CASE DESCRIPTION A 4-year-old spayed female mixed-breed rabbit was evaluated because of a 3-year history of sneezing and nasal discharge that were refractory to medical management. CLINICAL FINDINGS Signs of chronic left-sided rhinitis and sinusitis were observed on physical examination and confirmed by CT evaluation. Lysis of the rostral aspect of the left maxillary bone and destruction of nasal turbinates were evident on CT images. TREATMENT AND OUTCOME Pararhinotomy of the left maxillary sinus through the facies cribrosa was performed. Purulent material was removed from the maxillary sinus recesses, a middle meatal antrostomy was completed to allow permanent drainage into the left middle nasal meatus, and the tissues were closed routinely. Microbial culture of a sample from the maxillary sinus recesses revealed Bordetella bronchiseptica, undetermined fastidious nonenteric bacteria, and Streptococcus viridans. Medical management was continued, and nasal discharge resolved but sneezing persisted. Increased sneezing and bilateral nasal discharge developed 1.5 years later; CT examination revealed right-sided rhinitis, and culture of a nasal swab sample revealed Bordetella spp, Staphylococcus spp, and Micrococcus spp. Right-sided pararhinotomy and middle meatal antrostomy were performed, and medical management continued. A subsequent recurrence was managed without additional surgery; 4 years after the initial surgery, the rabbit was still receiving medical treatment, with mild intermittent nasal discharge and sneezing reported. CLINICAL RELEVANCE This report describes a surgical approach for treatment of chronic rhinitis in companion rabbits with maxillary sinus involvement that included creation of a permanent drainage pathway from the maxillary sinus to the middle nasal meatus.

OBJECTIVE:To report outcome and complications after percutaneous transvenous coil embolization (PTCE) and evaluate the clinical, laboratory, and imaging changes in dogs with intrahepatic portosystemic shunts (IHPSS) pre-PTCE and post-PTCE.STUDY DESIGN:Prospective clinical trial.ANIMALS:Twenty-five dogs (15 dogs in imaging subgroup) with IHPSS.METHODS:Clinical signs, hematologic, and biochemical parameters were recorded before and 3 months after PTCE. All dogs received the same medical treatment and underwent PTCE. In the imaging subgroup, ultrasonography, hepatic portal scintigraphy, and computed tomography-angiography were performed pre-PTCE and post-PTCE.RESULTS:All evaluated bloodwork values improved by at least 50% of their initial value, by 3 months post-PTCE. Liver volume increased after PTCE (P = .001), but remained lower than normal in 11/15 dogs. Hepatic arterial fraction decreased after PTCE (P = .029), consistent with increased portal blood flow to the liver. Twenty-four of 25 dogs were available for reevaluation at 3 months, and all abnormal clinical signs had resolved in 22/24 dogs.CONCLUSION:PTCE appears promising as a treatment for IHPSS, as clinical signs resolved in most cases, bloodwork abnormalities often normalized, and the procedure was performed safely with minimal complications. PTCE increased hepatic portal perfusion and liver volume in most dogs. These promising results justify a future randomized clinical trial comparing PTCE, other attenuation options, and medical management alone.

OBJECTIVE To characterize clinical findings, surgical procedures, complications, and outcomes in dogs undergoing extirpation of masses from the cranial mediastinum via video-assisted thoracic surgery (VATS) and establish preliminary guidelines for case selection when considering VATS for thymectomy in dogs. DESIGN Retrospective case series. ANIMALS 18 client-owned dogs that underwent extirpation of a cranial mediastinal mass by means of VATS at 5 academic referral hospitals from 2009 through 2014. PROCEDURES Medical records were reviewed and data extracted regarding signalment, clinical signs, physical examination findings, diagnostic imaging results, surgical approach and duration, cytologic and histologic examination results, complications, outcome, and cause of death, when applicable. RESULTS 16 dogs had a thymoma, 1 had thymic anaplastic carcinoma, and 1 had hemangiosarcoma. Seven had both megaesophagus and myasthenia gravis. Median approximate tumor volume was 113.1 cm3 (interquartile range, 33.5 to 313.3 cm3). Median duration of VATS was 117.5 minutes (interquartile range, 91.5 to 136.3 minutes). Conversion to an open thoracic surgical procedure was required for 2 dogs, 1 of which died during surgery. Median survival time following VATS for dogs with thymoma and concurrent myasthenia gravis and megaesophagus was 20 days. Dogs with thymoma without paraneoplastic syndrome survived for ≥ 60 days, and none of these dogs died of disease-related causes. CONCLUSIONS AND CLINICAL RELEVANCE VATS appeared to be an acceptable approach for extirpation of masses from the cranial mediastinum in dogs under certain conditions. Dogs with myasthenia gravis and megaesophagus had a poor postoperative outcome.

