REGIONAL BRAIN PERFUSION IN 10 NORMAL DOGS MEASURED USING TECHNETIUM-99m ETHYL CYSTEINATE DIMER SPECT

Single photon emission computed tomography (SPECT) of the brain using perfusion tracers allows estimation of regional brain perfusion. This allows in vivo examination of brain function in the setting of neuropsychologic and pathophysiologic changes. However functional imaging data on brain perfusion in dogs are limited. Hence, the aim of this study was to determine the scintigraphic regional perfusion pattern of the normal canine brain. Ten healthy shepherd type dogs were injected with 925 MBq Technetium-99m ethyl cysteinate (ECD) 20 minutes before the examination. Acquisition was performed using a triple head gamma camera equipped with fanbeam collimators. Uniform attenuation correction and triple energy window correction were applied. Computed tomographic images were obtained from the same dogs, reoriented along the orbito-meatal axis and SPECT perfusion data were coregistered to the CT-volume data. Based on morphological and suggested brain divisions, regions-of-interest (ROIs) were defined for the bilateral frontocerebral, temporocerebral, parietocerebral, occipitocerebral, cerebellar, thalamic, and striatal area. Regional count density was normalized on total counts. All dogs had the highest uptake in the thalamic/striatal area compared to a rather homogeneous cerebral uptake. No significant left/right count differences were found, but a rostro-caudal gradient (+12-13%) was present. In this group, age and gender did not influence the perfusion pattern.     

CLINICAL MAGNETIC RESONANCE VOLUMETRY OF THE HIPPOCAMPUS IN 58 EPILEPTIC DOGS*

Hippocampal atrophy, which is a component of hippocampal sclerosis and recognized commonly in human intractable epilepsy, is controversial in canine epilepsy. We examined the hippocampal volume in 58 epileptic dogs and 35 control dogs using magnetic resonance (MR) images, and calculated the relative hippocampal volume asymmetry of the right and left hippocampus. Subjectively, there were visible MR imaging abnormalities in seven of the 58 epileptic dogs (12%). The hippocampel volume asymmetric ratio of epileptic dogs (5.84±4.47%) was significantly greater than that of control dogs (1.62±0.88%). Using a cutoff threshold asymmetric ratio of 6% that is indicated in human epilepsy, 28 epileptic dogs (48%) were characterized as having unilateral hippocampus atrophy. The hippocampal volume asymmetry ratio cannot be used to detect bilateral atrophy. In conclusion, although less frequent than that observed in human epilepsy patients, hippocampal atrophy may occur in canine epilepsy.     

DOHUBLE-PHASE PARATHYROID SCINTIGRAPHY IN DOGS USING TECHNETIUM-99M-SESTAMIBI

The purpose of this study was to evaluate the utility of double-phase parathyroid scintigraphy using 99mTc-sestamibi for detecting and localizing hyperfunctioning parathyroid glands in hypercalcemic dogs. Fifteen hypercalcemic dogs that underwent parathyroid scintigraphy were included in this study: 3 dogs with hypercalcemia of malignancy, and 12 dogs with hyperfunctioning parathyroid tissue (parathyroid adenoma or parathyroid hyperplasia). The presence of parathyroid adenoma or parathyroid hyperplasia was documented by histopathologic examination. In 3 dogs with hypercalcemia of malignancy, parathyroid scintigraphy was negative for hyperfunctioning parathyroid tissue and the scans were classified as true negative. Parathyroid scintigraphy correctly identified the presence and location of hyperfunctioning parathyroid tissue in only 1 of 6 dogs with a parathyroid adenoma. False positive and false negative results occurred in dogs with parathyroid adenomas. Parathyroid scintigraphy failed to detect hyperfunctioning parathyroid tissue in 5 of 6 dogs with parathyroid hyperplasia and were classified as false negative. False positive results were obtained in the remaining dog with parathyroid hyperplasia. Sensitivity of parathyroid scintigraphy for detecting and localizing hyperfunctioning parathyroid tissue was 11%, specificity was 50%, and overall accuracy was 27%. Positive and negative predictive value were 25% and 27%, respectively. Sensitivity for detection of parathyroid adenomas was 25%, and sensitivity for detection of hyperplastic glands was 0 %. Results of this study indicate that double-phase parathyroid scintigraphy does not appear to have acceptable accuracy in detecting hyperfunctioning parathyroid glands in dogs. Due to the poor sensitivity and specificity of the technique in dogs, parathyroid scintigraphy is not recommended for definitive identification of abnormal parathyroid glands as the cause of hypercalcemia in dogs.     

