A healing incision changes in a straight line, and a failing one changes in hours. One check a day, at the same hour, 2 minutes long, with the same 5 points measured in the same order, catches almost every problem while it is still a phone call. Three findings skip the phone call and go straight to the clinic.
The check is 5 measurements you can write down, so day 9 can be compared with day 3 without relying on memory.
Once a day, at the same hour
Frequency is 1 check a day from day 1 to day 14. In the first 48 hours, add a second check at the evening dose, because swelling peaks at 48-72 hours and a hematoma under the skin shows up fast. Two minutes is enough once you have a routine.
Pick a calm hour with good light, usually after the evening meal. Redness read at 8 am and again at 11 pm can look like a 3 mm spread that is really just different lighting.
Wash and warm your hands first: a cold hand on a 5 cm incision gets a flinch you will misread as pain, and the flinch moves the skin.
The 5 points, in this order
Point 1 is the line itself: are the two edges touching along the full length, and is there a gap. Measure any gap in millimeters at its widest spot, not an average. A 1 mm gap at 1 point of a 6 cm line is a grade 1 finding; a 0 mm line with proud, gaping skin at 1 end is not.
Point 2 is the 1 cm rim around the line: the width of any pink or red band, measured from the edge of the incision outward. Write the number in millimeters. Normal is 1-2 mm of pink at day 3, fading to skin color by day 7.
Point 3 is discharge: none, a bead of clear serum, blood, or pus. Record color, amount and smell in 4 words rather than a paragraph.
Point 4 is thickness: pinch the skin 2 cm to the side of the incision, then over the incision, and compare. A difference of 2 mm or more is induration, which is the earliest sign of a fluid pocket under a closed line.
Point 5 is skin temperature: the back of your fingers on the incision, then on the same spot on the other flank or the opposite side of the belly. Warm by 1 C or more, felt as a clear difference, counts. A cat's normal rectal temperature is 37.5-39.2 C, so a warm wound is a local sign, not a fever.
Grading: 0 to 3, and what each grade buys you
Grade 0 is a dry line, edges together, 0 mm gap, rim the same color as the skin 2 cm away. Continue daily checks and change nothing.
Grade 1 is a pink rim of 2 mm or less, mild swelling of 2 mm or less, no discharge, and a cat that is eating. Keep checking daily, stop all licking with the cone, and photograph the site once.
Grade 2 is a red rim of 2-5 mm, swelling of 2-4 mm, a little serous ooze, or a gap under 2 mm. Call the clinic within 24 hours and send the photo; most grade 2 lines are managed with a clean and a recheck, not a second surgery.
Grade 3 is any gap of 2 mm or more, purulent or foul discharge, swelling over 4 mm, or skin that is hot and painful to a light touch. Grade 3 is a same-day visit, and after hours it is an emergency visit.
The 3 red lines
- A gap of 5 mm or more, or fat, muscle or a blue suture visible inside the opening.
- Pus, green or brown discharge, a foul smell, or redness spreading 1 cm or more within 12 hours.
- Rectal temperature at or above 39.5 C (103 F), or no food and no urine for 24 hours.
Any 1 of the 3 ends home monitoring. Do not clean or ointment a grade 3 line, and do not wait for morning: a line open 5 mm at 9 pm can be 15 mm by 7 am, which is the difference between 1 day in hospital and a 20-minute closure.
Photograph it the same way every day
Three photos, same distance of about 10 cm, same overhead light, no flash: straight on, from 45 degrees, and a close-up with a ruler or a coin in frame. The ruler is what makes day 6 comparable to day 4. Store them in date order and take them before cleaning.
A phone photo at 10 cm shows a 1 mm gap clearly, but not smell or warmth; those 2 stay in the written log.
What the line should look like, by day
| Day | Expected look | Gap, mm | Rim, mm | Checks per day |
| 0-2 | Edges together, slight swelling, dry | 0 | 1-2 | 2 |
| 3-5 | Pink, swelling peaks then fades | 0 | 2-3 | 2 |
| 6-9 | Pale pink, crust at the ends | 0 | 1-2 | 1 |
| 10-14 | Sutures out, line closing | 0 | 0-1 | 1 |
| 15-21 | Thin scar, no scab | 0 | 0 | Every 2 days |
What slows a line down
Licking is the first cause and it takes 3 seconds: a tongue on a fresh line delivers pressure and bacteria together. The cone stays on 24 hours a day for 14 days, off only while the cat eats under supervision.
Litter is the second: clay dust packs into a 1 mm gap, so use paper pellets for 10-14 days. Jumping is the third, since a 4 kg cat lands with about 3 times its body weight on the front legs and a 5 cm flank line opens most often around day 8.
Healing strength, and why day 14 is not the end
A skin line holds roughly 5% of its final strength at day 7, about 20% at day 10-14 when sutures come out, and only 70-80% after day 21. That is why checks continue past suture removal.
Full strength takes 6-8 weeks. Keep the cat off stairs and high furniture for 21 days after abdominal surgery.
When the check turns into a visit
Book the recheck before you leave the clinic on surgery day: day 3 for a wound check, day 10-14 for suture removal, day 21 for activity. A reopened line costs far more than a check: a second closure is usually quoted at USD 350-900, GBP 250-700 or CNY 1,500-4,000, and an after-hours visit adds USD 150-250 before treatment.
The 5-step routine
- Set a phone alarm for the same hour every day for 14 days.
- Measure the 5 points in the same order and write 5 numbers on the fridge door.
- Take 3 photos at 10 cm with a ruler in frame before cleaning anything.
- Grade the line 0-3 and act on the grade, not on how worried you feel.
- Book day 3, day 10-14 and day 21 visits on surgery day, not when the line looks bad.
The wider recovery rhythm sits in the 14-day post-op plan, and the monthly skin check that takes over afterwards is described in the skin check guide. Procedure prices by city are in the cost tables.
Terms mentioned in this article
Frequently asked
How often should I check the incision after cat surgery?
Once a day for 14 days, at the same hour and in the same light, plus a second check in the first 48 hours when swelling peaks at 48-72 hours. Each check takes about 2 minutes once you measure the same 5 points in the same order: gap, rim redness, discharge, thickness and skin temperature.
Is a little redness and swelling normal on day 3?
Yes, up to 2-3 mm of pink rim and about 2 mm of swelling is expected while the line peaks at 48-72 hours and then settles. Redness of 2-5 mm with mild ooze is a grade 2 finding that needs a call within 24 hours, and anything spreading 1 cm in 12 hours is a red line.
My cat's incision opened slightly. How much is an emergency?
A gap of 5 mm or more, or fat, muscle or a suture visible inside the opening, is an emergency and goes in the same day. A gap under 2 mm with a clean base is usually grade 2 and can wait for a call within 24 hours, but keep the cone on and photograph it first, because a gap widens fastest in the first 12 hours.