Ataxia and weakness as uncommon primary manifestations of hepatic encephalopathy in a 15‐year‐old trotter gelding

A 15‐year‐old trotter gelding was evaluated because of an acute onset of ataxia in all 4 limbs. There was no known history of trauma. The gelding showed grade 2/5 ataxia in all 4 limbs, which was localised after clinical neurological examination to the cervical vertebral spinal cord. Initial therapy consisted of oral anti‐inflammatory doses of prednisolone and antimicrobial treatment with potentiated sulphonamides. The ataxia progressed to grade 3/5 at Day 10 of hospitalisation. Additionally, the horse was slightly depressed and showed spontaneous yawning during examination. Facial sensation was blunted. Blood chemistry revealed a marked elevation of liver specific enzymes and blood ammonia levels. Transcutaneous abdominal ultrasonography revealed hepatomegaly. Due to a guarded prognosis, the horse was subjected to euthanasia. At necropsy the left lateral liver lobe was markedly enlarged and showed a firm texture, whereas the cranial part and the right and quadratic liver lobe displayed a severe and diffuse atrophy. Histopathologically, the left lateral liver lobe revealed a moderate to severe cirrhosis with a severe, diffuse hepatocellular iron‐accumulation. Increased numbers of Alzheimer type II astrocytes in the cerebral cortex and cerebral white matter vacuolisation were indicative for encephalopathy. These findings were interpreted as haemosiderosis and cirrhosis of the liver with consecutive hepatic encephalopathy. Aetiologically, haemosiderosis should be considered as a cause of liver cirrhosis with consecutive hepatic encephalopathy. Although hepatic encephalopathy in horses usually presents with predominating cerebral signs, it has to be taken into account as a differential diagnosis in cases of acute onset generalised ataxia.     

Cortical laminar necrosis detected by diffusion-weighted imaging in a dog suspected of having hypoglycemic encephalopathy

We describe a 5-year-old castrated male dog suspected hypoglycemic encephalopathy that was evaluated by using diffusion-weighted imaging (DWI). The dog experienced hypoglycemia after prolonged generalized and continued partial seizures. In the acute phase, DWI showed hyperintensity in the left temporal lobe. After about a month, DWI maintained hyperintensity, and left middle cerebral artery dilation was noted on magnetic resonance angiography (MRA). In the chronic phase, the left temporal lobe lesion was replaced by cerebrospinal fluid. In humans, it was reported that cortical laminar necrosis (CLN) with hypoglycemic encephalopathy presents hyperintensity in the cerebral cortex on DWI and increased vascularity of the middle cerebral artery branches on MRA. In conclusion, DWI has detected CLN in a dog suspected hypoglycemic encephalopathy.     

COLOR FLOW DOPPLER IMAGING AND DOPPLER SPECTRAL ANALYSIS OF THE BRAIN OF NEONATAL DOGS

Doppler ultrasonography was performed on the cerebral arteries o f 19 neontal dogs.Vascular structures were identified using anatomic preparations of brains pre-injected with a radiopaque silicone rubber product and cleared using a modified tissue clearing technique. Brain sections were subsequently radiographed of examined under a steromicroscope. Color flow Doppler imagin was used to facilitate positioning of the Doppler calipers for measurement of peak systolic velocity, minimum diastolic velocity, and resistance index. Blood flow velocities in the internal carotid and middle cerebral arteries were lower when measured intransvere images than in sagittal images. The rostral cerebral arteries could be measured using either plane but values obtained from different locations or using different methods of measurement were statistically different. Blood flow velocities generally increased during the first month after birth. Arterial signals were diphasic with flow throughout diastole. Resistance indices most often were between 0.6 and 0.7 and did not exceed 0.86.     

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.     

The comparison between the cerebral blood flow directly measures and cerebral blood flow velocity in the middle and basilar cerebral arteries measured by transcranial Doppler ultrasonography

Transcranial Doppler ultrasonography (TCD) may be useful for determining alterations in cerebral blood flow (CBF) during excessive hemodynamic changes by non-invasive measurement of the CBF velocity. The purpose of this study was to measure the correlation between CBF and the middle cerebral artery (MCA) and basilar artery (BA) flow velocities, as measured by TCD during excessive hemodynamic changes produced by hypertension and hypotension in adult dogs. The peak, diastolic, and mean flow velocities were measured by TCD. Arterial hypertension was induced by administration of dopamine at 5 and 15 microg/kg/min, and hypotension was induced by hemorrhage. During the hemodynamic changes, the BA velocity correlated more closely with the alteration in the CBF than the MCA velocity. In terms of percentages of the values during anesthesia, there was good correlation between CBF and the MCA and BA velocities. In conclusion, our findings indicate that MCA and BA velocity measurements, as a percentage of the values during anesthesia, both give an equally accurate indication of alterations in CBF during excessive hemodynamic changes.     

