If your reptile keeps getting sick, suspect the thermometer before the animal

Most reptile illness that walks into an exotic vet traces back to temperature, humidity or light rather than something the animal caught. Get the box right and a surprising number of problems just stop happening. Start with what you're measuring temperature with. Those stick on dial gauges that come in starter kits are close to useless. They read air near the glass and they're often badly off. What you want is a digital probe sitting on the basking surface where the animal actually puts its body, plus an infrared temp gun to spot check surfaces around the enclosure. Two tools, measuring two different things, and you want both. You also need a gradient, not a temperature. Reptiles are ectotherms and thermoregulate by moving, so the enclosure has to have a warm end and a cool end so the animal can pick. An enclosure that's one uniform temperature takes that choice away no matter how correct the single number is. Heat source on one side, always. No heat rocks, and no unregulated heat mats. Reptiles don't reliably move away from contact heat that's burning them, and the result is belly burns that take months to heal. Anything producing heat goes on a thermostat, no exceptions and no "it's only a small mat." Humidity is the other half of it. Run it too low and you get stuck sheds, retained eye caps on snakes, and retained shed on toes that constricts until the animal loses the toe, plus kidney trouble over the long run. Run it too high with poor ventilation and you get respiratory infections and scale rot. The right number is species specific and worth actually looking up. Which is the real point here. A ball python, a crested gecko, a bearded dragon and a leopard gecko want meaningfully different setups, even though the pet store will happily sell the same starter kit for all four. Look up your species, not "reptiles."