PREVALENCE OF LATERAL VENTRICLE ASYMMETRY IN BRAIN MRI STUDIES OF NEUROLOGICALLY NORMAL DOGS AND DOGS WITH IDIOPATHIC EPILEPSY

Asymmetry of the cerebral lateral ventricles is a common finding in cross‐sectional imaging of otherwise normal canine brains and has been assumed to be incidental. The purpose of this retrospective study was to compare the prevalence of ventricular asymmetry in brain MRI studies of normal dogs and dogs with idiopathic epilepsy. Brain MRI archives were searched for 100 neurologically normal dogs (Group 1) and 100 dogs with idiopathic epilepsy (Group 2). For each dog, asymmetry of the lateral ventricles was subjectively classified as absent, mild, moderate, and severe based on a consensus of two observers who were unaware of group status. Ventricular areas were measured from transverse T1W images at the level of the interthalamic adhesion. An asymmetry ratio was calculated as the ratio of the larger to smaller ventricular transverse area. There was excellent agreement between subjective assessments of ventricular asymmetry and quantitative assessments using asymmetry ratios (k = 0.995). The prevalence of asymmetry was 38% in Group 1 dogs and 44% in Group 2 dogs. Assymmetry was scored as mild in the majority of Group 2 dogs. There was no significant association between presence/absence and degree of ventricular asymmetry vs. dog group, age, gender, or skull conformation. Findings from the current study supported previously published assumptions that asymmetry of the lateral cerebral ventricles is an incidental finding in MRI studies of the canine brain.     

FDG‐PET IN HEALTHY AND EPILEPTIC LAGOTTO ROMAGNOLO DOGS AND CHANGES IN BRAIN GLUCOSE UPTAKE WITH AGE

Regional cerebral metabolism and blood flow can be measured noninvasively with positron emission tomography (PET). 2‐[¹⁸F]fluoro‐2‐deoxy‐D‐glucose (FDG) widely serves as a PET tracer in human patients with epilepsy to identify the seizure focus. The goal of this prospective study was to determine whether juvenile or adult dogs with focal‐onset epilepsy exhibit abnormal cerebral glucose uptake interictally and whether glucose uptake changes with age. We used FDG‐PET to examine six Lagotto Romagnolo dogs with juvenile epilepsy, two dogs with adult‐onset epilepsy, and five control dogs of the same breed at different ages. Three researchers unaware of dog clinical status visually analyzed co‐registered PET and magnetic resonance imaging (MRI) images. Results of the visual PET analyses were compared with electroencephalography (EEG) results. In semiquantitative analysis, relative standard uptake values (SUV) of regions of interest (ROI) drawn to different brain regions were compared between epileptic and control dogs. Visual analysis revealed areas of hypometabolism interictally in five out of six dogs with juvenile epilepsy in the occipital, temporal, and parietal cortex. Changes in EEG occurred in three of these dogs in the same areas where PET showed cortical hypometabolism. Visual analysis showed no abnormalities in cerebral glucose uptake in dogs with adult‐onset epilepsy. Semiquantitative analysis detected no differences between epileptic and control dogs. This result emphasizes the importance of visual analysis in FDG‐PET studies of epileptic dogs. A change in glucose uptake was also detected with age. Glucose uptake values increased between dog ages of 8 and 28 weeks and then remained constant.     

