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Case summary: Ductal plate malformations (DPMs) are poorly documented in the veterinary literature, particularly those of the polycystic liver disease (PCLD) phenotype. A 13-year-old female spayed cat presented with progressive icterus, abdominal distension, weight loss and elevated liver enzymes. Initial empirical treatment consisting of amoxicillin/clavulanate, ursodiol and later prednisolone was attempted; however, clinical signs progressed. On abdominal ultrasound, numerous large hepatic cystic masses were noted, characterized by an anechoic center with a heterogeneous, hyperechoic wall. A post-mortem examination confirmed numerous hepatic cysts, the larger of which resulted in hemorrhage and subsequent hemoabdomen. Histologically, these cysts were determined to be of biliary origin, and a diagnosis of PCLD was assigned. Relevance and novel information: Herein, we present a detailed report of clinical, gross and histologic findings in a cat clinically affected by PCLD. This case demonstrates that cysts present in this congenital disease can ultimately lead to hepatobiliary malfunction and clinical decline via marked expansion of cysts, compression of the liver and hemoabdomen from cyst rupture. DPMs, specifically PCLD, should be considered in cats presenting with multifocal large hepatic cysts. [ABSTRACT FROM AUTHOR]

Voltage-gated [Ca.sup.2+] channels (VGCCs) play a key role in neuronal signaling but can also contribute to cellular dysfunction and death under pathological conditions such as stroke and neurodegenerative diseases. We report that activation of N-methyl-D-aspartic acid receptors causes internalization and degradation of [Ca.sub.v]1.2 channels, resulting in decreased [Ca.sup.2+] entry and reduced toxicity. [Ca.sub.v]1.2 internalization and degradation requires binding to phosphatidylinositol 3-phosphate 5-kinase (PIKfyve), a lipid kinase which generates phosphatidylinositol (3,5)-bisphosphate (Ptdlns(3,5)[P.sub.2]) and regulates endosome and lysosome function. Sustained activation of glutamate receptors recruits PIKfyve to [Ca.sub.v]1.2 channels, increases cellular levels of Ptdlns(3,5)[P.sub.2], and promotes targeting of [Ca.sub.v]1.2 to lysosomes. Knockdown of PIKfyve prevents [Ca.sub.v]1.2 degradation and increases neuronal susceptibility to excitotoxicity. These experiments identify a novel mechanism by which neurons are protected from excitotoxicity and provide a possible explanation for neuronal death in diseases caused by mutations that affect Ptdlns(3,5)[P.sub.2] regulation. doi 10.1083/jcb.200903028

Objectives: The aim of this study was to evaluate the intra- and inter-rater reliability of epaxial muscle cross-sectional area measurement on feline CT images and to determine the relationship between normalized epaxial muscle area (EMA) and subjective muscle condition score (MCS). Methods: Feline transverse CT images including the junction of the 13th thoracic vertebrae/13th rib head were retrospectively reviewed. Right and left epaxial muscle circumference and vertebral body height were measured and an average normalized EMA (ratio of epaxial area:vertebral height) was calculated for each image. Measurements were performed by three individuals blinded to the clinical data and were repeated 1 month later. Intra- and inter-rater reliability of EMA was assessed with concordance correlation coefficient (CCC), and Bland–Altman analysis was performed to assess bias and limits of agreement (LoA) between and within observers at different time points. In cats for which MCS data were available, EMA was compared between differing MCSs via the Kruskal–Wallis test, with Bonferroni-corrected Wilcoxon rank-sum post-hoc analysis. Results: In total, 101 CT scans met the inclusion criteria for reliability analysis, 29 of which had muscle condition information available for analysis. Intra-rater EMA CCC ranged from 0.84 to 0.99 with minimal bias (range –0.16 to 0.08) and narrow LoA. Inter-rater EMA CCC ranged from 0.87 to 0.94, bias was larger (range –0.46 to 0.66) and LoA were wider when assessed between observers. Median EMA was significantly lower in cats with severe muscle atrophy (2.76, range 1.28–3.96) than in all other MCS groups (P <0.0001 for all comparisons). Conclusions and relevance: Measurement of EMA on CT showed strong intra-rater reliability, and median EMA measurements were significantly lower in cats with severe muscle wasting, as assessed on physical examination. Further studies correlating EMA to lean muscle mass in cats are needed to determine whether this method may be useful to quantify muscle mass in patients undergoing a CT scan. [ABSTRACT FROM AUTHOR]

