All cats should be able to walk, run and even jump easily, with strong, well-balanced back legs. There are a number of conditions that can affect the back legs, causing lameness, weakness, lack of stability, poor balance, and even complete collapse.
This article aims to explain the different reasons why the rear legs may become weak and collapse, along with the investigations needed to diagnose the cause of the problem, and the possible treatment options that may follow.
What Does It Mean When A Cat’s Back Legs Collapse?
Cats have powerful back legs, used to help a cat prowl, run, climb and jump as part of their normal activities, such as hunting. The function of the back legs is supported by a combination of strong muscles, with a rich blood supply, and an intricate nerve supply.
The muscles, blood supply and nerves can stop functioning normally for a number of different reasons, and when this happens, the back legs can become weaker, unable to support the cat’s weight properly.
This causes the cat’s hindquarters to flop down, either being carried lower than normal, or even collapsing completely, so that they are being dragged behind the cat. The issue may start with the cat just limping, then progress to more serious signs with difficulty walking.
Owners may notice the signs when the cat is carrying out certain specific behaviors, such as going upstairs, or using the litter box.
- Paraparesis is the technical term that means weakness of both hind legs
- Paraplegia is the technical term that means complete paralysis of both hind legs
With some causes, the front legs may also be affected: if all four legs are weak, this is known as quadriparesis, and if all four legs are paralysed, this is known as quadriplegia.
How Common Is It For The Back Legs To Collapse?
Paraparesis (weakness of the back legs) is common, while the more severe situation of paraplegia (paralysis) is less common. Both conditions are seen regularly in busy vet clinics.
What Causes The Back Legs To Collapse?
Any condition which disrupts the muscle or nerve function, or the blood supply, of the back legs can cause them to collapse.
The main common causes are listed below.
- Spinal disease, from trauma to slipped discs to tumors, can stop the normal functioning of the spinal cord providing the nerve supply to the back legs, leading to weakness and collapse. Rarely, some diseases affecting the central nervous system (brain) may be involved.
- Vascular disease, such as blood clots (e.g. thromboembolism affecting blood vessels such as the aorta, known as a saddle thrombus) can disrupt the blood flow to the back legs, causing severe weakness and collapse. Heart disease such as cardiomyopathy can predispose to this issue.
- Metabolic diseases, such as feline diabetes mellitus, can cause unusual signs (such as a neuropathy causing a plantigrade stance of the hind legs) which may present as the collapse of the back legs. Other metabolic diseases (such as kidney disease) can cause weakness which can present as rear leg weakness. Older cats may be more prone to these types of issues. Sometimes generalised diseases, such as feline infectious peritonitis, may also cause the back legs to collapse.
- Trauma of any kind can damage the physical structure of the back legs, from the feet up to the pelvis, causing collapse. This can affect the soft tissues (e.g. sprains of muscles and tendons), as well as the bones. Nerve damage is also possible.
- Old age changes, including osteoarthritis (e.g. due to hip dysplasia) can lead to lameness, weakness and collapse of the hind end of the cat.
Symptoms Of Collapse Of The Back Legs
The back legs should be strong, holding the hindquarters up in a normal position, and the legs should move in a normal fashion, coordinating well, allowing the cat to move normally.
When the back legs collapse, the hindquarters are held lower than usual, and the back legs do not move normally, dragging behind the cat, or stumbling, or allowing the feet to be in the incorrect position (e.g. the upper side of the feet being dragged on the ground).
Investigating Collapse Of The Back Legs
As part of responsible pet care, if your cat develops a collapse of the back legs, you need to take them to your DVM veterinarian without delay, so that the cause of the problem can be identified and so that treatment can be given. Your veterinarian may take the following steps:
1. Detailed History Taking
Your vet will discuss every aspect of your cat’s condition and review their overall cat health. There are a number of different possible causes of the collapse of the back legs, and this history will help to differentiate between them. Senior cats are more prone to certain problems than younger cats.
2. Physical Examination
Your veterinarian will check your cat’s body carefully all over, feeling the back legs, pelvis and spine carefully, searching for any physical abnormalities such as instabilities, swellings or disruption. They will also carry out a neurological examination, checking your cat’s reflexes to the hind legs. They will pay particular attention to the affected limb if only one hindlimb is affected.
A complete full physical examination of the whole cat is also carried out, in case there are other signs of illness that could contribute to the rear limb problem. This will include taking the cat’s temperature and listening to their chest with a stethoscope.
3. Routine Blood Tests
It’s very likely that your veterinarian may carry out blood work, including the usual panel of diagnostic tests, such as hematology (blood count) and biochemistry profiles (including important electrolytes such as potassium). This is known as the Minimal Database, and it’s carried out to review most sick cats, regardless of the signs of illness.
4. Specialised Blood Tests
Your veterinarian may recommend specific blood tests for some viral infections such as FeLV and FIV, since there are significant implications if your cat is positive for either of these.
5. Other Tests
Radiography (x-rays) may be taken to examine the details of the structure of the spine, pelvis and hind legs. Depending on the case, more detailed diagnostic imaging (such as CT or MRI scan) may also be recommended.
Blood pressure measurement may be recommended in some cases.
How Much Does It Cost To Treat A Cat With Collapsed Back Legs?
It is impossible to estimate this cost, as there are so many possible factors going on in the background of individual cases. You should ask your veterinarian for a detailed estimate before agreeing to proceed with treatment.
Costs could vary from €400 for a simple case to €4000 or more for an exceptionally complex case of the collapse of the back legs.
Treatment For Collapse Of The Back Legs
Treatment for the collapse of the back legs is very variable, depending on the cause.
- Spinal disease causes may just require strict rest, combined with anti-inflammatory medication, or in severe cases, spinal surgery may be needed to solve the issue.
- Vascular disease, such as blood clots (e.g. aortic thromboembolism) need intensive veterinary care, including pain relief and anti-inflammatory medication, as well as treatment of the underlying heart disease.
- Metabolic diseases, such as diabetes mellitus, require stabilization, with the specific treatment for the metabolic problem (e.g. restoring normal blood glucose levels in diabetes mellitus).
- Traumatic injuries need treatment for the physical damage, from anti-inflammatory pain relief, supportive supplements, and strict rest (e.g. keep your cat indoors, but away from your dog) in minor cases, to surgical correction (e.g. some fractured bones).
Monitoring And Prognosis
Again, this depends on the individual case, but in general, cats with collapsed back legs need frequent rechecks by their DVM veterinarian until they have returned to normal. As well as frequent physical rechecks, repeated blood samples and radiographs may be taken to monitor any changes.
Many cats make a full recovery, but the prognosis depends entirely on the individual case, and your own veterinarian will be able to give you the best answer to this question.
The collapse of the back legs, with either weakness or full paralysis of the back legs, has many possible causes, and should always be investigated and treated as soon as possible by a DVM veterinarian.
Frequently Asked Questions
What can cause collapsed back legs in cats?
Possible causes include trauma, spinal disease, vascular disease and metabolic disease (such as diabetes mellitus).
How do I know if my cat has collapsed back legs?
If your cat is unable to walk, run and jump on their back legs, then they are suffering from some degree of collapse of the back legs.
Can a cat survive collapse of the back legs?
Most cases of back leg collapse respond to treatment, but there are some serious causes (such as spinal fracture) where successful treatment may be impossible, and your veterinarian may recommend euthanasia.
How serious is collapse of the back legs in cats?
This is a serious condition that always requires a prompt examination by your DVM veterinarian.