Degenerative Myelopathy (2023)

By Jennifer Michaels, DVM, DACVIM (Neurology)
angell.org/neurology
neurology@angell.org
617-541-5140

Degenerative Myelopathy (DM) is a slowly progressive, degenerative disease affecting the spinal cord in older dogs. Degeneration begins in the axons then secondarily affects the myelin and the cells that produce it (oligodendrocytes) resulting in demyelination (Figure 1).

While definitive diagnosis of DM requires histopathologic evaluation of the spinal cord which is not possible ante-mortem, identifying cases where inclusion of DM as an appropriate differential is important for making appropriate diagnostic testing recommendations as well as providing information to owners regarding potential management options and prognostic information.

(Video) How to Care for a Dog with Degenerative Myelopathy

Figure 1. Spinal cord histopathology. A) Normal Dog: The white matter containing primarily axons and myelin is stained blue while the grey matter containing mostly neuronal cell bodies stains pink. B) DM-Affected Dog: Degeneration of the axons and myelin in the white matter is depicted by regions of palor (asterisk) which is classically most severe in the dorsal lateral funiculus (arrow). Images obtained from Awano T, et al. PNAS (2009). 106(8):2794-2799 and March PA, et al. Vet Path (2009). 46:241-250.

Signalment
DM affects older dogs with a vast majority of affected dogs being 8 years old or older. However, there have been infrequent reports of clinical DM in dogs as young as 5 years old. There is no sex predilection. It is a common misconception that DM affects only large breed or pure breed dogs. In fact, DM can occur in almost any breed, and has been reported in several small breed (e.g. Welsh corgi, pug, miniature poodle) and mixed breed dogs.

Prevalence of 0.19%.

Initial Clinical Signs
Classic clinical and historical features of degenerative myelopathy include:

  • Slowly progressive clinical signs
  • Paraparesis with an upper motor neuron (UMN) quality (i.e. spastic, long-strided gait with good muscle tone and normal pelvic limb spinal reflexes)
  • Proprioceptive ataxia in the pelvic limbs (Figure 2)
  • Lack of paraspinal hyperesthesia

These signs are consistent with a T3-L3 neuroanatomic localization. Clinical signs are often asymmetric.

While the classic T3-L3 myelopathy signs described above are the most common clinical presentation, about 10-15% of dogs with DM will initially present with lower motor neuron (LMN) signs in the pelvic limbs such as reduced patellar reflexes which is more suggestive of a L4-S2 myelopathy.

Disease Progression
Over time, the severity of the paraparesis and pelvic limb ataxia will progress such that the affected dog will become non-ambulatory and then paraplegic. At the point where motor function is minimal or lost entirely, patients will also develop urinary incontinence. With longer disease duration, patients will progress to LMN paralysis with loss of hind limb spinal reflexes and perineal reflex and development of LMN urinary and fecal incontinence. While eventually the disease will progress to involve the thoracic limbs, respiratory muscles resulting in hypoxemia and hypoventilation, and caudal brainstem resulting in dysphagia, it is extremely rare to see pets progress to these later stages as owners almost always elect for humane euthanasia prior to this time.

(Video) Degenerative Myelopathy in Dogs

The duration of this progression is variable, but on average a large breed dog with DM will progress to non-ambulatory paraparesis over 6-9 months. In general, smaller breed dogs including Welsh Corgis are noted to have a slower progression.

Figure 2. Pelvic limb proprioceptive deficits including crossing over (A) and knuckling (B). Proprioception is the sense of relative position of one’s own body. Proprioceptive abnormalities including ataxia and postural reaction deficits are signs of neurologic disease that would not be expected in patients affected by orthopedic disease alone.

