TL;DR: Sudden hind leg lameness is often caused by a ligament tear or fracture and requires a veterinary exam within 24 hours, or immediate emergency care if open wounds or paralysis are present.
What does it mean if my dog is suddenly not putting weight on a hind leg?
When a dog is suddenly non-weight bearing, it means they are holding their back leg completely off the ground and refusing to use it. This is usually a sign of acute pain or structural instability. Common causes include a torn cranial cruciate ligament (similar to an ACL tear in humans), a luxating patella (kneecap popping out), a fracture, or even a painful injury to the paw pad or nail bed.
When should I seek emergency veterinary care for my dog's lameness?
- Schedule a veterinary evaluation within 24 hours for most cases of sudden lameness.
- Seek immediate emergency care if there is an open wound or excessive swelling.
- Go to an emergency clinic immediately if your dog is unable to move any of their other limbs, as this could indicate a neurological issue.
How can a photo or video help the veterinarian triage my dog's injury?
- Clear photos allow the vet to see the exact angle of the limb and identify visible issues like swelling or foreign objects.
- A short video of your dog attempting to walk helps the vet assess the severity of the lameness before adrenaline masks the symptoms at the clinic.
- These visuals provide the clinical team with critical information about the injury before your pet even arrives for their appointment.
Clinical Context (Merck Veterinary Manual)
Sudden non-weight bearing hind leg lameness in dogs can be caused by several factors. Achilles tendon disruption, an acute traumatic injury to the common calcaneal tendon, is seen primarily in mature working and athletic dogs and can result in severe non-weight bearing lameness, tarsal hyperflexion, and a plantigrade stance. Palpation may reveal swelling, pain, and torn or fibrotic tendon ends, and radiographs may reveal avulsed bone fragments. When evaluating hindlimb lameness, a thorough examination should be performed, assessing the limbs from distal to proximal and palpating bones, joints, and soft tissues for abnormalities such as swelling, pain, instability, crepitation, reduced range of motion, and muscle atrophy. Helpful imaging procedures include survey and contrast radiography, ultrasonography, CT, and MRI.
Chapter: Neurology, Orthopedics
Source: The Merck Veterinary Manual, 11th Edition (Page 1096)