Recently, histologic subtypes of oral squamous cell carcinoma (SCC) corresponding to the human classification scheme have been proposed for dogs. A papillary squamous cell carcinoma subtype is characterized by dominant exophytic architectural growth with limited invasion, a lower metastatic rate, and better overall survival compared with conventional SCC. Whereas most canine oral conventional SCCs are easily diagnosed by histologic examination, the diagnosis of canine oral papillary squamous cell carcinoma (COPSCC) can be challenging since the exophytic portion lacks histologic features of malignancy and appears similar to oral nonviral papillomas. In contrast, the invasive portion of COPSCC has morphologic similarities to conventional SCC and canine acanthomatous ameloblastoma. The goals of this study were to immunophenotype these 3 entities and to potentially identify discriminating markers. A panel of 17 immunohistochemical markers was investigated in tissue microarrays that included 25 COPSCCs, 10 conventional SCCs, and 10 canine acanthomatous ameloblastomas. Additionally, COPSCCs were screened for papillomavirus as a potential cause using immunohistochemistry and in situ hybridization. COPSCC had immunophenotypical similarities with conventional SCC and acanthomatous ameloblastoma, but the combined differences in immunolabeling for AE1/AE3, 34βE12, p63, and calretinin discriminated between the entities. Papillomavirus was not detected in any COPSCC, making a viral pathogenesis unlikely. A better understanding of the immunophenotype of COPSCC will aid in a more accurate diagnosis and potentially improve therapeutic approaches.

Canine cutaneous mast cell tumors (ccMCTs) have a highly variable biological behavior and accurate prognostication is essential for therapeutic intervention. Internal tandem duplications (ITD) of exon 11 are the most commonly detected c-kit mutation in ccMCTs and are associated with poor prognosis and increased cellular proliferation. The prognostic value of detecting mutations in other exons of c-kit has not been systematically examined. In this study, we analyzed the prognostic value of ITD mutations of exon 8 in c-kit of ccMCTs in comparison to ccMCTs with ITD mutations of exon 11 and ccMCTs without mutations of exon 8 or 11. The mutational status, histological grade, KIT expression pattern, Ki67 index, AgNOR (argyrophilic nucleolar organizing region) score, and Ag67 score were determined in 221 ccMCTs, and outcome was available for 101 dogs. ITD mutations of exon 8 were found in 73/221 (33%), of exon 11 in 100/221 (45%), and none of these mutations in 50/221 (22%) of ccMCTs. None of the dogs with mutations of exon 8 died due to suspected ccMCT-related cause, but 23% dogs with ccMCTs with mutations of exon 11 died due to suspected ccMCT-related cause. Prognostic parameters in ccMCTs with exon 11 mutations were commonly associated with a high proliferative activity and poor prognosis, while prognostic markers in ccMCTs with mutations of exon 8 had lower values similar to those observed in ccMCTs without mutations in exons 8 or 11 of c-kit. This study indicates that screening for ITD mutations in exon 8 in ccMCTs may be helpful to identify less aggressive ccMCTs and may be recommended as a supplementary prognostic test.

Case summary A stray female domestic shorthair cat was presented to the emergency service after being hit by a car. The patient was recumbent and vocalizing, with a small wound over the right lateral thorax, and two palpably firm swellings in the right cervical and thoracic soft tissues. The patient was sedated and humanely euthanized to prevent further pain and suffering. Post-mortem whole-body radiographs and subsequent necropsy revealed abdominal wall rupture with herniation of two near-term fetuses within the subcutaneous tissues along the right ventrolateral thoracic wall and neck. Within the abdomen, the right uterine horn was ruptured and a third extra-luminal fetus was identified. The left uterine horn remained intact, containing a fourth fetus. Relevance and novel information Rupture of the abdominal wall or diaphragm are well-known potential complications of blunt force trauma, such as motor vehicle accidents. While traumatic uterine rupture and diaphragmatic herniation of the gravid uterus have both been reported in the veterinary literature, abdominal wall rupture with subcutaneous fetal herniation is highly uncommon.

Neoplasia of the tubular genital tract in goats, while rarely described, is most commonly reported as uterine adenocarcinoma, leiomyoma, or leiomyosarcoma. In this retrospective, single‐center, case series, medical records were searched for goats with a computed tomography (CT) diagnosis of tubular genital mass and a definitive histologic (surgical biopsy or necropsy) diagnosis of malignant neoplasia. Data recorded from CT images were presence of peritoneal/retroperitoneal fluid, urinary tract obstruction, abdominal lymphadenomegaly, additional abdominal nodules/masses, and pulmonary nodules. For masses, maximum cross‐sectional area, contrast enhancement, and uterine luminal fluid accumulation were also recorded. Seven goats met the inclusion criteria (leiomyosarcoma n = 5, adenocarcinoma n = 2). Both goats with adenocarcinoma had upper urinary tract obstruction, moderate to severe regional lymphadenopathy, peritoneal fluid, and peritoneal or hepatic nodules/masses; one goat with adenocarcinoma was discharged and subsequently euthanized, and the other had palliative mass debulking and was lost to follow up. Goats with leiomyosarcoma had infrequent, mild peritoneal fluid and mild sublumbar lymphadenopathy. Of the goats with leiomyosarcoma, two were euthanized at or near the time of CT imaging, two were euthanized at the time of surgery due to perceived mass non‐resectability, and one had mass regression approximately four months post ovariohysterectomy but was subsequently lost to follow up. Five goats had pulmonary nodules, three of which had pathologic confirmation (pulmonary metastasis in a single patient with adenocarcinoma, and lungworm granulomas in two goats with leiomyosarcoma). Severe sublumbar lymphadenopathy and obstructive uropathy were sequelae in the two caprine patients with genital adenocarcinoma, and in none with leiomyosarcoma.

Ultrasonographic intestinal muscularis thickening has not been described as an imaging feature of canine inflammatory bowel disease. In this retrospective case series, patients were identified by searching sonographic reports for “muscularis” and/or “muscular layer.” Patients were included if small intestinal muscularis thickening was reported, and sonographic images and histopathological samples of the small intestine were available for review. Cases with small intestines nodules, masses, or complete loss of wall layering were excluded. Sonographic images were retrospectively evaluated for jejunal muscularis layer thickness, and ratios of intestinal layer measurements were performed. Histological samples were retrospectively reviewed. Thirteen dogs met inclusion criteria: all dogs had sonographic intestinal muscularis thickening relative to the submucosa (>1.0, range of 1.3–2.5), and most dogs had muscular layer thickness above normal published ranges (11/13; all 13/13 above the weight‐specific mean). More than half of the patients had overall normal wall thickness (11/13) and several had normal mucosal echogenicity (6/13). Therefore, in some dogs, the only sonographic abnormality in the small intestine was muscularis thickening. No dogs had lymphadenomegaly. Endoscopic partial‐thickness (n = 11, duodenum and/or ileum) or surgical full‐thickness (n = 2) samples confirmed inflammatory bowel disease. Direct comparison between jejunum sonographic characteristics and histology features was limited due to both partial thickness biopsies and lack of direct comparison between anatomical locations of ultrasonographic assessment and biopsy site. However, no cases that met the inclusion criteria had normal small intestinal histology. Comparable to cats, dogs with ultrasonographic intestinal muscularis thickening may have inflammatory bowel disease, and further workup for enteropathy is indicated.