Health
He slammed on the brakes after the ball and has held a hind leg up ever since. Or he has been limping after walks for weeks. The knee is the first suspect.
Caution. Not putting the leg down at all after an hour's rest, a swollen and hot knee, a fall or a knock, lameness on both hind legs or a fever too: call your own vet today. Do not give human painkillers.
Do not look for the answer in a Facebook group, on TikTok or on a forum. Look for someone trained for this: your dog's own veterinarian, the only person who can examine, investigate and treat them.
Use this page to know what to observe, what to note and what to ask at the appointment, not to treat at home. If you still have doubts after a consultation, ask another vet or a specialist (dermatologist, internist) for a second opinion, not a group. And if you do not have a regular vet yet, find one now, while your dog is healthy: how to choose a veterinary clinic.
He chased the ball, slammed on the brakes on the grass, yelped once, and ever since he has held that hind leg up or barely touched the ground with his toes. For other dogs there was no single moment. For a few weeks he has been limping after long walks, getting up stiffly in the morning, and when he sits he sticks one leg out to the side instead of tucking it under like he used to. A torn cranial cruciate ligament (the dog's version of the ACL in people) is one of the commonest reasons for hind-leg lameness in dogs. People picture a footballer and a bad tackle. In most dogs the ligament gives way after slow weakening over months. This page covers what to watch for and note down, what to expect at the vet, and how to avoid making the knee worse in the meantime.
A limp is not automatically an emergency. A few situations do call for a phone call to your own vet today:
If he is toe-touching but moving about, eating and not in obvious severe pain, an appointment in the next few days is fine. Until then, strict rest.
Video. On level ground, at a walk, from 5 to 10 metres away: from behind, from the front and from the side. Then at a trot if he can manage it. On a screen your vet will spot things that disappear in the consulting room, where the dog is wound up and moves differently.
How he sits. Ask him to sit and look from behind. A dog with healthy knees tucks both hind legs under him evenly. One with a torn ligament often sits with the sore leg slightly out to the side, because he cannot bend the knee fully without pain. It is a clue, not a diagnosis.
How it started. Was there one moment (a hard stop, a jump, a slip)? Or has he been lame on and off for weeks, mainly after exercise? For a vet, the second story is the more typical one.
When it is worst. In the morning, after a long rest? After a walk? On the stairs, jumping into the car or onto the sofa?
The thigh muscles. Put your hands on both thighs at the same spot. After a few weeks the thigh on the sore side is often noticeably thinner, because he uses it less.
The other leg. Look at it just as carefully. In many dogs the ligament in the other knee starts to give way in the following months or years.
Everything else. Age, weight (weigh him), breed, whether he is neutered, whether he has been lame before.
| What you see | Cruciate tear | Other possible cause |
|---|---|---|
| Sudden lameness after a hard stop, adult dog | Typical | Thorn in the paw, torn nail, sprain |
| Lameness that comes and goes for weeks | Typical of a partial tear | Arthritis, luxating patella |
| The leg "skips" for a few steps, then he walks normally | Less common | Luxating patella, especially in small breeds |
| Young, large-breed dog lame on both hind legs | Possible | Hip dysplasia |
| Older dog, worsening pain, hard swelling on the bone | Rare | Bone tumour: get seen quickly |
Check the paw first: nails, pads, between the toes. A thorn or a cut can cause a limp that looks just as dramatic and takes minutes to sort out.
Ask about the other knee too: which signs to watch for and how to spare it.
Cruciate tears are common in active dogs, often in a knee that has been weakening for a long time. What helps: keeping his weight at the lean end of normal, a few minutes' warm-up before running or training, fewer hard stops on tiles and wet grass, and muscle built up through walks on slopes and mixed terrain. In mantrailing the dog pulls into the harness but rarely makes sharp turns. A dog who has had surgery can go back to trailing after rehab, with the vet's agreement and short trails to start with.
What dog owners search for most often on the internet about this problem, with the short answer. The answers are a guide only: the decision belongs to your dog's own vet, after an examination.
The usual signs: lameness on one hind leg, either sudden after a hard stop or a jump, or on and off for weeks; the leg held out to the side when sitting; trouble getting up; and a thigh that is losing muscle. Only your vet can confirm it, with the drawer test, sometimes under sedation, and X-rays.
The ligament does not knit back together. In small, light dogs the knee can sometimes stabilise through scar tissue, with strict rest, weight loss and rehab. In medium and large dogs the usual advice is surgery, because an unstable knee develops arthritis and often tears the meniscus. Your vet will tell you which route suits your dog.
Strict rest: short outings on lead, just for toileting, on level ground, with no running, jumping or stairs. Put rugs down on tiles and wooden floors, film him walking and cut his portion so he does not gain weight. Do not give him human painkillers: they are toxic to dogs.
Yes, it often does, because in dogs a tear usually comes from a weakening of the ligament that tends to affect both knees. That is why vets usually X-ray both legs. Keeping him at the lean end of normal and doing the rehab properly after surgery take load off the healthy knee.
The information on this page is educational and does not replace an examination. For full details and a diagnosis, consult your dog's own veterinarian.
They often come together: the same causes, plans that complement each other.
A paw on tiptoe after training, slow to get up in the morning, a leg held in the air. Three levels of urgency, and none of them is fixed with a pill from your cupboard.
Up in two stages, refusing the stairs, bunny-hopping at a run. Joint pain shows in what the dog stops doing, long before he whimpers.
You can no longer feel his ribs, the waist has gone, he pants after three flights of stairs. Fat creeps on and hides up close, but your hands find it in two minutes.
He runs, lifts a back leg, goes three steps on three legs and then carries on. In small breeds it is very often the kneecap slipping out of place.
We work with your dog's behaviour, not its health. For any sign described here, book an appointment with your own vet; the related services page explains how to choose a clinic.