DOPPLER ULTRASONOGRAPHIC ESTIMATION OF RENAL AND OCULAR RESISTIVE AND PULSATILITY INDICES IN NORMAL DOGS AND CATS

Resistive index (RI) and pulsatility index (PI) are indirect measurements of blood flow resistance that may be used to evaluate vascular changes in renal and ophthalmologic diseases. To our knowledge, no reports are available describing values for renal and ocular PI index in the unsedated dog and ocular RI and PI indices in the unsedated cat. The purpose of this study was to measure normal values for both intrarenal and ocular RI and PI within the same subject in unsedated clinically normal dogs and cats. Twenty-seven dogs and 10 cats were considered healthy by means of physical examination, CBC, biochemical profile, urinalysis, and ultrasonography. Systolic blood pressure was measured by Doppler ultrasonography. Intrarenal and ocular arteries were scanned by pulsed Doppler ultrasonography to calculate RI and PI. No significant differences were noted between the values obtained for the right vs. the left kidney and eye. The upper values of these indices were calculated as mean+2 standard deviations resulting in 0.72 and 1.52 for dog renal RI and PI; 0.7 and 1.29 for cat renal RI and PI; 0.76 and 1.68 for dog ocular RI and PI; and 0.72 and 1.02 for cat ocular RI and PI.     

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.     

Progressive changes in ophthalmic blood velocities in Beagles with primary open angle glaucoma

Objective To measure changes in the ocular and orbital blood flow velocities by color Doppler imaging (CDI) in beagles with primary open angle glaucoma as the disease progressed from early to advanced stages. Methods CDI measurements were performed periodically on 13 glaucomatous Beagles during the nontreated mild, moderate and advanced stages of POAG over the course of 4 years. CDI was performed with the dogs lightly anesthetized (butorphanol 0.1 mg/kg IV, acepromazine maleate 0.02 mg/kg IV, and atropine sulfate 0.05 mg/kg) while the CD transducer was placed directly on the cornea anesthetized with 0.5% tetracaine hydrochloride. Intraocular pressure (IOP) by pneumatonography or TonoPen XL, heart rate and mean arterial blood pressure were measured at the beginning, middle and end of each study. The ophthalmic vessels examined included: external ophthalmic arteries and veins, long and short posterior ciliary arteries, anterior ciliary arteries and veins, primary retinal arteries, and vortex veins. Recordings of each vessel included peak systolic velocity (PSV), end diastolic velocity (EDV) and time averaged velocity (TAV), and when possible the resistive index (RI) and pulsatility index (PI) were computed. Results CDI abnormalities were present before intraocular pressure exceeded the normal range. As the animals aged, and the glaucoma progressed with higher levels of IOP, significant changes occurred in nearly all vessels, and generally included a major increase in RI (P < 0.001) and an increase in the PI (P < 0.001). Mean arterial blood pressure (105 ± 18 mmHg) and heart rate (118 ± 33/min) remained reasonably constant. The IOP gradually increased as the disease progressed (early and normotensive: 19.4 ± 3.9 mmHg; moderate: 29.7 ± 2 mmHg; and advanced: 44.5 ± 6 mmHg). The ocular veins seemed most influenced early on in the disease. Late in the disease, ocular venous blood flow could not be consistently demonstrated. An increase in the PI of ocular veins occurred in the moderately and severely affected glaucomatous Beagles. As the IOP increased, there were trends of increasing resistive index and pulsatility index in most arteries, and periods of marked decreased velocities of the vortex and external ophthalmic veins in severe cases. Conclusion CDI measurements in Beagles with primary open angle glaucoma during the course of 4 years indicate easily measurable and repeatable progressive blood flow abnormalities before the elevation of IOP and, thereafter, with gradually increased levels of IOP.     

Doppler ultrasonographic changes in the canine kidney during normovolaemic anaemia

The haemodynamics of the canine left renal artery (LRA) and interlobar artery (ILA) were evaluated in eleven fasted, healthy, conscious beagles with severe acute (haematocrit [Hct] 16%), moderate chronic (Hct 26%) and mild chronic (Hct 34%) normovolaemic anaemia using Doppler ultrasound. Heart rate, peak systolic velocity (PSV), end diastolic velocity (EDV), time-averaged mean velocity (TAVmean), pulsatility index (PI) and resistive index (RI) were recorded. Doppler values in the dogs following the induction of anaemia states were compared with corresponding values in the same dogs prior to the induction of anaemia. Left renal artery mean PSV, mean PI and mean RI were significantly higher and the mean EDV was significantly lower in severe acute anaemia. No significant change was seen in mean values of the same parameters in moderate or mild chronic anaemia. There was no significant change in TAVmean of the LRA or mean PI and mean RI of the ILA in any grade of anaemia. Acute, severe normovolaemic anaemia significantly altered LRA Doppler parameters in resting dogs without influencing those of the ILA. Moderate or mild chronic anaemia had no effect on any renal Doppler parameter.     

