Within the structure of gynecological diseases in cows, ovarian cysts account for a large proportion and pose a considerable problem for theriogenologists, including insufficient theoretical interpretation of the etiopathogenetic mechanisms underlying their development and the practical issue of low therapeutic efficacy. The aim of our study was to determine the prevalence of ovarian cysts in cows and the predisposing factors for their occurrence. The material comprised infertile Holstein cows. Diagnosis of cysts was performed by transrectal palpation and ultrasonographic scanning of the ovaries. A follicular cyst was diagnosed when a follicular structure with a fluid-filled cavity greater than 20 mm in diameter was present in the absence of a corpus luteum. Luteal cysts were identified by a smaller cavity and a wall thickness of ≥ 3 mm. It was foud that the average annual incidence of cysts in cows was 15.6 %, with seasonal fluctuations from 7.7 % in late summer to 23.1 % in late spring. Follicular cysts were the most common, diagnosed in 53.7 % of cases. Luteal cysts were found in 29.2 % of cows, and cystic corpora lutea in 17.1 % of females with affected ovaries. A significant increase (p< 0.05) in the development of follicular cysts was observed in cows producing 7,500–8,900 kg of milk – 2.7 times higher compared with cows with lower yields; 72.7 % of such cows were high-producing. For luteal cysts, the analogous difference was minor – 5.8 %. In 82 % of cases, luteal cysts developed during the second to third lactation. In the majority of cases, follicular cystic formations developed in the ovaries during the second and third months postpartum – 34.5 % and 27.3 %, respectively; at longer intervals this pathology occurred in only 18.2 % of cows. Conversely, luteal cysts developed in 47.3 % (p < 0.05) of affected females within 91–120 days and in 26.3 % after ≥ 121 days. During the second to third month postpartum, luteinisation of non-ovulated follicles occurred in only 16.4 % of affected cows. Thus, the same factors exert different effects on the development of follicular versus luteal ovarian cysts in cows. Retrospective analysis revealed that 86.4 % of cows with follicular cysts and 78.9 % with luteal cysts had a complicated puerperium. In cows with follicular cysts, the most common pathology was subinvolution, occurring in 45.4 % of cases. In cows with luteal cysts, the highest proportion – 47.3 % – suffered from metritis in the postpartum period. According to cyst type, 13.6 % and 10.5 % of cows, respectively, experienced a puerperium complicated by subclinical ketosis. In addition, in the first group, 9.1 % of females were diagnosed with ovarian hypofunction prior to the onset of follicular cysts.

Key words: cows, infertility, follicular cyst, luteal cyst, milk yield level, lactation, subinvolution, metritis, ketosis, ultrasonographic diagnosis.