12-year-old, Female, Domestic Shorthair, Feline

This case was presented in one of our monthly virtual Abdominal Rounds sessions with Donald E. Thrall DVM, Ph.D., DACVR.

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History:  Vomiting was noticed 3 days ago.  Since then, the appetite has been poor.  Neutrophilia was detected on routine hematologic screening.

Imaging:  Right lateral (1A), left lateral (1B) and ventrodorsal (1C) radiographs of the abdomen were acquired.

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  • There is severe distention of the urinary bladder.  There are no radiopaque urinary calculi.
  • Both uterine horns are enlarged/thickened and/or distended with a moderate amount of mineralization of the uterine walls.  Mineralization within the uterine horns also has a pronounced sigmoid/convoluted appearance, potentially with separate thin-walled round/ovoid-shaped nodular lesions
  • There are no fetuses.
  • A large, but not pathologic, amount of desiccated-appearing fecal matter is present in the colon.
  • Peritoneal serosal detail is within normal limits, there is no evidence of peritoneal fluid or inflammation
  • No other abdominal abnormalities are present.
  • There is incidental lumbar spondylosis.


  • The enlarged/distended using horns with the mineralization is most likely due to chronic cystic endometrial hyperplasia with dystrophic calcification of the uterine walls and/or mineralization of endometrial cysts.  Concurrent pyometra should also be considered.  Neoplastic mineralization of the uterus is unlikely.
  • The urinary bladder distension is concerning for obstruction although there is no evidence of urolithiasis.  The possibility that the enlarged mineralized uterus and fecal matter are contributing to urine retention due to a partial obstruction from compression, or due to pain to urinate, should be considered.

Recommendations:  An ovariohysterectomy is recommended.  Follow-up was not obtained.


                Pyometra is the most common endometrial disorder in intact, sexually mature, queens and is characterized by uterine infection by ascending vaginal bacteria as a consequence of progesterone stimulation of the endometrium. It may involve diffuse or segmental enlargement of the uterus. Histological lesions range from simple cystic endometrial hyperplasia to endometrial atrophy (Nak, Nak Y, & Tuna, 2009).  Estrogen can also play a role, causing overexpression of progesterone receptors in the endometrium, and dilation of the uterine cervix that can allow ascending bacterial infection (Agudelo, 2005).

Pyometra is usually not accompanied by dystrophic mineralization of the mucosa, as suspected in this patient.  Only one additional similar patient was identified (Hayata, Ahrari-Khafi, Hassankhani, Mansourian, & Asghari, 2016).  That report concerns a 6 yr.old female DSH cat with anorexia and lethargy.  The cat was anemic and there was leucocytosis with immature leucocytes.  In abdominal radiographs there was mineralization of the uterus in a pattern very similar to that of the patient in this report, although slightly less severe.  The uterus was removed and histologically there was pronounced calcification in the mucous membrane of the uterus and severe granulomatous inflammation.

The specific cause of the uterine mineralization in these two cats is unknown but it resulted in a unique radiographic appearance.  Dystrophic mineralization in regions of chronic inflammation could be one possibility.

Uterine mineralization has been identified more frequently in zoo felids treated with melengestrol acetate (MGA)contraceptives (Munson, Gardner, Mason, Chassy, & Seal, 2002).  MGA contraceptives are widely used in zoo felids to regulate fertility and may have deleterious effects on endometrial health. In this study, the genital tract of 212 zoo felids (99 MGA treated; 113 control) was evaluated.  Adenomatous and cystic hyperplasia were prevalent in both MGA-treated (85%) and control (61%) groups. Treatment with MGA further increased the risk of developing advanced hyperplasia regardless of dose.  MGA treatment was associated with an increased risk of hydrometra and mineralization.  Endometrial mineralization was present in 38 MGA-treated felids but in only 2 controls.  Lesions of severe hyperplasia were often accompanied by extensive stromal mineralization.  A theory for uterine mineralization following endometrial hyperplasia was not provided

In summary, spontaneous uterine mineralization is rare in domestic animals but when present is a sign of endometrial hyperplasia and probable pyometra.


Agudelo, C. V. (2005). Cystic endometrial hyperplasia-pyometra complex in cats. A review. Veterinary Quarterly, 27, 173-182.

Hayata, F., Ahrari-Khafi, M. S., Hassankhani, M., Mansourian, M., & Asghari, S. (2016). A rare radiographic appearance of a calcified uterus in a queen with pyometra: a case report. Veterinarni Medicine, 61, 357-360.

Munson, L., Gardner, I. A., Mason, R. J., Chassy, L. M., & Seal, U. S. (2002). Endometrial hyperplasia and mineralization in zoo felids treated with melengestrol acetate contraceptives. Vet Pathol, 39, 419-427.

Nak, D., Nak Y, & Tuna, B. (2009). Follow-up examinations after medical treatment of pyometra in cats with the progesterone-antagonist aglepristone. J Feline Medicine and Surgery, 11, 499-502.

Photo by Karly Jones on Unsplash

One comment

  1. Mineralised uterus/endometrium. DDx pyometra, cystic hyperplasia, metastatic mineralisation, dystrophic mineralisation, long term prednisiolone administration or atypical neoplasia.

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