Peter Lord - Academia.edu (original) (raw)
Papers by Peter Lord
Investigative Radiology, 1985
Mid-shaft fractures of the radius and ulna were produced in 3 to 4 kg New Zealand white rabbits a... more Mid-shaft fractures of the radius and ulna were produced in 3 to 4 kg New Zealand white rabbits and quantitative uptake of 99mTc MDP and 67Ga determined at 11, 18, 25, 32, 51, and 78 days following fracture. Two hundred microCi of 67Ga was administered 24 hours prior to sacrifice and 1.5 mCi 99mTc MDP 2 hours prior to sacrifice. Specific activity ratios (SARs) were determined between fracture and control sides for bone, muscle and skin. SARs for bone were surprisingly similar for 99mTc MDP and 67Ga, reaching peak values of 6.07 +/- 0.64 (99mTc 18 days); 6.58 +/- 0.90 (67Ga 32 days), subsequently decreasing to minimum values at 78 days postfracture (99mTc MDP 2.25 +/- 0.14; 67Ga 2.18 +/- 0.08). There was no statistically significant difference in SAR for 99mTc MDP vs. 67Ga in bone at any time after fracture. Whole sections of limb were resected on selected animals and activity ratios determined for these sections as a function of the contribution of activity from the various tissues in the volume of interest. Total activity ratios of 67Ga were lower than bone SARs as a result of the contribution of activity from muscle and skin. Thus the apparent lower activity ratios noted on 67Ga images compared with 99mTc MDP images in this fracture model were not due to differences in bone SARs but rather due to the higher soft tissue background activity contribution in the 67Ga images.
Veterinary Anaesthesia and Analgesia, 2006
Objective To evaluate the effects of meloxicam on renal function in dogs anaesthetized and render... more Objective To evaluate the effects of meloxicam on renal function in dogs anaesthetized and rendered hypotensive with acepromazine-thiopental-isoflurane.
American Journal of Veterinary Research, 2003
To investigate the effects of IM administration of acepromazine on indices of relative renal bloo... more To investigate the effects of IM administration of acepromazine on indices of relative renal blood flow and glomerular filtration rate (GFR) by means of scintigraphy, as well as the effects on physiologic, hematologic, and serum biochemical variables in anesthetized dogs, compared with effects of administration of saline. 6 healthy Beagles. Acepromazine (0.1 mg/kg) or physiologic saline (0.9 NaCI) solution was administered IM 30 minutes prior to induction of anesthesia with thiopentone; anesthesia was maintained with inspired isoflurane for 2.25 hours. Blood gases and circulatory and ventilatory variables were monitored. Renal function was evaluated by scintigraphic measurements of GFR and relative renal blood flow and analyses of serum and urine. Statistical analyses used ANOVA or Friedman ANOVA. Values of relative renal blood flow and GFR remained high despite low blood pressures. After administration of acepromazine, mean +/- SD arterial blood pressure was 66 +/- 8 mm Hg during anesthesia; this value was below the threshold (80 mm Hg) for renal autoregulation of GFR. In comparison, mean arterial blood pressure after administration of saline was significantly higher (87 +/- 13 mm Hg). However, between treatments, there were no significant differences in GFR, relative renal blood flow, or other indices of renal function. Measurements of renal function and blood flow in dogs during anesthesia with thiopentone and isoflurane did not differ significantly between treatments, which suggested that acepromazine protects renal function despite inducing reduction in blood pressure, compared with effects of administration of saline.