Evaluation of intracranial pressure by transcranial Doppler ultrasonography in dogs with intracranial hypertension

Transcranial Doppler ultrasonography (TCD) has been used to confirm changes in cerebral hemodynamics. In this study, we investigated whether the parameters for the basilar artery measured by TCD were correlated with the intracranial and cerebral perfusion pressures in extreme intracranial hypertension. An intracranial hypertension model was produced in seven dogs by inflating a balloon inserted into the epidural space. The resistance index was compared with the corresponding intracranial pressure and cerebral perfusion pressure values during intracranial hypertension. A significant correlation was recognized between the resistance index and cerebral perfusion pressure. Therefore, measurement of the basilar artery by TCD in the dog with intracranial hypertension is useful in estimating the intracranial circulation in cases where the measurement of intracranial pressure is not available or not indicated.     

DOPPLER ULTRASONOGRAPHIC DIAGNOSIS AND ANATOMY OF CONGENITAL INTRAHEPATIC ARTERIOPORTAL FISTULA IN A PUPPY

A dilated, tortuous blood vessel was identified sonographically in the right medial liver lobe in a puppy with severe ascites. This vessel was thought to represent the dilated right medial portal vein branch. Using pulsed wave Doppler ultrasonography, retrograde, abnormally pulsatile flow was detected in both the dilated right medial portal vein branch and the main portal vein. The right medial liver lobe was surgically resected then fixed in formalin. Silicon rubber was injected and outlined the connection between the portal vein and hepatic artery.     

Doppler velocimetric parameters of the testicular artery in healthy dogs

This study aimed to examine the Doppler velocimetric pattern of the testicular artery of small dogs in two different locations. Testes of 21 dogs were evaluated by two-dimensional ultrasonography to measure testicular volume and by Doppler ultrasonography to record the velocimetric patterns of the testicular artery in the spermatic cord and marginal location. The volume of left testes (4.70 ± 1.22 cm³) was significantly higher than the volume of the right testes (4.45 ± 1.17 cm³). Peak systolic velocity (PSV) of the left spermatic cord was significantly higher than the right side. End-diastolic velocity was significantly higher in the marginal artery than the spermatic cord on both sides; however, resistance and pulsatility indexes were significantly lower in the marginal artery. Results demonstrate the viability of Doppler ultrasonography for characterization of the testicular artery in small dogs and Doppler velocimetric values vary according to the location of measurement along the artery.     

Magnetic resonance imaging findings of hepatic encephalopathy in a dog with a portosystemic shunt

A 6-year-old ShihTzu presented with tonic-clonic cluster seizure. T2-weighted magnetic resonance (MR) images showed bilateral diffuse hyperintense lesions at the cerebral cortex with enlarged sulci. Computed tomography revealed a portosystemic shunt (PSS) and azygos continuation. Based on the clinical signs, blood examinations and diagnostic images, the dog was diagnosed with hepatic encephalopathy secondary to PSS. The neurologic signs were gradually improved after medical therapy for hyperammonemia. This is the first report of hyperintensity of the cerebral cortex on T2-weighted MR images associated with acute hepatic encephalopathy in a dog.     

Power and Pulsed Doppler Evaluation of Prostatic Artery Blood Flow in Normal and Benign Prostatic Hyperplasia–Affected Dogs

This study was carried out with the objectives to test the differences in the haemodynamic characteristics of the prostatic artery in normal and benign prostatic hyperplasia (BPH)–affected dogs using Doppler ultrasonography. In sixteen male German shepherd dogs, prostatic volume was detected and prostatic biopsy was performed. The prostatic artery blood flow parameters determined were as follows: peak systolic velocity (PSV), end diastolic velocity (EDV), Resistive Index (RI) and Pulsatility Index. The power Doppler mode was used for colour flow mapping of the prostatic artery. In PW mode at marginal locations, the waveforms recorded showed a continuous pattern typical of the high‐resistance vessels, while in subcapsular locations, the waveforms recorded were continuous characteristic of the low‐resistance vessel. Peak systolic velocity and EDV in both locations were significantly higher in BPH group (p < 0.001) than normal group (p < 0.05). Pixel number in BPH group in both locations was significantly higher (p < 0.05) compared to the normal group. This study shows that Doppler ultrasonography represents a valid and non‐invasive method for the characterization of the blood flow in the prostatic artery in dogs affected with BPH. Moreover, statistically significant differences of blood flow velocities in prostatic artery in normal and BPH‐affected dogs were detected. The RI was not able to differentiate normal dogs from dogs affected by BPH and therefore is not a parameter usable for diagnostic purposes, while Power Doppler could represent an additional diagnostic tool.     

