A loose hip in a cat is usually a silent finding. The joint is lax on X-ray at 5 months and the same cat still jumps onto the fridge at 5 years, right up until the week it stops. Screening between 5 and 6 months is the one window where the hip can be scored before arthritis remodels it; after 24 months only the damage is left to see. Weight changes the outcome most: a cat held at a body condition score of 4 to 5 out of 9 from 5 months loads each hip with a fraction of what a cat 20% over target carries.
Why a dysplastic cat still jumps on the counter
Cats do not limp the way dogs do. A cat with sore hips shortens the stride, takes 2 stairs at a time instead of 3, and quietly stops jumping. Owners report a behavior change, not a lameness, so most cases turn up at 6 to 8 years on a dental X-ray. Five things to measure instead of guess:
- Jump height. Tape a mark on the highest shelf in use. A drop from 100 cm to 60 cm in 6 months is a 40% loss of range.
- Hesitation. A comfortable cat commits in under 1 second; a sore one pauses 3 to 8 seconds, then walks away.
- Landing. A bunny-hop landing, both hind legs together, offloads one hip at a time.
- Litter box. A box with a 25 cm lip becomes a wall; cats start urinating 20 to 30 cm outside it instead.
- Grooming. Skipping the hind end for 3 days or more usually means sore, not lazy.
Film one video a month in the same hallway. At 6-month intervals video beats memory.
Ortolani sign: 30 seconds per hip
The Ortolani test finds a hip that is partway out of the socket and clicks back in. Lay the cat on its side, flex the hip to 90 degrees, lift the femur toward the ceiling while pressing the knee inward, then slowly abduct. A palpable clunk at 30 to 45 degrees of abduction means the femoral head has dropped back into the acetabulum. Under 12 months that clunk is a clear reason to image; over 3 years it usually means the joint has already remodeled.
Muscle tension hides laxity, so a negative result in a tense, awake cat proves nothing; most vets repeat under sedation. The Barden test adds information: one hand lifts the whole pelvis off the table while the other steadies the spine. A positive on either test at 5 months buys an X-ray, not surgery.
Three X-ray views, one sedation
Hip scoring needs sedation: a tense cat can hold a dysplastic hip in a normal-looking position and produce a falsely clean film. Three views are standard:
- Ventrodorsal extended. Both femurs parallel, pulled straight down. This gives the Norberg angle: above 105 degrees is normal, 100 to 105 is borderline, below 90 means clear subluxation.
- Frog-leg flexed. Knees out, femurs rotated outward. Shows the dorsal acetabular rim and the shape of the femoral head.
- Distraction or dorsolateral subluxation. Measures how far the head pulls out under load. A distraction index of 0.3 or less is tight, 0.4 to 0.7 is loose, and above 0.7 carries a high risk of arthritis by 3 to 4 years.
Repeat films at 12 months: a borderline hip at 5 months can tighten as the joint remodels, and a cat with a loose hip often still jumps normally at 4 years, since laxity alone is not pain.
Weight and recheck schedule
| Age | Target BCS (/9) | Weigh-in | Imaging |
|---|---|---|---|
| 5 months | 4 to 5 | Every 14 days | 3 views |
| 6 months | 4 to 5 | Every 14 days | 3 views |
| 12 months | 5 | Every 30 days | 3 views |
| 18 months | 5 | Every 30 days | 2 views |
| 24 months | 5 | Every 60 days | 2 views |
Weight loss at 2% a week, never a crash
Start from the resting energy requirement: 70 times body weight in kg to the power 0.75. A 5 kg cat lands near 230 kcal a day, so a weight-loss plan sits near 185 kcal, or 80% of that. Aim for 1 to 2% of body weight a week: 50 to 100 g, so 600 g of excess takes 4 to 6 months. Keep protein at 40 to 50% of dry matter so muscle stays. Losing over 3% a week is dangerous, and 48 hours of food refusal needs a vet, not a stricter diet.
Joint support that earns its place
Omega-3: 20 to 40 mg/kg a day of combined EPA and DHA, or 100 to 200 mg for a 5 kg cat, split across 2 meals. Green-lipped mussel at 20 to 50 mg/kg is used by many vets. Glucosamine has thin evidence in cats; a 6 to 8 week trial is fair, kept only if the monthly video shows a change. For pain, robenacoxib at 1 mg/kg once daily suits short courses, with bloodwork at baseline, 2 weeks, then every 3 to 6 months. Frunevetmab at 1 to 2.5 mg/kg under the skin once a month is the longer option.
Never give a human painkiller. Ibuprofen at 50 mg/kg, which is one 200 mg tablet in a 4 kg cat, is where kidney damage starts, and acetaminophen from 10 mg/kg has caused fatal blood changes; one 500 mg tablet is 125 mg/kg.
The 6-month follow-up
Each visit: weight and condition score, a short pain questionnaire, and 3 tests the owner repeats at home. Measure hip extension with a goniometer — a normal hip reaches about 160 degrees, a sore one stops short — then the video jump, a timed 30-second stair climb, and the litter box lip. Before any NSAID, run a renal panel, urine specific gravity, and blood pressure; over 160 mmHg changes the plan. X-ray at 6 and 12 months, then every 12 months while stable.
When to call the vet today
Red lines: cannot rise within 24 hours, a hind leg dragged rather than carried, sudden non-weight-bearing lameness, a hot swollen joint, fever above 39.5 C, or loss of bladder control. Cold pale hind paws with loud crying is an aortic thromboembolism and is an emergency measured in hours. Also call if a cat on an NSAID stops eating for 24 hours or vomits 3 times a day.
What to do this week
- Book the 5 to 6 month check: Ortolani test plus 3 X-ray views on one sedation.
- Weigh the cat, write the number on the fridge, and repeat every 7 days.
- Tape a jump-height mark on the wall and film 1 video a month in the same hallway.
- Lower the litter box lip to 10 cm or less, and put a non-slip mat at the landing spot.
- Start omega-3 at 20 to 40 mg/kg of EPA and DHA, and stop all human painkillers today.
The chart at /tools/cat-age/ turns 5 months into a rough human equivalent when explaining the timeline at home. Cats on long-term steroids can develop a greasy black chin, covered in /health/feline-acne-chin/, and a cat that coughs rather than limps needs the spacer routine instead.
Terms mentioned in this article
Frequently asked
At what age should a cat's hips first be checked?
Between 5 and 6 months, with the Ortolani test plus 3 X-ray views taken under one sedation. That is the window before arthritis remodels the joint, and it gives a baseline to compare against at 12 months and 24 months.
Can hip dysplasia in cats be managed without surgery?
Yes, for most cats. Hold body condition at 4 to 5 out of 9, lose no more than 2% of body weight a week, feed omega-3 at 20 to 40 mg/kg of EPA and DHA, and use robenacoxib or frunevetmab for pain. Surgery is reserved for cats that keep hurting despite 3 to 6 months of that plan.
Does a clicking hip mean my cat needs an operation?
No. A positive Ortolani sign at 5 months means the hip is loose and needs imaging, not surgery. Laxity raises the risk of arthritis later, and many cats with a loose hip at 5 months still jump normally at 4 years.