Sentinel lymph node mapping can help to direct surgical oncologic staging and metastatic disease detection in patients with complex lymphatic pathways. We hypothesized that indirect computed tomographic lymphography (ICTL) with a water-soluble iodinated contrast agent would successfully map lymphatic pathways of the iliosacral lymphatic center in dogs with anal sac gland carcinoma, providing a potential preoperative method for iliosacral sentinel lymph node identification in dogs. Thirteen adult dogs diagnosed with anal sac gland carcinoma were enrolled in this prospective, pilot study, and ICTL was performed via peritumoral contrast injection with serial caudal abdominal computed tomography scans for iliosacral sentinel lymph node identification. Technical and descriptive details for ICTL were recorded, including patient positioning, total contrast injection volume, timing of contrast visualization, and sentinel lymph nodes and lymphatic pathways identified. Indirect CT lymphography identified lymphatic pathways and sentinel lymph nodes in 12/13 cases (92%). Identified sentinel lymph nodes were ipsilateral to the anal sac gland carcinoma in 8/12 and contralateral to the anal sac gland carcinoma in 4/12 cases. Sacral, internal iliac, and medial iliac lymph nodes were identified as sentinel lymph nodes, and patterns were widely variable. Patient positioning and timing of imaging may impact successful sentinel lymph node identification. Positioning in supported sternal recumbency is recommended. Results indicate that ICTL may be a feasible technique for sentinel lymph node identification in dogs with anal sac gland carcinoma and offer preliminary data to drive further investigation of iliosacral lymphatic metastatic patterns using ICTL and sentinel lymph node biopsy.

ObjectiveTo report the use of low‐pressure carbon dioxide insufflation during video‐assisted thoracoscopic surgery for resection of a noninvasive thymoma in a cat with secondary myasthenia gravis.Study DesignClinical case report.AnimalClient‐owned cat.MethodsAn 11‐year‐old castrated male domestic shorthair cat was examined for generalized weakness, voice change, hypersalivation, hyporexia, vomiting, coughing, and gagging. Thoracic ultrasound revealed a cranial mediastinal mass for which cytology was consistent with a thymoma (or lymphoid tissue). Acetylcholine receptor antibody concentration was elevated at 3.16 mmol/L (reference interval < 0.3 mmol/L). Thoracic computed tomography showed two round, contrast‐enhancing structures in the cranioventral mediastinum identified as the sternal lymph node and a cranial mediastinal mass (11 × 17 × 24 mm). A presumptive diagnosis of thymoma with paraneoplastic myasthenia gravis was made and surgical resection of both mediastinal masses was recommended.ResultsVideo‐assisted thoracoscopic resection of the cranial mediastinal mass and sternal lymph node were performed with low‐pressure carbon dioxide insufflation maintained at an intrathoracic pressure of 2–3 mmHg. The cat recovered from surgery without serious complications. Nineteen months after surgery, the cat developed hind limb stiffness. Thoracic radiographs ruled out a cranial mediastinal mass or megaesophagus. Acetylcholine receptor antibody concentration remained elevated at 2.72 mmol/L.ConclusionLow‐pressure thoracic insufflation facilitated video‐assisted thoracoscopic resection of cranial mediastinal masses in this cat.

OBJECTIVE To evaluate the outcome for cats with benign ureteral obstructions treated by means of ureteral stenting and to compare the outcome for these cats with outcome for a historical cohort of cats treated by means of ureterotomy only. DESIGN Prospective study with historical cohort. ANIMALS 62 client-owned cats with benign ureteral obstructions, including 26 cats treated with ureteral stenting and 36 cats previously treated with ureterotomy. PROCEDURES Data were recorded prospectively (ureteral stent cases) or collected retrospectively from the medical records (ureterotomy cases), and results were compared. RESULTS Cats treated with ureteral stents had significantly greater decreases in BUN and serum creatinine concentrations 1 day after surgery and at hospital discharge, compared with values for cats that underwent ureterotomy. Six cats in the ureteral stent group developed abdominal effusion after surgery, and cats in this group were significantly more likely to develop abdominal effusion when a ureterotomy was performed than when it was not. Cats that developed abdominal effusion after surgery were significantly less likely to survive to hospital discharge. Cats that underwent ureteral stenting were significantly more likely to have resolution of azotemia prior to hospital discharge than were cats that underwent ureterotomy alone. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that cats with benign ureteral obstructions treated with ureteral stenting were more likely to have resolution of azotemia prior to hospital discharge, compared with cats undergoing ureterotomy alone. Results of ureteral stenting were encouraging, but further investigation is warranted.

