Unusual case of pleural effusion caused by amlodipine in a dog with systemic hypertension.

OBJECTIVE: The aim of this report is to document the case of a dog that developed pleural effusion as a potential side-effect to the administration of a high-dose of amlodipine. CASE SUMMARY: A Yorkshire terrier dog (13-year-old, castrated male, 4.5 kg) presented with severe systemic hypertension (>200 mmHg), hyperkalaemia, and acute pancreatitis. The dog had hyperadrenocorticism, chronic valvular heart disease, chronic kidney disease, and cerebellar infarction as underlying diseases. Additionally, the dog had laboured breathing and tachypnoea during hospitalization. Screening examinations revealed a pleural effusion (pure transudate) for which hypoalbuminemia and thromboembolism were ruled out as the causes. Therefore, the adverse drug event of an anti-hypertensive drug (amlodipine) was tentatively diagnosed. CONCLUSIONS: Pleural effusion resolved within 24 h of reducing the dosage of amlodipine. Hence, the dog was diagnosed with amlodipine-induced pleural effusion. Rarely, amlodipine can cause pleural effusion after high-dose administrations in humans, but only two cases of peripheral edema have been reported in animals. If pleural effusion occurs in hypertensive patients administered amlodipine, it should be considered as the potential cause.

Translocation of the conus medullaris during dynamic lumbosacral magnetic resonance imaging in dogs.

OBJECTIVE: To investigate the change in the lumbosacral angle (ΔLSA) and conus medullaris (CM) displacement in healthy dogs undergoing dynamic MRI with changes in the posture of their pelvic limbs from neutral posture to flexion or extension posture and to evaluate for potential correlation between ΔLSA and CM displacement. ANIMALS: 9 healthy adult Beagles. PROCEDURES: Dogs underwent dynamic MRI with their pelvic limbs positioned in neutral, flexion, and extension postures. From T2-weighted sagittal midline plane MRI images, 2 observers measured the lumbosacral angle and CM location in duplicate for each posture for each dog. Intra- and interobserver agreement was assessed, and the Spearman rank correlation coefficient (ρ) was used to assess for potential correlation between ΔLSA and CM displacement for changes in pelvic limb posture from neutral to flexion or extension. RESULTS: Overall, the mean ΔLSA and CM displacement for changes in posture were 23° and 9.09 mm (caudal displacement) for the change from neutral to flexion posture, 8.4° and -2.5 mm (cranial displacement) for the change from neutral to extension posture, and 32.2° and 11.64 mm (caudal displacement) for the change from extension to flexion posture. The ΔLSA strongly correlated (ρ = 0.705; 95% CI, 0.434 to 0.859) with displacement of the CM. CONCLUSIONS AND CLINICAL RELEVANCE: The use of dynamic MRI, compared with conventional MRI, will better help to characterize clinically normal and abnormal features of the lumbosacral region of the vertebral column and associated spinal cord during postural changes. Further, when limited translocation of the CM is evident on dynamic MRI, veterinarians should suspect underlying lumbosacral pathophysiologic processes or anatomic abnormalities.

Engineering Vibrio sp. SP1 for the production of carotenoids directly from brown macroalgae.

Macroalgae is regarded as a promising third-generation marine biomass that can be utilized as a sustainable feedstock for bio-industry due to the high sugar level and absence of lignin. Alginate, composed of 1,4-linked D-mannuronate (M) and L-guluronate (G), is one of the major carbohydrates in brown macroalgae. It is difficult to be assimilated by most industrial microorganisms. Therefore, developing engineered microorganisms that can utilize alginate as a feedstock in order to produce natural products from marine biomass is critical. In this study, we isolated, characterized, and sequenced Vibrio sp. SP1 which rapidly grows using alginate as a sole carbon source. We further engineered this strain by introducing genes encoding enzymes under the control of synthetic expression cassettes to produce lycopene and ß-carotene which are attractive phytochemicals owing to the antioxidant property. We confirmed that the engineered Vibrio sp. SP1 could successfully produce 2.13 ± 0.37 mg L-1 of lycopene, 2.98 ± 0.43 mg L-1 of ß -carotene, respectively, from 10 g L-1 of alginate as a sole carbon source. Furthermore, our engineered strain could directly convert 60 g L-1 of brown macroalgae Sargassum fusiforme into 1.23 ± 0.21 mg L-1 of lycopene without any pretreatment which had been vitally required for the previous productions. As the first demonstrated strain to produce high-value product from Sargassum, Vibrio sp. SP1 is evaluated to be a desirable platform for the brown macroalgae-based biorefinery.

