Weight is one of the single most useful health metrics for any pet, but the right way to measure it, and how much a small change should actually worry you, depends entirely on scale. A method that works well for a cat is useless for a horse, and vice versa.
Matching the method to the pet
| Pet size | Best method | Meaningful change |
|---|---|---|
| Small pets (rabbit, guinea pig, bird) | Kitchen or baby scale, grams | As little as 2–5% |
| Cats & small dogs | Hold-and-subtract on bathroom scale, or a pet scale | Around 5% |
| Large dogs | Dedicated platform scale, most vets have one free to use | Around 5% |
| Horses | Weighbridge, or a weigh tape for an estimate | Around 5% of bodyweight |
The hold-and-subtract method, done properly
For cats and small dogs without access to a pet scale, weigh yourself alone on a bathroom scale, then weigh yourself holding the pet, and subtract. It's not perfectly precise, but done consistently, at the same time of day, on the same scale, it's genuinely useful for tracking trends over time, which matters more than any single exact number.
Why consistency matters more than precision
Weighing at the same time of day, ideally before feeding, and on the same scale each time, removes most of the noise that makes single readings hard to interpret. A trend across several weigh-ins tells you far more than any one number in isolation, whatever animal you're weighing.
Where the numbers actually go
Whatever the method, a weight log only becomes useful once it's somewhere you can actually see the trend, not scattered across old notes or memory. Halo's Vitals tab charts weight automatically over time, whatever units and however small the numbers, so a real shift is obvious at a glance.