Your dog’s finding it difficult to push up to standing from a lying down or sitting position. You are probably needing to give him help to stand up. When he does manage to stand, his rear legs/hips sink down. Or he may even suddenly collapse down again. Effectively, your dog’s back legs are not working.

His back legs may be shaking or trembling.

He’s having trouble walking, and finding it difficult. As your dog’s back legs are weak, it’s a struggle for him to generate the forward momentum needed to walk. He may be swaying, slipping, staggering or sliding as he walks, or his legs may be crossing over each other. He might be dragging the tops of his paws, rather than picking his paws up properly (Knuckling).

There may be muscle wastage or atrophying around his rear legs / hindquarters. Perhaps he’s licking or worrying at a particular joint in his back legs. 

There may be a pronounced limp or lameness that’s obviously originating from your dog’s rear legs. Or your dog may not be able to walk at all.  It might look like he’s losing his balance and his movements are uncoordinated.

He may be showing distress - crying or whimpering - when he tries to get up or walk. 

In serious cases, your dog may not be able to get up at all. This can either come and go, or be permanent.  Your dog may also be suffering from faecal or urinary incontinence. 

There are many causes for rear leg weakness. Even if you’re putting it down to old age, it’s best to see a vet so they can determine the underlying cause. Age, breed and size may make some conditions more likely. Your vet is best placed to diagnose. 

Your vet will likely ask you:

• Does the weakness come and go (episodic) or is it constant?
• Does exercise make the weakness worse?
• Did the weakness happen suddenly or has it been developing for a while?

What causes a dog’s hind legs to be weak?

It’s essential to get a definitive diagnosis of the underlying condition from your vet. This is because there are so many potential causes. An owner making an assumption about the condition (e.g. it’s just old age) means a dog might miss out on crucial, life saving treatment. 

If your dog experiences sudden onset rear leg weakness or paralysis, treat it as an emergency. Get veterinary help immediately. 

These are the categories of conditions that cause hind leg weakness in dogs:

• Orthopedic
• Neurological
• Metabolic / Endocrine
• Cardiac
• Infectious Diseases
• Trauma
• Muscular

• Chronic joint inflammation - arthritis or osteoarthritis (degenerative joint disease) can be very painful for your dog. With osteoarthritis, the cartilage that cushions the ends of the joints, completely erodes. This means bone might be rubbing against bone, causing immense pain. In addition, the muscles can ache or seize up. This is called compensatory pain. All of this makes your dog want to avoid being mobile. As your dog becomes increasingly sedentary, muscle strength and fitness is lost. This worsens the situation.

• Hip dysplasia - in healthy hips, the ligaments and joint capsules (soft tissues) stabilise the hip joint. The hip joint is a ball and socket joint. When hip dysplasia develops, the ligaments and joint capsules loosen and don’t stabilise the joint. Instead, there’s ‘hip laxity’ - the femur is too loose in the hip joint. As a result, the ‘ball’ at the end of the femur, which should fit neatly into the ‘socket’ of the hip joint, starts to deform. It flattens and the socket becomes saucer shaped instead. As well as being problematic in its own right, hip dysplasia means a dog will certainly develop secondary osteoarthritis of the hip. Most dogs have hip dysplasia on both sides. Read more about hip dysplasia here.

• Immune-mediated polyarthritis (IMP) - this immune system disorder results in inflammation in multiple joints. It’s comparable to rheumatoid arthritis and lupus in humans. A lot of similarly-presenting conditions will need to be ruled out first. It can be a primary or secondary condition (as a result of a separate primary condition). Dogs suffering from it can look as if they’re walking on eggshells.

• Lyme arthritis - the bite of the black-legged (or deer) tick can transmit the bacteria that causes Lyme’s disease. Once the bacteria has travelled through the system, symptoms can appear. One of these symptoms is swollen joints and limping. Symptoms can take weeks or months to appear after an infected tick’s bite. 

• Anterior Cruciate Ligament (ACL) Tears - In dogs, the ligament that corresponds to the human ACL is actually the Cranial Cruciate Ligament (CCL). Despite it being technically a CCL injury, it’s often referred to as an ACL injury even when talking about a dog. 

