Note: these information are only valid for Tibetan Terriers.

General Information

Degenerative Myelopathy (DM) in dogs is a serious, progressive, incurable neurological disease that affects the spinal cord, typically causing a slow, painless, and insidious decline in mobility. It typically begins at around 8 years of age. The first signs include weakness and coordination problems in the hind legs. As the disease progresses, the front legs may also be affected, potentially leading to paralysis and paraplegia of all limbs. Incontinence may also occur. It is often compared to Amyotrophic Lateral Sclerosis (ALS) in humans.

Degenerative myelopathy (DM) in dogs is frequently confused with or masked by the normal signs of old age. Because DM typically affects dogs older than 8 years - an age when arthritis, muscle loss, and general slowing down are common in many breeds (yet even 10-year-old TT is not old) - early symptoms are often attributed to "just getting old" or chronic orthopaedic issues like hip dysplasia or knee injuries. Therefore DM is likely to be very underdiagnosed in the breed.

DM is a slow-progressing, non-painful disease itself. The subtle onset makes it easy for owners to assume it is part of the normal aging process rather than a progressive disease. However, in long-lived breeds, it significantly shortens the dog's life expectancy and quality of life. Secondary diseases and injuries can be painful.

DM is autosomal recessive, butincomplete penetrance, meaning that not all dogs with the high-risk genetic marker (two copies of the SOD1 gene mutation, often labeled "DM/DM" or "Affected”) will develop clinical signs of the disease. While exact percentages are difficult to determine due to variation across breeds, a significant portion of affected dogs do not develop clinical symptoms, potentially because they do not live long enough or lack other required factors. There is ongoing research to identify other genetic factors that modify risk for DM in different breeds.

Clinical features

Hind Limb Weakness & Wobbiness: The early signs of DM—subtle hind limb weakness, difficulty rising, scuffed toenails, or a "drunken sailor" gait—are similar to arthritis, which is common in aging dogs. Difficulty Rising/Sitting: Challenges in standing up from a lying position, especially after resting. Insidious Onset: DM is a slow-progressing - subtle onset makes it easy for owners to assume it is part of the normal aging process rather than a progressive disease. However, in long-lived breeds, it significantly shortens the dog's life expectancy and quality of life. Co-occurring Diseases: Older dogs often have multiple, concurrent health issues. A dog can have both degenerative myelopathy and arthritis, which can make diagnosis challenging. That’s why genetesting is important. Secondary diseases: Even DM itself if non-painful, secondary diseases and injuries can be painful. Progressive: While "old age" slowing might stabilize, DM will worsen, leading to paralysis within 6 to 12 months. Reduced Life Expectancy: Progression to Paralysis progresses from walking difficulties to total inability to walk (paraplegia) usually over 6 to 24 months. Please note that symptoms and age-frames may also be of other types and may differ from those mentioned above.

Inheritance

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