Why are my 4-month-old Labrador puppy's back legs weak and slipping?

Poor guy. He is a bit young to have muscle weakness, so this is a bit concerning. I would highly recommend taking him to your vet to have his legs examined first. He may have an underlying disorder that is causing this, such as myasthenia gravis, a muscle injury, or something else entirely. Once the vet is able to diagnose the problem (using testing such as bloodwork +/- radiographs), then we will know what Lucky needs for treatment of his conditon. Also make sure you aren’t giving any kind of supplements to him, such as calcium, which can potentially cause musculoskeletal disorders in pets. Also feeding him a high quality puppy food such as Royal Canin, Hill’s science diet, Evo, Eukanuba or Merrick is also ideal for proper bone and muscle growth. I hope are able to find the issue soon and get Lucky feeling better. Best wishes and take care.

Nothing seems abnormal based on this pictures but that does not replace a good exam. If you are worried about confirmation or a bone problem then she needs to see a vet. They can actually move her legs evaluate the joints and bones to make sure there are no problems. If indicated they can even do an X-ray although she is too youn for hip dysplasia to show up

Your dog could have arthritis which makes him unstable. He could also suffer from hip dysplasia (which can lead to arthritis) or have some compression of the spinal cord which can affect the hind leg movement. A vet exam is recommended to check for these issues. Some may improve with anti-inflammatory medication available from your vet. In the meantime, using small throw rugs on the floor (that have grip on the back so they don't move) may help your pup get around on the floor.

I'm sorry to hear Lucky is having some issues. I would be concerned about an injury either to the spine or the the legs. Unfortunately there is not much you can do at home except make him REST. No walks, no running, no stairs and no jumping. This can help the body to heal. I would also recommend to take him to see the veterinarian to have an exam and possibly radiographs. Labs are a breed prone to hip dysplasia although he is young for signs to show up just yet. Hope Lucky starts doing better.

Poor Moose! Weakness can be due to bone, muscle or nerve injuries and in puppies a number of parasites such as neospora can also be involved. Blood tests, physical therapy, acupuncture and chiropractic care cold all be considered as long as there is still some sensation and withdrawal reflexes in the limbs. A full neurological assessment should be performed to help localise the origin of the problem

The Trineurosol is just a vitamin injection. That is not really treating anything. My suggestion would be to have him x-rayed. This can be a severe case of hip dysplasia or a problem with this spine (a protruding disk, a fractured vertebra, etc). He needs some stronger medications. If this is a neurological disorder then he needs steroids and if this is an orthopedic issue he needs strong non-steroidal anti-inflammatories. Start with the x-rays. This is not something you can treat at home with home remedies. Best wishes.

What you are describing can be normal in a hyper growing puppy that is still perfecting his coordination; however there are a few developmental disease that large breed puppies can get that can cause some altered gaits and intermittent lameness. Exercise will help if it is normal but may make it worse if there is a developmental problem. I would schedule an appointment with your vet to have Clive checked for an development disease