American Journal of Veterinary Research, 2002
Objective-To investigate effects of IV administered carprofen on indices of renal function and re... more Objective-To investigate effects of IV administered carprofen on indices of renal function and results of serum biochemical and hematologic analyses in dogs anesthetized with acepromazine-thiopentone-isoflurane that had low blood pressure during anesthesia. Animals-6 healthy Beagles. Procedure-A randomized crossover study was conducted, using the following treatments: saline (0.9% NaCl solution)-saline, saline-carprofen, and carprofensaline. Saline (0.08 ml/kg) and carprofen (4 mg/kg) were administered IV. The first treatment was administered 30 minutes before induction of anesthesia and immediately before administration of acepromazine (0.1 mg/kg, IM). Anesthesia was induced with thiopentone (25 mg/ml, IV) and maintained with inspired isoflurane (2% in oxygen). The second treatment was administered 30 minutes after onset of inhalation anesthesia. Blood gases, circulation, and ventilation were monitored. Renal function was assessed by glomerular filtration rate (GFR), using scintigraphy, serum biochemical analyses, and urinalysis. Hematologic analysis was performed. Statistical analysis was conducted, using ANOVA or Friedman ANOVA. Results-Values did not differ significantly among the 3 treatments. For all treatments, sedation and anesthesia caused changes in results of serum biochemical and hematologic analyses, a decrease in mean arterial blood pressure to 65 mm Hg, an increase of 115 pmol/L in angiotensin II concentration, and an increase of 100 seconds in time required to reach maximum activity counts during scintigraphy. Conclusions and Clinical Relevance-Carprofen administered IV before or during anesthesia did not cause detectable significant adverse effects on renal function or results of serum biochemical and hematologic analyses in healthy Beagles with low blood pressure during anesthesia. (Am J Vet Res 2002;63: 712-721)
Journal of veterinary medicine. A, Physiology, pathology, clinical medicine, 2003
The sources of variability in variability of scintigraphic measurements of glomerular filtration ... more The sources of variability in variability of scintigraphic measurements of glomerular filtration rate (GFR) have not been determined. The day to day variability of GFR was studied in 18 healthy beagle dogs. The renal uptake of 99mTc-diethylenetriaminepentaacetic acid (DTPA) of each dog was measured using a scintigraphic technique three times at intervals of 5-26 days. GFR was calculated from a regression equation relating uptake to plasma clearance, derived in our laboratory. The mean GFR was 3.97 +/- 0.72 (SD) ml/min/kg with values from 2.66 to 5.67 ml/min/kg. Analysis of variance (ANOVA) using a linear mixed model showed that most variability is a result of the dogs, less because of day to day variability and very little to the measurement variability. The repeatability coefficients for the day to day variability and measurement variability were 1.06 and 0.21 ml/min/kg respectively. The day to day variability can be caused by physiological homeostatic adjustments by the kidneys ne...
Veterinary Radiology <html_ent glyph="@amp;" ascii="&"/> Ultrasound, 2005
The vertebral heart size (VHS) method by Buchanan is based on anatomic landmarks. A potential sou... more The vertebral heart size (VHS) method by Buchanan is based on anatomic landmarks. A potential source of variation among observers is differences in the selection of measurement points. The objective was to test variability between observers with different levels of training in thoracic radiology and small animal clinical practice.
Veterinary Radiology <html_ent glyph="@amp;" ascii="&"/> Ultrasound, 2002
Determinations of different methods of measurement of uptake of ""Tc-DTPA using scintigraphy of g... more Determinations of different methods of measurement of uptake of ""Tc-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.
Veterinary Radiology <html_ent glyph="@amp;" ascii="&"/> Ultrasound, 2002
Two-dimensional (2-D) echocardiographic measurement of the left atrium (LA) has the potential to ... more Two-dimensional (2-D) echocardiographic measurement of the left atrium (LA) has the potential to be more accurate than the standard M-mode method, because the LA body can be measured. We evaluated a 2-D method for measuring LA and aorta (AO) in a right parasternal short-axis view and compared it to the M-mode method. An index for LA size (LMAO) was calculated in 166 cavalier King Charles spaniels, 56 normal and 110 dogs with mitral regurgitation (MR) of varying degrees secondary to chronic valvular disease. In normal dogs, the AO-2-D and LA/AO-2-D did not correlate to body weight (BW) or BW' ; whereas, all M-mode values and the LA-2-D were significantly (p < .05) related to both BW parameters. In normal dogs, there was no difference between M-mode and 2-D indices. For all dogs (normal and dogs with MR) there was an 11% bias between the M-mode and 2-D index with the LA/AO-2-D being higher than the LMAO-M. The association between the mean and the difference of the indices demonstrated a quadratic relationship. Dogs with a mean LA/AO of 2.0-2.5 showed the largest difference between the two indices. Small values for the 2-D coefficients of variation for respiration and stage of diastole were found; 3.4 and 3.1%, respectively. The 2-D index is more sensitive to LA enlargement than the M-mode index.
