Dog Won't Put Back Leg Down: Causes and What To Do Now

It can follow trauma, with sudden rupture more often in younger dogs, but more commonly it comes from gradual ligament degeneration that causes long-running lameness.¹ A slipped kneecap, a sore paw or a back problem can look the same from the kitchen doorway. This guide walks you through the likely causes, a safe check you can do at home, the red flags that mean go now, and how to protect the other back leg while your dog heals. For the bigger picture, start with our overview of back leg problems in dogs.

Why your dog won't put weight on a back leg

A dog that suddenly won't put weight on a back leg may have ruptured the cranial cruciate ligament in that knee, which leaves the joint unstable and painful.² Here are the causes vets see most, in plain English.

A torn cruciate ligament (the dog version of an ACL tear). Cranial cruciate ligament disease is a disease of the knee joint in which the ligament gradually weakens, and over time it may partially tear or rupture, causing an unstable knee that creates pain, arthritis and limping.² If it ruptures completely, a dog may suddenly become very lame and unable to bear weight on the affected leg,² and may cry out at the moment it tears.² Other signs include difficulty rising from a sit, trouble jumping into the car, decreased activity, muscle loss in the affected leg, and a popping or clicking noise, which may indicate a tear in the meniscus, the cartilage cushion inside the knee.³ Age-related ligament degeneration, obesity, poor physical condition, genetics, body shape and breed all play a part.³

A slipping kneecap (luxating patella). A patella is a kneecap, and "luxating" means out of place, so a luxating patella is a kneecap that moves out of its normal location.⁴ The most commonly seen sign is a "skipping" gait, which looks like a sudden three-legged hind limb lameness that quickly resolves after a few steps.⁵ With the common inward type, the dog usually holds up the lower part of the leg as long as the kneecap is out of place, then resumes normal walking once it returns to its groove.⁴ It affects primarily small dogs, especially breeds such as Boston and Yorkshire terriers, Chihuahuas, Pomeranians, and miniature poodles.⁶

A sore paw, nail or pad. It is the easiest thing to rule in or out, and it is the first place to look.

A strain from a bad landing. Not every held-up leg is a torn ligament. Muscles and soft tissue get sore too, and sorting a strain from something structural is exactly what the hands-on exam at the vet is for.

An arthritis flare. In dogs with a luxating patella, arthritis develops as the dog ages and results in decreased mobility and joint pain, and once arthritis develops it cannot be reversed.⁴ Surgery cannot prevent that arthritis, but it can slow it down, and weight control plus nutritional supplements may help delay its onset.² There is more on managing stiff, achy back leg joints in a separate guide.

A spinal problem, especially in older or long-backed dogs. Intervertebral disk disease (IVDD) is a neurologic condition affecting the disks that sit between the bones of the spine: the protective material around the spinal cord has undergone some kind of change, and the result can be pain, loss of function, or paralysis.⁷ Dogs with IVDD may show limping, dragging their legs, or hunching their back.⁷ Breeds such as Dachshunds, Pembroke Welsh Corgis and Basset Hounds have short legs and a long body that is low to the ground,⁷ while large dogs like Labrador Retrievers, Doberman Pinschers and German Shepherd Dogs are prone to a degenerative form of disk disease, where disks that are meant to cushion the spine become brittle with age and little pieces dry out and break off, causing damage to the spinal cord.⁷ Another cause is an injury from jumping or a hard landing: one moment your dog is playing, then they suddenly cry out in pain, and the force of the movement can damage a disk, resulting in sudden pain and pressure on the spinal cord.⁷

Toe-touching or truly not using the leg: how to tell

A toe-touching limp means your dog still trusts the leg a little; a truly non-weight-bearing leg never touches down at all. Some dogs "toe touch," placing only a small amount of weight on the injured leg.² Watch from behind as your dog walks away from you on a flat, non-slip surface. Look for whether the toes brush the floor, whether the foot takes any weight at the moment the opposite foot lifts, and whether the hip on that side drops at all.