Transitional cell carcinoma is the most common cancer of the canine urinary tract. The inconsistent appearance of transitional cell carcinoma in patients introduces error if applying mathematic models for extrapolating total tumor volume from linear measurements. Reliable techniques to assess tumor size are important for monitoring treatment response. A method comparison study was performed comparing four techniques for calculating tumor volume were compared: (1 and 2) contoured tracing of tumor margins using serial computed tomography (CT) images using pre‐(1) and postintravenous (2) contrast medium studies, (3) longest three linear dimensions using CT, and (4) longest three linear dimensions on abdominal ultrasound. Volumes of the transitional cell carcinoma tumor calculated by CT tracing techniques were significantly smaller than volumes calculated with an ellipsoid mathematic model using the linear measurements (P < 0.01). Intravenous contrast medium did not significantly change the volumes calculated from tracing tumor margins on CT for observer B; however, volumes differed for observer A. The volumes extrapolated from linear measurements using CT and ultrasound did not differ significantly. The interobserver reliability was highest for the precontrast CT contoured technique and was lowest using the ultrasound linear technique. Tumor volumes differed significantly between techniques of contoured tracing of the tumor margins on serial CT images compared to calculation of tumor volume from linear dimensions. The calculated volume of a transitional cell carcinoma depends upon the technique used. Characterizing the response of urinary bladder transitional cell carcinoma tumor size to therapy differs based on the method and modality used. [ABSTRACT FROM AUTHOR]

Hypertrophic cardiomyopathy (HCM) is an inherited disease of the heart muscle characterized by otherwise unexplained thickening of the left ventricle. Left ventricular outflow tract (LVOT) obstruction is present in approximately two-thirds of patients and substantially increases the risk of disease complications. Invasive treatment with septal myectomy or alcohol septal ablation can improve symptoms and functional status, but currently available drugs for reducing obstruction have pleiotropic effects and variable therapeutic responses. New medical treatments with more targeted pharmacology are needed, but the lack of preclinical animal models for HCM with LVOT obstruction has limited their development. HCM is a common cause of heart failure in cats, and a subset exhibit systolic anterior motion of the mitral valve leading to LVOT obstruction. MYK-461 is a recently-described, mechanistically novel small molecule that acts at the sarcomere to specifically inhibit contractility that has been proposed as a treatment for HCM. Here, we use MYK-461 to test whether direct reduction in contractility is sufficient to relieve LVOT obstruction in feline HCM. We evaluated mixed-breed cats in a research colony derived from a Maine Coon/mixed-breed founder with naturally-occurring HCM. By echocardiography, we identified five cats that developed systolic anterior motion of the mitral valve and LVOT obstruction both at rest and under anesthesia when provoked with an adrenergic agonist. An IV MYK-461 infusion and echocardiography protocol was developed to serially assess contractility and LVOT gradient at multiple MYK-461 concentrations. Treatment with MYK-461 reduced contractility, eliminated systolic anterior motion of the mitral valve and relieved LVOT pressure gradients in an exposure-dependent manner. Our findings provide proof of principle that acute reduction in contractility with MYK-461 is sufficient to relieve LVOT obstruction. Further, these studies suggest that feline HCM will be a valuable translational model for the study of disease pathology, particularly LVOT obstruction. [ABSTRACT FROM AUTHOR]

