Preliminary Evaluation of Cortical and Medullary Echogenicity in Normal Canine Fetal Kidneys during the Last 10 Days of Pregnancy.

The objective of this study was to assess changes in the echogenicity of the cortex and medulla of canine fetal kidneys in relation to days before parturition (dbp), maternal size and litter size. Monitoring of 10 healthy pregnant bitches (2-8 years old, 8.8-40.3 kg bw) was conducted from -10 to 0 dbp using ultrasound. A single renal sonogram was obtained by scanning in a longitudinal section the three most caudal fetuses. The mean gray level (MGL) and SD of a manually drawn region of interest (ROI) in the renal cortex and medulla were measured using the Fiji Image J software (Image J 1.51h, Java 1.6 0_24 64 bit). A linear mixed model taking into account the maternal size as a fixed effect, dbp and litter size as covariates and the bitch as a random and repeated effect was used. The regression coefficients (b) were estimated. Cortical SD (C-SD) and cortico-medullary SD (C/M-SD) were influenced by dbp, with a significant decrease at the approaching day of parturition (b = 0.23 ± 0.06, p < 0.001 and b = 0.5 ± 0.02, p = 0.038, respectively). Maternal size had a significant impact on C/M-MGL with differences observed in large-sized (1.95 ± 0.13) compared to small- (1.41 ± 0.10, p = 0.027) and medium-sized bitches (1.51 ± 0.09, p = 0.016). The C/M-MGL was influenced by litter size, showing a decrease as the number of pups increased (b = -0.08 ± 0.03, p = 0.018). C-SD and C/M-SD were exclusively affected by dbp, and not by maternal and litter size. This suggests their potential as valuable parameters, warranting further investigations in future studies.

Clinical use of the canine foetal kidney formula in dogs of different maternal sizes during the last ten days before parturition.

Data concerning the use of the canine foetal kidney length (L) formula in the prediction of parturition timing are still lacking. In our study, we aimed to evaluate the accuracy of the L formula in predicting the parturition date during the last 10 days of pregnancy. Twenty-five clinically healthy pregnant bitches, aged 2-9 years and weighing 3.5-52.2 kg, were ultrasonographically monitored from -11 to 0 days before parturition (dbp). Kidney L was measured for the three most caudal foetuses, and the parturition day was estimated using the kidney formula, whose accuracy was calculated as the percentage of cases estimated (ranges of ± 1 or ± 2 days) on the actual parturition date. A K-proportions test was performed to identify differences in the accuracy among maternal sizes and the sex ratio of pups, and a two-proportions z-test was performed to identify differences between litter size classes (≤ 7 vs. > 7 pups) and time ranges (-11/-5 and -4/0 dbp). An accuracy of 35% within ± 2 days was found in the range of -11/-5 dbp and an accuracy of 30% within ± 2 days was found in the range of -4/0 dbp. The accuracy differed between small (53% ±1 day and 60% ±2 days) and large (10% within ± 1 and ± 2 days) bitches (P = 0.019 within ± 1 day, and P = 0.007 within ± 2 days). For small litter sizes, the accuracy was 38% within ± 1 day and 44% within ± 2 days, and for large litter sizes, it was 14% within ± 1 and ± 2 days. A threshold value was found between litter size classes within ± 2 days. The use of the L formula during the last ten days of pregnancy did not seem to warrant good accuracy in the prediction of parturition date. Further studies on different maternal sizes should be performed.

Ultrasonographic changes in fetal gastrointestinal motility during the last ten days before parturition in dogs.

Fetal gastrointestinal motility (FGM) was suggested as useful to assess fetal maturity. Our study aimed to quantify FGM in relation to days before parturition (DBP), maternal size, and sex ratio of pups. During the last ten days of pregnancy, 23 clinically healthy pregnant bitches of 16 different breeds ranging in age from 2 to 9 years and body weight from 3.5 to 56.8 kg were monitored twice. The fetal intestine was observed in longitudinal and transversal scan on 3 of the most caudal fetuses in both uterine horns. Gestational age was counted backward from parturition day. The number of fetuses showing FGM was recorded in time in I (-11/-5 DBP) and II (-4/0 DBP). A Mann-Whitney test was performed to analyze variations of FGM% in relation to time and parity. A Kruskal-Wallis test was performed to identify variations of FGM% in relation to maternal size and sex ratio. Statistical significance was set at α = 0.05. A total of 147 FGM observations on 50 ultrasonographic monitoring points were performed. The FGM% was higher during time II compared to time I (median: 33%, range 0-100% vs. 100%, range 33-100%; P < 0.0001). FGM% was higher in small compared to large size bitches (median: 100%, range 67-100% vs. 67%, range 0-100%; P = 0.01). FGM% was not affected by parity and sex ratio. As previously reported, a significant increase in FGM% was observed in the last five DBP. FGM observation may be influenced by the maternal size, with easier evaluation in small size bitches, as well as ultrasound equipment and positioning.

Relationship between days before parturition and fetal kidney length, cortical thickness, medullary thickness and their ratio in dogs.

