The objective of the study was to describe the clinical, imaging, surgical and histological findings in a dog with Rathke's cleft cyst of the pituitary gland. A 6-year-old, female, neutered Staffordshire bull terrier was presented with an acute onset of abnormal behaviour. Magnetic resonance imaging of the skull showed a pituitary mass of 12.9 mm (height) × 8.8 mm (width) × 10.2 mm (length) with a pituitary height/brain area value of 0.73 (reference <0.31). Magnetic resonance imaging findings were suggestive of pituitary apoplexy or neoplasia. Transsphenoidal hypophysectomy was performed and a cystic mass was removed. Histopathology revealed a Rathke's cleft cyst lined by a layer of pseudo-stratified ciliated columnar epithelial cells and mucin-secreting goblet cells with remnant pituitary tissue with positive immunostaining against adrenocorticotropic hormone, alpha melanocyte and growth hormone in the periphery. Rathke's cleft cyst should be included in the differential diagnosis of pituitary masses in the dog, and transsphenoidal hypophysectomy is an effective treatment.

Background In dogs with a congenital extrahepatic portosystemic shunt (EHPSS), outcome after surgical attenuation is difficult to predict. Objectives Develop a minimally invasive test to predict outcome after surgical EHPSS attenuation and establish risk factors for postattenuation seizures (PAS). Animals Eighty‐five client‐owned dogs referred for surgical attenuation of a single EHPSS. Methods mRNA expression of 8 genes was measured in preoperatively collected venous blood samples. Outcome was determined at a median of 92 days (range, 26‐208) postoperatively by evaluating clinical performance, blood test results and abdominal ultrasonography. Multivariable logistic regression was used to construct models predicting clinical and complete recovery. The associations between putative predictors and PAS were studied using univariable analyses. Results Five of 85 dogs developed PAS. Risk factors were age, white blood cell (WBC) count and expression of hepatocyte growth factor activator and LysM and putative peptidoglycan‐binding domain‐containing protein 2. Clinical recovery was observed in 72 of 85 dogs and complete recovery in 51 of 80 dogs (median follow‐up, 92 days). The model predicting clinical recovery included albumin, WBC count, and methionine adenosyltransferase 2 alpha (MAT2α) expression, whereas the model predicting complete recovery included albumin, and connective tissue growth factor precursor and MAT2α expression. The areas under the receiver operating characteristic curves were 0.886 (95% confidence interval [CI]: 0.783, 0.990) and 0.794 (95% CI: 0.686, 0.902), respectively. Conclusions and Clinical Importance Two models were constructed for predicting outcome after EHPSS attenuation using venous blood samples. The model predicting clinical recovery showed the best diagnostic properties. Clinical application requires further validation.