Background: Effective therapies for transitional cell carcinoma (TCC) are limited, with objective response rates to most chemotherapeutic regimens below 20%. The purpose of this study was to investigate the biologic activity of combined toceranib phosphate and vinblastine chemotherapy for treatment of TCC. A secondary objective was to compare the utility of Computed Tomography (CT) and abdominal ultrasound (AUS) in tumor response assessments. Results: Dogs with TCC received vinblastine at 1.6 mg/m2 every 2 weeks and toceranib at 2.5-2.75 mg/kg on Monday/Wednesday/Friday. Tumor monitoring was achieved through CT and AUS. Five patients completed the 16-week study. Based on AUS assessments, 3 dogs experienced biologic response to therapy including partial responses (PR, n = 2) and stable disease (SD, n = 1). Based on CT, 5 dogs experienced a biologic response (n = 2 PR, n = 3 SD). Both imaging modalities (ultrasound and CT) were found to provide repeatable measurements between operators, however agreement between operator measurements was greater when CT images were used to assess tumor size. Conclusions: The combination of toceranib and vinblastine did not result in improved response rates. While agreement in tumor volume assessments between both AUS and CT were excellent between operators, this did not extend to assessment of tumor response. The higher rate of concordance between operators when assessing response to treatment with CT suggests that CT should be considered for future clinical trials involving canine bladder TCC to improve the accuracy and repeatability of tumor measurement. The data suggest that response to therapy as assessed by AUS or CT do not predict duration of clinical response. [ABSTRACT FROM AUTHOR]

Vomiting, often caused by mechanical intestinal obstruction, is common in dogs. Equivocal radiographic signs often necessitate repeat radiographs or additional imaging procedures. For our prospective, case-controlled, accuracy study, we hypothesized the following: (1) using computed tomography (CT), radiologists will be more sensitive and specific for detecting mechanical intestinal obstruction and recommending surgery compared to using radiographs; and (2) using measurements, radiologists will be more sensitive and specific using radiographs or CT for detecting mechanical intestinal obstruction and recommending surgery. Twenty dogs had abdominal radiographs and abdominal CT. Seventeen dogs had abdominal surgery and three dogs were not obstructed based on clinical follow-up. Confidence levels (five-point scale) of three experienced radiologists for mechanical intestinal obstruction and recommending surgery were recorded before and after making selected measurements. Eight dogs had surgically confirmed mechanical intestinal obstruction, and 12 dogs did not have obstruction. For detecting mechanical intestinal obstruction, CT was more sensitive (95.8% vs. 79.2%) and specific (80.6% vs. 69.4%) compared to radiographs, but the difference was not statistically significant. For recommending surgery, radiography was more sensitive (91.7% vs. 83.3%) and specific (83.3% vs. 72.2%) than using CT, but differences were not statistically significant. We reported objective CT measurements for predicting small mechanical intestinal obstruction. By incorporating these objective data, the diagnosis of mechanical intestinal obstruction changed in five of 120 instances (radiographs and CT). In no instance (0/120), did the objective data change the recommendation for surgery. Using CT or abdominal radiographs for the detection of canine mechanical intestinal obstruction is sensitive and specific when evaluated by experienced veterinary radiologists. [ABSTRACT FROM AUTHOR]

Regenerative medicine seeks to understand tissue development and homeostasis and build on that knowledge to enhance regeneration of injured tissues. By replenishing lost functional tissues and cells, regenerative medicine could change the treatment paradigm for a broad range of degenerative and ischemic diseases. Multipotent cells hold promise as potential building blocks for regenerating lost tissues, but successful tissue regeneration will depend on comprehensive control of multipotent cells- differentiation into a target cell type, delivery to a desired tissue, and integration into a durable functional structure. At each step of this process, proteins and small molecules provide essential signals and, in some cases, may themselves act as effective therapies. Identifying these signals is thus a fundamental goal of regenerative medicine. In this review we discuss current progress using proteins and small molecules to regulate tissue regeneration, both in combination with cellular therapies and as monotherapy. [ABSTRACT FROM AUTHOR]