QUANTITATIVE CONTRAST ULTRASOUND ANALYSIS OF RENAL PERFUSION IN NORMAL DOGS

Eight normal dogs with no evidence of renal disease, weighing between 8 and 25 kg were imaged using contrast harmonic ultrasound after injection of a microbubble contrast medium. All dogs received three separate bolus injections of 0.05 ml of commercial contrast medium (Definity). Time/mean pixel value (MPV) curves were generated for selected regions in the cortex and medulla of the left kidney in each dog. Upslope, downslope, baseline, peak intensity, and time to peak were calculated for each zone. For a bolus injection, within the renal cortex (averaging all subjects) the upslope was 7.4 +/- 1.5 MPV/s, downslope was -0.4 +/- .2 MPV/s, baseline was 66.8 +/- 9.3 MPV, peak was 103.6 +/- 8.2 MPV, time to peak (from injection) was 12.8 +/- 5.3 s and from time of contrast medium reaching the kidney was 5.1 +/- 2.0 s. Within the renal medulla (averaging all subjects), upslope was 2.8 +/- 1.7 MPV/s, downslope was -0.3 +/- .2 MPV/s, baseline was 39.3 +/- 6.0 MPV, peak was 65.2 +/- 14.3 MPV, time to peak from injection was 20.9 +/- 6.4 s and from time of contrast reaching the kidney was 11.6 +/- 4.1 s. These baseline data may prove useful in the evaluation of dogs with diffuse disease or vascular compromise.     

NORMAL REGIONAL DISTRIBUTION OF CEREBRAL BLOOD FLOW IN DOGS: COMPARISON BETWEEN 99mTc‐ETHYLCYSTEINATE DIMER AND 99mTc‐ HEXAMETHYLPROPYLENE AMINE OXIME SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY

Functional imaging provides important insights into canine brain pathologies such as behavioral problems. Two ^99mTc‐labeled single photon emission computed tomography (SPECT) cerebral blood flow tracers—ethylcysteinate dimer (ECD) and hexamethylpropylene amine oxime (HMPAO)—are commonly used in human medicine and have been used previously in dogs but intrasubject comparison of both tracers in dogs is lacking. Therefore, this study investigated whether regional distribution differences between both tracers occur in dogs as is reported in humans. Eight beagles underwent two SPECT examinations first with ^99mTc‐ECD and followed by ^99mTc‐HMPAO. SPECT scanning was performed with a triple head gamma camera equipped with ultrahigh resolution parallel hole collimators. Images were reconstructed using filtered backprojection with a Butterworth filter. Emission data were fitted to a template permitting semiquantification using predefined regions or volumes of interest (VOIs). For each VOI, perfusion indices were calculated by normalizing the regional counts per voxel to total brain counts per voxel. The obtained perfusion indices for each region for both tracers were compared with a paired Student's T‐test. Significant (P < 0.05) regional differences were seen in the subcortical region and the cerebellum. Both tracers can be used to visualize regional cerebral blood flow in dogs, however, due to the observed regional differences, they are not entirely interchangeable.     

MAGNETIC RESONANCE IMAGING FEATURES OF PRIMARY BRAIN TUMORS IN DOGS

Magnetic resonance images of twenty-five dogs with histopathologically confirmed primary brain tumors were evaluated. A lesion was visible in each dog. Meningiomas were extra-axial lesions that enhanced markedly withj gadolinium-DTPA. Glimas were Characteized by intra-axial location, significant mass effect and surrounding edema, and variable enhancement patterns. Choroid plexus tumors and pituitary tumors were differentiated by their location and marked enbancement. Prediction of general typeof tumor was correct in 24 of 25 dogs.     

