Cats eat rats because they are obligate carnivores with a hardwired hunting instinct that evolved over thousands of years. Even well-fed house cats will stalk, kill, and sometimes eat rodents, because the drive to hunt operates independently from hunger. Rats happen to be an ideal-sized prey that delivers exactly the nutritional profile a cat’s body demands.
Cats Are Built to Hunt and Eat Meat
Unlike dogs or humans, cats cannot thrive on plant-based foods. They are obligate carnivores, meaning their bodies require nutrients found only in animal tissue. A feral cat’s natural diet breaks down to roughly 52% protein and 46% fat by energy content, with only about 2% coming from carbohydrates. That ratio is almost impossible to achieve from anything other than whole prey animals.
Cats also have unusually high requirements for specific nutrients like taurine (an amino acid found almost exclusively in animal muscle), certain fatty acids, and vitamins A and D in their preformed state. Most omnivores can synthesize these compounds from plant precursors, but cats lost that ability over evolutionary time. Their metabolism is essentially locked into processing meat. A rat, eaten whole, provides protein, fat, taurine, vitamins, minerals, and even water in proportions that closely match what a cat’s body needs.
The Seven-Step Hunting Sequence
Cats follow a remarkably consistent behavioral pattern when hunting. According to International Cat Care, the sequence unfolds in seven stages: searching the environment, locating prey, approaching, capturing, killing, manipulating, and consuming. Each step is a distinct motor pattern driven by instinct rather than learning, which is why even kittens raised indoors will crouch, stalk, and pounce on toys in the same way feral cats pursue live prey.
During the approach, a cat moves in a low crouch with its head outstretched, making slow, deliberate movements that accelerate into a sprint as it closes distance. Just before striking, the cat freezes in a tense, coiled posture, then springs forward to pin the prey with one or both front paws. This entire sequence can fire off whether the cat is hungry or not, because the motivation to hunt and the motivation to eat are controlled by separate systems in the brain.
Why Well-Fed Cats Still Kill
If your cat brings home a dead rat and leaves it on the doorstep untouched, that’s not unusual. Research using animal-mounted video cameras found that about 28% of animals killed by cats were never eaten. Biologists call this “surplus killing,” and it increases when prey is abundant or easy to detect, such as in open habitats. The behavior makes evolutionary sense: in the wild, food availability is unpredictable, so a cat that hunts whenever the opportunity arises has a survival advantage over one that only hunts when hungry. The instinct persists even when a bowl of kibble is waiting inside.
This also explains why your indoor cat “hunts” feather toys, laser dots, and wadded-up paper with the same intensity as an outdoor cat chasing real prey. The predatory motor pattern is always loaded and ready. It just needs a trigger.
How Cats and Rats Shaped Human History
The relationship between cats, rats, and people is ancient. House mice were drawn to human dwellings in the Levant as early as 15,000 years ago, attracted by the ecological effects of long-term hunter-gatherer occupation. That was thousands of years before grain storage even existed. Once Neolithic farmers began storing millet and wheat, rodent populations around settlements exploded, creating a buffet for small wild cats.
The earliest archaeological evidence of cats living alongside farmers comes from settlements in China dating to roughly 5,500 years ago, where leopard cats hunted rodents within farming villages and may have even been fed by people. Near Eastern wildcats followed a similar path, gradually expanding their range into Europe by moving with settlements, livestock, and agriculture. In other words, cats essentially domesticated themselves by following the rats that followed the grain that followed the people. The entire reason cats live in our homes today traces back to their appetite for rodents.
Health Risks of Eating Rats
While hunting rats is natural for cats, eating them carries real health risks. The two most significant are parasitic infection and secondary poisoning.
Toxoplasma Gondii
Rats can carry the parasite Toxoplasma gondii, which has a fascinating and disturbing trick: it alters infected rats’ brains so they lose their innate fear of cat urine and may even become attracted to the scent. This manipulation increases the odds that an infected rat will be caught and eaten, completing the parasite’s life cycle. Cats are the only animal in which Toxoplasma can sexually reproduce, so the parasite has evolved to funnel itself from rodent to cat as efficiently as possible. An infected cat then sheds the parasite in its feces, which is how Toxoplasma can spread to humans and other animals.
Leptospirosis
Wild rats are common carriers of Leptospira bacteria, which cause leptospirosis. A study testing wild rats in Malaysia found that 72% had antibodies to the bacteria, and pathogenic strains were detected in 27% of kidney samples and 16% of urine samples. Cats that hunt and eat infected rats, or even contact their urine, can pick up the infection. While cats tend to show milder symptoms than dogs, they can still become ill and potentially pass the bacteria to humans through contaminated environments.
Rodenticide Poisoning
Perhaps the most preventable danger is secondary poisoning from rat bait. When a rat eats anticoagulant rodenticide and then gets caught by a cat before the poison kills it, the cat ingests the toxin too. These poisons work by preventing blood from clotting, and they accumulate in the liver. Studies on predatory mammals have found lethal concentrations of second-generation anticoagulant rodenticides in species like stoats and polecats, and cats face the same risk. If you use rat poison anywhere your cat hunts, secondary exposure is a serious concern. Signs include lethargy, difficulty breathing, and unexplained bruising or bleeding.
What This Means for Cat Owners
You cannot train the hunting instinct out of a cat. It is as fundamental to their biology as purring or grooming. If your cat goes outdoors, it will likely hunt rodents regardless of how much you feed it. Providing regular, protein-rich meals won’t stop the behavior, but it does reduce the chance your cat will actually eat what it catches.
If you want to minimize the risks, keeping your cat indoors is the most effective option. For cats that do go outside, avoiding rodenticide use on your property protects them from secondary poisoning. Regular parasite prevention, including deworming, helps manage the infectious risks that come with a cat doing exactly what its body was designed to do.