Multidetector contrast enhanced computed tomography with acquisition of 0.625-mm thick transverse images was used to measure the extent of appendicular osteosarcoma in 10 dogs. The measured length of tumor based on CT was compared to the true length of tumor using histopathology. There was a statistically significant association with good correlation between the true length of osteosarcoma compared to the length of intramedullary/endosteal abnormalities on CT with a mean overestimation of 1.8% (SD = 15%). There was not a statistically significant association between the true tumor length and the length of periosteal proliferation on CT with a mean overestimation of 9.7% (SD = 30.3%). There was a statistically significant association, but with poor correlation, between the true tumor length compared to the length of abnormal contrast enhancement with a mean overestimation of 9.6% (SD = 34.8%). The extent of intramedullary/endosteal CT abnormalities assessed from submillimeter transverse images may be of value in assessing patient candidacy and surgical margins for limb-sparing surgery [ABSTRACT FROM AUTHOR]

The article describes the case of ionized hypercalcemia secondary to blastomycosis in the domestic cat. It associates resolution of ionized hypercalcemia with decreased circulating calcitriol. It considers the case as the first domestic cat diagnosed with blastomycosis, ionized hypercalcemia, and evaluation of calcium-regulatory hormones.

Objective-To determine intra and inter observer variability of 2 veterinary radiologists and 2 veterinary general practitioners for detection of pulmonary nodules in standard and inverted (reversed gray scale) displays of digital thoracic radiographs of dogs. Design-Evaluation study. Sample-114 sets of 3-view (right lateral, left lateral, and ventrodorsal or dorsoventral views) digital thoracic radiographs from 114 dogs. Procedures-2 experienced board-certified veterinary radiologists and 2 experienced veterinary general practitioners individually evaluated 114 randomized sets of radiographs. Pulmonary nodules were present in radiographs of 60 of 114 dogs. Each reviewer examined all images in standard or inverted display mode and scored nodule detection on a confidence scale of 1 to 5. After ⩾ 2 months, the same individuals evaluated the same images in the remaining display mode. lntraobserver agreement for each display mode was determined via a K statistic; results between the 2 groups of reviewers were compared via receiver operator curve analysis. Results-There was no significant intraobserver variability in pulmonary nodule detection between the 2 display modes. Detection accuracy for board-certified radiologists was significantly greater than that of veterinary general practitioners for both display modes. Near perfect intraobserver agreement was detected between the 2 display modes for board certified radiologists, whereas moderate to slight intraobserver agreement was detected for the veterinary general practitioners. Conclusions and Clinical Relevance-Detection of pulmonary nodules in digital thoracic radiographs was comparable, whether a standard or inverted mode was used for evaluations. However, the board-certified radiologists had greater detection accuracy than did veterinary general practitioners. [ABSTRACT FROM AUTHOR]

