A complex CLCN1 variant associated with hereditary myotonia in a mixed-breed dog.

Hereditary myotonia (HM) is characterized by delayed muscle relaxation after contraction as a result of a mutation in the CLCN1 gene. We describe here a complex CLCN1 variant in a mixed-breed dog with clinical and electromyographic signs of HM. Blood samples from the myotonic dog, as well as from his male littermate and parents, were analyzed via amplification of the 23 exons encoding CLCN1. After sequencing the CLCN1 gene, a complex variant was found in exon 6 c.[705T>G; 708del; 712_732del], resulting in a premature stop codon in exon 7 and a protein that was 717 amino acids shorter than the normal CLC protein. The myotonic dog was identified as homozygous recessive for the complex CLCN1 variant; its parents were heterozygous, and its male littermate was homozygous wild-type. Knowledge of the CLCN1 mutations responsible for the development of hereditary myotonia allows greater clarification of this condition.

Treatment of acute rumen lactic acidosis with intravenous hypertonic sodium chloride or bicarbonate solutions followed by intraruminal water.

The effectiveness of 7% hypertonic saline solution (HSS) and 6% hypertonic bicarbonate solution (HBS) followed by intraruminal water administration for the treatment of acute rumen lactic acidosis (ARLA) has not been evaluated yet. The hypothesis of the study is that treatment with HBS causes a faster correction of imbalances and clinical recovery than treatment with HSS. ARLA was induced in six healthy mature female sheep with sucrose twice. The sheep received both treatment regimens in a cross over design. After 18 h of induction, rumen lavage was performed and IV infusion of 7% HSS (4 mL/kg BW) or 6% HBS (6.7 mL/kg BW) was done over 5 min, followed by intraruminal administration of water (8% BW). The solutions provided 4.8 mmol/kg BW of sodium. Physical and laboratory tests were performed for 168 h. Both treatments increased plasma volume. After HSS treatment, pH and HCO3- returned to baseline values at 144 h and BE at 168 h. With HBS treatment, pH returned to baseline at 24 h, and HCO3- and BE at 48 h. In both treatments, the ruminal motility and the maximum hay intake were restored at 96 and 120 h, respectively. In conclusion, administration of HSS or HBS followed by intraruminal water corrects dehydration and mild-to-moderate metabolic acidosis in sheep with ARLA. Treatment with HBS promoted a faster correction of metabolic acidosis and could be indicated for the most severe cases.