Differential Diagnoses
Differentials for DM include other non-painful, slowly progressive T3-S2 spinal cord diseases including:

  • Chronic intervertebral disc protrusions (Hansen type II)
  • Degenerative lumbosacral stenosis
  • Other degenerative causes of spinal canal stenosis (joint and ligament hypertrophy)
  • Subarachnoid diverticulum (more common in some of the smaller breeds such as Pugs)
  • Spinal cord neoplasia

The difficulty is that many DM patients will have concurrent neurologic (IVDD + DM) and orthopedic (DJD or hip dysplasia + DM) diseases. A thorough neurologic examination with findings including proprioceptive deficits should help distinguish between orthopedic and neurologic disease (Figure 2).

Genetics
Genome-wide association studies identified mutation in the SOD1 gene which codes for the superoxide dismutase 1 (SOD-1) protein. SOD-1 protein is abundant in the CNS and functions as a free-radical scavenger.

(Video) The 5 Stages of Degenerative Myelopathy in Dogs

The primary mutation associated with the development of DM is very widespread having been identified in over 124 breeds including mixed breed dogs. Dogs can either have a homozygous normal N/N, heterozygous N/A, or homozygous mutated A/A genotype. An estimated 60% of dogs with the homozygous mutated genotype will develop clinical DM compared to approximately 5% of heterozygous or homozygous normal genotypes.

It is important to note that the finding of a homozygous mutated genotype does not predict with certainty the development of, nor definitively diagnose, clinical DM. Similarly, although the number is quite small, there are reports of dogs that developed clinical DM despite having a heterozygous or homozygous normal genotype. With the exception of the Bernese Mountain dogs (BMD) described below, full genetic analysis of the entire SOD1 gene in those dogs revealed no additional mutations to explain the clinical development of DM.

Interestingly, a second, breed-specific mutation associated with development of clinical DM has been identified in BMD. Some of the dogs that tested heterozygous or homozygous normal for the originally identified, widespread mutation were BMD that subsequently tested positive for this breed specific mutation.

Diagnostic Testing
Definitive diagnosis of DM can only be made histopathologically. Accurate ante-mortem diagnosis is based on recognition of the appropriate clinical picture, exclusion of other possible causes of the clinical signs, and documentation of SOD1 homozygosity.

Genetic testing is a critical part of ante-mortem diagnosis of DM. Testing for the widespread mutation is readily available. An at-home, cheek swab kit can be ordered by owners through OFA (www.ofa.org/dna/testing). The kit will be sent to the owner who collects the sample and mails it in. Alternatively, veterinarians can submit blood samples directly to the University of Missouri Animal Molecular Genetics Lab (http://www.caninegeneticdiseases.net/dm/sampledm.htm).

Results do need to be interpreted with care and in the context of the patient’s clinical signs. A result of homozygous normal (N/N) or heterozygous (N/A) indicate that it is extremely unlikely that the patient has DM or will develop it in the future. However, as indicated above, there are reports of normal or heterozygous dogs developing clinical DM. A result of homozygous affected (A/A) indicates that patient is at high risk for having or developing DM. It is important to remember, however, that not all at-risk dogs will develop the disease. For patients with clinical signs compatible with DM and who are genetically at-risk, additional diagnostics can be useful in ruling out other possible causes thereby lending support to the DM diagnosis.

Testing for the species-specific mutation in BMD is an important component of diagnostic testing in this breed, particularly if the clinical signs are consistent with DM but the affected dog is homozygous normal or heterozygous for the widespread mutation. The University of Missouri Animal Molecular Genetics Lab can perform this additional genetic testing.

(Video) DEGENERATIVE MYELOPATHY IN DOGS

DM causes no observable changes on MRI and cerebrospinal fluid analysis is often normal or shows no-specific changes; however, thoracolumbar MRI and spinal fluid analysis are still recommended to rule out other possible structural causes of T3-L3 myelopathy. If an owner declines MRI and CSF analysis, genetic testing can still be very useful to determine the pet’s risk for developing DM.

