ACVIM Required Reading - Musculoskeletal Dz Flashcards
1
Q
Describe clinical presentation of a 6wk old Arabian cross foal with suspected congenital centronuclear myopathy.
A
- Normal at birth and first month of life.
- Generalised weakness and muscle atrophy.
- Only able to stand for 15-20mins w short, choppy gait.
- Electromyography: dec insertional activity, fibrillation potentials, positive sharp waves, and complex repetitive discharges in all of the muscles examined. Amplitudes of the motor unit action potentials were subjectively dec.
- Muscle histo: excessive variability in myofiber size, fibers with centrally located nuclei; electron microscopy: numerous vacuoles filled with granular debris consistent with dilatation of the t-tubular system and triads, z-line disruption and myofibrillar disarray; consistent w CNM in other spp.
- Supportive care through several hospital visits but found dead in stall at 5mo of age.
Ref: J. Vet. Intern. Med. 2014;28(6):1886–1891.
2
Q
Describe clinical presentation and evidence of myocardial dysfunction in an Arabian mare with masseter myodegeneration.
A
- 22yo Arabian mare w 2d Hx dysphagia, salivation and bilateral swelling of the masseter muscles.
- Good appetite but masseters swollen and painful and mastication ineffective; HR 60bpm, PE otherwise WNL.
- CBC WNL, elevated muscle and liver enzymes, marked pigmenturia, Se conc undetectable, Vit E conc WNL.
- U/S: masseter mm thickened, increased muscle echogenicity and patchy blurring of the fasciae within the muscle layers = inflammation and oedema.
- Tx: PBZ, dexamethasone, IM Vit E/Se, oral Vit E and methocarbabol, IV CRIs lignocaine and medetomidine –> CSx improved over week but persistent tachycardia.
- 24-h Holter ECG: sinus tachycardia with sporadic supraventricular and uniform ventricular dysrhythmias, cTnI = 11.6ng/mL (ref bilateral mm atrophy; gradually able to chew and swallow and cardiac function n; discharged on day 17 on Vit E/Se, masseter mm WNL at 6mo.
Ref: J. Vet. Intern. Med. 2011; 25(5):1171–1180.
