Comparison of Progesterone Concentrations in Saliva and Blood in Intact Bitches

ABSTRACT

Accurate determination of the optimal mating time is essential in canine breeding management, with serum progesterone measurement serving as a key diagnostic tool. However, repeated blood sampling causes stress in dogs, motivating research into non‐invasive alternatives. Salivary diagnostics have shown promise for other hormones in dogs, but progesterone detection in saliva has not yet been reliably established in this species. The objective of the present study was to measure progesterone in canine saliva as described in women and to ascertain whether these values correlate with serum progesterone concentrations. A total of 34 paired blood and saliva samples were collected from 21 intact female dogs with a mean age of 3.5 years (range 1–10 years) and a mean weight of 26.1 kg (range 7.5–58 kg). Samples were taken at different stages of the reproductive cycle to ensure a broad range of progesterone concentrations and analysed using a chemiluminescence immunoassay (CLIA; IMMULITE 2000 XPi, Siemens). Salivary progesterone was detectable in 30 of 34 samples. A significant positive correlation was found between saliva and serum progesterone concentrations ( p  = 0.005, marginal R ²  = 0.18, conditional R ²  = 0.68), accompanied by high individual variation. Although progesterone can be measured in canine saliva using CLIA, it is currently not reliable for clinical use. Salivary diagnostics remain a promising non‐invasive approach, but further methodological development and larger sample sizes are needed before salivary progesterone can be applied to oestrous cycle monitoring in bitches.