NON-INVASIVE DIAGNOSIS OF ISCHEMIC BRAIN DAMAGE AFTER CARDIOPULMONARY RESUSCITATION IN DOGS BY USING TRANSCRANIAL DOPPLER ULTRASONOGRAPHY

We have attempted to identify whether it is possible to utilize transcranial Doppler ultrasonography to evaluate the brain damage that occurs after resuscitation from 3 min (control group) and 12 min (damage group) of cardiac arrest in dogs. In this study we used transcranial Doppler ultrasonography to follow the basilar arterial flow and middle cerebral arterial flow for 180 min following the induction of cardiac arrests. Two abnormal waveform patterns (the "to-and-fro" and "diastolic no-flow" patterns) were found in all dogs in the damage group whereas abnormal waveforms were not detected in the control group. Pathological diagnosis revealed that, compared with the control group, the damage group recognized ischemic alteration at the level of the hippocampus and caudate nucleus. In conclusion, this study shows that the basilar arterial flow of observed with transcranial Doppler ultrasonography may be use for the prediction of outcome and the diagnosis of brain damage in the dog.     

RADIOGRAPHIC BONE LOSS CORRELATIONS AND TECHNETIUM-99m-MDP BONE UPTAKE IN LIGATURE-INDUCED PERIODONTAL DISEASE IN THE BEAGLE

The goal of this study was to develop an animal model for the study of acute periodontal disease using silk ligatures in combination with a soft diet in eleven purebred beagle dogs. The silk ligatures were placed subgingivally on the mandible second and fourth premolar on one side of the mouth; the opposite side served as a control. Dogs were monitored during the 16–20 weeks of ligature placement, and for 48 weeks after ligature removal. Development of periodontal disease was evaluated by radiopharmaceutical uptake into bone, radiographic evidence of alveolar bone loss, attachment loss, gingival index and prostaglandin level. Bone loss occurred on the ligatured side during the ligature phase of the study. Radiopharmaceutical uptake was correlated with radiographic evidence of bone loss during the ligature phase. No significant bone loss occurred during the post-ligature phase. Progressive periodontal disease was induced during ligature placement. However, a chronic less aggressive form was not sustained by soft diet alone after ligature removal.     

COMPUTED TOMOGRAPHY OF PRIMARY INFLAMMATORY BRAIN DISORDERS IN DOGS AND CATS

A retrospective study of 22 animals with histologically confirmed, primary inflammatory brain disease was undertaken to determine the value of computed tomography in such patients. The histologic diagnosis was confirmed at necropsy in 18 patients and by surgical biopsy in four. All affected animals had neurologic deficits; the most common presenting complaint was seizures. Abnormalities were identified on computed tomography images in 21 of the 22 patients. The abnormalities included ventricular changes, falcial deviation, edema, focal changes in parenchymal opacity, focal contrast enhancement, periventricular contrast enhancement, and a ring-like pattern of contrast enhancement. Many lesion types identified in this study, such as falcial deviation, changes in parenchymal opacity, and ring-pattern enhancement, have previously been associated with neoplasia. The abnormalities correlated well with the lesion localization predicted by neurologic examination and confirmed by surgery or necropsy. Although computed tomography findings were often judged to be compatible with inflammatory disease, they did not predict the type of pathologic process. The findings suggest that computed tomography is valuable in the evaluation of animals with primary inflammatory brain disorders, but differentiation of neoplasia from non-neoplastic diseases is not always possible.     

