars most certainly don’t do the teeth any favors.
Conclusion: I don’t feel a dry diet does anything to promote dental health. If you disagree, provide your cat with some chunks of raw or cooked meat or freeze-dried raw to chew on. As long as unsupplemented meat makes up no more than 10% to 15% of the diet, it should not cause any nutritional deficiencies.
Time/cost: Some people seem to think leaving canned food out for more than 20 to 30 minutes will cause deadly bacteria to form. I don’t think so. If that was the case, how many bacteria do you think are in those bags of meat-flavored cereal sitting on store shelves or in bowls for days?
Others think that meal-feeding is just too inconvenient. Honestly, if you can’t find a few minutes to dump some food in a bowl twice a day, I’m not sure you should have a pet. If your cat(s) are just bothering you for food more often – there are timed feeders, or you can freeze some canned food to leave out for later, or just free-feed canned food in lieu of free-feeding dry.
Conclusion: Just do it. If you can’t find “time” or money to feed canned food now, you’re really unlikely to have time or money to treat diabetes or kidney disease or urinary tract stones later.
Upset stomach: Some claim canned food makes their cat(s) vomit or have diarrhea. With any sudden diet change, you run the risk of upsetting a stomach, even if that change is for the better. If the cat is eating too fast, try smaller meals initially, or spreading food out on a plate rather than in a bowl. Transition slowly. Some cats have a hard time adjusting to the drastic reduction in fiber from dry to canned, you can add some psyllium or guar gum to the canned initially during transition (just add water as well so it doesn’t clump up and form a choking hazard).
Conclusion: Overall, eliminating dry food is much better for a cat’s gastro-intestinal health.
Palatability: Some owners reply with a “kitty doesn’t like canned food, kitty likes dry”. You know what? Some children don’t like vegetables or home-cooked meals, they like pizza and hamburgers. That doesn’t mean we should just feed them what they want.
Conclusion: Work with kitty. It took me months to get all my cats off dry food completely – you can do it too. Dr. Lisa has some great tips on transitioning dry food addicts to wet food.
Cancer: Last but certainly not least, some claim that canned food causes cancer. As far as I know, there is an antiquated study on humans that showed pop-top can linings might contribute to cancer. That’s the extent of the “proof” I know of. I can, on the other hand, point you to studies showing that many of the preservatives used in dry cat food (not canned) are known as carcinogens and the FDA limits their use in human products. I can show you evidence that high heat processing of grains or potatoes (such as used in dry food) produces acrylamide which the FDA cautions against as it’s a known carcinogen. Dry foods are higher in carbohydrates, and it’s known cancer cells prefer feeding on simple carbohydrates to proteins or fats, so that’s another issue. Then, of course, there’s all the stuff in our environment (smoke, flame retardants, etc.) that cats are exposed to – and the vaccines we pump into them on a regular basis – I really think linings of canned food are not the biggest of our problems.
Conclusion: Doesn’t scare me – but if it’s a problem for you, look for a pouched or canned food without a pop-top.
Overall: I think the benefits of canned foods greatly outweigh the risks. By far. If you have concerns, there’s always a raw diet – but please don’t try to tell me these “concerns” justify feeding a dry (kibble) diet.
Best article on all this stuff EVER. Thank you.
Found that Canned Cat food is Definitely better than dry food, and I use a powdered vitamin supplement to help keep My Cat from shedding. It works pretty well. I just put a little bit of vitamins in the food every dya and i don’t have as much hair on the furniture. I think this is the site, anyone else who’s cats shedd eveywhere, check this stuff out http://www.dinovitefeline.com
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