Point shear wave elastography of the liver in healthy adult cats.

OBJECTIVE: To evaluate stiffness of the liver parenchyma in healthy adult cats by means of point shear wave elastography (PSWE). ANIMALS: 18 client-owned adult (1- to 6-year-old) healthy cats. PROCEDURES: Echogenicity and echotexture of the liver parenchyma were assessed by means of conventional B-mode ultrasonography. The shear wave velocity (Vs) of the right and left portions of the liver were measured by means of PSWE. RESULTS: B-mode ultrasonography revealed no abnormalities in echotexture or echogenicity of the liver parenchyma in any cat. Mean (95% CI) Vs in the liver parenchyma was 1.46 m/s (1.36 to 1.55 m/s) for the right portion, 1.36 m/s (1.26 to 1.47 m/s) for the left portion, and 1.43 m/s (1.35 to 1.51 m/s) overall. The difference in mean Vs between the 2 portions of the liver was significant. No significant correlation was found between Vs and body weight or between Vs and the depth at which this variable was measured. CONCLUSIONS AND CLINICAL RELEVANCE: Quantitative PSWE of the liver was feasible in healthy adult cats. The obtained values for Vs may be useful for interpretation of and comparison with values measured in cats with liver disease. Additional research is needed to explore the potential usefulness of PSWE for diagnostic purposes.

Antegrade and retrograde CT urethrography with virtual urethroscopy in a dog with urethral narrowing after bilateral triple pelvic osteotomy.

An 8-month-old, castrated male Golden Retriever was unable to urinate without catheterization after a single-session bilateral triple pelvic osteotomy. To determine the cause, a retrograde urethrography was performed, but the results were equivocal. Antegrade (voiding by abdominal compression with heavy material) and retrograde CT urethrography were performed with virtual urethroscopy and revealed that the urethral diameter was narrowed near the pubic bone remnants due to pelvic canal narrowing. After corrective surgery, the patient was able to urinate normally. A combination of antegrade and retrograde CT urethrography with virtual urethroscopy was helpful for guiding surgical decision-making in this patient.

The urethra of healthy female dogs can be normally narrowed due to the urethral flexure in retrograde CT urethrography.

Quantitative analysis of urethral size in male dogs by retrograde CT urethrography using a power injector is a recently reported technique. The aim of the current, prospective, analytical study was to apply the same method to six, healthy, intact female Beagle dogs. The proximal (P < .0001) and middle (P = .0010) urethral volumes significantly differed between the empty and distended bladder states, although no significant difference was observed in the distal volume (P = .0971). Unlike male dogs, female dogs showed two patterns of the urethral course: a straight urethra and urethral flexure. The urethral flexure was always related to intrapelvic position of the urinary bladder, and the more caudal the location of the vesicourethral junction beyond the pecten of the pubic bone, the more marked the appearance of the urethral flexure. Analysis of the urethral diameter at five sites (adopted from the previous radiographic study) was performed, and the urethral diameter showed a significant difference between the empty and the distended bladder states at sites 1 (vesicourethral junction, P < .0001), 2 (P < .0001), and 3 (P = .0244). However, there were no significant differences at sites 4 (P = .2516) and 5 (inflatable retention bulb, P = .1260). The urinary bladder may be in part intrapelvically located in clinically healthy female dogs, and urethral flexure and urethral narrowing can result from the intrapelvic location of the bladder. Narrowing of the urethra should be interpreted with caution when the pelvic bladder is identified.