A CCL injury can range from a strain (injury to muscle), sprain (injury to ligaments / joint capsule), tear to a full rupture. Any injury means that the knee is no longer stabilised. CCL injuries are painful. Dogs will avoid putting weight on the injured leg. 

The weight which would normally be going through the injured leg gets distributed elsewhere. This can cause further problems. It’s common to find that the CCL of the healthy leg can get injured or compromised. Arthritis can also develop, because the thigh and shin bone start rubbing against each other. Read more about ACL injuries here.

• Patellar luxation - patellar luxation is when a dog’s patellar (knee cap) slips laterally in and out of place when the knee is flexed. Recognisable symptoms are a dog holding up their paw, doing ‘bunny hops’ or shaking or extending the leg before regaining its full use. There are 4 grades of severity for patellar luxation. To manage the condition, the grade of severity needs to be understood. The more severe the condition becomes, the more lame a dog will become. Read more about Patellar Luxation here.

• IVDD (Intervertebral Disc Disease / disc herniation / slipped / ruptured / bulging) - can be what causes sudden hind leg weaknesses in dogs. The intervertebral discs normally act as shock absorbers for the vertebrae. In IVDD these discs degenerate or herniate. IVDD can happens after a dog’s been exercising. Disc herniation can cause the rear legs to collapse or for there to be complete paralysis. IVDD can affect any breed but iis common in dachshunds, beagles, shih tzu and bichon frise. URGENT veterinary treatment and possibly surgery are needed. Don’t delay in taking your dog to the vet if this occurs in your dog. Read more about IVDD here.

• Fibrocartilaginous Stenosis (FCE) / spinal cord infarction - an FCE is a spinal stroke. A small piece of cartilage, from within a vertebral disc, enters the spinal cord’s vascular system. Blood flow to the spinal cord is then blocked. It generally happens in the middle part of the spinal cord, affecting the hind legs. When there’s an FCE in the neck, all 4 limbs become paralysed. 

At the time of an FCE, a dog who’s suffered it may cry out in pain but then seem to improve. However, their walking will show acute weakness, incoordination and paralysis. Neurologic symptoms may or may not improve. FCE is not a progressive condition. Recovery is sometimes possible. Depending on the area of blood flow affected, some dogs may never recover their mobility. If paralysis is severe, there's incontinence and no improvement after two weeks, you may have to consider your dog’s quality of life.

If your dog displays symptoms of an FCE, it’s an emergency. Take your dog to the vet immediately so diagnostic imaging can be done. 

Any breed of dog can suffer from an FCE. However, breeds that seem statistically more at risk are large- and giant-breed dogs including Labrador Retriever and Bernese Mountain Dogs. There also seems to be higher incidence in Miniature Schnauzers, Yorkshire Terriers and Shetland Sheepdogs. FCEs often occur in middle aged dogs (3-6 years). High impact sports are also implicated (frisbee or flyball), when a dog’s jumping, leaping and twisting a lot. However, it can also happen when a dog’s merely walking.

• Cancer / Spinal Tumours - there are several ways in which cancer can cause weak hind legs in your dog. It might be affecting the long bones of the rear legs, pelvis or soft tissues, depending on the the type of cancer or tumour. Osteosarcomas are aggressive, fast growing cancer. They typically attack the tibia and fibula bones in large breed dogs, causing limping, an avoidance of weight bearing in the affected limb, or even spontaneous fractures of the bone. 

There might be a large lump or swelling, and a dog with the condition may lose their appetite. The tumour might be causing enough pain that a dog will be reluctant to walk. Advanced imaging will give a specific diagnosis, and a treatment plan can then be decided.

Cancers are typically diagnosed through a CT scan or MRI.

• Diskospondylitis - is an infection - usually bacterial or fungal - of the intervertebral discs and adjacent vertebral bones. It’s often difficult to diagnose, but one of the symptoms is rear leg weakness. It can affect one area of the spinal column or several. 

Diskospondylitis can be blood born (infection through a wound), through direct contamination (bite or puncture wound) or migrating foreign body (e.g. grass seed) that’s made its way to the spinal cord via inhalation, ingestion or a penetrating wound. Dogs with chronic infections or immunosuppression may be predisposed to this condition.  Certain breeds also seem more prone to it: large breed dogs including Great Danes, German Shepherds, Boxers, Rottweilers, Dobermans and English bulldogs.