Veterinary Radiology & Ultrasound, 2007
Glomerular filtration rate (GFR) normalized to body fluid volumes to adjust for differing body si... more Glomerular filtration rate (GFR) normalized to body fluid volumes to adjust for differing body size and conformation is more physiologically correct than a relationship with body weight (BW). GFR can be normalized to plasma volume by a renographic method that uses the Rutland-Patlak plot with plasma activity and kidney activity inputs. A plasma time-activity curve is obtained from a region of interest (ROI) of the left ventricle (LV), the size of which is in theory not critical. The aims of the study were to evaluate the effect of different LV ROI sizes, the effect of extravascular activity in the thorax over the LV ROI, and different time intervals for the semilogarithmic LV plot. Seventy-two scintigrams were used, with three different-sized automatic and a manual LV ROI, all with and without subtracting extravascular activity, and with LV curve time intervals of 30-120 s and 60-240 s. GFR/plasma volume was not affected by LV ROI sizes but significantly affected by extravascular activity subtraction and different time intervals. Subtracting extravascular activity from the LV ROI did not improve precision, but increased variability caused by different LV ROI sizes and time intervals chosen for the LV plot. The ROI for measuring extravascular activity apparently contained a considerable and variable intravascular component, which when subtracted, created noisy and unreliable LV curves. Manual LV ROI, without extravascular subtraction, and a time interval for LV input between 1 and 4 min are recommended as they gave the least variability determined by statistical analysis. With these methods, normal individual GFR/plasma volume in normal beagle dogs was 29.2 AE 6.5 ml/min/l.
Veterinary Radiology <html_ent glyph="@amp;" ascii="&"/> Ultrasound, 2006
Observer variation in kidney depth measurement for correction of soft-tissue attenuation and kidn... more Observer variation in kidney depth measurement for correction of soft-tissue attenuation and kidney region of interest (ROI) drawing was evaluated using 60 clinical dogs with a wide range of glomerular filtration rate (GFR) for their effect on the calculated percentage uptake of 99m Tc-diethylenetriamine pentaacetic acid (DTPA) and individual kidney GFR by scintigraphy. Kidney depth was measured separately on the lateral image using two color tables: a threshold and a continuous red-green-blue. Within-observer variability of the semi-automatic ROI drawing of the estimated total GFR was up to 10% for the right kidney (RK) and 9% for the left kidney (LK). The variability was lower between observers, 6% for RK and 8% for LK. Manual ROI drawing caused more within observer variation than semi-automatic: up to 14% for RK and 11% for LK. Continuous red-green-blue table caused more variation within and between observers than threshold table. Average within-observer variability from both observers of kidney depth measurement on different color tables could vary up to 5.5% and 6.5% variation of the GFR of RK and LK, respectively. Most variation affecting the DTPA percentage uptake came from the ROI drawing technique. Variations of the method because of the effects of both kidney depth and kidney ROI drawing were up to 8% and 10% for RK and LK, respectively. To minimize these variations a threshold scale should be used for the kidney depth measurement and an automatic or semi-automatic ROI should be used whenever possible. In sequential examinations the same person should make all the measurements.
Journal of Veterinary Internal Medicine, 2002
We evaluated the long-term effect of early angiotensin-converting enzyme (ACE) inhibition (enalap... more We evaluated the long-term effect of early angiotensin-converting enzyme (ACE) inhibition (enalapril maleate) as monotherapy to postpone or prevent congestive heart failure (CHF) in asymptomatic dogs with mitral regurgitation (MR) attributable to myxomatous valvular disease (MVD) in a prospective, randomized, double-blinded, placebo-controlled multicenter trial involving 14 centers in Scandinavia. Two hundred twenty-nine Cavalier King Charles (CKC) Spaniels with MR attributable to MVD but no signs of CHF were randomly allocated to treatment with enalapril 0.25-0.5 mg daily (n ϭ 116) or to placebo groups (n ϭ 113). Each dog was evaluated by physical examination, electrocardiography, and thoracic radiography at entry and every 12 months (Ϯ30 days). The number of dogs developing heart failure was similar in the treatment and placebo groups (n ϭ 50 [43%] and n ϭ 48 [42%], respectively; P ϭ .99). The estimated means, adjusted for censored observations, for the period from initiation of therapy to heart failure were 1,150 Ϯ 50 days for dogs in the treatment group and 1,130 Ϯ 50 days for dogs in the placebo group (P ϭ .85). When absence or presence of cardiomegaly at the entrance of the trial was considered, there were still no differences between the treatment and placebo groups (P ϭ .98 and .51, respectively). Multivariate analysis showed that enalapril had no significant effect on the time from initiation of therapy to heart failure (P ϭ .86). Long-term treatment with enalapril in asymptomatic dogs with MVD and MR did not delay the onset of heart failure regardless of whether or not cardiomegaly was present at initiation of the study.