Evaluation of a dual-purpose contrast medium for radiography and ultrasonography of the small intestine in dogs.

OBJECTIVE: To evaluate a contrast medium that could be used for radiographic and ultrasonographic assessment of the small intestine in dogs. ANIMALS: 8 healthy adult Beagles. PROCEDURES: Carboxymethylcellulose (CMC; 0.5% solution) was combined with iohexol (300 mg of iodine/mL) to yield modified contrast medium (MCM). Dogs were orally administered the first of 3 MCMs (10 mL/kg [9.5 mL of CMC/kg plus 0.5 mL of iohexol/kg]). Radiographic and ultrasonographic assessment of the small intestine followed 10 minutes after administration and every 10 minutes thereafter, until MCM was seen within the ascending colon. Minimally, 1 week elapsed between dosing of subsequent MCMs (10 mL/kg [9 mL of CMC/kg plus 1 mL of iohexol/kg and 8.5 mL of CMC/kg plus 1.5 mL of iohexol/kg]) and repeated radiography and ultrasonography. RESULTS: Radiographic contrast enhancement of the small intestine was best with MCM that combined 8.5 mL of CMC/kg and 1.5 mL of iohexol/kg. Mean small intestinal transit time for all MCMs was 86 minutes. All MCMs did not interfere with ultrasonographic assessment of the small intestine and may have improved visualization of the far-field small intestinal walls. CONCLUSIONS AND CLINICAL RELEVANCE: An MCM that combined 8.5 mL of 0.5% CMC/kg and 1.5 mL of iohexol/kg could be an alternative to barium or iohexol alone for contrast small intestinal radiography in dogs, especially when abdominal ultrasonography is to follow contrast radiography.

Can distinction between the renal cortex and outer medulla on ultrasonography predict estimated glomerular filtration rate in canine chronic kidney diseases?

BACKGROUND: Quantitative evaluation of renal cortical echogenicity (RCE) has been tried and developed in human and veterinary medicine. OBJECTIVES: The objective of this study was to propose a method for evaluating RCE quantitatively and intuitively, and to determine associations between ultrasonographic renal structural distinction and estimated glomerular filtration rate (eGFR) in canine chronic kidney disease (CKD). METHODS: Data were collected on 63 dogs, including 27 with normal kidney function and 36 CKD patients. Symmetric dimethylarginine and creatinine concentrations were measured for calculating eGFR. RCE was evaluated as 3 grades on ultrasonography images according to the distinction between the renal cortex and outer medulla. The RCE grade of each kidney was measured. RESULTS: There was a significant difference in eGFR between the group normal and CKD (p < 0.001). As mean of RCE grades (the mean values of each right and left kidney's RCE grade) increases, the proportion of group CKD among the patients in each grade increases (p < 0.001). Also, severity of RCE (classified as "high" if any right or left kidney evaluated as RCE grade 3, "low" otherwise) and eGFR is good indicator for predicting group CKD (p < 0.001). CONCLUSIONS: The degree of distinction between the renal cortex and the outer medulla is closely related to renal function including eGFR and the RCE grade defined in this study can be used as a method of objectively evaluating RCE.

Proper fraction of inspired oxygen for reduction of oxygen-induced canine cerebrospinal fluid hyperintensity on fluid attenuation inversion recovery sequence using low-field magnetic resonance imaging.