Both patterns matter, and neither needs to come with crying to be serious. If you are hearing yelping as well, our guide on back leg pain with vocalising goes into that.

A safe head-to-toe check you can do at home

You can do a gentle check at home in about two minutes, as long as you stop the moment your dog tenses, pulls away or turns their head toward your hand. Never twist, bend or "test" a painful leg, and never try to feel for a loose knee yourself. That is the vet's job, and repeated handling makes a sore joint worse.

Work from the ground up, with your dog lying down and calm:

• Pads and between the toes. Spread the toes gently and look for cuts, a thorn, a burr, matted hair or anything wedged in the webbing.
• Nails. Look for a split, torn or overgrown nail, and for nails worn flat on one side, which tells you the foot is scuffing.
• Top of the paw and ankle. Compare left to right for puffiness or heat.
• Up the leg. Run a flat hand up the shin and thigh, comparing both sides for swelling, heat or an obvious difference in muscle bulk.
• Hips and back. Rest a hand along the spine and over the hips. Flinching, tensing or a hunched back is information for the vet, not a reason to press harder.
• Watch them stand. Note whether they square up or park the sore leg out to one side.

Write down what you find, with the date. That short note is worth a lot at the appointment.

Red flags: go now, versus book for tomorrow

Some signs need emergency care the same hour, not an appointment next week. Treat these as an emergency and call your vet or the nearest emergency clinic:

• Dragging the hind legs, walking as if drunk, or being unable to walk at all. These are IVDD symptoms that require immediate veterinary attention, and an inability to walk is an absolute emergency.⁷
• Loss of bladder or bowel control, or straining to go. Pressure on the spinal cord can make it difficult for dogs to urinate or have a bowel movement.⁷
• Crying out, an arched back, or obvious pain at rest. You might see your dog arching their back to try and relieve the compression on the spine.⁷
• Visible swelling, a deformed limb, or a leg that hangs at a wrong angle.

Time matters here. If a dog is unable to walk it means there is a great deal of compression on the spinal cord, and if the condition is not immediately treated with surgery, it can become irreversible.⁷ The sooner the vet examines your dog and starts treatment, the better your dog's chances of recovery.⁷

A next-day or next-available appointment is reasonable when it is one back leg only, your dog is bright, eating, able to walk and toilet normally, and there are no spinal signs. Still book it: a limp that persists or keeps coming back, including one that only shows up after long periods of rest, needs a hands-on exam.

What to do in the first 24 to 48 hours

Confine your dog and cut activity right back, starting now. Pain medication may improve comfort, but knee pain persists while the knee is still unstable, which is why strict activity restrictions such as leash-based activities are typically most effective at reducing pain.³ For spinal problems the message is the same: a dog with a mildly inflamed or partially slipped disk really needs rest, and sometimes that means a crate or playpen where they cannot walk around much or jump on anything.⁷

In practice, for the next couple of days:

• Keep your dog in one room, a pen or a crate, with bedding they can get on and off without a step up.
• No stairs, no sofa, no bed, no car jumping, no off-leash running, no ball.
• Short leash walks to toilet only, straight out and straight back.
• Put rugs, runners or yoga mats down over any slick floor they must cross. A kneecap that keeps slipping out of place strains the knee and makes other injuries more likely, especially a torn cruciate ligament.⁴
• Stop testing the leg. Trotting your dog up and down the hall to see "if it's still bad" is not a diagnosis, and every repetition is another load on an injured joint.
• No human medicines of any kind. Pain relief is prescribed by your vet, for your dog, after an exam.

What the vet will actually do

Most of the answer comes from a hands-on exam, not a machine. Expect your vet to watch your dog walk and trot, then feel every joint in both back legs and compare sides.