Clinical comparison of three methods to measure blood pressure in nonsedated dogs

OBJECTIVE: To determine arterial blood pressure in client-owned dogs, using direct arterial puncture, oscillometry, and Doppler ultrasonography in a clinical setting. DESIGN: Prospective study. ANIMALS: 8 clinically normal client-owned dogs. PROCEDURE: Blood pressures of nonsedated dogs were measured simultaneously, using each of the 3 methods. Mean values obtained were compared with published mean values. Ability of noninvasive methods (Doppler ultrasonography and oscillometry) to accurately predict results of the invasive method, and relationships between blood pressure and age, body weight, and degree of patient anxiety were determined. RESULTS: Calculated ranges of values (mean +/- 2 SD) determined by direct arterial puncture were: systolic pressure, 114 to 194 mm Hg; diastolic pressure, 66 to 102 mm Hg; and mean pressure, 85 to 129 mm Hg. Ranges determined by use of oscillometry were: systolic, 110 to 190 mm Hg; diastolic, 35 to 107 mm Hg; and mean, 78 to 138 mm Hg. Ultrasonographic and oscillometric values did not accurately predict direct values, but mean values of systolic and mean pressures were similar among methods. Relationships were not detected between age or body weight and blood pressure. Significant differences in blood pressure were not detected between anxious and nonanxious dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Mean values of systolic, diastolic, and mean arterial blood pressure measured in nonsedated client-owned dogs, using invasive and noninvasive methods in a clinical setting, are comparable with those determined for acclimatized, trained, or sedated dogs. However, results of noninvasive methods may not accurately reflect direct values.     

Increased renal vascular resistance in dogs with hepatic disease

Doppler ultrasound is a non-invasive technique that can be used to estimate vascular resistance by calculation of resistive index (RI) and pulsatility index (PI). Liver disease may increase renal RI and PI, and in humans with liver disease the indices are monitored to attain prognostic information. Systemic hypertension has been found in dogs with hepatic disease and is also related to increased renal vascular resistance in humans. The aim of this study was to examine renal vascular resistance increases in dogs with hepatic disease and to ascertain whether these may be related to blood pressure increases and biochemical parameters. Twenty dogs with hepatic disease were evaluated. The mean renal RI, PI, and systolic blood pressure were significantly higher than in normal animals. A positive correlation was found between the indices and alkaline phosphatase but not with systolic blood pressure. It is concluded that renal vascular resistance may increase in dogs with hepatic disease and in this study was above the limit value in 50% of the animals.     

Influence of normovolemic anemia on Doppler characteristics of the abdominal aorta and splanchnic vessels in Beagles

OBJECTIVE: To ultrasonographically evaluate hemodynamics in the abdominal aorta (AAo) and splanchnic vessels in dogs with experimentally induced normovolemic anemia. ANIMALS: 11 healthy Beagles. PROCEDURE: The AAo, cranial mesenteric artery (CMA), celiac artery (CA), hilar splenic artery (HSA), and main portal vein (MPV) were evaluated in conscious dogs immediately before and after experimental induction of severe normovolemic anemia (Hct, 16%) and during recovery from moderate and mild anemia (Hct, 26% and 34%, respectively). Peak systolic velocity (PSV) or peak velocity (PV), time-averaged mean velocity (TAVmean), pulsatility index (PI), resistive index (RI), blood flow, congestion index (CI), and heart rate (HR) were recorded. Results were compared for anemic and control states. RESULTS: Severe anemia caused significant increases in HR (25% to 70%), PSV (AAo, 45.8%; CMA, 56.1%; and CA, 41.9%), PV (MPV, 84.2%), and TAVmean, (AAo, 69.4%, CMA, 64.3%; CA, 29.7%; and MPV, 76.9%) and significant decreases in PI (AAo, 26.1%; HSA, 19.3%) and Cl (MPV, 45.2%).There was no significant change in PI of the CMA or CA, portal blood flow, or RI of any artery. Significantly higherTAVmean persisted in all vessels during moderate anemia, but higher PSV persisted only in the CMA; PI (CMA and CA) and RI (CA) decreased significantly, but portal blood flow increased significantly. Significant increase in TAVmean (AAo and CMA) persisted during mild anemia, and PI (AAo, CMA, and HSA) and RI (CMA) were significantly lower. CONCLUSIONS AND CLINICAL RELEVANCE: Doppler ultrasonography revealed hyperdynamic circulation in the AAo and splanchnic vessels in dogs with experimentally induced normovolemic anemia.     