A 10-year-old female koi subspecies (Cyprinus carpio) was presented with bilateral, asymmetric, sessile masses of the periventiductal tissue. The owner had first observed the masses for approximately 1 year before seeking a veterinary evaluation of the fish. Over the past year, the sessile masses continued to grow and develop in size. An incisional biopsy was performed under general anesthesia to further assess the abnormal tissue structures. Based on the histologic evaluation of the submitted biopsy sample, the growth was determined to be a benign spindle cell neoplasm. The koi also was diagnosed with a concurrent genital tract infection based on cytological examination of the reproductive tract fluid. Following transport to the Veterinary Medical Teaching Hospital for further evaluation, a coelomic ultrasound revealed local infiltration of the tissue to the surrounding tissue. To decrease the risks of recurrence following surgical debulking, chemotherapy was recommended to treat the tissue adjacent to the tumor. Cultures obtained from the genital pore resulted in the isolation of Aeromonas spp. susceptible to ceftiofur, which was elected as a preemptive antibiotic. Surgical debulking of the mass was performed, and bleomycin was administered intralesionally and at the periphery of the surgical site. The koi recovered successfully from anesthesia and was discharged later the same day and prescribed an analgesic regimen of meloxicam. After further histological examination of the submitted tissue samples from the periventiductal growths, the tumor was identified as a leiomyoma. No recurrence of the mass was detected 6 months following the surgical procedure and chemotherapy.

OBJECTIVE:To describe indications for, and outcomes after, pneumonectomy in dogs and cats, including assessment of immediate postoperative respiratory function in comparison to dogs undergoing single lung lobectomy. STUDY DESIGN:Retrospective case series. ANIMALS:Dogs (n=16) and cats (n=7) with naturally occurring pulmonary disease. METHODS:Medical records (1990-2014) of dogs and cats undergoing right or left pneumonectomy were reviewed. Data retrieved included signalment, history, preoperative diagnostics, operative descriptions, postoperative data including respiratory function, and postdischarge outcomes. For respiratory function comparisons, medical records of dogs having undergone a single lung lobectomy via median sternotomy (n=15) or intercostal thoracotomy (n=15) were reviewed. RESULTS:Twenty-three cases (16 dogs, 7 cats) were included. Pneumonectomy was performed for congenital (1 dog, 1 cat), neoplastic (8 dogs, 1 cat), and infectious (7 dogs, 5 cats) disease. Postoperative aspiration pneumonia occurred in 2 dogs; 15 of 16 dogs (94%) and 6/7 cats (86%) survived to hospital discharge. After pneumonectomy, dogs had a significantly higher postoperative PaO2 on 21% oxygen (P=.033) and lower postoperative A-a gradient (P=.004) compared to dogs undergoing single lung lobectomy. Survival times (right-censored at last follow-up) for dogs ranged from 2 days to 7 years (estimated median=1,868 days) and for cats from 1-585 days. CONCLUSION:Dogs and cats have acceptable respiratory function immediately postoperatively and most have protracted long-term survival after pneumonectomy for a variety of pulmonary diseases.

The objective of this study was to evaluate the influence of ameroid constrictor (AC) composition as well as glucose concentration in the surrounding fluid on the rate and completeness of AC closure. In a pilot study, four ACs (two metal, two plastic) were incubated in a solution containing 100mg/dL glucose, and in a follow-up study, two additional ACs (one metal, one plastic) were incubated in a solution of 100mg/dL glucose and six ACs (three metal, three plastic) were incubated in a solution of 50mg/dL glucose. Dimensions of the ACs were analyzed weekly for 57days. No significant difference was found in the rate or overall proportionate closure for either metal versus plastic ACs or ACs incubated in 50mg/dL versus 100mg/dL glucose. As there was no statistically significant difference in the proportionate closure of metal and plastic ACs, both types are clinically suitable for gradual attenuation of portosystemic shunts in animal patients. The lack of a significant difference in rate and completeness of closure of ACs incubated in different concentrations of glucose provides evidence that the glucose concentration of the surrounding fluid likely does not have a significant effect on AC closure. However, a significant difference in the proportionate closure of ACs occurred within the first week of the study between constrictors incubated in 50mg/dL glucose and those incubated in 100mg/dL glucose, and additional studies are indicated to determine the significance of this early difference in vivo.