B‐Mode and Doppler Sonography of the Mammary Glands in Dairy Goats for Mastitis Diagnosis

This study aimed to evaluate the sonographic characteristics of the udder and teats and to determine the Doppler indexes of mammary artery in healthy and undergoing subclinical and clinical mastitis goats. Thirty animals among Saanen and Alpine Brown goats were arranged in three groups, healthy goats (HG), goats with subclinical mastitis (SMG) and goats with clinical mastitis (CMG). Using the B‐mode, the sonographic characteristics (echotexture and echogenicity) and biometry (diameter and area of the udder cistern, diameter and area of the teat cistern and thickness of the teat wall) were evaluated. Using Doppler ultrasonography, the vascular indexes of the mammary artery were obtained. It was observed hyperechogenicity with solid component in the gland cistern when comparing animals with clinical mastitis and healthy mammary tissue. Regarding the echotexture of the breast tissue, there was heterogeneity in the mammary parenchyma on the three groups, for the milk, it was observed homogeneity for animals on HG and SMG and heterogeneity for animals on CMG. Grey‐scale quantitative assessment revealed increase in echogenicity (mean value) for all the structures when comparing the three groups. Biometry did not reveal statistical difference between groups, for none of the evaluated structures. Doppler examination of the mammary artery showed the decrease of end diastolic velocity and raise of pulsatility index between groups. The association of B‐mode and Doppler ultrasonography is useful for the evaluation of the udder of dairy goats with mastitis. It is a sensitive and specific method for the study of this disease. Doppler mode was unable to establish reliable criteria for diagnosis of subclinical mastitis. Moreover, the quantification of echogenicity is a useful technique for the evaluation of the milk in animals with mastitis; therefore, it is suggested that it can be used as complementary technique for the diagnosis of mastitis in goats.     

Severe involvement of cerebral neopallidum in a dog with hepatic encephalopathy

This report describes a unique distribution of cerebral cortical necrotic lesion, which was diagnosed as hepatic encephalopathy in a 2-year-old Maltese dog. The dog showed splenocaval shunt and small liver with marked hepatocellular fatty degeneration. Histopathologic examination revealed that diffuse laminar cortical necrosis composed of neuronal necrosis, marked infiltration of gitter macrophages, and astrogliosis were found bilaterally in the dorsolateral area of the cerebrum. No necrotic lesions were observed in the cerebral paleopallium and archipallium, the central gray matter, cerebellum, and brain stem. Astrocytes with large and pale nuclei (Alzheimer type II astrocytes) were apparent throughout the brain. Immunohistochemically, a decrease of immunostains for glutamine synthetase and glutamate transporter antibodies was seen in Alzheimer type II astrocytes and neuropil. This is, to our knowledge, the first report of extensive involvement of cerebral neopallidum in canine hepatic encephalopathy.     

Comparative study of ultrasonography and arteriography of the carotid artery of xylazine-sedated and halothane-anesthetized goats

The carotid artery of clinically normal goats was examined, using duplex ultrasonography and arteriography. The diameter of the carotid artery was measured by use of two-dimensional ultrasonography and Doppler ultrasonography, respectively, before and after xylazine administration. The diameter of the artery was also measured by use of an arteriography technique in halothane-anesthetized goats. There was no significant difference between the mean diameter of the carotid artery measured by ultrasonography in conscious nonsedated goats and that determined by arteriography in goats under halothane anesthesia. On the other hand, ultrasonography of xylazine-sedated goats revealed an increase of carotid artery diameter of 20 to 30%. There was no change in the velocity of blood flow after xylazine administration.     

