Epidemiology and Inheritance of Mitral Valve Prolapse in Dachshunds

One hundred ninety consecutive Dachshunds >2 years of age, including 18 families consisting of both parents and 4 or more offspring, were examined clinically and echocardiographically to study the epidemiology and inheritance of mitral valve prolapse (MVP) and other signs of myxomatous mitral valve disease in the dog. From video-recorded echocardiograms, MVP severity, jet size (color Doppler), and leaflet thickness were assessed. With regard to murmur intensity and each of these 3 echocardiographic measurements. the inheritance and the influence of age, gender, coat type, body weight, degree of obesity, heart rate, and thorax dimensions were evaluated. MVP severity correlated positively with age (P < .0001) and heart rate (P = .002), negatively with thorax circumference (P = .0005), and was related to coat type (P = .006). MVP severity progressed faster in males than in females (P = .0002). The other measures of disease severity (jet size, leaflet thickness, and murmur intensity) also correlated positively with age (all P < .0001). When compared in pairs, all 4 measures of disease severity correlated significantly with one other. Pedigree analyses did not disclose agreement with simple Mendelian models, but high disease prevalence made interpretation difficult. Mean parental MVP severity correlated significantly with MVP severity in the offspring (P = .03). The epidemiology of MVP in Dachshunds resembles that of MVP in humans, MVP severity correlates significantly with other measures of the degree of myxomatous mitral valve disease, and MVP is an inherited condition in Dachshunds. A polygenic mode of inheritance is suggested.     

Partial external mitral annuloplasty in dogs with myxomatous mitral valve degeneration and congestive heart failure: Outcome in 9 cases

Objective

To report the outcome of partial external mitral annuloplasty in dogs with congestive heart failure (CHF) due to mitral regurgitation caused by myxomatous mitral valve degeneration (MMVD).

Animals, materials and methods

Nine client-owned dogs with CHF due to mitral regurgitation caused by MMVD. Surgery consisted of a double row of pledget-butressed continuous suture lines placed into the left ventricle parallel and just ventral to the atrioventricular groove between the subsinuosal branch of the left circumflex coronary artery and the paraconal branch of the left coronary artery.

Results

Two dogs died during surgery because of severe hemorrhage. Two dogs died 12 and 36 h after surgery because of acute myocardial infarction. Three dogs were euthanized 2 and 4 weeks after surgery because of progression of CHF, 1 was euthanized 30 days after surgery for non-cardiac disease, and 1 survived for 48 months. In the 5 dogs that survived to discharge there was no significant change in the left atrium to aortic ratio with surgery (3.6 ± 0.56 before surgery; 3.1 ± 0.4 after surgery; p = 0.182), and no significant change in mitral regurgitant fraction in 4 dogs in which this measurement was made (78.7 ± 2.0% before surgery; 68.7 ± 7.5% after surgery; p = 0.09).

Conclusions

Partial external mitral annuloplasty in dogs with CHF due to MMVD was associated with high perioperative mortality and most dogs that survived to discharge failed to show clinically relevant palliation from this procedure. Consequently, partial external mitral annuloplasty is not a viable option for dogs with mitral regurgitation due to MMVD that has progressed to the stage of CHF.     

Neurohormonal and circulatory effects of short-term treatment with enalapril and quinapril in dogs with asymptomatic mitral regurgitation

The aim of the study was to compare the effect of 2 angiotensin-converting enzyme (ACE) inhibitors on neurohormonal and circulatory variables in Cavalier King Charles Spaniels (CKCSs) with asymptomatic mitral regurgitation (MR). Ten CKCSs with mild to severe untreated MR were treated with 2 ACE inhibitors, quinapril and enalapril (each at 0.5 mg/kg PO q24h for 7 days), in a double-blind, crossover study with a washout period of 7 days between treatments. Blood samples were drawn and echocardiography was performed on days 0, 7, 14, and 21. Both treatments reduced ACE activity (P < .001) and increased renin activity (P < .001) and atrial natriuretic peptide concentration (P < .005). The ACE inhibitors had no effect on the concentrations of nitrate and nitrite (NOx) or asymmetric dimethylarginine (ADMA). On day 0, a lower NOx concentration (P = .02) was found in samples taken in the clinic as compared to samples taken in the homes of the dogs. Quinapril caused a significant reduction in more variables that reflect the severity of MR (eg, jet size and left ventricular end diastolic diameter) than did enalapril. However, in terms of specific variables, no significant difference was identified between the effects of the 2 treatments on MR. These results suggest that ACE inhibitors do not affect NOx and ADMA concentrations in asymptomatic dogs, but exercise, stress, or some combination may influence NOx concentrations in these dogs.     

The cardiac biomarker sodium-calcium exchanger (NCX-1) can differentiate between heart failure and renal failure: a comparative study of NCX-1 expression in dogs with chronic mitral valvular insufficiency and azotemia

Background: The sodium‐calcium exchanger (NCX‐1), an established cardiac biomarker, was postulated previously as differentiating between heart failure (HF) and renal failure (RF) in dogs. The effect of azotemia on NCX‐1 expression has not been studied. Hypothesis: In contrast to other cardiac biomarkers (eg, N‐terminal‐proBNP), we hypothesized that the expression level of NCX‐1 is not influenced by either azotemia or decreased renal clearance. Animals: Fifteen client‐owned healthy control dogs, 14 dogs with chronic mitral valvular insufficiency (CMVI), classified based on severity of the disease by the established International Small Animal Cardiac Health Council classification system, and 15 dogs with RF, grouped according to the International Renal Interest Society stage classification. Methods: A comparative study of the expression levels of NCX‐1, evaluated in peripheral blood samples from dogs with HF, RF, and healthy controls by quantitative PCR. Results: NCX‐1 expression was significantly increased in moderate (2.99 ± 0.61 [fold changes relative to normal group]) to severe (4.35 ± 1.44) CMVI dogs (P < .01). In contrast, NCX‐1 expression was not increased in the azotemic dogs. Furthermore, there was also no correlation between increased concentrations of creatinine and urea nitrogen in serum and NCX‐1 expression in the RF group. Conclusions and Clinical Importance: Azotemia likely does not affect NCX‐1 expression.     

犬二尖瓣膜闭锁不全的诊断与治疗

[目的]为犬二尖瓣膜闭锁不全的预防、诊断、治疗提供借鉴。[方法]从流行病学、临床症状、心电图检查、X线检查、超声心动图检查和彩色多普勒超声显像等方面综述了该病的诊断方法。分析了该病的发病机理,介绍了该病保守治疗常用的药物以及手术治疗的手术方法、疾病护理要点和预防手段。[结果]犬二尖瓣膜闭锁不全的诊断可分为临床诊断和实验室诊断。犬二尖瓣膜闭锁不全的治疗可分为药物治疗和手术治疗。最后,对该病的日常护理和预防工作进行了阐述。[结论]今后还需要对二尖瓣膜的结构及其闭锁不全的致病机理进行深入研究。     

王小娟教授运用苓桂芥甘汤治疗胃食管反流病经验

胃食管反流病是临床常见的多发性、难治性消化系统疾病,中医认为其多为肝脾不和,临床常见肝胃不和、肝胃郁热、脾胃虚寒、中虚气滞、胃阴不足等证型。王小娟教授根据临床观察提出肝郁水逆之证型,并以苓桂芥甘汤为主方,根据患者情况加减温阳化饮、疏肝行气之品,治疗胃食管反流病肝郁水逆证取得较好的疗效。