Oxygen-induced cerebrospinal fluid (CSF) hyperintensity artifact is inevitable in fluid attenuation inversion recovery (FLAIR) magnetic resonance (MR) images of anesthetized animals. This experimental study aimed to confirm the occurrence of this artifact on low-field magnetic resonance imaging (MRI), and to determine the fraction of inspired oxygen (FiO2) that is safe and does not induce this artifact in canine brain MRI. Six healthy dogs underwent brain FLAIR MR scans under general anesthesia with 21%, 30%, 50%, 70%, and 100% FiO2. The signal intensity (SI) ratio was calculated as the SI of CSF spaces divided by that of normalizing regions. The SI ratios of 21% FiO2 images were significantly different from those of 100% FiO2 images, indicating the presence of artifacts on 100% FiO2 images. The SI ratios of 30% FiO2 images were not significantly different from those of 21% FiO2 images for any of CSF spaces. However, they were significantly different from those of 100% FiO2 images in the cerebral sulci, third ventricle, interpeduncular cistern, mesencephalic aqueduct, and subarachnoid space at the level of the first cervical vertebra (P<0.05). All dogs had normal partial pressure of arterial oxygen (PaO2) during inhalation of 30% FiO2, while two dogs had low PaO2 during inhalation of 21% FiO2. Our findings support the hypothesis that high FiO2 induces CSF hyperintensity artifact on low-field FLAIR MR images in dogs. FiO2 of 30% is appropriate for obtaining brain FLAIR MR images with fewer artifacts in dogs.

Contrast-enhanced ultrasound sonography combined with strain elastography to evaluate mandibular lymph nodes in clinically healthy dogs and those with head and neck tumors.

Determining lymph node metastases in dogs with neoplasia is important in staging and developing a therapeutic plan. In this study, the clinical efficacy of combined lymphosonography and strain elastography was evaluated for its ability to identify metastatic mandibular lymph nodes. Data from clinically healthy dogs (n = 16) and those with head/neck tumors (n = 11) were enrolled. Strain elastographic patterns were classified according to the percentage of the stiffness lymph node area (grade 1-4/4). Lymphosonographic images were evaluated quantitatively (visualization of lymphatic vessels/lymph nodes; contrast transit time) and qualitatively (enhancement pattern). There was a significant difference in the strain elastographic pattern (P = 0.011) and lymphosonographic contrast enhancement (P = 0.001) in the metastatic nodes compared to clinical healthy or non-metastatic nodes. Mandibular lymph nodes with filling defects after lymphosonography and high-grade strain elastographic patterns suggested metastasis, and the combination of lymphosonography and strain elastography was useful for identifying malignancy.

Transplantation of hMSCs Genome Edited with LEF1 Improves Cardio-Protective Effects in Myocardial Infarction.

Stem cell-based therapy is one of the most attractive approaches to ischemic heart diseases, such as myocardial infarction (MI). We evaluated the cardio-protective effects of the human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) stably expressing lymphoid enhancer-binding factor 1 (LEF1; LEF1/hUCB-MSCs) in a rat model of MI. LEF1 overexpression in hUCB-MSCs promoted cell-proliferation and anti-apoptotic effects in hypoxic conditions. For the application of its therapeutic effects in vivo, the LEF1 gene was introduced into an adeno-associated virus integration site 1 (AAVS1) locus, known as a safe harbor site on chromosome 19 by CRISPR/Cas9-mediated gene integration in hUCB-MSCs. Transplantation of LEF1/hUCB-MSCs onto the infarction region in the rat model significantly improved overall survival. The cardio-protective effect of LEF1/hUCB-MSCs was proven by echocardiogram parameters, including greatly improved left-ventricle ejection fraction (EF) and fractional shortening (FS). Moreover, histology and immunohistochemistry successfully presented reduced MI region and fibrosis by LEF1/hUCB-MSCs. We found that these overall positive effects of LEF1/hUCB-MSCs are attributed by increased proliferation and survival of stem cells in oxidative stress conditions and by the secretion of various growth factors by LEF1. In conclusion, this study suggests that the stem cell-based therapy, conjugated with genome editing of transcription factor LEF1, which promotes cell survival, could be an effective therapeutic strategy for cardiovascular disease.

Retrograde CT urethrography using a power injector quantitatively reveals effects of bladder distension on urethral size in healthy male Beagle dogs.