EVALUATION OF PLASMA TIME-ACTIVITY CURVES OF TECHNETIUM-99M-MEBROFENIN FOR MEASUREMENT OF HEPATIC FUNCTION IN DOGS

In this study, plasma time-activity curves of 99mTc-mebrofenin were used to quantify hepatic function in dogs before and after induction of hepatic damage using a hepatotoxic agent. Nine dogs were determined to be healthy on the basis of physical examination, laboratory data and hepatic imaging. Plasma samples were collected 1, 3, 5, 7, 9, 15, 20, 30, 40, 50, and 60 minutes following a peripheral venous injection of 111-222 MBq (3-6 mCi) of 99mTc-mebrofenin. The area under the plasma time-activity curve (AUC) was calculated using two different methods and compared to direct measurement of the hepatic extraction efficiency. First pass hepatic extraction efficiency of 99mTc-mebrofenin was calculated from differential equation analysis of a two-compartment model following mesenteric venous injection of the radiopharmaceutical. In 7 of the original 9 dogs and 2 additional healthy dogs, plasma clearance and hepatic extraction efficiency determination were repeated following induction of hepatic injury by thiacetarsamide (3 mg/kg IV twice daily for 1 day). In one additional dog, hepatic injury was induced using carbon tetrachloride (0.3 ml/kg IP). Plasma time-activity curves of 99mTc-mebrofenin had kinetics of a two compartment model. Area under the curve was highly correlated with hepatic extraction efficiency. The AUC integrated from 1-60 minutes (AUC60) had the best correlation with hepatic extraction efficiency (r2 = 0.978, p < 0.001). A formula for calculation of hepatic extraction efficiency was derived using linear regression analysis: hepatic extraction efficiency = 105.583 - 3.099 x 10(5) x AUC60. Plasma clearance of a peripheral venous injection of 99mTc-mebrofenin is a simple, non-invasive, convenient method to quantify hepatic function which can be performed without a gamma camera.     

DETECTION OF CARDIAC MASSES IN DOGS BY TWO-DIMENSIONAL ECHOCARDIOGRAPHY

From a two-year review of diagnostic two-dimensional real-time echocardiographic studies, a diagnosis of cardiac mass lesion was made in 18 dogs. Thirteen of 18 also had pericardial effusion. Three types of lesions were identified: (1) right atrial masses (7 dogs; 5 confirmed as hemangiosarcoma) originating from the wall of the right atrium of right auricle and projecting into the atrial lumen, pericardial space, or both; (2) large cavitary pericardial masses (2 dogs; both confirmed as abscesses) located over the right ventricle; (3) heartbase masses (9 dogs; 6 confirmed as neoplasms) attached to the ascending aorta, with varying degrees of infiltration of heartbase structures. Although extrapericardial portions of the masses were not outlined as well as intrapericardial portions, surgical accessibility was correctly predicted in most dogs. It was concluded that two-dimensional echocardiography (2DE), performed systematically using multiple imaging planes, allowed accurate detection and localization of cardiac and pericardial masses in dogs and was useful in predicting surgical accessibility of these lesions.     

UTILITY OF MAGNETIC RESONANCE IMAGING FOR DISTINGUISHING NEOPLASTIC FROM NON-NEOPLASTIC BRAIN LESIONS IN DOGS AND CATS

The aim of this study was to identify magnetic resonance (MR) signs that aid differentiation of neoplastic vs. non-neoplastic brain diseases in dogs and cats. MR images of 36 dogs and 13 cats with histologic diagnosis of intracranial disease were reviewed retrospectively. Diagnoses included 30 primary and three metastatic brain tumors, 11 infectious/inflammatory lesions, three vascular, one degenerative disease, and one developmental malformation. Upon univariate analysis of 21 MR signs, there were seven that had a significant association with neoplasia: single lesion (P = 0.004), shape (P = 0.015), mass effect (P = 0.002), dural contact (P = 0.04), dural tail (P = 0.005), lesions affecting adjacent bone (P = 0.008), and contrast enhancement (P = 0.025). Increasing age was also found to be associated with neoplasia (P = 0.0001). MR signs of non-neoplastic brain diseases in dogs and cats were more variable than those of brain neoplasia.     

