Juniper was eleven, slept more than she used to, and — as her owner put it — "was just getting older." A PG10 GPS Track Logger had been clipped to her collar for months purely out of curiosity. Nobody expected the map to become the most useful thing in the house.
Nobody noticed week by week
Here's what makes a slow decline so easy to miss: nothing happens. No collapse, no dramatic symptom. In Juniper's logs, her nightly range shrank week after week by somewhere between 8% and 15%. Then one day the comparison feature stacked three months side by side, and the change wasn't gradual at all — it was almost 70% smaller than spring.
Her owner hadn't noticed because cats don't announce a smaller territory. They just quietly stop doing one thing at a time.
The first thing to go was the height
Long before the range shrank, the log showed something subtler: Juniper stopped going up. The climbing route onto the garden wall — a route she had used four or five nights a week for two years — simply stopped appearing in the data, three months before anything else changed. Looking back, that was the earliest line in the record. At the time, nobody was reading records.
"The vet asked when the change started. I couldn't answer. Then I put the three months of tracks on the table and she said — that's your answer, right there. It started in June."
Then the patrols got shorter
Juniper's famous loop — the one her owner called "doing her rounds" — didn't disappear. It got shorter. The same route, walked as far as the second corner instead of the fourth, then back to the door. Same confidence, fewer metres. That detail, more than anything, is what convinced her owner to book the appointment rather than wait another month.
What the vet found
Arthritis in her hips, plus dental pain nobody could see from the outside. Not a crisis — but very treatable, and considerably easier to treat in August than it would have been in December. Two weeks after starting medication, Juniper's nightly loop came back to the third corner. Two months later she did the full round for the first time since June.
The PG10 didn't diagnose anything. It just refused to let a slow change stay invisible — and that turned out to be the useful part.
Why logging beats guessing
- The trend is the evidence. A single bad day means nothing; three months of shrinking maps is a pattern a vet can actually use.
- It records without watching. PG10 stores the path locally and replays it later — no live tracking, no geofence alarms, nothing to "check" every hour.
- No SIM, no monthly fee. Months of continuous logging costs nothing beyond the device — which is what makes a long baseline possible at all.
- Light enough to forget. At 22 g, an older cat accepts it as part of the collar, not as equipment.
Juniper is still eleven. She still sleeps in the good spot by the radiator. But her loop is back to all four corners, and this time it's in the map where anyone can see it.
A GPS track logger is not a medical device and this is one household's story — but a quiet trend in writing is a much better thing to bring to a vet than "I think she's slowing down".
Also in the field: Moving house: building a new territory · A cat's night, mapped by GPS