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Splenic torsion is a rare potentially life-threatening condition characterized by rotation of the spleen around the gastrosplenic and phrenosplenic ligaments leading to occlusion of venous drainage and arterial supply. This retrospective study describes the CT characteristics for dogs with surgically confirmed splenic torsion from 2013 to 2018 using the submissions to a large multinational teleradiology database. Eight dogs had the splenic torsion confirmed with surgery. Seven of eight cases had histology confirming congestion, hemorrhage, and necrosis, and one had concurrent myelolipoma infiltration. The CT characteristics included an enlarged (8/8), rounded (7/8), folded C-shaped spleen (8/8) with a difference of median parenchymal attenuation between pre- and postcontrast of +1.15 HU (Hounsfield units). Other common features included a mainly homogeneous parenchyma on pre- and post-contrast images (6/8), lack of subjective and objective vascular and parenchymal contrast enhancement (6/8) and free peritoneal fluid (6/8). A "whirl sign" was seen in the majority of cases (7/8) alongside a strongly hyperattenuating center (95-416 HU) on the precontrast images (5/7), which has not been previously described in the veterinary literature. Gastric position was normal in all cases. More variable CT characteristics of the confirmed torsions were attributable to suspected partial torsion and myelolipomatous infiltration. Overall, primary splenic torsion confirmed with surgery showed consistent characteristics on CT.

FLASH radiotherapy is the delivery of ultra-high dose rate radiation several orders of magnitude higher than what is currently used in conventional clinical radiotherapy, and has the potential to revolutionize the future of cancer treatment. FLASH radiotherapy induces a phenomenon known as the FLASH effect, whereby the ultra-high dose rate radiation reduces the normal tissue toxicities commonly associated with conventional radiotherapy, while still maintaining local tumor control. The underlying mechanism(s) responsible for the FLASH effect are yet to be fully elucidated, but a prominent role for oxygen tension and reactive oxygen species production is the most current valid hypothesis. The FLASH effect has been confirmed in many studies in recent years, both in vitro and in vivo, with even the first patient with T-cell cutaneous lymphoma being treated using FLASH radiotherapy. However, most of the studies into FLASH radiotherapy have used electron beams that have low tissue penetration, which presents a limitation for translation into clinical practice. A promising alternate FLASH delivery method is via proton beam therapy, as the dose can be deposited deeper within the tissue. However, studies into FLASH protons are currently sparse. This review will summarize FLASH radiotherapy research conducted to date and the current theories explaining the FLASH effect, with an emphasis on the future potential for FLASH proton beam therapy.

A six-year-old male neutered pug presented as an emergency with acute-onset dyspnoea. The patient was stabilised with a temporary tracheostomy. Further investigations revealed the presence of anatomical malformations commonly encountered in dogs suffering from brachycephalic obstructive airway syndrome (BOAS). A CT scan of the patient’s head also revealed the root of the right maxillary canine tooth (104) extending into the right nasal cavity. Rhinoscopic examination confirmed partial occlusion of the nasal airway by the presence of the tooth root. The right maxillary canine tooth was extracted, and postremoval rhinoscopy demonstrated an increase in the nasal cavity air-filled space on the right side. Subsequently, the patient underwent BOAS surgery but was unable to tolerate long-term removal of the tracheostomy tube postoperatively due to severe laryngeal collapse. A permanent tracheostomy was performed and the patient was discharged showing no signs of respiratory difficulties.

An 8-year-old male intact miniature poodle presented for blindness, obtundation, tetraparesis, and vestibular signs. Magnetic resonance imaging, radiography, and ultrasound revealed a left piriform lobe lesion, right cerebellar and left brainstem lesions, and hydrocephalus and bilateral calvarial defects. Histopathology confirmed a choroid plexus carcinoma with meningeal and intraventricular metastases. The calvarial defect did not show evidence of necrosis, osteoclastic resorption, inflammation or neoplastic infiltration, reflecting a quiescent calvarial atrophy or dysplasia. These novel findings supported inclusion of bone atrophy secondary to chronic increased intracranial pressure as a differential diagnosis for large calvarial defects in dogs with choroid plexus carcinoma.

Canine mast cell tumor staging is commonly performed using abdominal ultrasonography and fine-needle aspiration cytology of masses, lymph nodes, and hepatic and splenic parenchyma. Computed tomography is used for abdominal, thoracic, or whole body imaging in staging mast cell tumors in the authors' institution enabling evaluation of multiple body areas in one examination. The aim of this study was to compare the CT examinations acquired for staging of mast cell disease to their subsequent liver and spleen cytology findings. Medical records of dogs with primary mast cell tumors that underwent abdominal CT and concurrent liver and spleen aspirates were reviewed. The CT examinations were evaluated for attenuation, size, and margination of the liver and spleen. The relationship between CT findings and cytology results was analyzed. Forty-nine dogs matched the inclusion criteria: five of forty-nine dogs with cutaneous mast cell tumors were positive for metastasis from liver and/or spleen aspirates. Of the five dogs with cytological evidence of liver or spleen metastasis, four had normal CT liver attenuation and size, one dog had concurrent primary hepatocellular neoplasia, four dogs had abnormal splenic parenchyma (two nodular and two diffuse heterogeneity), and one dog had a normal attenuation of the spleen. In four dogs, the spleen was subjectively enlarged. Computed tomographic evaluation of the liver showed no consistent pattern associated with mast cell metastasis and did not predict cytology results. Multifocal splenic hypoattenuating lesions more commonly coincided with mast cell metastasis. Sampling of the liver and spleen remains to be considered in the absence of abnormal CT findings for full staging.