Therapeutic trials can also be a useful adjunct diagnostic tool. Steroids have no effect on clinical signs or progression of DM-affected dogs. In a patient where DM is suspected but cannot be distinguished from other differentials, a trial of anti-inflammatory steroids can help you decide if there is a structural cause of the clinical signs. For example, a patient with intervertebral disc protrusion(s) or spinal neoplasia may respond positively to steroids. If clinical improvement is seen with steroids, then you can confidently say that there is some other cause of clinical signs. However, it is important to recognize the limitation of this approach. If a patient responds to steroids suggesting some other etiology, this patient may still have DM and simply be concurrently affected by a steroid-responsive condition. Also, if a patient does not respond positively to steroids, this does not mean he/she has DM. Other etiologies such as disc disease or neoplasia don’t always respond positively to steroids.

Treatment
Unfortunately, there is no treatment currently shown to improve clinical signs or slow progression of disease in DM-affected dogs. Treatments that have been studied include: steroids, aminocaproic acid, vitamin B, C, and E, N-acetylcysteine, cobalamin, and tocopherol. No benefit was appreciated from any of these treatments.

One study documents an improved survival time in DM-affected patients treated with physiotherapy with survival time improving as the intensity of physical therapy increased.

No physiotherapyMST = 55 days
Moderate physiotherapyMST = 130 days
Intensive physiotherapyMST = 225 days

Despite these promising results, there are limitations to this study which include lack of randomization, lack of definitive post-mortem histologic diagnosis, and owner bias. Still, physiotherapy is the only therapy to date that has shown even a potential benefit for DM-affected dogs, and it may improve quality of life for affected pets and their owners. Therefore, physiotherapy is strongly recommended for patients diagnosed with DM.

Prognosis
Long-term prognosis is grave as this is an invariably progressive disease; however, in the short term, many dogs can live a good quality of life while still ambulatory or even once they become non-ambulatory with the assistance of a cart. Survival time for an individual patient is highly dependent upon the owner’s willingness and comfort with caring for a severely neurologically affected dog. Owner education regarding expected progression of clinical signs including milestone changes (loss of independent ambulation, loss of voluntary urination, weakness in thoracic limbs, etc.) as well as necessary nursing and supportive care and tools for maximizing quality of life (e.g. physiotherapy, cart) is extremely important.

Survival times for smaller breed dogs tend to be longer (e.g. 20 months for Welsh Corgi vs. 11-16 months for Boxers and GSD); however, it’s difficult to know how much of this discrepancy is due to faster disease progression in the larger breed dogs or simply a reflection of the relative difficulty of caring for a large-breed dog compared to small-breed dog.

(Video) Canine Degenerative Myelopathy

References:

  • Coates JR, Wininger FA. Canine degenerative myelopathy. Vet Clin Small Anim. (2010). 40: 929-950.
  • Kathmann I, Cizinauskas S, Doherr MG, et al. Daily controlled physiotherapy increases survival times in dogs with suspected degenerative myelopathy. J Vet Intern Med. (2006). 20: 927-932.
  • Oyake K, Kobatake Y, Shibata S, et al. Changes in respiratory function in Pembroke Welsh corgi dogs with degenerative myelopathy. J Vet Med Sci. (2016). 78: 1323-1327.
  • Wininger FA, Zeng R, Johnson GS, et al. Degenerative myelopathy in a Bernese Mountain dog with a novel SOD1 missense mutation. J Vet Intern Med. (2011). 25: 1166-1170.
  • Zeng R, Coates JR, Johnson GC, et al. Breed distribution of SOD1 alleles previously associated with canine degenerative myelopathy. J Vet Intern Med. (2014). 28: 515-521.

FAQs

How long will my dog live with degenerative myelopathy? ›

Sadly, most dogs with degenerative myelopathy eventually lose control of their legs, bladder and bowels completely, and need to be put to sleep. The average life expectancy of a dog with degenerative myelopathy is 1-2 years from diagnosis.

What are the first signs of degenerative myelopathy? ›

Early clinical signs include: The hind paws "knuckle" or turn under so that the dog walks on its knuckles, especially when turning. The dog's hindquarters appear to sway when standing still. The dog falls over easily when pushed from the side.