Diskospondylitis’s first symptom is often back pain and a dog suffering from it will not be their usual active self. Symptoms can progress slowly - your dog may look stiff, not like being touched in certain parts of their spine because it’s painful, and resistant to getting on and off furniture. There can be muscle weakness and stiffness. Sometimes a dog can become completely paralysed.

Diagnosis is through X Ray (usually multiple are needed)  or CT Scans, MRIs and even a cerebrospinal fluid tap. (CFT). Treatment is usually a 6-12 month course of antibiotic or antifungal treatment. Sometimes surgery is necessary. Typically an affected dog will also be given pain relief.

• Lumbosacral stenosis (cauda equina syndrome)- the spinal cords narrows, often due to the pressures put on it by ruptured intervertebral discs, fractures, spinal osteoarthritis or tumours. It specifically affects the lumbosacral joint, which connects the last vertebrae to the pelvic area. The stenosis makes it hard to stand. Once standing, a dog with the condition will be very wobbly on their feet or when walking. Paralysis of the tail and incontinence are other symptoms of lumbosacral stenosis. It’s a very painful condition because the lumbosacral area is where all the peripheral nerves branch off from the spinal nerves. These peripheral nerves then go to the hind end. Anything pressing on these nerves causes nerve pain, which is an extreme type of pain. Slower growing tumours may end up pressing against spinal nerves and compromising rear leg mobility. 

• Degenerative myelopathy (DM) - degenerative myelopathy is a progressive, genetic neuromuscular disorder of the spinal cord. It’s usually diagnosed when a dog’s around 8 years old, although this is a generalisation. Sadly, it’s ultimately fatal. It occurs in many purebred and mixed breed dogs. The symptoms worsen slowly in time, but generally start with ataxia (loss of coordination) and dragging (knuckling)  in the rear legs. You may also notice your dog is no longer able to jump up into the car, or go up stairs easily.  As your dog’s mobility deteriorates, the knuckling and rear leg weakness will become more severe. Incontinence may develop.  When DM’s in its advanced stages, a dog will become completely paraplegic (total rear leg paralysis) and the front legs will begin weakening. DM isn’t generally painful for dogs who suffer from it. Read more about DM here

• Myasthenia Gravis - this autoimmune neuromuscular disorder disrupts the transmission of nerve impulses to muscles. Symptoms vary, depending on the progression of the condition but weakness and fatigue are obvious ones. A dog suffering from it may get up as normal after resting, but then within minutes be staggering and slipping until he’s no longer able to stand. He will rest and seem normal again (affected neuromuscular transmitters have restored during the rest) and then weakness comes on again. The cycle repeats. The weakness can be so bad, sometimes a dog can no longer walk at all. Another recognisable symptom is acquired megaoesophagus. A couple of hours after eating, a dog regurgitates their meal. Medication can treat Myasthenia Gravis. However, if left undiagnosed, it may lead to full paralysis and ultimately be fatal.

• Exercise Induced collapse - This genetic neuromuscular disorder generally affects Labrador Retrievers and a few other breeds. After strenuous exercising, an affected dog will appear unco-ordinated and getting weaker and weaker, until there’s a full, life-threatening collapse. This happens a few minutes after the exercise. Apart from this, the dog appears completely healthy. Exercise induced collapse can’t be cured. The disorder is managed by avoiding strenuous exercise. Diagnosis can be through genetic testing for the EIC gene in dogs who show these symptoms.

• Idiopathic vestibular syndrome (‘old dog vestibular disease’/’geriatric vestibular disease’) - geriatric dogs are more prone to suffering from this and it’s often a cause for sudden onset hind leg weakness and poor co-ordination in this age group. Other symptoms are a head tilt, leaning the body in one direction (usually the same direction as the head tilt), balance issues, jerking eye movements (nystagmus) and obvious disorientation.A dog with this condition can look like they’ve had a stroke or are drunk. The cause of this condition is unknown, although sometimes a tumour which is affecting the ear receptors or nerves might be found. Dogs usually recover from idiopathic vestibular syndrome. Supportive care and sometimes physiotherapy help recovery. Recovery time is generally 2-5 weeks.