CONTRAST‐ENHANCED HARMONIC ULTRASONOGRAPHY OF MEDIAL ILIAC LYMPH NODES IN HEALTHY DOGS

Herein, we describe the normal contrast‐enhanced harmonic, color, and power Doppler ultrasonographic characteristics of the medial iliac lymph nodes in healthy dogs. Contrast‐enhanced harmonic ultrasonography of the medial iliac lymph nodes was performed on 14 healthy dogs after intravenous administration of the lipoprotein‐bound inert gas‐filled microbubble contrast media Definity^®. Time–pixel intensity curves were generated for 1‐min postinjection. Quantification of these curves was performed using Philips QLab software. Non‐contrast‐enhanced power and color Doppler examinations were performed in each node to assess vascular patterns subjectively. Normal lymph nodes exhibited a mean contrast wash‐in phase beginning at 6.3 s from the time of injection with mean peak pixel intensity at 12.1 s. Angioarchitecture was best visualized with contrast‐enhanced harmonic ultrasound compared with power and color Doppler. Normal lymph nodes in dogs have a central artery with a centrifugal and uniform branching pattern. Contrast‐enhanced harmonic ultrasonography is a noninvasive examination that demonstrates improved visibility of the intranodal architecture of healthy medial iliac lymph nodes in dogs compared with conventional, non‐contrast‐enhanced Doppler methods that may have future clinical applications.     

Spectral Doppler ultrasound in the major arteries of normal conscious immature micropigs

Spectral waveform analysis of blood flow velocity in the major arteries of six healthy, conscious immature micropigs was determined using Doppler ultrasonography. Doppler spectral tracings were recorded from the external iliac artery, femoral artery, and renal arcuate artery. Tracings were also taken from three parts of the common carotid artery and two parts of the abdominal aorta. Spectral Doppler parameters included peak systolic velocity, early diastolic velocity, peak systolic velocity-to-end diastolic velocity ratio, resistive index, and pulsatility index. In addition, the diameter of major arteries and indirect blood pressure were measured. These results from spectral Doppler analysis in major arteries may be useful as reference ranges in the future studies of vascular hemodynamics in immature micropigs.     

ASSESSING CIRCLE OF WILLIS BLOOD CIRCULATION IN DOGS WITH TRANSCRANIAL COLOR-CODED DUPLEX SONOGRAPHY

Insonation of Circle of Willis by transcranial Doppler duplex color sonography is described in 30 healthy dogs with 15 weighing <33 lb and 15 weighing >33 lb. Imaging was via a temporal window to explore the rostral, middle, and caudal cerebral arteries on both the left and right-hand sides; and through an suboccipital window to study the basilar artery. Normal mean values of the peak systolic velocity (PSV), end diastolic velocity, mean velocity, resistance index (RI), and pulsatility index (PI) were characterized and compared with those obtained in previous studies. There was significant differences in the PSV, RI, and PI in the rostral cerebral artery between dogs weighing <33 vs. >33 lb. Mean PSV was higher in weighing over 33 lb, whereas the mean resistive index and mean PI were lower in these dogs.     

Duplex Doppler Estimation of Pourcelot Resistive Index in Arcuate Arteries of Sedated Normal Cats

Renal failure is an important cause of morbidity and mortality in feline patients. In human patients, intrarenal blood flow values obtained with duplex Doppler ultrasonography have been used to aid in the diagnosis and prognosis of renal failure. The purpose of this report is to present values for resistance to intrarenal blood flow in normal cats, derived by duplex Doppler ultrasonography. Ten mature clinically healthy conditioned domestic shorthaired cats were screened for normal renal anatomy and function by CBC, serum biochemical profile, urinalysis, urine protein/creatinine ratio, endogenous creatinine clearance, and renal B-mode ultrasonography; and for normal systemic blood pressure with Doppler pressure cuff measurement. Subsequently, the cats were sedated with ketamine hydrochloride, and values for mean intrarenal (arcuate artery) resistance to blood flow were determined by duplex Doppler ultrasonography, and expressed as the Pourcelot resistive index, a ratio of systolic to diastolic flow commonly used in duplex Doppler sonography in human patients. After duplex Doppler sonographic examination, histological normalcy of the kidneys was verified by evaluation of ultrasound-guided percutaneous renal biopsy. Based on the obtained resistive indices, 95% confidence intervals for normal values were calculated as follows: left kidney, 0.52 to 0.60; right kidney, 0.55 to 0.63. No statistically significant difference was noted between the values obtained for the right versus the left kidney. J Vet Intern Med 1996;10:28–33. Copyright © 1996 by the American College of Veterinary Internal Medicine .     

