Influence of estrous stages on electrocardiography, clinical pathology and ovarian weight of experimental beagle dogs: a retrospective analysis

Abstract

Estrous cycle is a repetitive phenomenon occurring during the reproductive life of a female dog. The duration of the canine estrous cycle is considerably longer than one in the most of the other animals and is broadly grouped into follicular phase (proestrus and estrus), luteal phase (diestrus) and non-seasonal anestrus. Dogs in the same stage of cycle can be inadvertently assigned to same group during routine safety and metabolic studies leading to possible erroneous interpretation of test-item related effects. This retrospective analysis was conducted by analyzing data of 86 female beagle dogs from control/placebo treated groups to correlate any possible effect of estrous stages with electrocardiography, clinical pathology and ovarian weight. Different estrous cycle stages of beagles were confirmed histologically by evaluating ovary, uterus, vagina and mammary glands. The incidence of beagles in diestrus was the highest, followed by anestrus, proestrus and estrus. No significant effect was noticed on heart rate, P–A, P–D, RR, QRS and QT intervals across different stages of estrous cycle. However, significantly higher PQ (PR) interval in dogs in proestrus stage was observed compared to dogs in anestrus and estrus. Marginally higher WBCs, neutrophils, lymphocytes, RBCs, hemoglobin, AST and lower hematocrit, lipid profile (total cholesterol, HDL, LDL, triglycerides), ALP level was evident in estrous period. Relative ovary weight was significantly higher in dogs in diestrus stage. Considering these results, one may need to exercise caution while interpreting experimental data from female beagle dogs.

Evaluation of cardioprotection and bio-efficacy enhancement of stevioside and diltiazem in rats

“…The sympathetic hyperactivity has a direct impact on ECG by extension of the QT interval. The prolongation QT interval at times of myocardial stress is an indication of arrhythmias and sudden cardiac collapse [32][33][34]. Oral pre-treatment of STV-100 and STV-200 alone and with DTZ was potent enough to avoid prolongation of QT interval representing the absence of arrhythmias.…”

Luteal phase decrease in packed cell volume in healthy non‐pregnant and pregnant bitches

“…to be higher than at other stages by some authors (Chitrang et al, 2019;Günzel-Apel et al, 1997;Willson et al, 2012). The increase to anoestrus PCV was also impacted by litter size and previous pregnancies.…”

“…The 20‐week sample represents the end of metestrus/start of anoestrous. Anoestrus PCV/Hct values within the literature have been reported to be higher than at other stages by some authors (Chitrang et al., 2019 ; Günzel‐Apel et al., 1997 ; Willson et al., 2012 ). The increase to anoestrus PCV was also impacted by litter size and previous pregnancies.…”