We evaluated 3 rabbits (8 months to 1.5 years old) for nonspecific clinical signs including hyporexia/anorexia, lethargy, and decreased/absence of fecal output 5 days to 4 months after undergoing ovariohysterectomy (OHE) procedures. Each external physical examination performed on the rabbits revealed decreased gastrointestinal sounds, abdominal pain on palpation, and a caudal abdominal mass. Complete blood counts and biochemical analyses from the rabbits on presentation were within reference values. Abdominal radiographic findings included gas distension of the intestines along with multiple other distended, ingesta-filled loops. Abdominal ultrasonography was performed on all 3 rabbits, and abnormalities included that the colon tapered abruptly at the level of the uterine stump, a mass was seen around the caudal colon, and that the colon was distended. Positive contrast colonograms were performed in 2 of the rabbits. All 3 rabbits initially responded to medical management; however, after a recurrence of abnormal clinical signs, an exploratory laparotomy was performed on each animal. Of the rabbits, 2 had adhesions from the transected uterine body to the small intestine mesentery, resulting in circumferential stenoses. The 2 rabbits with intestinal stenosis were euthanized intraoperatively owing to the poor prognosis for resection and anastomosis of the colon. In one of the rabbits, sutures placed around the uterine stump during the OHE procedure had inadvertently penetrated the colon; the affected area of the colon was resected but the patient died during the postoperative period. Colonic obstruction following OHE is rare for any species, yet 3 cases of this disease presentation in domestic rabbits are presented in this report. In rabbits, clinical signs might mimic functional ileus; therefore, results of additional testing, including abdominal ultrasonography and a radiographic contrast study, are necessary to obtain a definitive diagnosis. Early surgical exploration and correction of the adhesions before irreversible colonic damage is recommended in suspected cases.

An 8-year-old male neutered miniature Rex rabbit (Oryctolagus cuniculus) was evaluated for progressive left rear limb lameness. A smooth, hard mass was palpated over the proximolateral aspect of the left tibia. Initial radiographic evaluation of the area surrounding the mass revealed a proliferative bony lesion lateral to the tibia without evidence of pulmonary metastases. Cytology of the lesion was consistent with osseous proliferation. Follow up radiographs of the mass after the initial presentation, provided evidence of the mass increasing in size so a second cytologic evaluation was requested. The diagnostic interpretation of the second cytologic submission collected from the mass was osteosarcoma. A coxofemoral amputation was performed on the left rear limb of the rabbit, after which the patient recovered uneventfully from the procedure. Histopathologic evaluation of the mass confirmed osteoblastic osteosarcoma. There was no evidence of metastasis in radiographic images performed at 4 and slightly more than 6 months after the amputation procedure. The rabbit died 190 days after the amputation and several days after recovery from a gastrotomy for gastric bloat. A necropsy was not performed.

OBJECTIVE:To evaluate the relationship between hepatic steatosis and increase in liver size and resolution of shunting after surgical attenuation of congenital extrahepatic portosystemic shunts in dogs. STUDY DESIGN:Prospective study. ANIMALS:Dogs (n = 20) with congenital extrahepatic portosystemic shunts. METHODS:Shunts were attenuated using ameroid ring constrictors. Portal blood flow and liver volume were evaluated using computed tomography before and ≥8 weeks after surgery. Hepatic steatosis was quantified by stereological point counting of lipid droplets and lipogranulomas (LG) in liver biopsies stained with Oil-red-O. Associations between steatosis and preoperative liver volume, liver growth after surgery, and development of acquired shunts were evaluated. RESULTS:Acquired shunts developed in 2 dogs (10%). Dogs with larger preoperative liver volumes relative to bodyweight had fewer lipid droplets per tissue point (P = .019). LG per tissue point were significantly associated with age: 0.019 ± 0.06 for dogs <12 months versus 0.25 ± 0.49 for dogs >12 months (P = .007). There was a significant positive association between liver growth after surgery and the number of LG/month of age in dogs >12 months (P = .003). There was no association between steatosis, presence of macrosteatosis, the number of LG or development of acquired shunts. CONCLUSIONS:This preliminary study suggests that the presence of hepatic lipidosis and LG has no demonstrable effect on development of acquired shunts or the magnitude of increase in liver volume after attenuation of congenital extrahepatic portosystemic shunts in dogs.