For the knee, your veterinarian will check for abnormal movement using the drawer test or tibial compression (thrust) test, which look for abnormal forward movement of the shin bone in relation to the thigh bone, indicating instability caused by damage to the cranial cruciate ligament.² Cruciate tears can be diagnosed from hands-on exam alone, which is easy in sudden complete ruptures but may be more subtle in long-standing or partial tears.³ If your dog is in pain, has strong leg muscles, or is unable to relax, sedation may be needed to allow a thorough examination of the joint.²

For the kneecap, your vet diagnoses a luxating patella by feeling the abnormal movement or position of the kneecap during examination of the leg,⁴ and will assign a grade of 1 to 4 to help guide treatment recommendations based on the severity.⁵

X-rays may follow. Although ligaments are not generally visible on X-rays, your vet may see evidence associated with ligament damage, such as inflammation within the knee joint or abnormal positioning of the bones.²

If the picture looks neurological, the exam shifts. In dogs whose condition is deteriorating or who can no longer walk, the vet will check whether the dog can still feel deep pain in the toes.⁷ From there your vet may refer you for advanced imaging and a specialist opinion.

Good questions to ask at the desk: which leg and which structure do you think is involved, do you need X-rays today or can we start with rest, what exactly should activity look like for the next two weeks, and what should make me call you sooner. If surgery comes up, we cover what knee surgery involves and what recovery looks like afterwards separately.

Sudden limp versus a back end that is slowly going

A sudden single-leg limp and a slowly failing back end are two different stories, and they need different conversations with your vet. Think back over the last six months. Sudden injury looks like a dog who was normal on Monday and three-legged on Tuesday. Progressive weakness creeps.

The progressive pattern looks like this:

• Scuffed, worn-down nails on the hind feet.
• Slipping and splaying on wood or tile.
• A bunny-hopping run, both back legs moving together.
• A wobbly, swaying back end, crossing feet or knuckling.
• Sitting with the back legs to one side in a "lazy sit" instead of sitting squarely, hesitating before stairs, and muscle loss in a hind leg.²

In degenerative myelopathy, a slowly progressive disease of the spinal cord, unsteadiness in the back legs caused by loss of position sense, meaning the dog no longer registers where their feet are, is an early sign.⁸ If your dog seems wobbly rather than sore, read back leg weakness without obvious pain.

The conditioning trap: protecting the other back leg

This is the part most pages skip, and it matters more than almost anything else you will read here.

Dogs that rupture the cranial cruciate ligament in one knee are at increased risk of developing a rupture in the other knee.² The numbers are sobering: up to 50% of animals diagnosed with cruciate disease in one knee will develop the same condition in the other knee, usually within the first 12 to 18 months after diagnosis.³ In overweight dogs, the other knee is at greater risk of a cruciate injury, particularly during the recovery period.²

Obesity or excess weight can significantly increase the risk of cranial cruciate ligament injury or rupture, because carrying excess weight places additional strain on the ligament and may also cause changes that make it more likely to tear.² If your dog is overweight, recovery after surgery will often take longer.² Weight loss is an important part of promoting a return to normal function and reducing stress on your dog's joints, and your veterinarian can help develop an appropriate weight-loss plan.² There is a fuller discussion in our guide to weight and a dog losing use of the back legs.

Muscle goes quickly too. Muscle atrophy, meaning decreased muscle mass in the affected leg, is a recognised sign in dogs with cruciate disease.³ That is why structured rehab is worth asking about rather than pure cage rest forever: rehabilitation may help strengthen the muscles around the knee joint and can help delay surgery in dogs with partial cruciate tears,³ and physical rehabilitation can speed up a dog's recovery and improve final outcomes regardless of the chosen surgical technique.³ It usually includes passive range of motion, meaning you gently move the joint for your dog, plus balance exercises and controlled walks on a leash, starting immediately after surgery.³ Gentle hands-on work at home, like simple back leg massage, can complement a plan your vet has set, not replace it.

Braces come up a lot in this conversation. Custom knee bracing is relatively new to canine orthopedics, there is little data on outcomes, and braces can be pricey and have potential complications such as sores, continued pain, and patient intolerance.³ If you want to weigh that option, see our page on bracing an arthritic back leg, and take the idea to your vet before you buy.

