TL;DR: Muscle wasting in a dog's rear legs is often caused by pain or mobility issues and typically requires a vet visit within a few days. However, if your dog suddenly cannot stand or is in severe pain, seek emergency care immediately.
What is muscle wasting in my dog's rear legs and what causes it?
Muscle wasting, medically known as atrophy, is the loss of muscle mass in your dog's hindquarters. This usually happens because the dog is not using those muscles fully, often due to pain, nerve issues, or limited mobility. Common underlying causes include osteoarthritis, hip dysplasia, or age-related conditions like Degenerative Myelopathy.
Is muscle wasting in my dog's back legs a veterinary emergency?
- Schedule a veterinary appointment within the next few days for gradual muscle wasting, as it is rarely a life-threatening emergency.
- Seek immediate emergency care if the wasting is accompanied by a sudden inability to stand or dragging of the paws.
- Contact a veterinarian immediately if your dog shows signs of severe pain.
How can taking photos of my dog help the triage process?
- Capture clear photos of your dog from a top-down view and a side profile to help a veterinarian assess leg symmetry and muscle loss severity.
- Use these images to provide a vital baseline to monitor if the condition is progressing or improving once treatment begins.
Clinical Context (Merck Veterinary Manual)
Muscle wasting in the rear legs of dogs can stem from several causes. Labrador Retriever myopathy, an autosomal recessive condition, leads to marked muscle atrophy, particularly affecting type II muscle fibers, and a stiff gait in puppies, with signs worsening with cold, stress, or exercise; signs typically stabilize by 6-8 months of age, and the prognosis is generally favorable. Dermatomyositis, seen in Collies and Shetland Sheepdogs (inherited as a dominant trait), causes atrophy and weakness of distal limb muscles, potentially with masticatory muscle involvement, and is often associated with dermatitis of the face and extremities. Chronic relapsing idiopathic polyradiculoneuritis, a rare inflammatory condition affecting mature dogs, can also result in hindlimb weakness and ataxia. In cases of polyradiculoneuritis, electromyography reveals denervation, and nerve conduction studies indicate slowed conduction; treatment is primarily supportive.
Chapter: Neurology
Source: The Merck Veterinary Manual, 11th Edition (Page 1200)