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The mechanisms governing corpus luteum (CL) function in domestic dogs remain not fully elucidated. The upregulated expression of cyclooxygenase 2 and prostaglandin (PG) E2 synthase (PGES) at the beginning of the canine luteal phase indicated their luteotrophic roles, and the steroidogenic activity of PGE2 in the early canine CL has been confirmed in vitro. Recently, by applying a cyclooxygenase 2 (COX2)-specific inhibitor (firocoxib [Previcox]; Merial) from the day of ovulation until the midluteal phase, the luteotrophic effects of PGs have been shown in vivo. This is a follow-up study investigating the underlying endocrine mechanisms associated with the firocoxib-mediated effects on the canine CL. Experimental groups were formed with ovariohysterectomies performed on Days 5, 10, 20, or 30 of firocoxib treatments (10 mg/kg bw/24h; TGs = treated groups). Untreated dogs served as controls. A decrease of steroidogenic acute regulatory (STAR) protein expression was observed in TGs. The expression of PGE2 synthase was significantly suppressed in TGs 5 and 10, and both PGE2 and PGF2 levels were decreased in luteal homogenates, particularly from CL in TG 5. Similarly, expression of the prolactin receptor (PRLR) was diminished in TGs 5 and 20. The expression of PGE2 receptors PTGER2 (EP2) and PTGER4 (EP4), the PG-transporter (PGT) , and 15-hydroxy PG dehydrogenase (HPGD) was not affected in TGs. Our results substantiate a direct luteotrophic role of PGs in the early canine CL, i.e., by upregulating the steroidogenic machinery. Additionally, the possibility of an indirect effect on PRL function arises from the increased prolactin receptor expression in response to PGE2 treatment in canine lutein cells observed in vitro.

The aim of this study was to evaluate the prevalence and etiological agents of subclinical mastitis at the end of lactation in nine dairy herds in North-East Poland. In total, 387 Polish HF were involved in the study. The diagnosis of mastitis was performed on the basis of clinical examination of the udder, macroscopic evaluation of milk, determination of somatic cell count and bacteriological examination of milk. Subclinical mastitis was found in an average of 36.7% (range from 21.0% to 53.1%) of cows and of 15.7% (range from 9.6% to 25.2%) of quarters. Coagulase negative staphylococci (CNS; 31.6% of quarters), Streptococcus (Str.) agalactiae (15.6% of quarters), Staphylococcus (Staph.) aureus (12.1% of quarters) and fungi (12.2% of quarters) were most frequently isolated from subclinical mastitis. Etiological agents of subclinical mastitis differed strongly between herds. The results of this study showed that the incidence of subclinical mastitis at the end of lactation in dairy herds in North-East Poland is high. CNS were the most frequently isolated from subclinical mastitis cases, however mastitis caused by the contagious pathogens Str. agalactiae and Staph. aureus is still a problem. The fungal infections of the mammary gland also play an important role.

Thirty clinically healthy dogs with poor semen quality were used in the study. Fifteen dogs were supplemented daily with selenium (0.6 mg/kg organic selenium from yeast) and vitamin E (5 mg/kg) per os for 60 d. The control group (15 dogs) was not supplemented. Semen was collected from all dogs by manual manipulation on days 0, 30, 60, and 90. The sperm concentration and motility parameters were evaluated with a Hamilton Thorne sperm analyser, version IVOS 12.3. For the assessment of sperm morphology, Diff-Quik stain was used. The percentage of live and dead spermatozoa was estimated on dried smears stained with eosin-nigrosin. The concentration of spermatozoa, most motility parameters determined (PMOT, VSL, VCL, ALH, BCF, RAPID, MEDIUM, SLOW, and STATIC), and the percentage of spermatozoa morphologically normal and live increased significantly (P < 0.05) after 60 d of supplementation. In the control group, there were no changes in motility parameters while the concentration and total sperm count decreased over the duration of the study. In conclusion, supplementation with selenium and vitamin E for 60 d can improve the quality of semen in dogs with lowered fertility.

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