Journal of Veterinary Internal Medicine, 2009
The contribution of right heart (RH) chamber enlargement to general heart enlargement seen on tho... more The contribution of right heart (RH) chamber enlargement to general heart enlargement seen on thoracic radiographs in mitral regurgitation (MR) is not known. To determine the size and shape of the RH chambers in normal dogs and dogs with varying degrees of MR. Fifty-four privately owned dogs: 13 normal, 41 with varying degrees of MR including 25 with congestive heart failure (CHF). Archived first pass radionuclide angiocardiograms were used to produce static images of the RH and left heart (LH) chambers. Indexes of size and shape of the RH and LH chambers were related to severity of MR determined by heart rate-normalized pulmonary transit time (nPTT), vertebral heart scale (VHS), and clinical status. RH shape was measured by a circularity index of RH short axis/long axis. A 2nd degree polynomial fit best described the ratios; RH/LH dimension to nPTT (R(2)= 0.62) and to VHS (R(2)= 0.43), RH/LH area to nPTT (R(2)= 0.64) and to VHS (R(2)= 0.58), all P < .001. RH circularity was decreased in CHF, P < .001. In CHF, the RH chambers of 16 dogs were both flattened and enlarged, whereas 9 had convex septal borders. RH chambers are not significantly dilated in dogs with mild to moderate MR without CHF. In CHF, RH chambers enlarge and also may be compressed by the LH chambers. Pulmonary hypertension probably is present in some dogs with CHF. Increased sternal contact is not a useful sign of right-sided heart dilatation in MR.
Journal of Veterinary Internal Medicine, 2003
Pulmonary transit time (PTT) normalized to heart rate (nPTT) is a measure of the pulmonary blood ... more Pulmonary transit time (PTT) normalized to heart rate (nPTT) is a measure of the pulmonary blood volume (PBV) to stroke volume ratio (PBV/SV). It is an index of cardiac performance. To determine the effect of compensated mitral regurgitation (CMR) and decompensated mitral regurgitation (DMR) caused by valvular endocardiosis on the index nPTT, we measured nPTT by first-pass radionuclide angiocardiography and ECG in 13 normal dogs, 18 dogs with CMR, and 13 dogs with DMR. PTT was measured as time between onset of appearance of activity at the pulmonary trunk and the left atrium. In the normal dogs, the relationship between PTT and mean R-R interval (mRR) was PTT = 4.08 x mRR + 0.15 (R2 = 0.71). Normal nPTT was 4.4 +/- 0.6 (SD) (range. 3.6-5.3). in CMR, 6.3 +/- 1.6 (SD) (range, 4.0-9.7). and in DMR, 11.9 +/- 3.4 (SD) (range, 8.0-18.8). The differences among all groups were significant. Heart rates were 110 +/- 22 bpm in normal dogs, 111 +/- 20 in dogs with CMR, and 144 +/- 18 in dogs with DMR (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .001 for difference between DMR group and normal and CMR groups). Increased nPTT in CMR indicates preclinical heart pump dysfunction. Heart rate-normalized pulmonary transit times may be a useful index of heart function in mitral regurgitation.