• Hypoglycaemia (low blood sugar) - This metabolic disorder has non specific symptoms. Muscle twitching and tremors, ataxia (lack of co-ordination), exercise intolerance, weakness and collapse are some of them. If left untreated, it can be fatal. There are many underlying causes for low blood sugar. Some are more serious than others. Initial diagnosis is through blood glucose measurement and, possibly, additional blood tests. Once the initial crisis is treated (e.g. glucose or corn syrup being rubbed on gums or via concentrated dextrose IV fluid infusion), the underlying cause will need to be diagnosed. Further management will depend on that. Sometimes it’s simply because a dog has been over-exercised. Instructions to prevent a recurrence will be given.

• Anaemia (low red blood cell count) - Anaemia is the reduction of red blood cells (haemoglobin) in the blood. Oxygen is carried around the body by red blood cells. Therefore, a lack of haemoglobin causes weakness and fatigue. Blood loss, malnutrition or an autoimmune disease can all cause anaemia. So it might be a symptom of another condition. Your vet can do blood tests to determine whether anaemia is contributing to, or causing, your dog’s back legs not working.

• Hypokalemia (low potassium) - if a dog has severe hypokalemia, it will have generalised muscle weakness and difficulty getting up and walking. It may appear ‘drunk’. Rarely, the dog won’t be able to hold its head up normally. He may appear depressed, without appetite and even have constipation. Hypokalemia at this level is life-threatening. Once diagnosed, potassium supplementation is given to reverse hypokalemia’s effects, including muscle weakness. Once the underlying cause of low potassium is discovered, further treatment can be decided.

• Hypothyroidism - Hypothyroidism affects the levels of hormone thyroxine being produced. There’s a lack of it. Thyroxine regulates metabolism, and a lack of it causes weakness and fatigue. Beyond that, along with hypothyroidism, a type of neuropathy can occur. Neuropathy affects the peripheral nerves. It can manifest as weak hind legs when a dog’s exercising.

• Addisons Disease (hypoadrenocorticism) - this disorder of the adrenal glands causes dysregulation of the hormones that govern metabolism, immune system function and blood pressure. Dogs suffering from Addisons Disease lack these hormones. This results in weakness, lethargy or even collapse. This is a serious disease and can be life threatening without prompt treatment.

Hepatic encephalopathy (HE) - this is a secondary condition to liver disease. It causes episodic confusion and weakness, usually after a dog’s eaten. The liver isn’t working properly, so there are changes to blood chemistry that affect normal brain function. Symptoms of this include seizures, an unsteady gait, drooling and muscle tremors. Diagnosis is through physical examination and blood tests.Treatment to stabilise a dog suffering from acute HE will likely include an IV. Once stabilised, appropriate nutrition (decreasing protein intake) and antibiotics might be needed. Further diagnostic tests might be needed to identify the underlying liver disease.

• Congestive heart failure - is a condition that results from heart failure. A healthy heart pumps blood, that carries oxygen, around the body. If there’s congestive heart failure, the heart can’t pump enough blood around the body. Adequate oxygen isn’t reaching the bloodstream. This can result in weakness, fatigue or collapse. It’s estimated that 10% of dogs and 75% of senior dogs have some form of heart failure. If heart failure affects a dog’s rear legs, it’s likely the most severe stage of heart failure.

• Arrhythmia - an electrical heart problem, where the heartbeat becomes dysfunctional.  Rear limb weakness is one of the symptoms of arrhythmia.

• Heartworm disease - heartworms in dogs can block the heart’s valves or even the entire heart chamber, causing all the symptoms of heart disease, which lead to rear leg weakness. Preventative treatment is strongly recommended.

• Cardiomyopathy is a weakening of the heart muscle through disease, which causes the heart to enlarge. Blood no longer circulates efficiently around the body. This can result in muscle weakness because the leg muscles aren’t getting the blood and oxygen needed to function. 

