Prolonged anoestrus in a cow with uterine fibrous leiomyoma: Clinical, surgical and histopathological findings

Abstract A 5‐year‐old cow presented with prolonged anoestrus and an unclear history of mating, underwent transrectal, haematological examination, transrectal ultrasonography and exploratory surgery. On transrectal examination, neither palpable fetal structures nor fremitus was marked. On transrectal ultrasonography, a hypoechogenic structure was marked inside the uterus. Intraoperative findings revealed a well‐defined mass within the uterine wall from which a small section was excised and submitted for histopathological analysis. Histopathological examination revealed hyperplasia of fibroblasts and fibrocytes, confirming the presence of uterine fibrous leiomyoma. The tumour was characterised by the presence of abundant connective tissue fibres, mostly collagen fibres of a benign tumour. Surgical intervention with histopathology provided a definitive diagnosis and cause of prolonged anoestrus of the cow. The presence of fibrous leiomyoma in the inner layer of the uterus blocks the production of prostaglandin 2α, further leading to the absence of luteolysis of the Corpus luteum in the ovary. Thus, continuous production of progesterone from the corpus luteum, having negative feedback on the hypothalamus and anterior pituitary, blocks the exhibition of oestrus in cows for a prolonged duration.