Ovarian Cysts in Bitches and Queens: Prevalence, Types and Risk Factors

Ovarian cysts are fluid-filled structures that develop within or on the surface of the ovaries in bitches and queens. They may be clinically silent, detected incidentally, or become relevant when hormonal activity affects the reproductive cycle. For veterinarians, recognizing which animals are more likely to have ovarian cysts and understanding the differences between cyst types can help put ovarian findings into the right clinical context. 

How Common Are Ovarian Cysts?¹ 

A large-scale analysis of available data found a pooled ovarian cyst prevalence of 41.66% (95% CI: 21.72–61.61%) in bitches and queens. The considerable variation between populations means this figure should not be interpreted as the expected prevalence in every clinical setting. Nevertheless, the finding indicates that ovarian cysts are not uncommon and may be encountered during reproductive evaluation, surgery or pathological examination. 

A clear species difference was also observed. Dogs were more likely to have ovarian cysts than cats, with a risk ratio of 3.34 and an odds ratio of 7.12 (p < 0.001). For clinical practice, this finding reinforces the importance of considering ovarian cysts when evaluating reproductive abnormalities in bitches, while still recognizing that queens can also be affected. 

Which Cysts Are Most Frequently Encountered? 

Ovarian cysts comprise several distinct entities, including follicular cysts, lutein cysts, cysts of subsurface epithelial structures, cystic rete ovarii, and cystic corpus luteum^1,2. 

Among classified cysts, follicular cysts were the most frequently identified, accounting for 42.1% (114/272). Subsurface epithelial cysts accounted for 37.9% (103/272), followed by rete ovarii cysts at 13.1% (35/272) and corpus luteum cysts at 6.9% (18/272). 

This classification is clinically relevant because different cysts can have different hormonal effects. Follicular cysts may produce sustained estradiol and have been associated with persistent estrus, prolonged proestrus, and hyperestrogenism^1,2. Prolonged hormonal activity may also contribute to reproductive and uterine abnormalities. 

Luteinized follicular cysts, luteal cysts and cystic corpus luteum are associated with progesterone hypersecretion and may produce mammary gland hyperplasia and pregnancy-like behavioural changes^1,3. 

Are Older Animals More Likely to Be Affected?¹ 

Age appears to be an important factor. A strong positive association was observed between mean age and ovarian cyst prevalence, with a Spearman’s ρ of 0.955. This suggests that ovarian cysts are more frequently identified in older animals. 

In dogs, reported mean ages ranged from 1.8 to 9.6 years, with individual ages extending from 0.3 to 16 years. Available feline age data ranged from 0.6 to more than 13 years. 

The age association is particularly relevant when examining older females or breeding animals. However, the age analysis was based on data from only seven populations, so the strength of this relationship should be interpreted cautiously. 

Why Does This Matter in Practice? 

The clinical importance of an ovarian cyst depends on more than its presence alone. Cysts that produce steroid hormones may interfere with normal reproductive physiology, contribute to uterine pathology, and affect fertility^1,2. 

Key Takeaways 

• Ovarian cysts are relatively common findings in bitches and queens, with a pooled prevalence of 41.66%. 

• Follicular cysts were the most frequently identified cyst type. 

• Dogs showed a significantly higher likelihood of ovarian cysts than cats in the available data. 

• Increasing age was strongly associated with higher cyst prevalence. 

• Cyst type matters because hormonally active lesions can influence estrous behaviour, uterine health and fertility. 

• Older and breeding females may warrant particular attention to ovarian abnormalities, especially when ovarian tissue is available for detailed examination. 

References 

1. Domrazek K, Kondratek K, Tobolewski F, Jurka P. Prevalence, diagnosis, and treatment of ovarian cysts in bitches and queens: a meta-analysis. Animals. 2025 Sep 25;15(19):2800. https://www.mdpi.com/2076-2615/15/19/2800 

2. Knauf Y, Köhler K, Knauf S, Wehrend A. Histological classification of canine ovarian cyst types with reference to medical history. Journal of veterinary science. 2018 Nov;19(6):725-34. https://synapse.koreamed.org/upload/synapsedata/pdfdata/0118jvs/jvs-19-725.pdf 

3. Pires, M.A.; Payan-Carreira, R. Ovarian Cysts in Dogs’ Practice. In Advances in Medicine and Biology. Chapter 4; Berhardt, L.V., Ed.; Nova Science Publishers: New York, NY, USA, 2016; Volume 94, ISBN 9781634841856 https://repositorio.utad.pt/bitstreams/7efe7ff2-8f01-4087-9b87-4f9d74be77a3/download