The study was performed on 45 bitches in different cycle phases that were divided into the following groups: anoestrus (I, n=15), heat (pro-oestrus (n=7) or estrous (n=8) (II, n=15) and metestrus (III, n=15). Moreover, all experimental dogs were grouped according to their age: younger than 5 years (Y, n=35) and older than 5 years (O, n=10). The endometrial status was evaluated using cytological, bacteriological and biopsy samples obtained after ovariohyster- ectomy.

The main uterine pathology diagnosed by biopsy was endometritis, since 40%–66% of bitches, independent of the experimental group, developed this condition. No significant differences were found among the cycle phase groups (p>0.05). By contrast, significant differences were found in the age groups; the prevalence of this pathology was higher in older bitches (p=0.0019). The general prevalence of cystic endometrial hyperplasia (CEH) and a normal endometrium (NE) was lower (6.7–26.7% vs 26.7–53.3%) in all groups, and no statistically significant differences were found between certain groups (p>0.05). The percentage of polymorphonuclear neutrophilic leukocytes (PMNs) in endometrial cytology was generally low (< 2%) and did not differ signifi- cantly among the experimental groups (p=0.142). In general, a low degree of correlation was found between the diagnostic results by endometrial cytology and biopsy (Kappa Coeffi- cient=0.046). Positive bacteriological findings were found in approximately 50% of the bitches, independent of the cycle phase and health status of the endometrium. No correlation was found between the bacteriological and histopathological findings (p=0.883).

In conclusion, uterine cytology is not a reliable diagnostic method to detect the subclinical inflammatory and degenerative uterine pathologies in cyclic bitches.

The chronic degenerative endometritis (CDE) is recognised as directly related to age and infertility in the mare. In this study, the 14 days post ovulation (PO) pregnancy rate was assessed in 60 barren mares affected by CDE, submitted to platelet-rich-plasma intrauterine infusion (PRPI) 24 hours PO. Data showed a significant positive effect of PRPI on the chance to become pregnant in mares affected by Kenney I-II CDE. The overall 14 days PO pregnancy rate was 75%. Sixty-nine % of the overall pregnancies was achieved with the 1st PRPI, but an additional 31% was obtained with the 2nd PRPI at the subsequent heat, increasing significantly the number of pregnancies. Although the 1st PRPI lead to a higher pregnancy rate than the 2nd PRPI (52 vs 23%), the repetition of the treatment had a significant positive effect on the overall pregnancies. Mare’s young age positively influenced the chance to become pregnant and was associated to endometritis Kenney I. Mares with endometritis Kenney I had better chance to become pregnant than those with endometritis Kenney II. The PRPI proved, therefore, to be beneficial in barren mares with CDE, and resulted in high overall pregnancy rate achievement in barren mares.