Can testicular artery Doppler velocimetry values change according to the measured region in dogs?

Testicular tissue maintenance is performed by the testicular artery, and the hemodynamics of this artery can be evaluated using Doppler ultrasonography. The aim of this study was to characterize the peak systolic velocity (PSV), end diastolic velocity (EDV), pulsatility index (PI) and resistivity index (RI) of five regions of the testicular artery in dogs, including two proposed regions and three that have been previously described. Twenty‐two dogs were used, and the PSV, EDV, PI and RI of the testicular artery were measured in five regions: proximal, medial and distal supratesticular; marginal; and intratesticular. The median values for PSV (cm/s), EDV (cm/s), PI and RI in the five regions were as follows: proximal supratesticular (23.1, 3.7, 2.1 and 0.8); medial supratesticular (17.2, 4.5, 1.5, and 0.7); distal supratesticular (12.2, 5.7, 0.8, and 0.5); marginal (11.3, 6.5, 0.5, and 0.4); and intratesticular (5.7, 3.5, 0.5, and 0.4). There was a difference between the PSV of the medial and distal supratesticular regions. There were differences in the PSV, EDV, PI and RI among the distal supratesticular, marginal and intratesticular regions. Measurements of PSV, EDV, PI and RI of the testicular artery in dogs at the proposed regions showed different results due to the hemodynamic and morphological differences of the artery during its course in the spermatic cord and to the testicles. It is necessary to identify the region in testicular artery Doppler velocimetric evaluations of dogs, given that there is a difference according to the region measured.     

EVALUATION OF RENAL HEMODYNAMICS IN AWAKE AND ISOFLURANE-ANESTHETIZED CATS WITH PULSED-WAVE DOPPLER AND QUANTITATIVE RENAL SCINTIGRAPHY

The feasibility and reproducibility of obtaining the pulsed-wave Doppler measurements of resistive index (RI) and pulsatility index (PI) were investigated in intrarenal arteries of normal, nonsedated cats, and cats anesthetized with isoflurane. In addition, relative renal function and relative renal blood flow were evaluated using quantitative renal scintigraphy. The percentage of injected dose uptake, time to peak activity, and two indices of renal blood flow (K/A ratio and flow index) obtained during the first pass of ^99mTc-MAG₃, were determined for both awake and anesthetized cats. Results indicate that measuring RI and PI in nonsedated cats is readily accomplished and that the results are reproducible within an animal. Mean RI and PI values in the awake cats were 0.55 and 0.8, respectively. Significant differences between the awake and anesthetized cats were found for all pulsed-wave Doppler and quantitative renal scintigraphic measurements evaluated.     

CHARACTERIZATION OF NORMAL AND ABNORMAL CANINE SUPERFICIAL LYMPH NODES USING GRAY-SCALE B-MODE, COLOR FLOW MAPPING, POWER, AND SPECTRAL DOPPLER ULTRASONOGRAPHY: A MULTIVARIATE STUDY

The objective of this study was to characterize the ultrasonographic patterns of normal superficial lymph nodes and to evaluate whether ultrasonography can help discriminate between different lymphadenopathies (reactive, lymphoma, and metastases) in dogs. Three hundred and eighteen superficial lymph nodes in 142 dogs were studied by B-mode, color flow mapping, power, and spectral Doppler ultrasonography. Size, echogenicity, nodal border definition, presence of a nodal hilus, acoustic enhancement and distribution of vascular flow, as well as perfusion indices were measured. Multivariate statistics using discriminant analysis was used to determine which parameters can be used to predict the diagnosis of the lymph node. The size of the lymph node, distribution of vascular flow within the lymph node, and pulsatility index (PI) in combination gave a classification error of 23% for the four groups of lymph nodes. This was improved to 11% if the nodes were divided into two groups: benign and malignant. There was a significant difference in resistive index (RI) and PI between benign and malignant nodes. Cut-off values were determined using receiver operator curves, 0.68 RI and 1.49 PI.     

