Canine Injury to the Lumbar L4 and L5

The canine spinal column has four major vertebral regions: neck, mid back, low back and pelvic. Dogs have seven lumbar vertebrae labeled L1 through L7. Disease and accidents can damage disks and nerves located between each lumbar vertebra. Injuries to a dog's L4 and L5 vertebrae occur in the lower back region. Many spinal injuries that occur in dogs are similar to those in people. Symptoms and treatment are also very similar between the two species.

  1. Subluxation

    • Subluxation in the L4 and L5 lumbar vertebrae occurs when one or more vertebrae move out of position, creating pressure on spinal nerves. Pressure on spinal nerves interferes with signals traveling from those nerves, resulting in a malfunction of some parts of the body. Subluxation also affects the surrounding muscles and soft tissues that hold vertebrae in place. Some causes of subluxation are bone spurs, degeneration, inflammation and trauma.

    Lesions

    • Lesions between lumbar vertebrae L4 and L5 typically results in weakness or paralysis of the rear limbs. Lesions cause a loss of femoral nerve function that manifests as a decrease in tendon reflex and the inability to support weight in the rear legs. Rear leg weakness in dogs can indicate neurologic disease, muscle disease or systemic illness. Symptoms include stumbling, falling or dragging rear legs.

    Ruptured Disc

    • About 80 percent of ruptured discs in dogs occur in the lower back between L3 and L7 vertebrae. Discs between vertebrae act as shock absorbers. A disc is a rim of tough, fibrous tissue that surrounds a gel-like center called a nucleus. When a disc ruptures the fibrous tissue breaks, allowing the nucleus to push through the opening. Ruptured discs are common among small breeds, especially dachshunds.

    Bulging Disc

    • When the fibrous tissue does not break, the entire disc can bulge outward. Bulging discs tend to occur more frequently in large breeds rather than in small breeds. German shepherds and Labrador retrievers seem to be highly susceptible at 5 to 12 years of age. A bulging disc is extremely painful and your dog will show signs of being in pain, such as a hunched back, panting or whining.