Myokymia and neuromyotonia in a cat

A 6-year-old spayed female domestic shorthair cat was examined because of a 2-week history of rhythmic muscle movements. Physical examination revealed thoracic limb rigidity, contracture of the carpi, generalized muscle atrophy, and rhythmic rippling of the muscles of all 4 limbs. Results of a CBC and serum biochemistry profile were unremarkable other than high creatine kinase activity. Electromyography revealed unique high-frequency discharges, including rhythmic bursts of single motor unit potentials appearing as doublets (myokymia) and more prolonged bursts of nonrhythmic motor unit potentials with characteristic waning amplitudes (neuromyotonia). Histologic examination of muscle biopsy specimens revealed noninflammatory necrotizing myopathy with regeneration. The cat did not respond to treatment with carbamazepine or prednisone but improved rapidly after treatment with phenytoin was initiated. Six months after initial examination, electromyography revealed a substantial decrease in the amount of spontaneous activity in previously affected muscles. However, the myokymic and neuromyotonic discharges were still present, albeit with a substantial decrease in frequency.     

CHOROID PLEXUS CYST IN A DOG

A 6-year-old male Doberman Pinscher had a 2-month history of dysequilibrium. Lesion localization was determined to be the cerebellomedullary pontine angle. In computed tomographic images, a well-defined, circular, hypoattenuating mass was visible at the cerebellomedullary pontine angle. The lesion, which was isoattenuating to cerebrospinal fluid, was 4 x 8 mm in diameter. Peripheral ring enhancement was evident after contrast medium administration. A choroid plexus cyst was diagnosed histopathologically.     

Embryonic Development of Cuban Gar (Atractosteus tristoechus) Under Laboratory Conditions

The embryonic development of Cuban gar (Atractosteus tristoechus) was described under controlled laboratory conditions. During the whole embryogenesis seven periods were defined: the zygote (0–½ h), cleavage (¾–4 h), blastula (5–10 h), gastrula (12–20 h), segmentation (24–40 h), pharyngula (48–66 h) and hatching (72–96 h) periods. The stages were based on morphological features, generally readily identified by examination of the embryo with the dissecting stereomicroscope. Hatching occurred 96 ± 4 h after spawning at 28°C.