Canine gestational age can be estimated based on fetal kidney length (L) although accuracy, sensitivity and specificity decrease during the last 5 days of pregnancy. In humans, fetal renal cortical and medullary thickness (CT and MT) and their ratio (CT/MT) are described as useful tools for monitoring the development of fetal kidneys. The aim of this study was to evaluate a potential relationship between canine fetal kidney parameters and gestational age. Ten clinically healthy pregnant bitches of different breeds were monitored by ultrasound at least twice from -10 to 0 days before parturition (dbp). L, CT, MT and CT/MT were measured on the three most caudal fetuses of both uterine horns. Statistical analysis was performed using a linear mixed model considering maternal size (small ≤10 kg, N = 4, medium 11-25 kg, N = 3, and large 26-40 kg, N = 3) as fixed effect, dbp (-10 to 0) and litter size as covariates, and the bitch as a random and repeated effect. Dbp and L, CT, MT showed a negative and linear correlation, and their estimated regression coefficients were -0.68 ± 0.14, -0.04 ± 0.01 and -0.12 ± 0.02 mm, respectively (P < 0.01). CT/MT decreased as parturition approached, whereas MT and CT increased. A statistically significant difference was found for L between small and large bitches (17 ± 1 vs 24 ± 2 mm, P = 0.03) and, for CT, between small, medium and large bitches (1.57 ± 0.04 vs 1.77 ± 0.04 vs 1.99 ± 0.05 mm, P < 0.001). None of the renal parameters were affected by litter size. L, CT, MT and CT/MT are related to dbp and may be considered for predicting parturition in dogs.

A case report of a rapid development of fetal anasarca in a canine pregnancy at term.

A 5-year-old healthy pluriparous pregnant Flat-coated Retriever bitch was monitored by ultrasound on post-ovulation days 30 and 57: no deviation from normality picture were observed. On day 60, one of the three most caudal fetuses showed ultrasonographic signs of fetal anasarca: subcutaneous edema and anechoic fluid in thoracic and abdominal cavities. There was an increased volume of extra-fetal fluids. On day 64 a Cesarean section was performed and one of the seven pups that were delivered, a female, showed generalized subcutaneous edema and died soon after birth. She weighed 660 g, compared to a mean of 472 g for the other 6 normal fetuses. A total of 295, 40 and 27.5 mL of liquid were collected from subcutaneous tissue, abdominal and thoracic cavity, respectively. Liver showed sub-glissonian necrotic areas. Molecular analyses with PCR method for canine Herpesvirus, Parvovirus, Adenovirus, Leptospira interrogans, Chlamydia spp., Neospora caninum and Toxoplasma gondii from pools of organs (spleen, kidney and brain) and pleural effusion tested negative. This is the first reported case of fetal anasarca with a rapid onset diagnosed on day 60 post-ovulation just three days after observing a normal ultrasonographic pattern in Flat-coated Retriever. Ultrasonographic diagnosis of fetal anasarca is of primary importance when assisting parturition, due to its inherent risk of dystocia. Ultrasonographic monitoring in the immediate prepartum period may be useful in all breeds as it may help to detect ultrasonographic alterations occurring right before term such as anasarca.

Usefulness of Maternal and Fetal Parameters for the Prediction of Parturition Date in Dogs.

An accurate parturition timing is of key importance for breeders and veterinarians in order to give professional assistance to parturition in dogs. However, pregnancy length calculated from the breeding date has a wide variability. Different parameters and formulas have been described and calculated, as well as their accuracy which is affected by various factors: stage of pregnancy, litter and maternal size. Therefore, the selection of the most appropriate parameter panel poses the challenge of weighing their influences and impact on the overall accuracy. The aim of this review is to analyze the parameters useful for parturition timing, especially their accuracy, and to propose the addition of fetal maturity and criteria for its evaluation to detect readiness for parturition. Parameters, as described in literature, are classified as: (i) maternal parameters, (ii) fetal parameters, (iii) ultrasonographic assessment of maternal and fetal heart rate and blood flow, (iv) parameters indicating fetal maturity. A focus on recently described parameters-such as fetal gastrointestinal motility and fetal lung development detected by quantitative ultrasound-is reported. Currently, the most accurate way to predict parturition day is represented by a prepartum progesterone drop, but the identification of a panel of ultrasonographic parameters combining their significance and their accuracy throughout pregnancy is still needed.

Ultrasonographic analysis of fetal gastrointestinal motility during the peripartum period in the dog.

The aim of this study was to investigate fetal gastrointestinal motility (FGM) of dogs using ultrasonic imaging and its association with vaginal and rectal temperature, serum progesterone concentrations and fetal heart rate. Pregnant bitches were examined after day 54 of gestation and there were determinations of vaginal and rectal temperature and serum progesterone concentrations. The fetal abdomen was evaluated for 30 s using longitudinal and transversal assessments, and FGM was scored as 0 (no peristalsis) or 1 (evident peristalsis). Number of fetuses with a 1 or 0 score were determined for each bitch (number and the percentage of fetuses with FGM). A total of 135 FGM measurements were recorded. There was FGM in 0/3, 0/6, 1/6 (16.7 %), 3/20 (15 %), 5/18 (27.3 %), 18/28 (64.3 %), 12/17 (70.6 %), 14/22 (63.6 %), 6/9 (66.7 %), 4/6 (66.7 %) fetuses from day -9 until 0 preceding parturition, respectively. In the last 5 days before parturition, 63.3 % of fetuses had FGM. Vaginal and rectal temperature were strongly and positively correlated (P < 0.001). Vaginal temperature was positively correlated with progesterone concentrations and fetal heart rate (P < 0.01), and there was a small negative correlation with FGM (r = -0.331, P < 0.05). Due to ease of data collection, the assessment of FGM is a valuable procedure for evaluation of fetal maturity in dogs. Vaginal and rectal temperatures are reliable variables to be assessed during the last week of pregnancy for estimating the time of parturition.