• Pericardial effusion - the double-walled sac containing the heart and heart vessels becomes swollen with excess fluid. Normal heart contractions are restricted and the fluid puts extra pressure on the heart, so it can’t fill properly. The heart stops working properly. As a result, blood circulation to the muscles is restricted. A dog’s hind legs can weaken as a result.

• Cardiac or pericardial tumours - heart cancer is relatively rare in dogs. Middle-aged to older dogs (7-15 years) are typically affected. Golden retrievers and German Shepherds seem more prone to developing this type of cancer. Hemangiosarcoma is an aggressive, malignant tumour that spreads to organs, including the heart. Weakness is one of the symptoms of cardiac tumours.

Infectious diseases

• Lyme’s disease - see above

Trauma

• Fracture - fractures that cause rear leg weakness can happen for any number of reasons - falling/jumping off a height, car accident. Prompt veterinary attention is essential to assess the extent of the damage and initiate appropriate treatment.

Protecting your dog from all the categories of diseases and conditions listed is impossible. A few risks can be minimised through common sense - eg. keep your dog safe from car accidents; stop your dog from jumping off high surfaces; check for ticks - but many causes of rear-leg weakness are unavoidable.

Keep your dog healthy with appropriate exercise, good nutrition and the right weight. Consider a joint supplement for arthritis and osteoarthritis. 

Perhaps most important is ensuring that your dog has regular veterinary check-ups.  

Consider genetic testing if you know your dog might be predisposed to a breed-specific, inherited condition.

What breeds and ages suffer from rear leg weakness?

Different age groups and breeds can suffer from rear leg weakness due to different conditions. It’s impossible to generalise.

Treatment depends on the cause of your dog’s rear leg weakness. Sometimes it’s a symptom of an incurable condition. Other times, a dog can recover if given the appropriate treatment. Surgery, medication, pain relief and physical therapy are all possible treatments.

Where relevant, you can help your dog by considering these options:

• Mobility aids to improve quality of life - wheelchairs and / or Maximus Paws Up. Dogs don’t need to be completely paralysed to benefit from a wheelchair. They can also be used to aid rehabilitation.

• Rear lift harnesses - particularly ones that are comfortable enough to be left on for long periods of time and let your dog toilet normally

• A full body harness if your dog needs to get up and down stairs, or generally needs support while walking (e.g.after an attack of idiopathic vestibular syndrome)

• Physiotherapy and hydrotherapy - where appropriate

• Stem Cell therapy for arthritic joints. It can help repair damaged tissue and heals musculoskeletal injuries

• Acupuncture for pain relief 

• Post operative laser therapy for IVDD

• Massage and grooming - this can stimulate blood supply and the muscles. Look here for a canine massage therapist (UK) or you can massage your dog yourself

• Diet and weight management - maintaining a healthy weight is crucial to reduce stress on the joints, particularly for dogs prone to orthopaedic issues. Being overweight makes everything more difficult for a dog.

Several tried and tested ways exist to help your dog around the house. Firstly consider your dog’s safety when left alone. If you have to go out, do you need to put him in a crate to prevent him from falling, or trying to jump on and off furniture?

Stair gates might be needed to stop him trying to get up and down stairs while alone, and falling.

A comfortable bed is essential - to cushion sore bones and joints. When your dog’s unable to turn on their own, when lying down, you will need to turn them every four hours to prevent pressure sores, and damage to the muscles from prolonged pressure.

Anti-slip socks are a simple and effective way to give him more grip when getting up from resting or sitting. They prevent the rear legs from slipping or sliding under him when walking on uncarpeted floors.

Rear lift harnesses can help you help your dog up from sitting or lying.

Conclusion

Understanding the various factors that can contribute to hind leg weakness in dogs is essential for pet owners to provide the best possible care. It should never be dismissed as just a side effect of old age.

Early detection, prompt veterinary attention and a comprehensive approach to treatment can significantly improve a dog’s chance of recovery and restore their zest for life. 

Back leg paralysis isn’t necessarily an end-of-life situation. Discuss mobility aid options with your vet, based on quality of life and what’s best for your dog.

If you notice any signs of hind leg weakness in your dog, seek professional veterinary advice to ensure a timely and effective intervention.