OBJECTIVETo describe surgical techniques for multiple port laparoscopic splenectomy (MLS) in dogs and report short-term outcome.STUDY DESIGNRetrospective case series.ANIMALSDogs (n = 10) with naturally occurring splenic disease.METHODSMedical records (March 2012-March 2013) of dogs that had MLS were reviewed. Data retrieved included signalment, weight, clinical signs, physical examination findings, preoperative laboratory and ultrasonographic findings, port number, size, and location, patient positioning, additional procedures performed, surgical duration, histopathologic diagnosis, duration of hospitalization, and perioperative complications.RESULTSTen dogs (median weight, 28.7 kg; range, 20.2-46.0 kg) had MLS using a 3 or 4 port technique and a vessel-sealing device for tissue dissection along the splenic hilus. Dog positioning varied because of additional laparoscopic or laparoscopic-assisted procedures including adrenalectomy (n = 2), ovariectomy (1), gastropexy (1), and intestinal resection and anastomosis (1). Conversion to an open approach was necessary in 1 dog because of inadequate visibility caused by omental adhesions. One dog had hemorrhage from an omental vessel, but open conversion was not required.CONCLUSIONSMLS was associated with little perioperative morbidity and few complications in this cohort of dogs and may be a reasonable option for surgical management of dogs requiring elective splenectomy.

OBJECTIVE:To describe the clinicopathologic features of a cohort of dogs with adrenocortical masses that underwent laparoscopic adrenalectomy and to compare perioperative morbidity and mortality rates in these dogs with rates for dogs that underwent open adrenalectomy for resection of similarly sized (maximal diameter, ≤ 5 cm) adrenocortical masses.DESIGN:Retrospective case series.ANIMALS:48 client-owned dogs that underwent laparoscopic (n = 23) or open (25) adrenalectomy for noninvasive tumors (ie, tumors that did not invade the vena cava or other surrounding organs). Procedures-Medical records were reviewed. History, clinical signs, physical examination findings, clinicopathologic findings, imaging results, and surgical variables were recorded. A 3- or 4-port approach was used for laparoscopic adrenalectomy. Surgical time, perioperative complications, postoperative and overall hospitalization times, and perioperative deaths were recorded and compared between groups.RESULTS:The surgical method for 1 dog was converted from a laparoscopic to an open approach. Perioperative death occurred in no dogs in the laparoscopic group and 2 dogs in the open adrenalectomy group. Surgical time was shorter for laparoscopic (median, 90 minutes; range, 40 to 150 minutes) than for open (median, 120 minutes; range, 75 to 195 minutes) adrenalectomy. Laparoscopic adrenalectomy was associated with shorter hospitalization time and more rapid discharge from the hospital after surgery, compared with the open procedure.CONCLUSIONS AND CLINICAL RELEVANCE:With careful patient selection, laparoscopic adrenalectomy was associated with a low complication rate and low conversion rate for resection of adrenocortical masses as well as shorter surgical and hospitalization times, compared with open adrenalectomy.

OBJECTIVE:To evaluate the in vivo pattern of ameroid constrictor closure of congenital extrahepatic portosystemic shunts in dogs. STUDY DESIGN:Prospective study. ANIMALS:Dogs (n = 22) with congenital extrahepatic portosystemic shunts. METHODS:Contrast-enhanced computed tomography was performed immediately before, and at least 8 weeks after placement of ameroid ring constrictors. Plastic-encased ameroid constrictors were used in 17 dogs and metal constrictors in 5 dogs. Presence of residual flow through the portosystemic shunt, additional anomalous vessels, acquired shunts and soft tissue associated with the ameroid constrictor was recorded. Postoperative internal diameter was recorded for the 17 plastic constrictors. Correlations between internal diameter and pre- and postoperative serum protein concentration were analyzed. RESULTS:No ameroid constrictor closed completely: shunt occlusion was always dependent on soft tissue within the ameroid ring. Residual flow through the shunt was present in 4 dogs (18%), although this caused persistent elevation of shunt fraction in only 1 dog (dog 8). The change in ameroid constrictor internal diameter was not significantly correlated with serum protein concentration. CONCLUSIONS:Complete shunt occlusion after AC placement is usually dependent on soft tissue reaction. Ameroid constrictors ≥5 mm diameter may not promote complete shunt occlusion.