Quantitative analysis of the normal retrograde urethrogram is well reported in radiography, but studies on CT urethrography are lacking. Recently, a method of retrograde CT urethrography using a power injector was described. The purpose of the current, prospective, analytical study was to quantify the urethral size of five, healthy, intact, male Beagle dogs using retrograde CT urethrography and a power injector. With the injection rate of the power injector set at 0.3 mL/s, 1 mL/kg of diluted contrast medium (15 mg I/mL) was injected, and a CT examination was performed. The state of the initial urethrogram taken was defined as "empty bladder." The same procedures were repeated with the injection of an additional 1 mL/kg of diluted contrast medium until the ureteral reflux was seen (distended bladder). There was a significant difference in volumes between the empty and distended bladder, but the membranous urethra showed the least difference (P = .0044) among the three regions (P < .0001 for the prostatic and penile urethra). Urethral diameters at six sites were measured from sagittal images, and the sites of measurements were adopted from the earlier radiographic studies. The most significant difference in the urethral diameters between the empty and distended bladder occurred at the cranial and middle prostatic urethra (P < .0001). The results of this study can be useful for interpreting the results of retrograde CT urethrography. Care must be taken when narrowing is suspected at the prostatic urethra, and if necessary, further distension of the urinary bladder should be tried.

Feasibility and Reliability of Two-Dimensional Shear-Wave Elastography of the Liver of Clinically Healthy Cats.

Given the broad overlap of normal and abnormal liver tissue in the subjective evaluation of the liver in conventional B-mode ultrasonography, there is a need for a non-invasive and quantitative method for the diagnosis of liver disease. Novel two-dimensional shear-wave elastography (2-D SWE) can measure tissue stiffness by propagation of the shear wave induced using acoustic radiation force impulse in real time. To the best of our knowledge, two-dimensional shear-wave measurement of the liver in cats has not been reported to date. This study assessed the feasibility, reliability, normal values, and related influencing factors of 2-D SWE for assessment of the feline liver without anesthesia and breath-holding. Two-dimensional shear-wave ultrasonography was performed by two evaluators at the right and left sides of the liver. Twenty-nine client-owned clinically healthy adult cats were included. The means and standard deviations for the shear-wave speed and stiffness in the right liver were 1.52 ± 0.13 m/s and 6.94 ± 1.26 kPa, respectively, and those for the left liver were 1.61 ± 0.15 m/s and 7.90 ± 1.47 kPa, respectively. Shear-wave speed (P = 0.005) and stiffness (P = 0.002) were significantly lower in the right liver when compared to the left. The intraclass correlation value for liver stiffness was 0.835 and 0.901 for the right and left liver, respectively, indicating high interobserver agreement. Age, weight, body condition score (BCS), gabapentin administration, and measurement depths were not significantly correlated with liver stiffness or elastography measurements (P > 0.05). Our findings suggest that 2-D SWE measurements of the liver are not influenced significantly by age, weight, or BCS and can be reliably performed without anesthesia and breath-holding in cats. The values determined here can help form the basis for reference elastography values for evaluation of the feline liver.

Computed tomographic lymphangiography of the thoracic duct by subcutaneous iohexol injection into the metatarsal region.

OBJECTIVE: To evaluate the efficacy of subcutaneous iohexol injection into the metatarsal region for thoracic duct lymphangiography in dogs and to determine the minimum effective dose. STUDY DESIGN: Experimental study and clinical report. ANIMALS: Five healthy beagle dogs and one dog with chylothorax. METHODS: For the experimental study, iohexol was injected subcutaneously into the metatarsal region of five dogs at three doses (0.5, 0.75, and 1 mL/kg), and the injection sites were massaged gently. Computed tomography (CT) was performed 1, 3, 5, 7, 10, 15, and 20 minutes after iohexol injection. Subjective quality was assessed, and Hounsfield unit values were measured at several regions of interest (T1, T4, T8, T13, and L3). In the dog with chylothorax, iohexol (1.0 mL/kg) was injected into the right metatarsal region prior to CT. RESULTS: The thoracic duct was visualized and enhanced by contrast in all dogs after injection of 0.75 and 1.0 mL/kg of iohexol, and in two dogs after injection of 0.5 mL/kg at 3, 5, and 7 minutes. The thoracic duct was gradually attenuated with increasing doses of iohexol. In the dog with chylothorax, the entire thoracic duct was well enhanced and dilated, and tortuous cranial mediastinal lymphatics were detected. CONCLUSION: The thoracic duct was visualized when at least 0.75 mL/kg of iohexol was injected subcutaneously into the metatarsal region of dogs. CLINICAL SIGNIFICANCE: Subcutaneous injection of iohexol into the metatarsal region offers a simple alternative to conventional thoracic duct lymphangiography.