Journal of Small Animal Practice, 2003
Journal of Small Animal Practice, 2009
Equine Veterinary Journal, 2010
Osteoarthrosis (OA) in the distal tarsal joints, bone spavin, is a well known condition which is ... more Osteoarthrosis (OA) in the distal tarsal joints, bone spavin, is a well known condition which is common in Icelandic horses age 6-12 years. To determine the nature, location and age of appearance of early radiographic and histological changes in the centrodistal tarsal joint (CD) of young Icelandic horses. Slab sections from the CD of young Icelandic horses were examined by high detail radiography (age 6 months to 6 years, n = 111) and histology (age 6 months to 4 years, n = 82) to detect and describe the early changes indicative of OA. Horses younger than 5 years were unridden. Chondronecrotic lesions histologically similar to those described in the early pathogenesis of OA were seen in 33% of the joints, located both medially and laterally. Radiographic sclerosis of the subchondral bone was recorded in 60% of the specimens, most often medially. Medial location was not associated with chondronecrosis, but was strongly related to age. Sclerosis was an infrequent finding on the lateral side, and was probably secondary to chondronecrosis in the corresponding part of the joint. Small defects in the subchondral bone were considered to be the most specific radiographic sign of OA as they were strongly associated with chondronecrosis. The high prevalence of chondronecrosis in the young horses indicates an early onset and slow progression of the disease. The early appearance also shows that the initiation of the disease is unrelated to the use of horses for riding. As clinical manifestation of OA in the distal tarsal joints is most often described in mature or old horses, the first stages of the disease are not likely to result in clinical signs. Subchondral bone sclerosis did not appear to be a primary factor in the development of OA in the CD but was considered to reflect an uneven distribution of biomechanical forces within the joint. The development of OA in the CD of young Icelandic horses seems to be due to poor conformation or joint architecture rather than trauma or overloading. These aetiological factors are likely to be of importance for OA in the distal tarsal joints in other breeds as well. The influence of hindlimb conformation and the architecture of the distal tarsal joints on the biomechanics of joints need to be investigated, preferably by locomotion analysis in young horses.
Investigative Radiology, 1985
Mid-shaft fractures of the radius and ulna were produced in 3 to 4 kg New Zealand white rabbits a... more Mid-shaft fractures of the radius and ulna were produced in 3 to 4 kg New Zealand white rabbits and quantitative uptake of 99mTc MDP and 67Ga determined at 11, 18, 25, 32, 51, and 78 days following fracture. Two hundred microCi of 67Ga was administered 24 hours prior to sacrifice and 1.5 mCi 99mTc MDP 2 hours prior to sacrifice. Specific activity ratios (SARs) were determined between fracture and control sides for bone, muscle and skin. SARs for bone were surprisingly similar for 99mTc MDP and 67Ga, reaching peak values of 6.07 +/- 0.64 (99mTc 18 days); 6.58 +/- 0.90 (67Ga 32 days), subsequently decreasing to minimum values at 78 days postfracture (99mTc MDP 2.25 +/- 0.14; 67Ga 2.18 +/- 0.08). There was no statistically significant difference in SAR for 99mTc MDP vs. 67Ga in bone at any time after fracture. Whole sections of limb were resected on selected animals and activity ratios determined for these sections as a function of the contribution of activity from the various tissues in the volume of interest. Total activity ratios of 67Ga were lower than bone SARs as a result of the contribution of activity from muscle and skin. Thus the apparent lower activity ratios noted on 67Ga images compared with 99mTc MDP images in this fracture model were not due to differences in bone SARs but rather due to the higher soft tissue background activity contribution in the 67Ga images.
Veterinary Anaesthesia and Analgesia, 2006
Objective To evaluate the effects of meloxicam on renal function in dogs anaesthetized and render... more Objective To evaluate the effects of meloxicam on renal function in dogs anaesthetized and rendered hypotensive with acepromazine-thiopental-isoflurane.
American Journal of Veterinary Research, 2003
To investigate the effects of IM administration of acepromazine on indices of relative renal bloo... more To investigate the effects of IM administration of acepromazine on indices of relative renal blood flow and glomerular filtration rate (GFR) by means of scintigraphy, as well as the effects on physiologic, hematologic, and serum biochemical variables in anesthetized dogs, compared with effects of administration of saline. 6 healthy Beagles. Acepromazine (0.1 mg/kg) or physiologic saline (0.9 NaCI) solution was administered IM 30 minutes prior to induction of anesthesia with thiopentone; anesthesia was maintained with inspired isoflurane for 2.25 hours. Blood gases and circulatory and ventilatory variables were monitored. Renal function was evaluated by scintigraphic measurements of GFR and relative renal blood flow and analyses of serum and urine. Statistical analyses used ANOVA or Friedman ANOVA. Values of relative renal blood flow and GFR remained high despite low blood pressures. After administration of acepromazine, mean +/- SD arterial blood pressure was 66 +/- 8 mm Hg during anesthesia; this value was below the threshold (80 mm Hg) for renal autoregulation of GFR. In comparison, mean arterial blood pressure after administration of saline was significantly higher (87 +/- 13 mm Hg). However, between treatments, there were no significant differences in GFR, relative renal blood flow, or other indices of renal function. Measurements of renal function and blood flow in dogs during anesthesia with thiopentone and isoflurane did not differ significantly between treatments, which suggested that acepromazine protects renal function despite inducing reduction in blood pressure, compared with effects of administration of saline.