Voltage-gated Ca[sup 2+] channels (VGCCs) play a key role in neuronal signaling but can also contribute to cellular dysfunction and death under pathological conditions such as stroke and neurodegenerative diseases. We report that activation of N-methyl-D-aspartic acid receptors causes internalization and degradation of Ca[sub v]1.2 channels, resulting in decreased Ca[sup 2+] entry and reduced toxicity. Ca[sub v]1.2 internalization and degradation requires binding to phosphatidylinositol 3-phosphate 5-kinase (PIKfyve), a lipid kinase which generates phosphatidylinositol (3,5)-bisphosphate (PtdIns(3,5)P[sub 2]) and regulates endosome and lysosome function. Sustained activation of glutamate receptors recruits PIKfyve to Ca[sub v]1.2 channels, increases cellular levels of PtdIns(3,5)P[sub 2], and promotes targeting of Ca[sub v]1.2 to lysosomes. Knockdown of PIKfyve prevents Ca[sub v]1.2 degradation and increases neuronal susceptibility to excitotoxicity. These experiments identify a novel mechanism by which neurons are protected from excitotoxicity and provide a possible explanation for neuronal death in diseases caused by mutations that affect PtdIns(3,5)P[sub 2] regulation. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the utility of single-detector computed tomographic arthrography (CT arthrography) for the diagnosis of cranial and caudal cruciate ligament and meniscal lesions in the dog stifle. Four normal and 25 abnormal stifle joints, determined to have lesions related to intra-articular ligamentous insufficiency based on clinical history, orthopedic examination, and survey orthogonal radiographs, were imaged using a previously developed CT arthrography protocol. Surgery was performed immediately following the CT procedure. Three board-certified radiologists inexperienced at interpreting CT stifle arthrograms reviewed all CT studies independently, and then as a group, without knowledge of surgical or necropsy findings. Sensitivity, specificity, positive predictive value, and negative predictive value for determination of cranial and caudal cruciate and meniscal tears were calculated for each individual reviewer and based on group consensus. All reviewers identified the normal canine stifle joints imaged correctly. Reviewers did well in discriminating normal from torn cranial cruciate ligaments, with sensitivities of 96–100% and specificities of 75–100%. No reviewer correctly identified the solitary caudal cruciate ligament tear and specificity ranged from 89.3% to 100%. Reviewers were less adept at discriminating normal from torn meniscal fibrocartilage, with sensitivities of 13.3–73.3% and specificities of 57.1–100%. Interpretive accuracy improved slightly when consensus scores were compared with surgical findings. Single-detector CT arthrography may be useful for identifying pathology of the canine cruciate ligaments but is of limited value for assessing the menisci. [ABSTRACT FROM AUTHOR]

Summary: Voltage-gated calcium channels (VGCCs) convert electrical activity into calcium (Ca2+) signals that regulate cellular excitability, differentiation, and connectivity. The magnitude and kinetics of Ca2+ signals depend on the number of VGCCs at the plasma membrane, but little is known about the regulation of VGCC surface expression. We report that electrical activity causes internalization of the L-type Ca2+ channel (LTC) CaV1.2 and that this is mediated by binding to the tumor suppressor eIF3e/Int6 (eukaryotic initiation factor 3 subunit e). Using total internal reflection microscopy, we identify a population of CaV1.2 containing endosomes whose rapid trafficking is strongly regulated by Ca2+. We define a domain in the II-III loop of CaV1.2 that binds eIF3e and is essential for the activity dependence of both channel internalization and endosomal trafficking. These findings provide a mechanism for activity-dependent internalization and trafficking of CaV1.2 and provide a tantalizing link between Ca2+ homeostasis and a mammalian oncogene. [Copyright &y& Elsevier]

Objective To report treatment of a unilateral comminuted fourth carpal bone (C4) fracture associated with carpal instability by partial carpal arthrodesis (PCA) of the middle carpal joint (MCJ) and carpometacarpal joint (CMCJ). Study Design Case Report. Animals An 8-month-old Arabian filly. Methods A C4 slab fracture was diagnosed radiographically; however, fracture comminution was conclusively diagnosed after computed tomographic (CT) imaging. PCA of the MCJ and CMCJ was performed with 2 narrow dynamic compression plates. Results PCA provided appropriate carpal stability and correct limb alignment immediately after surgery. Complete bony fusion with substantial carpal flexion and no lameness at walk or light trot was observed 8 months after surgery. Conclusions Carpal CT was successfully used to define fracture configuration after standard radiographic examination failed to delineate comminution. PCA was selected because of joint instability and lateral carpal collapse of MCJ and CMCJ and can be successfully used to treat comminuted C4 slab fractures associated with carpal instability. Moderate MCJ osteoarthritis without radiocarpal joint involvement allows pain-free, substantial carpal flexion and thus, return to low-level pleasure riding may be possible. Clinical Relevance CT imaging may more adequately characterize traumatic carpal bone injury, particularly, when carpal bone fracture configuration cannot be determined on standard radiographs. Early PCA of the MCJ and CMCJ is an useful alternative to treat comminuted C4 slab fractures that cannot be reconstructed. [ABSTRACT FROM AUTHOR]