Semi-quantitative strain elastography may facilitate pre-surgical prediction of mandibular lymph nodes malignancy in dogs.

Evaluation of mandibular lymph nodes in a patient with head and neck cancer is important for stage determination and prognosis development, and, in human medicine, the use of sonoelastography for differentiating between non-metastatic and metastatic lymph nodes has been reported. Our prospective, cross-sectional study aimed to evaluate the diagnostic performance of strain elastography and to determine elastographic cut-off values for predicting malignancy. Sixty-six mandibular lymph nodes were included (clinical healthy, n = 45; non-metastatic, n = 8; and metastatic, n = 13). Elastographic images were evaluated qualitatively (elastographic pattern) and semi-quantitatively (mean hue histogram and stiffness area ratios). Elastographic patterns were classified as grades 1 to 4, according to the percentage of high elasticity determined by visualization. The mean hue histogram was defined based on as the mean pixel color values within the lymph node. Stiffness area ratios were determined by computer program analysis of the stiff area. Among the criteria, receiver operating characteristic curve analyses revealed cut-off values for the prediction of malignancy of 92.26 for mean hue histogram (sensitivity: 100%, specificity: 92%), and 0.17 for stiffness area ratios (sensitivity: 86%, specificity of 100%). Reproducibility and repeatability were excellent. In conclusion, semi-quantitative evaluation via strain elastography holds potential for predicting lymph node malignancy.

Erratum: A retrospective study of theophylline-based therapy with tracheal collapse in small-breed dogs: 47 cases (2013-2017).

This corrects the article on e57 in vol. 20, PMID: 31565900.

A retrospective study of theophylline-based therapy with tracheal collapse in small-breed dogs: 47 cases (2013-2017).

Theophylline acts as a bronchodilator and has an anti-inflammatory effect. In addition, theophylline can be applied in patients where there are concerns regarding the side-effects of corticosteroids. This retrospective case series evaluated theophylline-based therapy in tracheal collapse (TC) canine patients. Forty-seven dogs with TC that received theophylline-based therapy during 2013-2017 were investigated. A fluoroscopic examination was performed to diagnose and grade TC. Theophylline was prescribed (7.5-30 mg/kg PO q12h) and the theophylline serum concentrations were measured. Coughing was assessed using a coughing scoring scale. The mean coughing score decreased after the theophylline-based therapy compared with that observed before treatment. Clinical improvements were observed in 46/47 patients (97.9%). As the intrathoracic TC grading increased, the final theophylline dosage also increased (p value 0.019). The symptom-free period (SFP) with therapy was 189.7 ± 194.45 days (range, 0-720 days) and there was no statistically significant correlation between the SFP and age, sex, or TC grade on fluoroscopy. Although theophylline has generally been used as a third-line treatment, it was used as the main treatment in this study and most patients showed improvements. Dogs have a wider therapeutic index of serum concentrations than humans, and any undesirable effects were easily overcome. With further research, this therapy may prove to be a useful approach, but its safety for long-term use in the treatment of canine TC patients needs to be established.

Effect of catheter diameter and injection rate of flush solution on renal contrast-enhanced ultrasonography with perfluorobutane in dogs.