TRANSSPLENIC PORTAL SCINTIGRAPHY USING 99MTC-MEBROFENIN IN NORMAL DOGS

Transsplenic portal scintigraphy using sodium pertechnetate is superior to per-rectal portal scintigraphy due to improved visualization of the portal vasculature with decreased patient and personnel exposure. The purpose of this study was to describe the use of 99mTc-mebrofenin, the radiopharmaceutical of choice for the evaluation of hepatic function, in place of pertechnetate for transsplenic portal scintigraphy in normal dogs. Sixteen juvenile dogs underwent transsplenic portal scintigraphy using 37-130 MBq 99mTc-mebrofenin in a 0.2-0.5 ml volume. After the initial dynamic acquisition obtained at 4 frames/s in right lateral recumbency, static right lateral, and ventral views were obtained at 5, 10, 15, 20, 25, 30, 40, 50, and 60 min. A nuclear angiogram of the splenic and portal veins was visible in all dogs, followed by rapid distribution of the radiopharmaceutical in the liver. Hepatic morphology was more easily defined than with pertechnetate. Transit time could not be calculated due to the high hepatic extraction of 99mTc-mebrofenin. Mean +/- SD shunt fraction was 0.8 +/- 0.8%. Time to peak liver activity was 3.1 +/- 1.1 min, and hepatic excretion T1/2 was 19.4 +/- 6.3 min. No visible blood pool and cardiac activity was seen after 5 min. The mean +/- SD time to visualization of defined biliary activity was 8.8 +/- 2.9 min. Absorption from the spleen was significantly higher than that reported for pertechnetate (87.9 +/- 8.2%, vs. 52.5 +/- 19.1%). 99mTc-mebrofenin can be used in place of pertechnetate for transsplenic portal scintigraphy, with the advantage of combining quantitative parameters of liver function with the already known advantage of transsplenic portal scintigraphy.     

ANATOMY OF EXTRAHEPATIC PORTOSYSTEMIC SHUNTS IN DOGS AS DETERMINED BY COMPUTED TOMOGRAPHY ANGIOGRAPHY

Congenital extrahepatic portosystemic shunts are anomalous vessels joining portal and systemic venous circulation. These shunts are often diagnosed sonographically, but computed tomography (CT) angiography produces high‐resolution images that give a more comprehensive overview of the abnormal portal anatomy. CT angiography was performed on 25 dogs subsequently proven to have an extrahepatic portosystemic shunt. The anatomy of each shunt and portal tributary vessels was assessed. Three‐dimensional images of each shunt type were created to aid understanding of shunt morphology. Maximal diameter of the extrahepatic portosystemic shunt and portal vein cranial and caudal to shunt origin was measured. Six general shunt types were identified: splenocaval, splenoazygos, splenophrenic, right gastric‐caval, right gastric‐caval with a caudal shunt loop, and right gastric‐azygos with a caudal shunt loop. Slight variations of tributary vessels were seen within some shunt classes, but were likely clinically insignificant. Two shunt types had large anastomosing loops whose identification would be important if surgical correction were attempted. A portal vein could not be identified cranial to the shunt origin in two dogs. In conclusion, CT angiography provides an excellent overview of extrahepatic portosystemic shunt anatomy, including small tributary vessels and loops. With minor variations, most canine extrahepatic portosystemic shunts will likely be one of six general morphologies.     

EFFECT OF REGION OF INTEREST SELECTION AND UPTAKE MEASUREMENT ON GLOMERULAR FILTRATION RATE MEASURED BY 99mTc-DTPA SCINTIGRAPHY IN DOGS