Colour Doppler ultrasound imaging of blood flows variations in neoplastic and non‐neoplastic testicular lesions in dogs

Testicular tumours are the most common neoplasms in male dogs accounting for approximately 90% of all tumours affecting the genitourinary tract. Gray‐scale ultrasonography in combination with colour and power Doppler imaging has been well accepted as an accurate technique for assessing scrotal lesions and vascularization of the testis. Colour Doppler sensitivity for low blood flows appears promising in the study of testicular disorders. The aim of this study was to assess if colour and power Doppler ultrasound is a good tool for the investigation of testicular lesions in dogs, to report the sonographic features of lesions and to measure colour and power Doppler parameters such as resistive index (RI), pulsatility index (PI), hypovascularization and hypervascularization (VI) determining if they can be used to distinguish testicular neoplasms from the wide spectrum of non‐neoplastic pathological findings. In this study, 50 male dogs of various breeds, aged between 7 and 14 years, presented with testicular disorders were selected. RI and PI were calculated. Mean RI values for neoplastic, inflammatory and degenerative lesions were 0.54, 0.45 and 0.58, respectively. Mean PI values were 0.62, 0.55 and 0.63, respectively. Hypovascularization and hypervascularization of the lesion were evaluated throughout the vascularity index (VI). Vascular signals in neoplasms were significantly intensified around and inside the mass if compared with those measured during inflammatory and degenerative lesions. VI markedly increased in solid tumours. Pathological testes were removed; macroscopical, histological and immunoistochemical evaluations were carried out. Colour Doppler showed increased intralesional and peripheral flows in all neoplastic lesions analysed. No flows were detected around cysts.     

Colour-coded duplex sonography of the testes of dogs

Colour-coded duplex sonography was used to examine the testes of 42 dogs whose testes were normal on clinical examination. With colour Doppler, the blood flow in the supratesticular region could be displayed clearly in 70 per cent of the cases, independent of the dog's age, bodyweight, pulse rate and the volume of its testes. The marginal artery could be displayed clearly in 56 per cent of the cases, and the clarity was correlated with bodyweight (P<0.001), testicular volume (P<0.001), and pulse rate (P<0.001). The intratesticular blood flow could not be discerned in 42 per cent of the cases. With pulsed Doppler, the mean resistive index (RI) in the supratesticular region was 0.57, and the mean pulsatility index (PI) was 1.00. In the marginal artery, the mean RI was 0.49, and mean PI was 0.78. In the intratesticular arteries, the mean RI was 0.47, and the mean PI was 0.75. At all three sites both indices were independent of age, bodyweight, pulse rate and testicular volume.     

Comparative Doppler imaging of the ophthalmic vasculature in normal Beagles and Beagles with inherited primary open-angle glaucoma

The objective of this study was to compare orbital and ocular vasculature velocity, measured by Doppler imaging, in normal Beagles and Beagles with inherited primary open-angle glaucoma. Eight normal Beagles and 13 Beagles with different stages of primary open-angle glaucoma were evaluated twice with a 2–4-week period between measurements. Doppler imaging was performed with the dogs anesthetized, and the Doppler transducer applied directly on the corneal surface. The majority of the orbital vasculature (external ethmoidal artery; internal ophthalmic artery and vein; and external ophthalmic artery and vein) and ocular blood vessels (anterior ciliary artery and veins; long posterior ciliary arteries; short posterior ciliary arteries; primary retinal arteries; and the vortex veins) were identified and Doppler blood velocity parameters were determined. The glaucomatous dogs demonstrated significant differences in the Doppler velocity parameters of several orbital vessels (external ethmoidal, external ophthalmic, and internal ophthalmic arteries), and several ocular vessels (anterior ciliary, short posterior ciliary, and long posterior ciliary arteries). These differences included decreased blood velocities, and increased pulsatility and resistive indexes. The Doppler blood flow velocities of the primary retinal arteries were unchanged between the normal and glaucomatous dogs. In the glaucomatous dogs, the Doppler imaging suggests increased vascular resistance downstream in both the orbital and ocular vasculature. These blood velocity parameter changes may be primary or secondary, and may offer therapeutic opportunities to increase perfusion, prolong the retina and optic nerve head function, and maintain vision in the canine glaucomas.     

