Degenerative Myelopathy in Dogs: Understanding a Progressive Neurological Disease

Degenerative myelopathy (DM) is a chronic and progressive spinal cord disease that primarily affects large-breed dogs, especially aging German Shepherds. The condition is characterized by gradual degeneration of the spinal cord, particularly in the T3-L3 region, leading to neurological deficits such as proprioceptive ataxia and spastic paraparesis. Interestingly, the disease shares several similarities with human amyotrophic lateral sclerosis (ALS), making it an important subject in comparative neurology research¹. 

Most affected dogs are between 5 and 14 years of age, with clinical signs commonly appearing around 9 years^1,2. Although the overall prevalence in dogs is relatively low at 0.19%, the prevalence increases significantly in German Shepherds, reaching 2.01%¹. Histological confirmation has also been documented in breeds such as Boxers, Pembroke Welsh Corgis, Chesapeake Bay Retrievers, Rhodesian Ridgebacks, Pugs, and Siberian Huskies^1,2,3. 

The Genetic Link Behind DM 

The exact cause of DM remains complex and not fully understood, but recent studies have highlighted mutations in the SOD1 gene as one of the primary contributors to the disease⁴. The SOD1 gene is responsible for producing superoxide dismutase, an enzyme involved in neutralizing harmful free radicals within cells¹. Mutations in this gene can lead to abnormal protein accumulation and neuronal toxicity, contributing to spinal cord degeneration¹. 

The relationship between DM and ALS has attracted significant scientific attention because both diseases involve SOD1 mutations¹. However, while ALS is usually inherited as an autosomal dominant disease in humans, DM in dogs follows an autosomal recessive inheritance pattern¹. These genetic parallels have encouraged researchers to use canine DM as a model for studying neurodegenerative therapies applicable to human medicine. 

Diagnosing a Disease of Exclusion 

Diagnosing DM can be particularly challenging because its clinical signs resemble several other spinal cord disorders commonly seen in geriatric dogs. Conditions such as Hansen type II intervertebral disc disease, neoplasia, meningoencephalomyelitis, and fibrocartilaginous embolism must first be ruled out¹. 

A complete diagnostic workup generally includes neurological examination, cerebrospinal fluid analysis, MRI or CT imaging, and blood testing to exclude infectious and inflammatory diseases^1,5. Definitive diagnosis depends on a compatible clinical history, exclusion of compressive spinal lesions, and confirmation of the SOD1 gene mutation. Researchers are also exploring biomarkers such as phosphorylated neurofilament heavy chain (pNFH), which may help detect axonal degeneration earlier and more accurately in the future¹. 

Current Treatment Approaches and Prognosis 

Unfortunately, there is currently no curative treatment for DM. Medical management mainly focuses on supportive care and maintaining quality of life. Anti-inflammatory drugs and corticosteroids such as prednisolone may help manage neurological signs, although evidence supporting their ability to slow disease progression remains limited^1,6. 

Multimodal management strategies have shown more promising results. Physical rehabilitation combined with nutritional supplementation, including Vitamin B, Vitamin E, aminocaproic acid, and N-acetylcysteine, may help reduce oxidative stress and inflammation associated with the disease. Studies have demonstrated that dogs undergoing intensive physiotherapy survive significantly longer than those without rehabilitation support¹. 

Studies have demonstrated that dogs undergoing intensive physiotherapy survive significantly longer than those without rehabilitation support. One study reported survival times of nearly 8 months in dogs receiving intensive physiotherapy, compared to approximately 2 months in dogs without therapy. Some dogs under long-term rehabilitation protocols survived for more than four years with relatively stable neurological function¹. 

Despite these encouraging findings, the prognosis for DM remains poor, and many dogs are euthanized within 6 to 12 months after the onset of clinical signs due to progressive paralysis and declining quality of life¹. 

Conclusion 

Degenerative myelopathy continues to be one of the most devastating neurological diseases seen in aging dogs. While the condition remains incurable, advances in genetics, early diagnosis, rehabilitation medicine, and supportive care are gradually improving survival time and quality of life. The growing understanding of SOD1 mutations and their similarity to ALS has also opened new doors for future therapeutic research, making DM not only a veterinary concern but also a valuable model for human neurodegenerative disease studies. 

Reference 

1. Gouveia D, Correia J, Cardoso A, Carvalho C, Oliveira AC, Almeida A, Gamboa Ó, Ribeiro L, Branquinho M, Sousa A, Lopes B. Intensive neurorehabilitation and allogeneic stem cells transplantation in canine degenerative myelopathy. Frontiers in Veterinary Science. 2023 Jul 13;10:1192744. https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2023.1192744/pdf 

2. Zeng R, Coates JR, Johnson GC, Hansen L, Awano T, Kolicheski A, Ivansson E, Perloski M, Lindblad-Toh K, O'Brien DP, Guo J. Breed distribution of SOD1 alleles previously associated with canine degenerative myelopathy. Journal of veterinary internal medicine. 2014 Mar;28(2):515-21. https://academic.oup.com/jvim/article-pdf/28/2/515/66686237/jvim12317.pdf 

3. Ogawa M, Uchida K, Yamato O, Inaba M, Uddin MM, Nakayama H. Neuronal loss and decreased GLT-1 expression observed in the spinal cord of Pembroke Welsh Corgi dogs with canine degenerative myelopathy. Veterinary pathology. 2014 May;51(3):591-602. https://journals.sagepub.com/doi/pdf/10.1177/0300985813495899 

4. Mandrioli L, Gandini G, Gentilini F, Chiocchetti R, Turba ME, Avallone G, Pellegrino V, Menchetti M, Kobatake Y, Kamishina H, Cantile C. Degenerative myelopathy in hovawart dogs: molecular characterization, pathological features and accumulation of mutant superoxide dismutase 1 protein. Journal of comparative pathology. 2021 Jan 1;182:37-42. https://www.academia.edu/download/116537354/j.jcpa.2020.11.00620240702-1-taoyb2.pdf 

5. Cooper JJ, Young BD, Griffin IV JF, Fosgate GT, Levine JM. Comparison between noncontrast computed tomography and magnetic resonance imaging for detection and characterization of thoracolumbar myelopathy caused by intervertebral disk herniation in dogs. Veterinary Radiology & Ultrasound. 2014 Mar;55(2):182-9. https://repository.up.ac.za/bitstream/handle/2263/40319/Cooper_Comparison_2014.pdf?sequence=1 

6. Kobatake Y, Nakata K, Sakai H, Sasaki J, Yamato O, Takashima S, Nishii N, Maeda S, Islam MS, Kamishina H. The long-term clinical course of canine degenerative myelopathy and therapeutic potential of curcumin. Veterinary sciences. 2021 Sep 12;8(9):192. https://www.mdpi.com/2306-7381/8/9/192