Determinations of different methods of measurement of uptake of 99mTc-DTPA using scintigraphy of glomerular filtration rate (GFR) were made from 29 studies on 10 healthy beagle dogs. GFR was measured by calculating the percentage dose uptake (integral method) and rate of uptake (slope method) of 99mTc-DTPA using manual kidney regions of interest (ROI) and automatic kidney and background ROIs at different time periods of the uptake phase. These results were compared using linear regression analysis to the GFR obtained from 99mTc-DTPA plasma clearance using multiple blood samples. The best correlation coefficient between percentage DTPA uptake and GFR by DTPA clearance (r = 0.84, P < 0.001) was derived from time intervals between 30s-120s with a perirenal background ROI at 1 or 2 pixels out from the kidney ROI using automatic kidney ROI at 20% threshold. With the slope method, the best correlation coefficient (r = 0.85, P < 0.001) was obtained from time intervals between 30s-peak with the background ROI at 2 pixels out from the kidney ROI using automatic ROI at 35% threshold. The offset was higher, and the correlation varied more with different ROIs and the method was unreliable at time intervals extending beyond the peak radioactivity. Manual kidney ROIs with automatic background ROIs had slightly lower correlations. With DTPA renography both integral and slope uptake method with automatic kidney and background ROIs are accurate methods to estimate the GFR, but that the integral method is much more stable to variations in ROI size and the duration of the uptake phase of the renogram.     

MITRAL ANNULUS MOTION AS DETERMINED BY M-MODE ECHOCARDIOGRAPHY IN NORMAL DOGS AND DOGS WITH CARDIAC DISEASE

M-mode echocardiography was used to assess apical mitral annulus motion (MAM) in 103 normal dogs and 101 dogs with cardiac disease, to obtain information on systolic left ventricular long axis function. In normal dogs, a close relationship was found between MAM and body weight (r = 0.80, P < 0.001). There was a weak correlation between MAM and heart rate (r = -0.25, P < 0.05), but no correlation between MAM and age or left ventricular shortening fraction (P > 0.05). Mean MAM (95% confidence intervals) were established for normal dogs of differing body weight, and were 0.70 cm (0.65 to 0.75) in dogs < 15 kg, 1.08 cm (1.03 to 1.13) in dogs weighing 15 to 40 kg, and 1.51 cm (1.21 to 1.81) in dogs > 40 kg. "Cut-off" values to define decreased MAM for normal dogs of differing body weight were 0.45 cm (dogs < 15 kg), 0.80 cm (dogs 15-40 kg), and 1.20 cm (dogs > 40 kg). In dogs with cardiac disease, median MAM was normal in mitral valve endocardiosis or aortic stenosis, but significantly decreased (P < 0.05) in dilated cardiomyopathy. All dogs with mitral valve endocardiosis (n = 54) or aortic stenosis (n = 26) had MAM above the above-mentioned "cut-off" values, suggesting normal or increased left ventricular longitudinal systolic shortening, whereas 81% (17/21) of dogs with dilated cardiomyopathy had MAM below the "cut-off" value, indicating decreased long axis systolic function. It is concluded that MAM may be used to evaluate systolic left ventricular long axis performance in dogs and may add useful information on global left ventricular contraction dynamics.     

PULMONARY VENOUS FLOW CHARACTERISTICS AS ASSESSED BY TRANSTHORACIC PULSED DOPPLER ECHOCARDIOGRAPHY IN NORMAL DOGS

Transthoracic Doppler echocardiography was used to evaluate the technique of measuring and normal patterns of pulmonary venous flow in fourteen normal dogs. Polyphasic pulmonary venous flow profiles were obtained in all dogs, consisting of one (S) or two (S_E and S_L) systolic forward flow waves, one early diastolic forward flow wave (D), one reverse flow wave (R) related to atrial contraction, and one reverse flow wave (R₂) observed after cessation of systolic flow. Pulmonary venous flow was laminar in 9 dogs (65%). Maximal flow velocity during systole (0.39 ± 0.14 m/sec) was significantly lower (P < 0.01) than in early diastole (0.56 ± 0.14 m/sec). During late diastole peak flow velocity was 0.20 ± 0.08 m/sec and maximum R₂ velocity was 0.17 ± 0.05 m/sec. Duration of mitral A-wave was significantly greater (P < 0.05) than R-wave duration in all dogs (0.075 ± 0.10 vs 0.058 ± 0.012 sec). These results can be used for comparison with patterns found in disease states.