DIAGNOSIS OF URINARY TRACT OBSTRUCTION IN DOGS USING DUPLEX DOPPLER ULTRASONOGRAPHY

The ability of duplex Doppler ultrasonography to assist with the diagnosis of urinary tract obstruction was investigated in a study of 5 dogs with surgically induced, unilateral ureteral obstruction. The resistive index (RI) of obstructed kidneys was compared to that of controls and to the contralateral unobstructed kidneys. The RI was also evaluated following relief of obstruction. On the basis of an RI measurement ≥0.70 indicating obstruction, a sensitivity of 73% and a specificity of 77% was determined for the diagnosis of obstruction with Doppler ultrasonography. Although mean RI was elevated in obstructed kidneys compared to controls, it was concluded that a high false-negative rate (27%) limits the clinical usefulness of Doppler ultrasonography for the detection of urinary obstruction in dogs. The RI difference between obstructed and nonobstructed kidneys was also evaluated within individual animals, but the magnitude of difference between kidneys did not significantly improve the detection rate for obstruction.     

Influence of food composition on splanchnic blood flow during digestion in unsedated normal dogs: a Doppler study

The effect of dietary components in gastrointestinal blood flow was investigated non-invasively in dogs. Doppler ultrasound (US) waveform analysis of the celiac artery (CA) and the cranial mesenteric artery (CMA) of eight healthy dogs was performed both in the fasting state and at 20, 40, 60 and 90 min after feeding maintenance, high protein, high carbohydrate and high fat diets. Resistive index (RI), pulsatility index (PI) and the percentage differences between measurements were calculated.In fasted dogs, the CA showed significantly (p<0.05) lower resistance than the CMA. With all diets, post-prandial RI and PI values decreased significantly in both vessels (CA: RI=-12-13%; PI=-25-29%; CMA: RI=-13-15%; PI=-27-29% [p<0.05]), and in all cases significantly earlier in the CA than in the CMA (p<0.05). With all diets except high fat the maximum decrease in RI and PI was reached in the CA at 40 min and in the CMA at 60 min. High fat diets were unique in that the maximum decrease in RI and PI in the CMA occurred earlier (at 20 min) and values were slower to return to normal (p<0.05). We conclude that Doppler US can be used in dogs to quantify significant differences in the response of splanchnic blood flow to different dietary components.     

Spectral waveform analysis of major arteries in conscious dogs by Doppler ultrasonography

Normal values of arterial blood flow velocity and waveforms in major arteries of 10 healthy conscious Beagle dogs were determined using Doppler ultrasonography. Peak systolic, early diastolic, and end-diastolic velocities of the basilar artery, common carotid artery, abdominal aorta, external iliac artery, femoral artery, and peak ejection velocity of the valvular aorta were evaluated. Pulsatility index (PI) of the basilar artery and blood pressure were recorded. All arteries had a high-resistance flow pattern with triphasic flow velocity except the basilar artery, which had a low-resistance pattern. Mean peak systolic velocities of the basilar artery, common carotid artery, abdominal aorta, external iliac artery, and femoral artery were 72 +/- 19, 115 +/- 17, 121 +/- 24, 105 +/- 25, and 110 +/- 17 cm/s, respectively. The PI of the basilar artery and peak ejection velocity of the valvular aorta were 1.37 +/- 0.13 and 96 +/- 16 cm/s, respectively. Mean systolic and diastolic blood pressures were 137 +/- 13 and 78 +/- 15 mmHg, respectively. Present findings may be used as references in future studies on vascular diseases and hemodynamics in dogs.     

Effects of a medetomidine-midazolam-butorphanol combination on renal cortical, intestinal and muscle microvascular blood flow in isoflurane anaesthetized dogs: a laser Doppler study

Objective To obtain renal cortical, ileal, colonic and skeletal muscle microvascular blood flow measurements in dogs using the laser Doppler technique and to characterize the effects of medetomidine‐midazolam‐butorphanol combination on these flows. Study Design Prospective randomized experimental study. Animals Fourteen clinically normal beagles (two groups of seven), aged 1–4 years and weighing 13.2 ± 1.8 kg. Methods All dogs were anaesthetized with 1.7% end‐tidal isoflurane in oxygen. In the treatment group, after instrumentation and when anaesthesia was considered stable, medetomidine (1 mg m^?2 body surface area (BSA)) was administered intramuscularly (time 0). Midazolam (1 mg kg^?1) and butorphanol (0.1 mg kg^?1) were administered intravenously 20 minutes later. Atipamezole (2.5 mg m^?2 BSA) was administered intramuscularly 60 minutes after medetomidine. In the control group, saline (0.5, 2.5 and 0.25 mL) was administered at the corresponding times. Heart rate, systolic, diastolic and mean arterial pressures, body temperature, renal cortical, ileal, colonic and skeletal muscle microvascular blood flows were measured before time 0, and 5, 15, 25, 40, 60, 65, 70 and 90 minutes thereafter. Results Heart rate, ileal and skeletal muscle blood flows decreased in the treatment group, while no changes were observed in the control group. Conclusions Laser Doppler flowmetry allowed the measurement of microvascular blood flow in different organs. The medetomidine‐midazolam‐butorphanol combination decreases intestinal and skeletal muscle microvascular blood flows, while renal cortical blood flow is maintained. Clinical relevance Medetomidine‐midazolam‐butorphanol combination can be used to induce a short duration anaesthesia in dogs, but it will induce cardiovascular depression. This depression appears to be accompanied by a redistribution of blood flow.     

