Prolactin has been recently regarded as a potential biomarker of both acute and chronic stress in several species. Since only few studies until now have focussed on domestic dogs, this study was aimed at evaluating whether prolactin, cortisol and stress behaviour correlated with each other in sheltered dogs. Both cortisol and prolactin analysis were performed in serum samples through a hormone-specific ELISA kit. For each dog, a stress score was calculated by summing the number of occurrences of stress-related behaviours. The presence/absence of fear during the time spent in the collection room was also scored for each individual. Results revealed a weak negative correlation between cortisol and prolactin levels. Neither of the hormones was correlated with the stress score, nor did their values seem to be influenced by showing fear in the collection room. The weak negative correlation found between cortisol and prolactin values agrees with results obtained in other studies, indicating that prolactin response might be an alternative to cortisol response. This, together with the high serum prolactin levels compared to those reported by other authors for healthy domestic dogs, may indicate that prolactin might be a good biomarker of chronic stress, and although further studies are needed to better understand the potential role of prolactin in the evaluation of canine welfare.

Prolactin has been reported to be a remarkable index of stress response, both acute and chronic, in several species. The use of biological matrixes other than blood is receiving increasing interest in the study of hormones, due to the lower invasiveness in collection. This research aimed to investigate the possibility of using a commercial ELISA (enzyme-linked immunosorbent assay) kit for measuring canine prolactin in blood for the quantification of canine prolactin in saliva. Study 1 consisted of a validation protocol, using saliva samples collected from lactating and non-lactating dogs. Study 2 was conducted to investigate a possible correlation between prolactin concentration in saliva and plasma in sheltered dogs by using the same kit. Prolactin values were reliably read only when they came from blood samples, not from saliva, but tended to be low in most of the cases. Study 1 showed that saliva had a matrix effect. In study 2, saliva prolactin levels were low and in 42.9% of cases, not readable. No correlation between prolactin values in plasma and saliva was found (ρ = 0.482; p = 0.274). These findings suggested that the determination of prolactin in dog saliva through an ELISA kit created for measuring prolactin in dog blood was unreliable.

Context. The present study aims to promote fertility control as a non-lethal means of managing wild animal populations, specifically red deer (Cervus elaphus) in a region of Spain. The control of fertility in cervids through the use of long-acting contraceptives or other sterilization approaches has been advocated as a reasonable tool in the face of the challenges posed by overpopulation, especially in areas close to urban spaces. Among the contraceptive methods known to date, immunocontraception appears to be the most effective and favorable methodology with respect to the welfare of the animals.Aims: This action plan proposes the use of a single dose injectable immunocontraceptive vaccine (GonaConTM Immunocontraceptive Vaccine) in red deer that inhabit Monte de El Pardo, accompanied by a follow-up study to determine: (1) determine the effectiveness of the GonaConTM vaccine over 3 years in the prevention of pregnancy, (2) determine the possible secondary effects (contraindications), (3) identify any weaknesses and drawbacks of the treatment and (4) propose improvements and future perspectives. As far as we know, it would be the first to establish theoretical bases for the first use of this vaccine in wild red deer in Spain.Methods: The vaccine will be injected into a total of 200 wild female reed deer of reproductive age in Monte de El Pardo. The control group will consist of 50 females who will not be vaccinated but will be evaluated in the same way. The treated individuals in the study will be marked and identified, and follow-up will be carried out for a period of 3 years. The effectiveness of GonaConTM will be quantified by measuring physiological and ethological parameters (behavioral observations). These data will be compared with the results of the control group.Key results. We expect to achieve an average inhibition of reproductive production of more than 80% over the three year period, and it is hoped that in the first year the effectiveness will reach 90-100%, without notable detrimental effects on the physiology or behavior of the individuals in relation to the control group. Similarly, no significant differences are expected between the results from the non-reproductive behavior of the treated deer and that of the control group, in individuals between the start of vaccination and 12 months later (Quy et al. 2014), in the subsequent sampling throughout the 3 years of the study. It is expected that the deer treated with GonaConTM will exhibit a secretion response of sufficient anti-GnRH antibodies to achieve an inhibition in their reproductive behavior and physiology and, therefore, in their fertility (of at least 80% average effectiveness over the 3 years).Implications. The development of this method of population control is essential in urban and suburban areas, where lethal control, by poisoning or capture compromises animal welfare, in addition to the potential risk for the human population. It is expected that stability in the number of deer present in Monte de El Pardo will reduce potential threats that derive directly from collisions with vehicles and transmission of diseases. We suggest that a greater effort to develop less invasive and non-lethal population control modalities is justifiable.