Canine Degenerative Myelopathy (DM): A Condition That Causes Dogs to Lose Sensation in Their Four Legs

Canine degenerative myelopathy (DM) is not painful; in fact, dogs affected by it do not experience pain because the nerves from the brain to the limbs become paralyzed. Over approximately a year, dogs progressively lose sensation or control of their four legs. As time goes on, the condition causes the hind legs of dogs to lose coordination gradually, ultimately leading to paralysis.

What is Canine Degenerative Myelopathy?
Canine degenerative myelopathy is a disease that slowly paralyzes dogs, very similar to ALS (amyotrophic lateral sclerosis) in humans. Dogs gradually develop the disease, which typically progresses through three different stages over six months to a year.

Symptoms of Canine Degenerative Myelopathy

In the early stages of degenerative myelopathy, subtle changes occur in the hindquarters of dogs, often unnoticed by many owners. It is a stealthy disease that can easily be overlooked in its early stages. One clue is uneven wear of the dog's hind toenails.

In the middle stages of degenerative myelopathy, you may occasionally hear the dog's nails scraping the ground as it walks. Dogs begin to show difficulty in standing; they may struggle to balance when standing but can adjust themselves. At this stage, if you flip the dog's toes downward, it may still right its foot, though perhaps with a slower response time than before.

Other symptoms may include:

1. Difficulty rising
2. Uneven wear of nails, causing them to become very short
3. Crossing of hind legs under the dog's body, as the dog loses sensation in the hindquarters and doesn't know where it has actually placed its feet
4. Crossing of hind legs causing the dog to trip over itself while standing

When standing, gently pushing the dog to the left or right with your hand may cause it to lose balance and fall. If there are raised thresholds or stairs on the path, you may notice the dog's movements are abnormal, affected by the loss of sensory function due to degenerative myelopathy.

As the condition worsens, the dog's tail will wag less frequently. If the dog has a longer tail, it may easily wrap its legs around it. Lifting the dog's foot so that its nails touch the ground may not cause discomfort immediately, and it may take some time for the dog to correct its position. This is because the dog has begun to lose sensation in its feet. For a dog with feeling in its hind feet, this position would be uncomfortable.

With the progression of degenerative myelopathy, late-stage symptoms will include:

• Uncontrolled spasms of the hind legs and tail, where nerve impulses short-circuit
• Unexplained kicking, where the tail suddenly goes up and down as if the dog is preparing to defecate
• Cross-reactions, if you pinch one footpad, the other foot will react
• Difficulty maintaining balance while defecating: when the dog squats, it loses balance and falls
• In the final stage, the dog will be unable to bear the weight of its hind legs alone. Without some form of support, the dog will be unable to stand, or once picked up, will be unable to maintain an upright position. This can happen overnight or within a few days. At the same time, there will be incontinence of both size and measure.

Causes of Canine Degenerative Myelopathy

Degenerative myelopathy is a genetic disease, with DNA mutations in the SOD1 gene usually beginning after the age of eight. Degeneration occurs in the white matter of the spinal cord and nerves, resulting in the brain losing control of the limbs. During the disease, the dog loses sensation and control of movement in all four limbs. Degenerative myelopathy cannot be prevented!

Treatment and Prevention of Canine Degenerative Myelopathy

There are many diseases similar to degenerative myelopathy, including disc herniation, tumors, and cysts, injuries, strokes, and infections. Once these are eliminated through tests such as x-rays and MRI, the remaining is degenerative myelopathy. Alternatively, owners can get genetic testing, which is currently the simplest and most convenient way to test for disease.

Currently, there is no effective treatment to slow down or cure degenerative myelopathy. Therefore, treatment focuses solely on improving the dog's quality of life. Owners should encourage activities such as walking and swimming, and physical therapy can help maintain muscle vitality. Since dogs with this condition do not feel pain in their feet, they may not be aware of injuries, so simply using shoes does not fully protect their hind legs. When walking the dog, using a rear leg sling can help lift the dog's hindquarters into the correct position. Alternatively, a dog wheelchair can allow the dog to sit comfortably and observe the world. Never grab the tail of a dog with degenerative myelopathy, as this could potentially cause harm or even break the tail.

If you notice your dog walking strangely, especially when navigating stairs, it's advisable to visit the vet. Even if it's not degenerative myelopathy, there may be issues with your dog's other joints. Joint problems should not be underestimated as they affect the later life of elderly dogs.