DOPPLER MEASUREMENT OF SPLANCHNIC BLOOD FLOW DURING DIGESTION IN UNSEDATED NORMAL DOGS

The purpose of this study was to measure splanchnic blood flow during digestion in unsedated dogs by using duplex Doppler sonography. The study population consisted of 12 healthy dogs. Blood flow in the cranial mesenteric artery, the celiac artery, and the aorta was measured before a test meal and at 20, 60, and 90 minutes after eating. The following measurements were made or calculated: vessel diameter, peak systolic velocity, end diastolic velocity, mean velocity, resistive index, pulsatility index, and flow volume. There was a significant postprandial decrease in the resistive and pulsatility indices in both the cranial mesenteric (preprandial RI = 0.867, postprandial RI = 0.796, preprandial PI = 3.033, postprandial PI = 2.173) and the celiac (preprandial RI = 0.854, postprandial RI = 0.769, preprandial PI = 2.639, postprandial PI = 1.930) arteries. In both vessels the end diastolic velocity, the mean velocity, and the flow volume increased significantly postprandially. These changes occurred significantly earlier in the celiac artery than in the cranial mesenteric artery. The findings most likely correspond to postprandial splanchnic vasodilation. Doppler ultrasound provide a good methode of detecting changes in postprandial splanchnic blood flow in the dog.     

Effects of medetomidine on doppler variables of major abdominal arteries in normal dogs

The purpose of this study was to evaluate the effects of medetomidine administration on the Doppler variables of abdominal arteries. The study population consisted of 20 healthy dogs. The haemodynamic effects of the medetomidine were defined using Doppler variables of the abdominal aorta, renal arteries, cranial mesenteric artery and celiac artery. The dogs were monitored continuously and different measurements were performed before medetomidine injection, at 10, 40 and 80 minutes after medetomidine medication and after atipamezole administration. Changes in the characteristic Doppler spectra of different vessels were more marked in the abdominal aorta, in which a greater reverse flow was found. There was a significant decrease in peak systolic velocity (PSV), end diastolic velocity (EDV), and mean velocity (MV) at ten minutes in every vessel studied and this effect persisted until atipamezole administration. Pulsatility index (PI) increased significantly in the abdominal aorta at ten minutes and persisted during the study until atipamezole administration. Resistive index (RI) did not vary significantly in any vessel. A significant decrease was found in flow volume of the abdominal aorta, the cranial mesenteric artery and the celiac artery at ten minutes, persisting until atipamezole administration. We conclude that medetomidine can be a good sedative in aiding sonographic evaluation of RI in all the abdominal vessels studied. On the other hand, the changes in other Doppler variables suggest that medetomidine administration causes significant hemodynamic differences between sedated and non-sedated dogs.     

Effects of two preanesthetic regimens for ophthalmic surgery on intraocular pressure and cardiovascular measurements in dogs

The effects of different preanesthetic medications (acepromazine plus either meperidine or butorphanol) given before the induction of anesthesia with midazolam and ketamine on intraocular pressure, heart rate, and arterial blood pressure were investigated in 20 dogs. Following administration of preanesthetics and induction of anesthesia, dogs were intubated and anesthesia was maintained with halothane for 10 minutes. Intraocular pressure was significantly higher (P <.05) at several evaluations for dogs premedicated with acepromazine/meperidine than for those premedicated with acepromazine/butorphanol. Mean heart rate and diastolic arterial blood pressure were significantly (P <.05) higher 5 minutes after administration of acepromazine/meperidine than after acepromazine/butorphanol. Results of this study suggest that acepromazine/butorphanol is a satisfactory preanesthetic combination to use before induction of anesthesia with midazolam and ketamine for ophthalmic surgery in dogs.