DOPPLER MEASUREMENT OF HEPATIC ARTERIAL FLOW IN DOGS: TECHNIQUE AND PRELIMINARY FINDINGS

The common hepatic artery in 10 healthy adult beagles, 20 healthy pups (13 Deerhounds and seven Irish Wolfhounds), and seven dogs with either a congenital or acquired hepatic disorder was examined by duplex-Doppler ultrasonography. Peak systolic velocity (Vs), resistive index (RI), pulse rate, angle of insonation, and sample volume depth were recorded. Measurements in Beagles were made after a 24 h fast and repeated 2 h after feeding. The mean Vs and RI in fasted Beagles were 1.5 m/s (range 1.1-2.3 m/s) and 0.68 (range 0.62-0.74), respectively. Postprandially, there were no significant differences in any of these variables. Mean Vs and RI were lower in pups: 1.0 m/s (range 0.8-1.3 m/s) and 0.59 (range 0.46-0.65), respectively (P < .001). Two dogs with congenital arterioportal fistula had higher mean Vs (P < .001) and lower mean RI (P < .05) than normal pups. No significant differences were detected between normal Beagles, three dogs with portal vein thrombosis, and two dogs with acquired hepatic insufficiency. Differences in measured hepatic blood flow in dogs of different age or breed will complicate diagnostic use of hepatic arterial Doppler measurements.     

Quantitative evaluation of contrast enhanced transcranial Doppler signal using galactose based echo-contrast agent in dogs

Transcranial Doppler ultrasonography (TCD) is hindered by insufficient ultrasound penetration through the temporal bone. The use of echo-contrast agents to enhance the Doppler signal is an important step toward the solution of this problem. The aim of the present study was to investigate the tolerability and diagnostic value of the intravenous echo-contrast agent, Levovist. Levovist was administered intravenously in 8 dogs with two doses (0.2 and 0.3 ml/kg) at different concentrations (300 and 400 mg/ml). In right middle cerebral artery (RMCA), the duration and degree of the signal enhancement were measured by TCD. All 32 administrations of Levovist produced an increase in TCD signal of the RMCA without complications. The first assessable pulse curve could be seen on the screen after 4 to 7 seconds after injection. There was no significant difference of latency period between different concentration and dosage. The signal amplitude was increased homogeneously by more than 30 dB when 0.3 ml/kg with 300 mg/ml concentration of Levovist and 0.2 and 0.3 ml/kg with 400 mg/ml concentration were administered. There was no significant difference in the duration of optimal contrasting between 0.3 ml/kg with 300 mg/ml concentration of Levovist and 0.2 and 0.3 ml/kg with 400 mg/ml concentration. The duration of the signal enhancement was 144 to 422 seconds, depending on the degree of concentration and dose of administration. Optimal TCD signal enhancement of RMCA was obtained using 0.3 ml/kg with 300 mg/ml concentration of Levovist in dogs, which is considered to provide quality visualization.     

Contrast‐enhanced ultrasonography is a feasible technique for quantifying hepatic microvascular perfusion in dogs with extrahepatic congenital portosystemic shunts

Extrahepatic‐congenital portosystemic shunt is a vascular anomaly that connects the portal vein to the systemic circulation and leads to a change in hepatic microvascular perfusion. However, an assessment of hepatic microvascular perfusion is limited by conventional diagnostic modalities. The aim of this prospective, exploratory study was to assess hepatic microvascular perfusion in dogs with extrahepatic‐congenital portosystemic shunt using contrast‐enhanced ultrasonography (CEUS) using perfluorobutane (Sonazoid^®). A total of 17 dogs were included, eight healthy dogs and nine with extrahepatic‐congenital portosystemic shunt. The time‐to‐peak (TTP), rising time (RT), and rising rate (RR) in the hepatic artery, portal vein, and hepatic parenchyma, as well as the portal vein‐to‐hepatic parenchyma transit time (ΔHP‐PV) measured from time‐intensity curve on CEUS were compared between healthy and extrahepatic‐congenital portosystemic shunt dogs. The RT of the hepatic artery in extrahepatic‐congenital portosystemic shunt dogs was significantly earlier than in healthy dogs (P = 0.0153). The TTP and RT of the hepatic parenchyma were significantly earlier in extrahepatic‐congenital portosystemic shunt dogs than in healthy dogs (P = 0.0018 and P = 0.0024, respectively). ΔHP–PV was significantly shorter in extrahepatic‐congenital portosystemic shunt dogs than in healthy dogs (P = 0.0018). CEUS effectively revealed changes in hepatic microvascular perfusion including hepatic artery, portal vein, and hepatic parenchyma simultaneously in extrahepatic‐congenital portosystemic shunt dogs. Rapid hepatic artery and hepatic parenchyma enhancements may reflect a compensatory increase in hepatic artery blood flow (arterialization) caused by a decrease in portal vein blood flow and may be used as an additional diagnostic test to distinguish extrahepatic‐congenital portosystemic shunt dogs from healthy dogs.