Introduction: HCM is a disease of heart muscle associated with heart failure and sudden death, usually caused by mutations in sarcomere protein genes. The mechanisms by which mutations cause disease are uncertain, partly because of the lack of model systems amenable to integrated translational studies. Methods: We generated Yucatan minipigs with heterozygous knockin of the human HCM MYH7 R403Q mutation. We conducted serial serum biomarker analyses, cardiac imaging and histologic and omic analyses of LV biopsy samples of wildtype and R403Q pigs (n =14/group). Results: Cardiac MRI (CMR) and echocardiography showed heterogeneity in the pattern of hypertrophy in R403Q pigs (concentric vs asymmetric), similar to humans. Histology showed lower capillary density (x102/mm2) in R403Q vs WT pigs (13.0±0.0.9 vs 10.1±0.4, p <0.01). CMR showed regional myocardial flow reserve (FR) in response to dipyridamole was decreased in R403Q pigs and was negatively correlated with the severity of hypertrophy (Figure: Panel A shows a plot of all pigs; Panel B shows an R403Q pig with greater impairment of FR in the hypertrophic septum than the relatively normal posterior wall). Serum TnI (ng/L) was elevated in R403Q vs WT pigs at ages 1 month (167.3±20.1 vs 90.5±9.9, p <0.01), 3 months (202.0±30.6 vs 20.0±4.3, p <0.01), 6 months (134.5±69.6 vs 6.7±8.3, p <0.01), and 9 months (206.1±66.8 vs 0.0±0.0, p <0.001). There was increased fibrosis (% area) in R403Q vs WT pigs at ages 3 months (11.4±5.2 vs 2.9±3.1, p <0.01) and 9 months (15.7±8.5 vs 3.5±3.1, p <0.01), with increased myocyte disarray. Intramyocardial arterioles in R403Q pigs showed intimal hyperplasia with decreased luminal diameters. RNAseq and proteomic analyses showed upregulation of pro-fibrotic pathways. Conclusions: This first large-animal genetic model of HCM allows studies such as FR not possible in rodents. Our data suggest that a limitation in perfusion of hypertrophic myocardium leads to chronic injury and fibrosis. [ABSTRACT FROM AUTHOR]

OBJECTIVE To characterize and compare MRI susceptibility artifacts related to titanium and stainless steel monocortical screws in the cervical vertebrae and spinal cord of canine cadavers. SAMPLE 12 canine cadavers. PROCEDURES Cervical vertebrae (C4 and C5) were surgically stabilized with titanium or stainless steel monocortical screws and polymethylmethacrylate. Routine T1-weighted, T2-weighted, and short tau inversion recovery sequences were performed at 3.0 T. Magnetic susceptibility artifacts in 20 regions of interest (ROIs) across 4 contiguous vertebrae (C3 through C6) were scored by use of an established scoring system. RESULTS Artifact scores for stainless steel screws were significantly greater than scores for titanium screws at 18 of 20 ROIs. Artifact scores for titanium screws were significantly higher for spinal cord ROIs within the implanted vertebrae. Artifact scores for stainless steel screws at C3 were significantly less than at the other 3 cervical vertebrae. CONCLUSIONS AND CLINICAL RELEVANCE Evaluation of routine MRI sequences obtained at 3.0 T revealed that susceptibility artifacts related to titanium monocortical screws were considered mild and should not hinder the overall clinical assessment of the cervical vertebrae and spinal cord. However, mild focal artifacts may obscure small portions of the spinal cord or intervertebral discs immediately adjacent to titanium screws. Severe artifacts related to stainless steel screws were more likely to result in routine MRI sequences being nondiagnostic; however, artifacts may be mitigated by implant positioning. [ABSTRACT FROM AUTHOR]

