Peer-reviewed veterinary case report
Canine myasthenia gravis types and treatment outcomes in 167 dogs
By Dos Santos, Rui Xavier et al.Ā·Published in Journal of veterinary internal medicineĀ·2025Ā·Department of Veterinary Medicine, United KingdomĀ·View original on PubMed ā
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Original publication title: Case Series of Canine Myasthenia Gravis: A Classification Approach With Consideration of Seronegative Dogs.
- Species:
- dog
Plain-English summary
A group of 167 dogs diagnosed with myasthenia gravis (MG), a condition that affects muscle strength, were studied to understand different types of the disease. Among these dogs, 22% were found to have seronegative MG, meaning they tested negative for common antibodies associated with the condition. Dogs with this type were generally younger and less likely to have swallowing problems compared to other forms of MG. The study highlighted that dogs with esophageal weakness had a shorter survival time, while those without it had a better chance of recovery. More research is needed to improve diagnosis and treatment options for these dogs.
People also search for: dog myasthenia gravis symptoms Ā· seronegative myasthenia gravis in dogs Ā· treatment for dog swallowing problems
Abstract
BACKGROUND: Myasthenia gravis (MG) is categorized into several subgroups, including seronegative MG. Seronegative human patients are well documented, but seronegative dogs remain clinically uncharacterized and their prevalence unknown. OBJECTIVES: This study aims to evaluate the clinical presentation, diagnosis, treatment, and outcome of canine MG subgroups. ANIMALS: One hundred sixty-seven owner-owned dogs diagnosed with MG from three referral centers. METHODS: Retrospective case series. We classified myasthenic dogs into subgroups, adhering to human guidelines. RESULTS: We classified 167 dogs into four subgroups: acetylcholine receptor (AChR) antibody-positive generalized (49.7%, n = 83/167), focal (19.2%, n = 32/167) and thymoma-associated MG (9%, n = 15/167) and seronegative MG (22.2%, n = 37/167). Dogs with thymoma-associated MG were older (median 102 months; Interquartile Range (IQR) 96-120; p < 0.001) and seronegative dogs were younger (median 30 months; IQR 11.5-66; p = 0.017), compared to the generalized subgroup (median 67 months; IQR 36-96). Seronegative dogs presented less frequently with megaesophagus, compared to the generalized subgroup (63.8% vs. 85.7%; Odds Ratio 3.4; 95% confidence intervals (C.I.) 1.4-8.9; p = 0.025). Myasthenic dogs' survival time was significantly reduced when thymoma (Hazard Ratio (H.R.) 3.7; 95% C.I. 1.4-9.9; p = 0.028) or esophageal weakness (H.R. 3.8; 95% C.I. 2.0-7.0; p < 0.001) was present. Conversely, a higher likelihood of remission was achieved when esophageal weakness was absent (H.R. 3.8; 95% C.I. 1.4-10.0; p = 0.007). CONCLUSION AND CLINICAL IMPORTANCE: Dogs with seronegative MG are more common than previously reported. Myasthenic subgroups differ in presentation and outcome, with esophageal weakness key to survival and remission. Diagnostic tests for seronegative dogs and effective treatments for esophageal weakness in myasthenic dogs are urgently needed.
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Search related cases āOriginal publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/40298067/