What is the treatment for degenerative myelopathy? ›

Unfortunately, there is no cure for degenerative myelopathy, but there is treatment. Intensive physical rehabilitation and selected assistive equipment (when properly fitted, of course) can extend a dog's survival time by up to three years, versus six months to a year for dogs who do not receive therapy.

Are dogs with degenerative myelopathy in pain? ›

Degenerative myelopathy is not a painful condition and, as a result, affected dogs are generally well and keen to exercise, despite their disability. A German Shepherd Dog with degenerative myelopathy – the hindlimbs are weak and inco-ordinated, and the toes of the right hind paw are being dragged.

Should you walk a dog with degenerative myelopathy? ›

Yes, dogs with Degenerative Myelopathy should stay as active as possible. Keeping a DM dog active can actually help slow down the progression of the disease. Physical therapy and regular structured exercises, including walking, can help dogs with DM maintain muscle strength and minimize their risk of muscle atrophy.

Can an MRI detect degenerative myelopathy? ›

Background: Degenerative myelopathy (DM) in dogs is a progressive neurodegenerative condition that causes white matter spinal cord lesions. These lesions are undetectable on standard magnetic resonance imaging (MRI), limiting diagnosis and monitoring of the disease.

Is myelopathy visible on MRI? ›

MRI scans are the preferred diagnostic method for cervical myelopathy, but other methods can also be used to help rule out other conditions. Cervical myelopathy is best treated with spine decompression surgery.

Does myelopathy show on MRI? ›

Preoperative MRI of a patient with cervical myelopathy shows compression of the spinal cord. At Mayo Clinic, patients with suspected cervical myelopathy have MRI to check for spinal cord compression.

How long can you live with myelopathy? ›

Conclusion: The patients who underwent cervical laminoplasty caused by compression myelopathy due to CS and OPLL had a long life expectancy, averaging more than 13 years. Life expectancy did not differ between patients with CS and patients with OPLL. Neurological deficit did not directly affect the life expectancy.

How fast does myelopathy progress? ›

How quickly does degenerative myelopathy progress? Unfortunately DM tends to progress very quickly. Most dogs that have been diagnosed with degenerative myelopathy will become paraplegic within six months to a year.

Does degenerative myelopathy affect the brain? ›

Degenerative myelopathy (DM) is also known as chronic degenerative radiculomyelopathy (CDRM). It is a progressive disease that affects the spinal cord and eventually the brain stem and cranial nerves, which results in complete paralysis.

How do I make my dog with degenerative myelopathy comfortable? ›

Treatment for Degenerative Myelopathy in Dogs

Veterinarians may be able to treat some related symptoms to relieve discomfort, but a healthy diet and plenty of exercise, including walking and swimming, are the main ways to keep dogs with the condition as mobile as possible.

When should you put a dog down with degenerative myelopathy? ›

When to put down a dog with degenerative myelopathy? Generally, a dog with canine degenerative myelopathy will be euthanized or put down within 6 months to 3 years after diagnosis. Based on the stage of the disease and how it impacts your dog's quality of life, the vet will advise when to put down a dog accordingly.

How do vets test for degenerative myelopathy? ›

How is it diagnosed? Degenerative myelopathy (DM) can only definitively be diagnosed by identifying classic microscopic changes in the spinal cord on autopsy. DM is strongly suspected in dogs where all other causes for neurologic disease are ruled out.

What is the best treatment for myelopathy? ›

Myelopathy is a disorder that results from severe compression of the spinal cord. The only way to treat the compression of the spinal cord is through decompression surgery.

Is DM in dogs fatal? ›

Canine degenerative myelopathy (DM) was previously known as chronic degenerative radiculomyelopathy (CDRM) and is a progressive degenerative spinal cord disease. Ultimately it is a fatal disease with devastating consequences for the dogs and can be distressing for owners caring for them.