OBJECTIVE: To assess effects of catheter diameter and injection rate of flush solution (saline [0.9% NaCl] solution) on renal contrast-enhanced ultrasonography (CEUS) with perfluorobutane in dogs. ANIMALS: 5 healthy Beagles. PROCEDURES: CEUS of the kidneys was performed by IV injection of contrast medium (0.0125 mL/kg) followed by injection of 5 mL of saline solution at rates of 1, 3, and 5 mL/s through a 20-gauge or 24-gauge catheter; thus, CEUS was repeated 3 times for each catheter diameter. Time-intensity curves were created for regions of interest drawn in the renal cortex and medulla. Repeatability was determined by calculating the coefficient of variation (CV). Statistical analysis was used to assess whether perfusion variables or CV of the perfusion variables was associated with catheter diameter or injection rate. RESULTS: Perfusion variables did not differ significantly between catheter diameters. Time to peak enhancement (TTP) in the renal cortex was affected by injection rate, and there were significantly lower values for TTP at higher injection rates. The CEUS variables with the lowest CVs among injection rates were TTP for the renal cortex; the CV for TTP of the renal cortex was the lowest at an injection rate of 5 mL/s. CONCLUSIONS AND CLINICAL RELEVANCE: Use of a 24-gauge catheter did not alter CEUS with perfluorobutane; therefore, such catheters could be used for CEUS of the kidneys of small dogs. Moreover, a rate of 5 mL/s is recommended for injection of flush solution to obtain greater accuracy for renal CEUS in Beagles.

Usefulness of a saline chaser to reduce contrast material dose in abdominal CT of normal dogs.

Use of a saline chaser has been reported to allow reduction of contrast dose and artifacts during computed tomography (CT) examination in humans. This study assesses the extent of contrast dose by using a saline chaser in abdominal CT scans of normal dogs. Five beagles underwent abdominal CT scans. Three protocols were applied: 600 mg I/kg iohexol without saline chaser (protocol 1), 30% lower dose of iohexol (420 mg I/kg) followed by a 10 mL saline chaser (protocol 2), and 40% lower dose of iohexol (360 mg I/kg) followed by a 10 mL saline chaser (protocol 3). Attenuation values were obtained from aorta, portal vein, and liver parenchyma. The maximum enhancement values (MEVs) in protocol 2 were significantly higher than those in protocols 1 and 3 in the aorta; no difference was seen in the portal vein in all protocols. The liver parenchymal MEVs in protocols 1 and 2 were significantly higher than those obtained in protocol 3. In this study, the use of a saline chaser and a reduced dose of contrast material did not affect vessel enhancement. In conclusion, use of a saline chaser for abdominal CT of dogs is recommended because it allows a 30% reduction of contrast dose without decreasing vascular and hepatic parenchymal enhancement.

Effects of airway pressure on contrast enhancement and diameter of the pulmonary artery in healthy dogs as determined by use of computed tomography angiography.

OBJECTIVE: To evaluate effects of airway pressure on contrast enhancement and diameter of the pulmonary artery and determine the optimal airway pressure for pulmonary CT angiography in dogs. ANIMALS: 8 healthy Beagles. PROCEDURES: Thoracic CT was performed at end-expiration (0 cm H2O) and 2 positive-pressure end-inspirations (10 and 20 cm H2O). Attenuation curves of enhancement for the sinus of the pulmonary trunk artery were obtained by use of a bolus technique. Contrast medium (300 mg of I/kg) was administered IV, and CT imaging began at the time of peak enhancement. At each pressure, time to peak enhancement, ratio of blood flow from the caudal vena cava to the right side of the heart (KCdVC), and enhancement characteristics and diameter changes of the pulmonary artery were evaluated. RESULTS: All dogs had a significant delay for time to peak enhancement in the sinus of the pulmonary trunk artery as airway pressure increased. The KCdVC progressively increased as airway pressure increased, and there was low contrast enhancement and increased pulmonary artery filling defects at 20 cm H2O. All pulmonary arteries had marked increases in diameter as pressure increased. Arterial distensibility in the gravity-dependent cranial lung region was greater than that in the gravity-independent caudal lung region at the 2 positive-pressure end-inspirations. CONCLUSIONS AND CLINICAL RELEVANCE: Airway pressure affected time to peak enhancement, KCdVC, contrast enhancement, and pulmonary artery diameter. Results suggested that 10 cm H2O could be an optimal pressure for evaluation of the pulmonary artery of dogs by use of CT angiography. (Am J Vet Res 2019;80;756-763).