Effects of Behavior Responses on the Vasovagal Tonus Index in Healthy Dogs บทคั ดย่ อ ผลของพฤติ กรรมต่ อความแปรปรวนของอั ตราการเต้ นหั วใจในสุ นั ขปกติ วลาสิ นี มู ลอามาตย์ 1* ไกรพิ ชญ์ สุ ธรรมมาภรณ์ 2 ฐาปนา จารุ ธรรมสิ ริ 3 รุ ่ งโรจน์ โอสถานนท์ Vasovaga

Abstract The vasovagal tonus index (VVTI) is a time-domain analysis method of heart rate variability acquired over a short period. It is a useful measurement for evaluating severity and prognosis heart failure in dogs. Behavior responses can be used to evaluate stress in each dog individually. Stress during clinical examination may interfere with the VVTI since it influences the sympathetic nervous system. The aim of this study was to investigate the effect of behavior responses during clinical examination on the VVTI. Data set obtained from physical examination, systolic blood pressure measurement, electrocardiography, VVTI calculation, and video recording were collected from 50 healthy dogs. Behavior scores were analyzed from video recording and dogs were classified into three groups; group 1 (passive), group 2 (quite active), and group 3 (highly active). The results showed that the VVTI was not different between the three groups (p=0.77). Medians and interquartiles of the VVTI in group 1, 2, and 3 were 8. 45 (6.86-9.05), 7.65 (6.82-8.94), and 7.26 (5.80-8.90) respectively. There was a negative correlation between VVTI and heart rate (Pearson's r= -0.68, p<0.001). Therefore, the effect of behavior responses during clinical examination did not affect the VVTI measurement in healthy dogs

Longitudinal Electrocardiographic Evaluation of Dogs with Degenerative Mitral Valve Disease

BACKGROUND: Increased heart rate (HR) and decreased heart rate variability (HRV) are evident in some dogs with degenerative mitral valve disease (DMVD). OBJECTIVES: Evaluation of the factors influencing HR and HRV (assessed by the vasovagal tonus index; VVTI) and their change over time in dogs with DMVD. ANIMALS: Client‐owned dogs (n = 257) with DMVD recruited from first opinion practice. METHODS: Prospective longitudinal follow‐up at six‐monthly intervals of dogs with DMVD. Dogs followed up for at least 18 months (n = 102) were grouped according to their outcome as dogs dying/euthanized because of cardiac disease (n = 28; Group 1), noncardiac disease (n = 40; Group 2) and dogs alive (n = 34; Group 3). HR and VVTI were measured on 1‐minute ECG recordings. Repeated measures linear models were constructed to investigate the factors that influence HR and VVTI and their changes over time. RESULTS: Heart rate and VVTI were affected by disease severity and were different in Cavaliers compared to other breeds. Group 1 and Group 2 dogs underwent an increase in HR and decrease in VVTI, evident at least 18 months before death. Group 1 had a further decrease in VVTI followed by an increase in HR approximately 1 year and 6 months before death, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs with DMVD have an increase in HR and decrease in HRV over a year before death, with greater changes in those dogs dying/euthanized because of cardiac disease. Both HR and VVTI can potentially be regarded as biomarkers for all‐cause mortality

Low-density Lipoprotein Improves Motility and Plasma Membrane Integrity of Cryopreserved Canine Epididymal Spermatozoa

Cryopreservation of caudal epididymal spermatozoa is an effective technique to conserve genetic potentials of superior dogs when it is not possible to collect ejaculated spermatozoa. Although hen egg yolk is commonly supplemented into the semen extender, active substances within the egg yolk which protect sperm against cryoinjury remain to be discovered. Among its compositions, low-density lipoprotein (LDL) has been reported to have a cryoprotective property for sperm cryopreservation. However, the effects of LDL on dog epididymal spermatozoa during cryopreservation have not yet been investigated. This study aimed to investigate the effects of LDL on epididymal spermatozoa quality following cryopreservation and thawing. After routine castration of 12 dogs, caudal epididymides from individuals were separated from the testes and cut into a few pieces in a Tris-buffer. Spermatozoa recovered from each sample were examined at once for sperm quality and divided into six groups of extender: no LDL, 20% egg yolk, 4%, 8%, 16%, and 24% LDL, before cryopreservation. The sperm aliquots were then equilibrated and conventionally frozen. After thawing, sperm motility, morphology, plasma membrane integrity, and acrosome integrity were evaluated. The results revealed that 4% LDL and 20% egg yolk yielded significantly higher sperm motility (57.69% and 52.69%, respectively, p<0.05) than other LDLs. In addition, 4% LDL yielded the significantly highest plasma membrane integrity (70.54%, p<0.05). In conclusion, the supplementation of 4% LDL in Tris-glucose extender could be applied for cryopreservation of canine epididymal spermatozoa