“My Shih Tzu is having trouble with his back legs. What harness would you recommend?”

We suggest looking at the Walkabout Rear End Harness for dogs. This is a very good value, good quality rear harness that you may want to consider. You will need to measure your shih-tzu to find the best size. Measure once around your dogs high.

“Hi. Just wondered which product you’d recommend for my 12 year old dog who is suffering from rear paw knuckling. She’s very unstable at times due to the knuckling and is very tired after walking very short distances. We were looking at the Maximus PawsUp Superflex or the Walkin’ bootie dog splint. Thanks”

We would advise against the Bootie Splint if you want a pair (both back paws) as they can be heavy and not that comfortable when walking. Maximus PawsUp are good but it might be best if you send in a video of your dog knuckling, we work very closely with Maximus Skates and can send them the video over and they can check they would work well for your dog. Our email is: woof@zoomadog.co.uk.

“Would this be suitable for a fully ruptured Achilles Tendon? Our dog is 13 yrs, too old for an operation and back hock is flat on the ground when walking? Otherwise he hopes putting strain on his other hind leg.”

Please first speak to your vet about the splint and get their recommendations on it. If surgery isn't an available option, it would seem that a splint or support is the alternative but we want to know what your vets think too before committing to a suggestion. I hope that this is understandable. Do let me know if you want to discuss further as we are here to help.

“Hi – my dog can’t get up from their bed and are losing mobility quickly. Would a hip brace help him get back to action again?”

If your dog is losing mobility, is it worth considering a dog wheelchair. You haven't given much information about the loss of mobility but if your dog has two good front legs, the rear wheelchairs are amazing at restoring a dog's mobility. If there are front leg issues too, then a quad can be a great solution. You can read more here and see videos. Let me know if you'd like any more information on these.

“Need a rear leg help for my Maltese Terrier whose hind legs are paralysed. Can you please advise?”

If your dog is paralysed, please look at the rear dog wheelchairs.

“Hi - my lurcher is having cruciate ligament surgery on Monday and I would like to get him a support to help with recovery. What would you recommend?“

These are the variety of knee braces that we have. The highest level of support is the Balto Ligatek - if you were considering that probably helpful to get your vet's opinion on it for post-surgery - it works for some dogs and not for others depending on the individual situation. The Balto Jump is very popular. It sounds like the Balto Jump is a good measure as it is excellent for post surgery support but not rigid like the Ligatek. It sounds like your vet is up-to-date on the support needed and in some respects is waiting to see what happens post-operatively so would likely recommend Ligatek if appropriate.

“Hi. My dog is really struggling with arthritis and knuckling on the back paws. I’m looking for something which will hold the paw flat to prevent the knuckling. What do you recommend? Do the knuckling protection boots just provide protection or do those also help with the knuckling by helping prevent it happening? Thanks”

They're just protection. Yes, there are two approaches which are just to protect the paws or to correct. Walkin' Bootie splint is corrective, as are the PawsUp Superflex. It's a slightly longer process to get the PawsUp but they get very good feedback. The breathable WagWear are also recommended. They have the flat surface for the paw but mainly work protectively.

“Our Collie is waiting for an operation on her rear left leg to have an arthrodesis on her hock joint. Her tendon is shot so we needed something to keep her leg straight until she is operated on.”

We have a rear leg splint which is completely rigid, this will keep your dogs leg straight and immobilised. We also have an adjustable leg splint, again rigid but the angle can be changed to fit your dog.

“My 12 year old lab has severe rear leg arthritis. He has a huge swelling round his right hock and is now nearly walking on his his lower leg to bottom hock. Would this splint be suitable for him?”

Thank you for your message about your Labrador with rear leg arthritis. The Walkin' Full Adjustable Dog Splint is a rigid splint but has the benefit of being adjustable in terms of width and angle. It provides complete support to the lower leg, allowing support to arthritic joints. It is lightweight and has a rubber non-slip base. We would recommend that you build up the amount of time that it is worn over a couple of days to allow your dog to get used to it and to avoid rubbing. It should be removed at night or when your dog is resting. If you would like to provide the width of your dog's paw and also the width of his hock where he has the swelling, I can check if the splint would be able to fit his leg.