It is not uncommon for veterinarians to observe anomalies of the uterus during elective ovariohysterectomy surgeries in cats and dogs. In animals in which 1 abnormality is found, other urogenital anomalies, particularly ipsilateral to the abnormality, may also be present.1–12
Uterine anomalies such as unicornuate uterus and segmental agenesis have been detected in many domestic species, including cats, dogs, cows, horses, deer, sheep, pigs, ferrets, and alpacas.1–8,13–22 In several retrospective studies, the prevalence of uterine anomalies in livestock14–16 and women has been evaluated.9 However, no large-scale studies have been conducted to determine the frequency of congenital uterine anomalies in cats and dogs. An association between uterine anomalies and renal agenesis has long been recognized in women,10 as well as in dogs and cats,1–8 but has not been reported for any other domestic species. One common finding in all species is the presence of both ovaries in most individuals with detected urogenital anomalies.1–8,14–18
Uterine anomalies in women are classified according to the degree of failure of usual development.23 The classification scheme for women cannot be directly applied to dogs and cats because women have a simplex uterus and dogs and cats have a bicornuate uterus, but the same principles can be applied. Uterine horns can have developmental abnormalities ranging in severity from hypoplasia to complete agenesis. The degree of development or developmental failure is determined by the histologic appearance of the tissue. In cats and dogs, anomalies are best described as hypoplastic uterine horn, segmental agenesis of a uterine horn, and unicornuate uterus. Hypoplastic uterine horn is defined as a uterine horn that is underdeveloped but still possesses fairly normal tissue layering and a lumen connecting it to the uterine body. Unicornuate uterus is defined as complete agenesis of 1 uterine horn. In that situation, the tissue in place of the uterine horn that connects the uterine body to the uterine tube lacks normal layering and a lumen and is often referred to as a rudimentary horn in human and veterinary medicine. Segmental agenesis is defined as an undeveloped portion of the uterine horn.
The purpose of the study reported here was to determine the types and frequency of uterine anomalies and the incidence of concomitant ipsilateral renal agenesis in cats and dogs undergoing elective ovariohysterectomy.
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Classification of gross and histologic uterine horn anomalies in dogs and cats.
|Abnormality||Histologically normal layers||Central lumen|
|Uterine horn segmental agenesis||Only in the healthy segment; usually||Only in the healthy segment;|
|attenuated by fluid distention||enlarged by fluid accumulation|
|Uterine horn hypoplasia||All layers present, but variably underdeveloped||Yes|