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ContentsThe purpose of this study was to define (i) the interval between treatment and sterility, and (ii) semen quality in male dogs administered a 4.7-mg deslorelin implant. Six healthy, adult dogs of various breeds and body weights were implanted with deslorelin (Suprelorin, Virbac) and followed every 2 weeks with semen and blood collections. Semen quality remained stable or even improved during the first month following treatment and then showed a progressive decline until the end of the study, except for sperm morphology, which was unaffected by the treatment. Complete sterility was achieved on post-treatment days 70, 84, 60, 23, 51 and 40 for dogs 1 to 6, respectively. The 4.7 mg deslorelin implant caused a significant (p < 0.05) decrease in serum testosterone as well as sperm motility. Our results (i) confirm the efficacy of deslorelin in causing reversible sterility in male dogs, (ii) confirm and provide details about endocrine and seminal parameters involved in this process and (iii) contribute to define the interval between treatment and achievement of complete sterility. Practitioners should be aware that such interval may be longer than 2 months in some cases, and that fertility may actually be increased during the first 2-4 weeks post-treatment.

Circulating cell-free DNA (cfDNA) has been considered an interesting diagnostic/prognostic plasma biomarker in tumor-bearing subjects. In cancer patients, cfDNA can hypothetically derive from tumor necrosis/apoptosis, lysed circulating cells, and some yet unrevealed mechanisms of active release. This study aimed to preliminarily analyze cfDNA in dogs with canine mammary tumors (CMTs). Forty-four neoplastic, 17 non-neoplastic disease-bearing, and 15 healthy dogs were recruited. Necrosis and apoptosis were also assessed as potential source of cfDNA on 78 CMTs diagnosed from the 44 dogs. The cfDNA fragments and integrity index significantly differentiated neoplastic versus non-neoplastic dogs (P<0.05), and allowed the distinction between benign and malignant lesions (P<0.05). Even if without statistical significance, the amount of cfDNA was also affected by tumor necrosis and correlated with tumor size and apoptotic markers expression. A significant (P<0.01) increase of Bcl-2 in malignant tumors was observed, and in metastatic CMTs the evasion of apoptosis was also suggested. This study, therefore, provides evidence that cfDNA could be a diagnostic marker in dogs carrying mammary nodules suggesting that its potential application in early diagnostic procedures should be further investigated.

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Proapoptotic factor Fas ligand (FASL) and its cell surface receptor FAS are tumor necrosis factor superfamily members that trigger apoptosis in different cell types. However, their influence on luteal steroidogenesis is not clearly understood. The aim of the present work was to determine (i) the presence of the cytokine FASL and its receptor FAS in the mare's corpus luteum (CL) throughout the luteal phase, as well as (ii) the influence of FASL alone, or together with the cytokines tumor necrosis factor alpha (TNF) and interferon gamma (IFNG), on equine luteal cell production of luteotrophic and luteolytic factors, cell viability, and apoptosis. FASL and FAS protein expression and mRNA transcription were evaluated in different luteal stages of the equine CL by Western blotting and real-time PCR assays, respectively. Protein expression and FASL mRNA transcription increased in the late CL. Also, FAS and FASL proteins were present in large steroidogenic and endothelial CL cells throughout the luteal phase, as demonstrated by immunohistochemistry. Equine luteal cells isolated from midluteal phase CL were stimulated without (control) or with exogenous cytokines: FASL (10 ng/ml); TNF+IFNG (10 ng/ml each; positive control) or FASL+TNF+IFNG (10 ng/ml each). FASL clearly inhibited in vitro progesterone and prostaglandin E(2) (PGE(2)) production by equine luteal cells but increased prostaglandin F(2alpha) (PGF(2alpha)). Furthermore, FASL effect on equine luteal cell viability depended on the presence of cytokines TNF and IFNG. In conclusion, this study shows the presence of FASL and FAS in the equine CL and suggests their importance in functional luteolysis.