Forty-five dogs with incompletely excised grade II mast cell tumors were treated with radiation using a cobalt 60 teletherapy unit (15 fractions of 3.2 Gy for a total of 48 Gy). Twenty-four of the dogs underwent prophylactic regional lymph node irradiation. Three (6.7%) dogs had tumor recurrence, two (4.4%) dogs developed metastasis, and 14 (31%) dogs developed a second cutaneous mast cell tumor. No difference in overall survival rate was observed between the dogs receiving and not receiving prophylactic irradiation of the regional lymph node. [ABSTRACT FROM AUTHOR]

OBJECTIVE To assess whether cardiac MRI or various biomarkers can be used to detect myocardial ischemia and fibrosis in dogs with cardiomegaly secondary to myxomatous mitral valve disease (MMVD). ANIMALS 6 dogs with cardiomegaly secondary to naturally occurring stage B2 MMVD being treated only with pimobendan with or without enalapril and 6 control dogs with no cardiac disease. All dogs were ≥ 5 years old with no systemic illness. PROCEDURES Serum cardiac troponin I and concentrations were measured, and dogs were anesthetized for cardiac MRI with ECG-triggered acquisition of native T1- and T2-weighted images. Gadolinium contrast was administered to evaluate myocardial perfusion and late gadolinium enhancement (LGE). Mean T1 and T2 values and regions of LGE were measured with dedicated software. Extracellular volume (ECV) was estimated on the basis of Hct and T1 values of myocardium and surrounding blood. Subjective analysis for myocardial perfusion deficits was performed. RESULTS Dogs with MMVD had significantly (P = .013) higher cardiac troponin I concentrations than control dogs, but galectin-3 concentrations did not differ (P = .08) between groups. Myocardial fibrosis was detected in 4 dogs with MMVD and 3 control dogs; no dogs had obvious myocardial perfusion deficits. Native T1 and T2 values, postcontrast T1 values, and ECV values were not significantly different between groups (all P > .3). CLINICAL RELEVANCE Results suggest that some dogs with cardiomegaly secondary to MMVD may not have clinically relevant myocardial fibrosis. [ABSTRACT FROM AUTHOR]

Objective-To compare long-term results of radiotherapy alone versus radiotherapy followed by exenteration of the nasal cavity in dogs with malignant intranasal neoplasia. Design Retrospective study. Animals-53 dogs with malignant intranasal neoplasia. Procedure-All dogs underwent radiotherapy consisting of administration of 10 fractions of 4.2 Gy each on consecutive weekdays. For dogs in the surgery group (n = 13), follow-up computed tomography was performed, and dogs were scheduled for surgery if persistent or recurrent tumor was seen. Results-Perioperative complications for dogs that underwent surgery included hemorrhage requiring transfusion (2 dogs) and subcutaneous emphysema (8). Rhinitis and osteomyelitis-osteonecrosis occurred significantly more frequently in dogs in the radiotherapy and surgery group (9 and 4 dogs, respectively) than in dogs in the radiotherapy-only group (4 and 3 dogs, respectively). Two- and 3-year survival rates were 44% and 24%, respectively, for dogs in the radiotherapy group and 69% and 58%, respectively, for dogs in the surgery group. Overall median survival time for dogs in the radiotherapy and surgery group (44.7 months) was significantly longer than time for dogs in the radiotherapy-only group (19.7 months). Conclusions and Clinical Relevance-Results suggest that exenteration of the nasal cavity significantly prolongs survival time in dogs with intranasal neoplasia that have undergone radiotherapy. Exenteration after radiotherapy may increase the risk of chronic complications. [ABSTRACT FROM AUTHOR]