Where a sling or a rear support wheelchair fits in

A sling or a rear support wheelchair is for the dog whose back end can no longer carry them, and it is a supplement to veterinary care and rehab, never a substitute for either. If the dog's front limbs are strong enough, the vet may recommend a mobility device like a cart to help your dog get around.⁷

A sling is a padded strap that goes under the belly or hips so you can take some of your dog's weight while they walk a few steps to toilet. It is for short, supported trips: out the door, down the ramp, back in. Keep it under the hips rather than the ribs, lift only enough to unload the back end, and let your dog set the pace.

A rear support wheelchair is a wheeled frame that carries the back half of the body so the front end can do the walking. For a dog whose back legs are failing, it means they can keep moving without dragging their feet along the pavement and without you carrying them.

The OldPal Rear Support Dog Wheelchair is built for exactly that dog. The padded harness carries weight through the hips and chest rather than the spine, and every strap adjusts. The frame is set so the back legs hang free or lightly brush the ground, and dogs can squat and go to the bathroom while in the chair. The frame is lightweight aluminum with all-terrain wheels, and each frame adjusts in height within its range.

Talk to your vet before you order, especially if the cause of the limp has not been diagnosed yet or your dog is on restricted activity after an injury or surgery. Your vet should tell you when wheels are appropriate and how long sessions should be.

Sizing, simply: there are five sizes (Mini, Small, Medium, Large, XL) covering rear leg heights from 3 to 27 inches. You need one measurement: rear leg height, from the top of the hip straight down to the toe pad, with your dog lying on their side and the leg at its natural bend. Our size guide and fit finder walks you through it, and if you would rather have a person check, email a photo and your measurement to help@oldpalpets.com. There is a Fit Guarantee: if the size does not fit, the frame can be exchanged for the size that does. Mini, Small and Medium arrive within 1 to 2 weeks of your order, Large and XL within 2 to 3 weeks. We ship to the continental US only.

Setting up the house for a failing back end

A few changes make the difference between a dog who keeps moving and a dog who is afraid to try. Lay rugs, runners or rubber-backed mats along every route your dog uses, especially from the bed to the door. Block stairs with a gate and use a ramp for the car and any single step. Stop all jumping on and off furniture. Raise food and water bowls to a comfortable height so your dog is not bracing on sore legs to eat. Keep nails short, because long nails change how the foot lands and make slipping worse. Keep bedding thick and dry, and turn a dog who cannot shift position themselves.

Hygiene matters if your dog can no longer posture to toilet. Dogs that cannot get clear of their own waste need constant bathing and may get skin infections from lying in it.⁷ Dogs that can't empty their bladder properly can suffer from urinary retention and urinary tract infections, so tell your vet straight away if your dog is having trouble urinating.⁷ If you have a larger dog, helping them into a harness or getting them in and out of the bathtub can be more difficult.⁷

How to track progress so you can tell improvement from decline

Film your dog's walk from behind, on the same flat surface, once a week. A ten-second clip is enough, and it will show you things your eye misses day to day: whether the foot is touching down, whether the hips are swaying more, whether the nails are catching.

Alongside the video, keep a short weekly note:

• How many attempts to stand up from lying down.
• Whether the dog managed the ramp or step without help.
• How long the limp lasts after a walk, in minutes.
• Any knuckling, slipping, or accidents in the house.
• Appetite, sleep, and whether they wanted to go out at all.

Bring the clips and the notes to every appointment. "He's worse" is hard to act on; "three weeks ago he rose in one try, now it takes four, and the limp lasts an hour after walks" is something your vet can use.

Frequently asked questions

Related guides

• Back leg problems in dogs: the full overview
• Weight and a dog losing use of the back legs
• Back leg weakness without obvious pain
• Stiff and painful back leg joints
• Back leg surgery: what to expect
• How to measure your dog for a wheelchair

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