Can a dog with degenerative myelopathy wag their tail? ›

In the late stages of degenerative myelopathy, after about one year, your dog will show spasmodic movement in the hind legs and tail.

Can you reverse degenerative myelopathy in dogs? ›

A multifaceted treatment protocol can slow, halt or even temporarily reverse the progression of degenerative myelopathy. Degenerative myelopathy (DM) is a progressive disease of the spinal cord. It's found mainly in large breed dogs, with the onset of symptoms typically occurring between seven and 14 years of age.

Can CBD oil help degenerative myelopathy? ›

CBD oil for dogs may help with degenerative myelopathy:

have less inflammation. reduce pain. enjoy more energy. metabolize food better.

What does gabapentin do for dogs with degenerative myelopathy? ›

Controlling Pain

It's most commonly used for the chronic pain associated with degenerative joint disease. It has also shown to be beneficial when used in combination with other pain medications—such as nonsteroidal anti-inflammatories or opioids—to help with pain associated with surgery.

What mimics degenerative myelopathy? ›

Other neurologic and orthopedic disorders that can mimic the signs of degenerative myelopathy include intervertebral disc disease, tumors of the spinal cord, degenerative lumbosacral stenosis, and advanced hip dysplasia.

Is there a blood test for degenerative myelopathy? ›

Only $75 with results in 7 business days. Our Degenerative Myelopathy DNA Testing is a fast and effective way of determining whether or not your dog has the potential to develop Degenerative Myelopathy (DM), or pass it on to any offspring.

What vitamins help with degenerative myelopathy? ›

Some antioxidants beneficial to Degenerative Myelopathy-affected dogs or to help prevent the development of the disease are: ascorbic acid (vitamin C), vitamin E, vitamin A, carotenoids, selenium, glutathione peroxidase, super oxide dismutase, coenzyme Q 10, S- Adenosyl-L-Methionine (SAMe), N-Acetylcysteine, and ...

Does myelopathy make you tired? ›

Patients with myelopathies commonly have excessive daytime sleepiness and disturbed sleep, including reduced rapid eye movement (REM) sleep, increased need for sleep medications, snoring, and sleep-apnea syndrome.

Is myelopathy a symptom of MS? ›

Specifically, cervical stenosis with myelopathy (CSM) can present with MS-like symptoms including gait ataxia, extremity weakness, spasticity and sensory loss due to spinal cord compression. When the two diseases occur concurrently (Figure), management is exceedingly difficult.

How can myelopathy cause death? ›

Myelopathy describes any neurologic symptoms related to the spinal cord and is a serious condition. It occurs from spinal stenosis that causes pressure on the spinal cord. If untreated, this can lead to significant and permanent nerve damage including paralysis and death.

How do you get myelopathy? ›

Causes of Myelopathy

Myelopathy is the result of compression of the spinal cord and nerve roots caused by inflammation, arthritis, bone spurs and spinal degeneration due to aging. Myelopathy can also take an acute form or result from a spine deformity at birth.

Is myelopathy a degenerative terminal? ›

Degenerative myelopathy (DM) is a fatal neurodegenerative disease that affects older dogs. It initially results in paralysis of the pelvic limbs but progresses to affect all limbs.

How do you diagnose myelopathy? ›

To accurately diagnose myelopathy, your healthcare provider will perform a thorough physical exam and order tests. These tests may include: Imaging tests, such as spine X-ray, MRI or CT scan.

Is exercise good for myelopathy? ›

Exercises and techniques that may help relieve symptoms of cervical myelopathy include cervical traction, manual therapy techniques, proprioceptive neuromuscular facilitation, cervical stabilisation exercises and dynamic upper and lower limb exercises.

Can you recover from myelopathy? ›

The average recovery rate during the 4-month follow-up was 32.5% with a range of 0%–60%. The average recovery rate during the 6-month follow-up was 72.83% with a range of 0%–100%.