Objective —To evaluate fluid production and factors associated with seroma formation after placement of closed suction drains in clean surgical wounds in dogs. Design —Retrospective case series. Animals —77 client-owned dogs with a subcutaneous closed suction drain placed following a clean surgical procedure. Procedures —Medical records (January 2005 to June 2012) were reviewed, and signalment, site of surgery and underlying disease process, histologic evaluation results, total drain fluid production, fluid production rate (mL/kg/h) at 12-hour intervals, cytologic evaluation of drain fluid, and development of dehiscence, infection, or seroma were recorded. Associations among variables were evaluated. Results —The most common complication was dehiscence (n = 18), followed by seroma (14) and infection (4). Dogs that developed a seroma had significantly greater total drain fluid volume relative to body weight and greater fluid production rate at 24 and 72 hours as well as the last time point measured before drain removal. Dogs in which drains were removed when fluid production rate was > 0.2 mL/kg/h (0.09 mL/lb/h) were significantly more likely to develop a seroma. Conclusions and Clinical Relevance —Seroma formation was more common in dogs with a higher rate of fluid production relative to body weight, but was not associated with the number of days that a closed suction drain remained in situ. Dogs may be at greater risk of seroma formation if their drains are removed while drainage is still occurring at a rate > 0.2 mL/kg/h.

OBJECTIVES To determine the heritability of extra-hepatic portosystemic shunts and elevated post-prandial serum bile acid concentrations in Maltese dogs.MATERIALS AND METHODS Maltese dogs were recruited and investigated by a variable combination of procedures including dynamic bile acid testing, rectal ammonia tolerance testing, ultrasonography, portal venography, surgical inspection or necropsy. In addition, nine test matings were carried out between affected and affected dogs, and affected and unaffected dogs.RESULTS In 135 variably related Maltese, shunt status could be confirmed in 113, including 19 with anextra-hepatic portosystemic shunt (17 confirmed at surgery, 2 at necropsy). Rectal ammonia tolerance testing results and post-prandial serum bile acid concentrations were retrievable for 50 and 88 dogs, respectively. Pedigree information was available for these 135 and an additional 164 related dogs. Two consecutive test matings were carried out between two affected animals (whose shunts had been attenuated), with 2 of 8 (25%) of offspring having an extra-hepatic portosystemic shunt. Six test matings were carried out between an affected and an unaffected animal, with 2 of 22 (9%) offspring affected. Heritability of extra-hepatic portosystemic shunt was 061 calculated using variance components analysis [95% confidence interval (CI) 014 to 10, P=0001]. The best fitting model from segregation analysis was a common, partially penetrant, recessive model (allele frequency 034, penetrance 099, CI 009 to 10). The heritability of elevated post-prandial serum bile acid (and thus likely portal vein hypoplasia) was 081 (CI 043 to 10, P=02) after logarithmic transformation of post-prandial serum bile acid concentrations.CLINICAL SIGNIFICANCE There is strong support for extra-hepatic portosystemic shunts and elevated post-prandial serum bile acid concentrations both being inherited conditions in Maltese.

ObjectiveTo correlate changes in hepatic volume, hepatic perfusion, and vascular anatomy of dogs with congenital extrahepatic portosystemic shunts, before and after attenuation with an ameroid constrictor.Study DesignProspective study.AnimalsDogs (n=22) with congenital extrahepatic portosystemic shunts.MethodsCT angiography and perfusion scans were performed before and after attenuation of a portosystemic shunt with an ameroid constrictor. Changes in hepatic volume, hepatic perfusion, and vascular anatomy were measured. Portal scintigraphy was performed in 8 dogs preoperatively and 22 dogs postoperatively.ResultsDogs with smaller preoperative liver volumes had greater increases in liver volume postoperatively compared with those with larger preoperative liver volumes. Hepatic arterial fraction was increased in dogs preoperatively and returned to normal range after shunt attenuation, and was correlated with increase in liver size and decreased shunt fraction. Three dogs with no visible portal vasculature preoperatively developed portal branches postoperatively.ConclusionsDogs with smaller preoperative liver volumes had the largest postoperative increase in liver volume. Hepatic arterial perfusion and portal scintigraphy correlate with liver volume and are indicators of successful shunt attenuation. Dogs without visible vasculature on CT angiography had visible portal vasculature postoperatively.