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The aim was to study number, volume, apoptosis of corpora lutea (CL), and serum P 4 concentrations in early, middle, and late diestrus of dogs. Thirty-six bitches were ovari-hysterectomized (OVX): Early Diestrus (Group [G]1; OVX 20 days after end of estrus [DEH]); Mid-diestrus (GII; OVX between 21 and 40 days after DEH), and Late-diestrus (GIII; OVX between 41 and 60 days after DEH). Before OVX a blood sample was collected to quantify P 4 . After OVX, the number of CL (NCL) was recorded, CL measured using both ultrasonography (US) and caliper (CAL), and the volume (mm 3 ) was calculated. Based on abundances of caspase-3, apoptotic luteal cells were detected. Bitches in early-diestrus had greater P 4 concentrations than bitches in mid- and late-diestrus (23.52 ± 3.78 and 10.86 ± 3.88 ng/mL; P < 0.05). The NCL, cumulative USCLV, and CALCLV were similar among diestrus stages (P > 0.30). Bitches with CL (≥5) had twice the serum P 4 concentrations as bitches with CL1-2 and CL3-4 (22.71 ± 3.70 and 10.97 ± 4.06 ng/mL; P < 0.05). There were correlations between P 4 concentrations with USCLV, CALCLV, and NCL (r = 0.64, r = 0.67, r = 0.44; P < 0.0001). When serum P 4 concentrations were adjusted for stages of diestrus, however, there were only correlations during early diestrus. The percentage of apoptotic cells was greater in GIII compared with GI and GII (13.75 ± 2.26 % compared with 4.5 ± 0.68 % and 4.6 ± 1.5 %, respectively; P < 0.05). As days of diestrus increased, number of apoptotic cells increased, and serum P 4 concentrations decreased., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The aim of the study was to determine the time after treatment with a 4.7 mg deslorelin implant until Tomcat spermatogenesis activity was restored, and seminal parameters reached pre-implant values. Tomcats (n = 6) were randomly assigned to one of two treatments. Three cats (n = 3) received a deslorelin implant (4.7 mG; Suprelorin ® , Virbac, France) in the interscapular subcutaneous region whereas three (n = 3) received no implant and served as control group. Semen samples were collected by electroejaculation every 4 wk from 3 mo before treatment (pretreatment samples) until reestablishment of pre-treatment sperm quality, 32 mo post-implant insertion (PI). Each semen sample was assessed for motility, velocity, concentration, total sperm count, viability, acrosome integrity, plasma membrane integrity and sperm morphology. After semen collection, testicular volume and presence/absence of penile spines were recorded. Additionally, blood samples were taken to measure testosterone concentration. An increase in sperm concentration and total sperm count was present 1 mo PI despite of an abrupt decrease in serum testosterone concentrations after 2-4 weeks. This initial stimulatory effect was followed by a decrease in seminal parameters, reduction of testicular volume and disappearance of penile spines 2 mo PI. A single Suprelorin ® 4.7 mg implant suppressed sperm production for 22-25 months. No clinically side effect was observed during the study period. All toms returned to their initial seminal quality 23-28 months after treatment. Therefore, we conclude that Suprelorin ® 4.7 mg is a safe option for reversible reproduction control during long periods in tomcats., (Copyright © 2018. Published by Elsevier B.V.)