December 19, 2016

Adult onset acquired myasthenia gravis in three great dane littermates

Acquired canine myasthenia gravis (MG) is an autoimmune disease where antibodies target acetylcholine receptors in the muscles. Acetylcholine is the neurotransmitter that allows for muscle movement. This case study concerns three great dane puppies from the same litter who all developed MG. A 26-month old spayed female was brought in because of an abnormal gait which had persisted for 6 days. The dog then became unsteady in the front limbs and started regurgitating. The dog was unable to support itself and could not walk. Three months beforehand, one of the dog’s littermates was brought in for partial paralysis of the hind limbs. The dog also was diagnosed with megaesophagus and pneumonia. Reflexes on the kneecap were present, but not withdrawal reflexes in the thoracic limbs. The dog was euthanized and myofiber degeneration was found upon autopsy. Another of the dog’s littermates was brought in presenting with non-specific lameness in the thoracic limbs, megaesophagus, and pneumonia. The dog was started on 5 mg/kg enrofloxacin twice daily for the pneumonia. The diagnose the dogs with MG, the veterinarians measures the amount of antibodies in the blood which targeted ACh-receptors.

Compared with mix breeds, purebreds have an increased chance of developing MG. Vaccinations have also been shown to act as triggers for the immune response and can lead to recurrence of clinical symptoms. Although it was not observed in all three dogs, the one dog which underwent an autopsy had an enlarged thymus. While purebreds do have a higher chance of developing MG, great danes typically have relatively low risk for MG, suggesting that there is a genetic link at play. Breeders should take care when breeding from families of great danes where one or more members have MG.


Reviewed by Jason Hammerman.

Original article:


Kent, M., Glass, E. N., Acierno, M. and Shelton, G. D. (2008), Adult onset acquired myasthenia gravis in three great dane littermates. Journal of Small Animal Practice, 49: 647–650. doi:10.1111/j.1748-5827.2008.00627.x