Table 1. The criteria used to assign cases to a diagnostic confidence grouping.

	Diagnostic confidence grouping
Criterion	Definite	Probable	Possible
Muscle biopsy showing inflammatory pathology	Yes	Yes	No
2 M antibody negative or additional muscle site biopsy	Yes	No	No
AChR antibody negative, high CK or MM atrophy	Yes	Yes	Yes
Dysphagia/sialorrhea	Yes	Yes	Yes
Number of dogs	13	4	12