A colleague of mine diagnosed a 4-year-old domestic shorthair with dilated cardiomyopathy last year. Young cat, no genetic predisposition to heart disease, owner who cooked all the cat's food herself from chicken breast and rice. The owner was devastated and confused. She'd been reading ingredient labels on commercial food and wanted to do better.
The food she'd made had no taurine in it. Not enough, anyway. Chicken breast muscle is among the lower-taurine cuts — at roughly 18 mg per 100g, it's a poor source compared to chicken heart (around 170 mg per 100g) or dark meat. Heart tissue and organs are where taurine concentrates, and chicken breast with rice provides almost none.
That cat recovered with taurine supplementation and dietary correction, which was fortunate. The heart doesn't always bounce back.
Taurine: The Non-Negotiable
Taurine is a sulfur-containing amino acid found in high concentrations in animal tissue, especially heart muscle, brain, and retinal cells. Most mammals can synthesize enough taurine from other amino acids (methionine and cysteine specifically) to meet their needs. Cats cannot — their enzymatic pathway for taurine synthesis is severely limited by low activity of cysteine sulfinic acid decarboxylase (CSAD), as documented in The Journal of Nutrition, and their bodies don't conserve taurine as efficiently as other species.
The result: cats must get dietary taurine from their food. Every meal, consistently, for life.
Taurine deficiency causes two conditions, both of which are serious and one of which is irreversible:
Dilated cardiomyopathy (DCM) — the heart muscle weakens, the chambers enlarge, pumping function decreases. In many cats, this is reversible with taurine supplementation if caught early. In advanced cases, it's not. Symptoms include labored breathing, weakness, and sometimes sudden cardiac death.
Feline central retinal degeneration (FCRD) — the photoreceptor cells in the retina degenerate. This begins with reduced night vision and progresses to complete blindness. Unlike DCM, retinal damage is permanent.
Commercial cat foods have been required to contain supplemental taurine for decades after an epidemic of feline DCM in the 1980s revealed the deficiency. Raw meat diets (particularly those emphasizing organ meats and heart) typically supply adequate taurine. The gap occurs with home-cooked diets using lean muscle meat, and with plant-heavy formulations.
The Moisture Problem
The second major deficiency I want to cover isn't a single nutrient — it's water. Or rather, the structural inadequacy of a dry-food-only diet for an animal that evolved to get its fluids through prey.
Wild cats are hunters of small prey. A mouse is roughly 70% water. Cats eating their natural diet are simultaneously hydrating with every meal, which is why cats have a lower thirst drive than dogs — historically, they didn't need to seek water separately. Their kidneys are good at concentrating urine; this adaptation helped them survive arid environments.
That efficiency becomes a liability when the diet shifts to dry kibble. Kibble is typically 8 to 12% moisture — compared to roughly 65–70% in whole prey — and a cat eating only dry food is consuming dramatically less water than their physiology was designed for. They often don't compensate by drinking more water at the bowl.
Chronic mild dehydration matters for two feline health conditions specifically:
Feline lower urinary tract disease (FLUTD) — concentrated, low-volume urine creates ideal conditions for crystal formation, mucus plugs, and inflammation in the bladder. Male cats especially can develop urethral obstructions that are life-threatening. Diluting urine through increased moisture intake directly reduces this risk — this is well supported in the feline urology literature and is a core recommendation in dietary management of FLUTD.
Chronic kidney disease (CKD) — CKD is the most common serious disease in cats over 10 years old. Whether chronic dehydration causes CKD or accelerates it remains an area of active investigation. But kidneys that work harder to concentrate urine over a lifetime — as happens on a dry-only diet — plausibly experience more cumulative stress. The epidemiological evidence connecting wet food feeding to slower kidney disease progression is growing, though causality is difficult to establish definitively.
What This Looks Like in Practice
For the average healthy cat: some wet food component daily is genuinely worth doing. I'm not saying dry food is dangerous — plenty of cats live long healthy lives on dry food. But if you're managing the odds, the moisture argument is real.
For cats already diagnosed with urinary or kidney disease, wet food transitions from "worth doing" to "treatment." High-moisture diet is literally part of the therapeutic protocol.
For home-cooked diets: taurine supplementation is not optional. It needs to be in the recipe, in the right amount, consistently. A veterinary nutritionist can specify the exact supplementation needed for a given recipe formulation.
Understanding obligate carnivore nutrition helps explain why taurine is so critical — it's one of several nutrients cats cannot obtain or synthesize from plant sources. The complete guide to cat nutrition covers the broader picture of how all of this fits into a practical feeding strategy.
Taurine and moisture aren't the exciting parts of cat nutrition. They're the boring foundations. But a cat whose diet gets these right is a cat who avoids two of the most serious health conditions I treat.