American Journal of Veterinary Research, 2002
Objective-To investigate effects of IV administered carprofen on indices of renal function and re... more Objective-To investigate effects of IV administered carprofen on indices of renal function and results of serum biochemical and hematologic analyses in dogs anesthetized with acepromazine-thiopentone-isoflurane that had low blood pressure during anesthesia. Animals-6 healthy Beagles. Procedure-A randomized crossover study was conducted, using the following treatments: saline (0.9% NaCl solution)-saline, saline-carprofen, and carprofensaline. Saline (0.08 ml/kg) and carprofen (4 mg/kg) were administered IV. The first treatment was administered 30 minutes before induction of anesthesia and immediately before administration of acepromazine (0.1 mg/kg, IM). Anesthesia was induced with thiopentone (25 mg/ml, IV) and maintained with inspired isoflurane (2% in oxygen). The second treatment was administered 30 minutes after onset of inhalation anesthesia. Blood gases, circulation, and ventilation were monitored. Renal function was assessed by glomerular filtration rate (GFR), using scintigraphy, serum biochemical analyses, and urinalysis. Hematologic analysis was performed. Statistical analysis was conducted, using ANOVA or Friedman ANOVA. Results-Values did not differ significantly among the 3 treatments. For all treatments, sedation and anesthesia caused changes in results of serum biochemical and hematologic analyses, a decrease in mean arterial blood pressure to 65 mm Hg, an increase of 115 pmol/L in angiotensin II concentration, and an increase of 100 seconds in time required to reach maximum activity counts during scintigraphy. Conclusions and Clinical Relevance-Carprofen administered IV before or during anesthesia did not cause detectable significant adverse effects on renal function or results of serum biochemical and hematologic analyses in healthy Beagles with low blood pressure during anesthesia. (Am J Vet Res 2002;63: 712-721)
Journal of veterinary medicine. A, Physiology, pathology, clinical medicine, 2003
The sources of variability in variability of scintigraphic measurements of glomerular filtration ... more The sources of variability in variability of scintigraphic measurements of glomerular filtration rate (GFR) have not been determined. The day to day variability of GFR was studied in 18 healthy beagle dogs. The renal uptake of 99mTc-diethylenetriaminepentaacetic acid (DTPA) of each dog was measured using a scintigraphic technique three times at intervals of 5-26 days. GFR was calculated from a regression equation relating uptake to plasma clearance, derived in our laboratory. The mean GFR was 3.97 +/- 0.72 (SD) ml/min/kg with values from 2.66 to 5.67 ml/min/kg. Analysis of variance (ANOVA) using a linear mixed model showed that most variability is a result of the dogs, less because of day to day variability and very little to the measurement variability. The repeatability coefficients for the day to day variability and measurement variability were 1.06 and 0.21 ml/min/kg respectively. The day to day variability can be caused by physiological homeostatic adjustments by the kidneys ne...
Veterinary Radiology <html_ent glyph="@amp;" ascii="&"/> Ultrasound, 2005
The vertebral heart size (VHS) method by Buchanan is based on anatomic landmarks. A potential sou... more The vertebral heart size (VHS) method by Buchanan is based on anatomic landmarks. A potential source of variation among observers is differences in the selection of measurement points. The objective was to test variability between observers with different levels of training in thoracic radiology and small animal clinical practice.
Veterinary Radiology <html_ent glyph="@amp;" ascii="&"/> Ultrasound, 2002
Determinations of different methods of measurement of uptake of ""Tc-DTPA using scintigraphy of g... more Determinations of different methods of measurement of uptake of ""Tc-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.
