A cat that drags a hind leg needs a decision in the next 60 minutes, not the next 3 days. If the leg is cool to the touch, the paw pads are pale or blue, and the cat cries when you lift it, treat it as a vascular emergency and be at a clinic within 90 minutes, because a blocked artery starts to injure nerve and muscle after 4 to 6 hours and the limb can be lost by 24 hours. If the leg is warm and the cat still stands, you have a 24 hour line: a neuro exam the same day, since spinal cases still walking at 24 hours usually keep that ability.
Why the first 6 hours decide the leg
Blood reaches the hind leg through the aorta, which splits at the lower back into two iliac arteries about 1 cm wide. A clot that lodges at that split, the saddle thrombus, usually cuts flow to both legs and sometimes to only one. Muscle survives 4 to 6 hours without flow; after that, cells break down and release potassium and myoglobin, which also strain the heart. That is why the exam starts with a pulse and a temperature, not with an X-ray. Cats with this clot almost always have heart disease behind it, usually hypertrophic cardiomyopathy, and many arrive breathing 60 to 80 times a minute instead of the normal 20 to 30.
Three cause groups
Group 1 is spinal: a fibrocartilage embolus that blocks a spinal vessel, a disc that presses on the cord, or bruising after a fall, all with a weak or dragging leg and a normal pulse. Group 2 is vascular: a saddle thrombus or a clot in one iliac artery, with a cold, painful, pulse-less leg. Group 3 is orthopedic and metabolic: a fractured pelvis or femur, a dislocated hip, low potassium in a cat that has been off food, or nerve damage from long-standing diabetes. Age and shape sort them: a middle-aged overweight cat with a murmur fits group 2, a young cat that fell from a height fits group 3, a sudden painless drag fits group 1.
Grading table: how fast to move
| What you see | Paw pad temp (C) | Femoral pulse | Act within |
|---|---|---|---|
| Drags the leg, still bears weight, warm paw | 37 to 38 | Strong, both sides | 24 hours |
| Knuckles over, cannot right the paw, warm | 36 to 37 | Strong, both sides | 12 hours |
| Leg cool, pads pale, cat cries on handling | 34 to 36 | Weak on one side | 90 minutes |
| Both hind legs limp, nails blue, breathing 60 plus | Under 34 | Absent both sides | Now, 30 minutes |
| Open wound or a leg at an odd angle after a fall | Variable | Variable | 2 hours |
A pad temperature 2 to 3 C below the other leg is the most useful thing an owner can measure: no training needed, and it changes the triage level.
Four things to record in the first 10 minutes
Write the time the drag started, to the minute, because the 4 to 6 hour muscle window and the 24 hour line are counted from it. Second, test the paw: turn the back of the paw down on the floor and see whether the cat puts it right within 2 seconds, which tells you the spinal cord is still talking to the foot. Third, compare both femoral pulses with two fingers high inside the thigh, and feel both paw pads with the back of your hand for 5 seconds each, noting any difference in color from pink to gray. Fourth, count breaths over 30 seconds and double it, and look at the gums: a rate over 40 with pale gums points to the heart, not the leg. Photograph the leg from 2 angles.
Two exams that set the plan
The neuro exam takes 10 to 15 minutes and needs no machine: posture, the paw-righting test, knee and withdrawal reflexes, and pain perception in the tail and toes, scored 0 to 4. Loss of deep pain is the finding that changes the prognosis and the clock. The second exam is imaging and flow: Doppler ultrasound of both femoral arteries takes 5 to 10 minutes and shows whether blood is moving, an echocardiogram looks at the heart wall and the clot source, and an X-ray of the pelvis and spine takes 2 views. A cat with a cold leg gets the Doppler first; a cat with a warm leg and a weak reflex gets the X-ray first.
Three things never to do on the way
Do not pull, stretch, or massage the leg: a cat with a disc or spinal clot can lose function that was still there, and a fractured femur can shift 1 to 2 cm. Do not give any human painkiller: paracetamol and ibuprofen are toxic to cats at a fraction of a human tablet, and a single 200 mg ibuprofen tablet can cause kidney failure. Do not tape the legs together or force the cat to walk to see if it improves, and do not let it drag across tiles for hours, because the skin over the hock wears through in 2 to 3 days and turns a nerve case into an open wound. Carry the cat on a flat board or in a low-sided box.
The 24 hour line and the 8 week window
Spinal cases are graded again at 24 hours: a cat with pain perception and a voluntary step then has a good chance of walking by 8 weeks. Rechecks are set at 24 hours, 7 days, and 4 weeks, with physio starting in week 1 and 10 to 15 minutes of assisted standing twice a day once the vet agrees. Vascular cases that survive the first 48 hours are watched for 2 weeks for skin loss over the paw and the hock, and many need 4 to 6 weeks of bandaging. Orthopedic cases are rechecked at 10 to 14 days for a fracture, and at 6 weeks for a healed pelvis. Ask for the neuro score at each visit.
Related signs worth reading
A cat weak in both hind legs but still walking is a different case; pattern and speed of onset separate them, and hind leg weakness covers the walking version. A leg that cannot move at all, with no pain perception, is covered in hind leg paralysis. If the cat had access to lilies, human pills, or antifreeze, check the toxicity list, since some poisons cause a sudden rear-leg weakness that looks orthopedic.
Five steps for the next hour
- Feel both paw pads and both femoral pulses, and note the temperature difference.
- Time the onset to the minute, then photograph the leg from 2 angles.
- Cold leg, pale pads, or crying: call and drive within 90 minutes.
- Carry the cat flat, do not pull the leg, do not give human painkillers.
- Book the 24 hour neuro recheck before you leave the clinic.
Frequently asked
How do I know if a dragging leg is an emergency?
Feel the paw pads and both femoral pulses. A leg that is 2 to 3 C cooler than the other, with pale pads and no pulse, is a clot until proven otherwise, and the muscle starts to die after 4 to 6 hours. Drive within 90 minutes. A warm leg with a normal pulse and a cat that still stands can wait up to 24 hours for a neuro exam.
Can a cat recover from a spinal clot or a disc?
Many do, and the 24 hour exam is what predicts it. A cat that still has deep pain perception and a voluntary step at 24 hours has a fair chance of walking by 8 weeks with rest and 10 to 15 minutes of assisted standing twice a day. Loss of deep pain is the finding that changes the plan, which is why the neuro score is written down at every visit.
Why not just rest the leg at home for a few days?
Because skin over the hock wears through in 2 to 3 days of dragging, and an open wound on a leg with poor blood flow is much harder to treat. A clot also keeps damaging muscle for as long as it sits there, and a spinal case that is losing function needs a score today, not in 3 days, to decide on surgery or rest.