What is the difference between arthritis and degenerative myelopathy? ›

Arthritis, as we know, is a disease of the joints, and it's very, very painful. Whereas degenerative myelopathy is actually a degeneration of the spinal cord. So it's a neurological disease and it's not actually painful. So they're very different conditions.

Does alcohol affect myelopathy? ›

Damage to the spinal cord (myelopathy) has been reported in patients with alcoholism (4,5). As portosystemic blood shunting associated with liver cirrhosis causes hepatic myelopathy (5-9), it has been considered to be the major cause of myelopathy in chronic alcoholics.

Does degenerative myelopathy cause incontinence? ›

Degenerative myelopathy (formerly, chronic degenerative radiculo-myelopathy, CDRM) is a cause of progressive weakness, wobbliness and incontinence in dogs. The condition typically affects middle aged to older adult dogs (5-11 years with a median age of 9 years) of either gender.

Does degenerative myelopathy affect barking? ›

Urinary and/or fecal incontinence occur very late in the course of the disease You may also note a hoarseness or loss of volume to the bark.

How many stages are the in degenerative myelopathy in dogs? ›

Degenerative Myelopathy is split into five different stages, based on the clinical symptoms. In each of the stages, your veterinarian will be able to help and guide you on what is best for your dog and what you can do to help it as well!

Can Massage Help degenerative myelopathy? ›

Massage techniques will also help stimulate the nerves in the limbs, which are wasting away as a result of Degenerative Myelopathy. This nervous stimulation can assist in delaying the resulting muscle wastage.

Will Leg braces help a dog with degenerative myelopathy? ›

Keeping your dog healthy through exercise and diet is always helpful. Please note, orthopedic braces like what we offer here at Ortho Dog DO NOT help dogs with Degenerative Myelopathy.

How do you prevent degenerative myelopathy in dogs? ›

The only way to prevent degenerative myelopathy in dogs is to selectively breed. Before purchasing an at-risk dog, ask the breeder to show you the results of SOD-1 gene mutation testing on the parents, proving that both carry two copies of the normal gene.

Is degenerative myelopathy in dogs fatal? ›

Canine degenerative myelopathy (DM) was previously known as chronic degenerative radiculomyelopathy (CDRM) and is a progressive degenerative spinal cord disease. Ultimately it is a fatal disease with devastating consequences for the dogs and can be distressing for owners caring for them.

How do vets diagnose degenerative myelopathy? ›

How is it diagnosed? Degenerative myelopathy (DM) can only definitively be diagnosed by identifying classic microscopic changes in the spinal cord on autopsy. DM is strongly suspected in dogs where all other causes for neurologic disease are ruled out.

What mimics degenerative myelopathy in dogs? ›

Degenerative myelopathy is a diagnosis of exclusion. The clinical signs can mimic other neurologic conditions including intervertebral disc disease, lumbosacral disease, vascular events and neoplasia. Orthopedic conditions such as bilateral cruciate tears and hip dysplasia can also be confused for DM.

Does DM in dogs affect breathing? ›

“This results in a loss of motor control that begins in the hind limbs, but can spread to involve the front limbs as well as the pathways that control breathing, urination, and defecation. Currently, these changes are irreversible. Advanced cases may cause difficulty breathing as well.

Can a dog recover from DM? ›

Dogs generally live with DM for anywhere between six months and three years. Rehab therapy and regular exercise can help improve the quality of life for dogs with DM. Unfortunately, Degenerative Myelopathy has no cure at the moment. What is certain is that the symptoms worsen as time progresses.

What age do dogs start DM? ›

DM is an inherited neurologic disease typically affecting dogs around eight years of age or older. It causes gradual muscle wasting and incoordination in the hind limbs, and then progresses to an inability to walk after six to twelve months.

Videos

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4. Arthritis vs Degenerative Myelopathy | Ask a Vet
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5. Understanding Degenerative Myelopathy (DM) in Dogs (Feat. Dr. Michael Wong)
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