Nemaline myopathy

From Dog
Immunolabelling of skeletal muscle sections with anti-nemaline antibodies. White areas are positive for nemaline[1]

Nemaline myopathy is a rare pathological process occasionally observed microscopically in a number of myopathic diseases in dogs.

Cases of congenital nemaline myopathy has been reported in the Border Collie and Schipperke breeds as an early onset disease (under 12 months of age).

Nemaline myopathy has also been reported in association with hypothyroidism[2] and hyperadrenocorticism[3].

Clinical symptoms in affected dogs include exercise intolerance and muscle weakness. Adult-onset cases often present with lethargy, inappetence, weakness, abdominal distension and generalised muscle atrophy[4].

Electromyography usually shows mild to moderate diffuse spontaneous activity.

Diagnosis of nemaline rod myopathy requires muscle biopsy, showing the presence of numerous pathognomonic rods within muscle tissue.

A differential diagnosis would include polymyositis, Duchenne muscular dystrophy and muscle parasites such as Neospora caninum and Toxoplasma gondii.

There is no known treatment for this condition.

References

  1. Sewry CA et al (2001) Abnormalities in the expression of nebulin in chromosome-2 linked nemaline myopathy. Neuromuscul Disord 11(2):146-153
  2. Rossmeisl JH et al (2009) Longitudinal study of the effects of chronic hypothyroidism on skeletal muscle in dogs. Am J Vet Res 70(7):879-889
  3. Delauche AJ et al (1998) Nemaline rods in canine myopathies: 4 case reports and literature review. J Vet Intern Med 12(6):424-430
  4. Nakamura RK et al (2012) Adult-onset nemaline myopathy in a dog presenting with persistent atrial standstill and primary hypothyroidism. J Small Anim Pract 53(6):357-360