Cats are obligate carnivores, which is a more demanding label than it first sounds. It means they have not simply adapted to a meat-based diet but depend on one for nutrients they cannot make in sufficient quantity themselves. Taurine, arachidonic acid, and preformed vitamin A all have to arrive ready-made in the food. A dog can convert beta-carotene from plants into vitamin A; a cat cannot. This is the single most important reason cats should never be fed dog food long-term, and it is why choosing the right food matters more for a cat than for most other pets.
What a Complete Cat Food Needs to Provide
Protein sits at the centre of feline nutrition. Cats use protein for energy continuously, not only for building tissue, which is why their requirement stays high throughout life — including in old age, when the outdated advice to cut protein for senior cats has largely been reversed.
Taurine is an amino acid cats cannot produce in adequate amounts. A prolonged shortage can lead to dilated cardiomyopathy, a serious heart condition, and to degeneration of the retina. Complete commercial cat foods are supplemented with it; homemade diets frequently are not.
Fats supply concentrated energy and essential fatty acids, and they carry the fat-soluble vitamins. They also show up directly in coat quality — a dull or flaky coat is sometimes the first visible sign of a dietary gap.
Water deserves its own place on this list. Cats descend from desert-dwelling ancestors and have a famously weak thirst drive, so they tend not to compensate well for a dry diet by drinking more. Chronic mild dehydration puts extra work on the kidneys and urinary tract over a lifetime.
When comparing products, look for a statement on the label confirming the food is complete and balanced for your cat’s life stage, formulated to AAFCO nutrient profiles or tested in feeding trials. That is a more useful signal than the marketing on the front of the bag, and it is a good thing to review together at a preventive care visit.
Wet, Dry, and How Much to Feed
Both wet and dry food can be part of a healthy diet, and the sensible answer for most households is a combination.
Wet food is roughly 70 to 80 percent water, which meaningfully raises daily water intake. That matters for cats prone to urinary problems and for those with early kidney changes. It is generally more satisfying per calorie, which helps with weight control. Dry food is convenient, keeps well, and works in puzzle feeders and food toys — a genuine benefit for indoor cats who need mental stimulation. Its drawback is that it is easy to overfeed, especially when left available all day.
Portion size is where most well-intentioned feeding goes wrong. The guidance printed on packaging is a starting estimate for an average unneutered adult, and most neutered indoor cats need noticeably less. Measure meals with a proper scoop or a kitchen scale rather than estimating, and count treats within the daily total — they add up faster than people expect.
Body condition is a better guide than the number on the bag. You should be able to feel your cat’s ribs easily under a thin layer of fat, see a visible waist from above, and see the belly tuck up when viewed from the side. Obesity is one of the most common preventable health problems in cats in Canada, and it raises the risk of diabetes, arthritis, and urinary disease. It also makes grooming physically difficult, which is why overweight cats so often develop a scruffy coat along the back. A body condition assessment takes only a few minutes at any appointment.
Life stage matters too. Kittens need energy-dense growth food, adults need maintenance, and cats over about seven benefit from monitoring rather than an automatic switch to a senior formula. Pregnant and nursing cats have substantially higher requirements. In a multi-cat household with a range of ages, feeding separately is usually easier than trying to find one food that suits everyone.
Foods to Avoid, and Signs Worth a Conversation
Several everyday foods are genuinely unsafe for cats. Onions, garlic, chives, and leeks damage red blood cells, in powdered form as well as fresh. Chocolate and caffeine are toxic. Grapes and raisins have been linked to kidney injury. Alcohol and raw bread dough are dangerous. Xylitol, a sweetener in some sugar-free products, is well documented as toxic in dogs and is best kept away from cats entirely.
Milk deserves a mention because the image is so persistent. Most adult cats are lactose intolerant, and a saucer of cow’s milk commonly causes digestive upset rather than pleasure.
Raw diets are a subject owners ask about often. The main concerns are bacterial contamination — affecting the household as well as the cat — and the difficulty of achieving a balanced nutrient profile without professional formulation. If you are considering one, it is worth discussing it with our team before starting rather than after.
Some changes around food warrant an appointment rather than an adjustment at home: a cat who suddenly eats much more or much less; unexplained weight loss, particularly in an older cat; increased thirst or urination; or repeated vomiting and diarrhoea. Dropping food, chewing on one side, or approaching the bowl and then walking away often points to dental pain rather than a fussy appetite.
Sudden weight loss alongside a good appetite in a middle-aged or older cat is a particularly important pattern, and it is one where bloodwork and diagnostic testing should not be delayed.
Frequently Asked Questions
Q: Should I feed my cat wet food, dry food, or both?
A: Both work, and many cats do well on a combination. Wet food contributes usefully to daily water intake, which supports urinary and kidney health; dry food is convenient and suits puzzle feeders. The more important variables are that the food is complete and balanced for your cat’s life stage, and that the total amount is right.
Q: How much should I feed my cat?
A: Package guidance is only a starting point — most neutered indoor cats need less than the label suggests. Measure portions rather than free-pouring, count treats within the daily total, and adjust based on body condition. We are happy to assess body condition and set a target at any visit.
Q: Can cats eat dog food?
A: Not as a regular diet. Dog food does not contain enough taurine, arachidonic acid, or preformed vitamin A for a cat, and prolonged feeding risks serious heart and eye disease. A stolen mouthful is not an emergency, but it should not become a habit.
Q: My cat barely drinks water. Should I be concerned?
A: A low thirst drive is normal for the species, which is precisely why it matters. Wet food, a pet water fountain, and several bowls placed away from food and litter all tend to help. A genuine increase in drinking is the more concerning direction and should be checked, as it can indicate kidney disease, diabetes, or thyroid problems.
Q: Is a raw diet safe for my cat?
A: It carries real risks — bacterial contamination affecting both the cat and the people in the home, and nutritional imbalance without professional formulation. Please talk to us before starting a raw diet so it can be assessed for your individual cat.
Not sure whether your cat’s diet is meeting their needs? Book a nutrition consultation or call us at (604) 900-8383. Brentwood Animal Hospital is located at 4489 Hastings Street in Burnaby, serving cat owners across Brentwood, Capitol Hill, Willingdon Heights, and the surrounding area. You can also read more about our care for cats.