Veterinary Radiology <html_ent glyph="@amp;" ascii="&"/> Ultrasound, 2002
Two-dimensional (2-D) echocardiographic measurement of the left atrium (LA) has the potential to ... more Two-dimensional (2-D) echocardiographic measurement of the left atrium (LA) has the potential to be more accurate than the standard M-mode method, because the LA body can be measured. We evaluated a 2-D method for measuring LA and aorta (AO) in a right parasternal short-axis view and compared it to the M-mode method. An index for LA size (LMAO) was calculated in 166 cavalier King Charles spaniels, 56 normal and 110 dogs with mitral regurgitation (MR) of varying degrees secondary to chronic valvular disease. In normal dogs, the AO-2-D and LA/AO-2-D did not correlate to body weight (BW) or BW' ; whereas, all M-mode values and the LA-2-D were significantly (p < .05) related to both BW parameters. In normal dogs, there was no difference between M-mode and 2-D indices. For all dogs (normal and dogs with MR) there was an 11% bias between the M-mode and 2-D index with the LA/AO-2-D being higher than the LMAO-M. The association between the mean and the difference of the indices demonstrated a quadratic relationship. Dogs with a mean LA/AO of 2.0-2.5 showed the largest difference between the two indices. Small values for the 2-D coefficients of variation for respiration and stage of diastole were found; 3.4 and 3.1%, respectively. The 2-D index is more sensitive to LA enlargement than the M-mode index.
Veterinary Radiology & Ultrasound, 2007
Glomerular filtration rate (GFR) normalized to body fluid volumes to adjust for differing body si... more Glomerular filtration rate (GFR) normalized to body fluid volumes to adjust for differing body size and conformation is more physiologically correct than a relationship with body weight (BW). GFR can be normalized to plasma volume by a renographic method that uses the Rutland-Patlak plot with plasma activity and kidney activity inputs. A plasma time-activity curve is obtained from a region of interest (ROI) of the left ventricle (LV), the size of which is in theory not critical. The aims of the study were to evaluate the effect of different LV ROI sizes, the effect of extravascular activity in the thorax over the LV ROI, and different time intervals for the semilogarithmic LV plot. Seventy-two scintigrams were used, with three different-sized automatic and a manual LV ROI, all with and without subtracting extravascular activity, and with LV curve time intervals of 30-120 s and 60-240 s. GFR/plasma volume was not affected by LV ROI sizes but significantly affected by extravascular activity subtraction and different time intervals. Subtracting extravascular activity from the LV ROI did not improve precision, but increased variability caused by different LV ROI sizes and time intervals chosen for the LV plot. The ROI for measuring extravascular activity apparently contained a considerable and variable intravascular component, which when subtracted, created noisy and unreliable LV curves. Manual LV ROI, without extravascular subtraction, and a time interval for LV input between 1 and 4 min are recommended as they gave the least variability determined by statistical analysis. With these methods, normal individual GFR/plasma volume in normal beagle dogs was 29.2 AE 6.5 ml/min/l.
Veterinary Radiology <html_ent glyph="@amp;" ascii="&"/> Ultrasound, 2006
Observer variation in kidney depth measurement for correction of soft-tissue attenuation and kidn... more Observer variation in kidney depth measurement for correction of soft-tissue attenuation and kidney region of interest (ROI) drawing was evaluated using 60 clinical dogs with a wide range of glomerular filtration rate (GFR) for their effect on the calculated percentage uptake of 99m Tc-diethylenetriamine pentaacetic acid (DTPA) and individual kidney GFR by scintigraphy. Kidney depth was measured separately on the lateral image using two color tables: a threshold and a continuous red-green-blue. Within-observer variability of the semi-automatic ROI drawing of the estimated total GFR was up to 10% for the right kidney (RK) and 9% for the left kidney (LK). The variability was lower between observers, 6% for RK and 8% for LK. Manual ROI drawing caused more within observer variation than semi-automatic: up to 14% for RK and 11% for LK. Continuous red-green-blue table caused more variation within and between observers than threshold table. Average within-observer variability from both observers of kidney depth measurement on different color tables could vary up to 5.5% and 6.5% variation of the GFR of RK and LK, respectively. Most variation affecting the DTPA percentage uptake came from the ROI drawing technique. Variations of the method because of the effects of both kidney depth and kidney ROI drawing were up to 8% and 10% for RK and LK, respectively. To minimize these variations a threshold scale should be used for the kidney depth measurement and an automatic or semi-automatic ROI should be used whenever possible. In sequential examinations the same person should make all the measurements.
Journal of Veterinary Internal Medicine, 2002
We evaluated the long-term effect of early angiotensin-converting enzyme (ACE) inhibition (enalap... more We evaluated the long-term effect of early angiotensin-converting enzyme (ACE) inhibition (enalapril maleate) as monotherapy to postpone or prevent congestive heart failure (CHF) in asymptomatic dogs with mitral regurgitation (MR) attributable to myxomatous valvular disease (MVD) in a prospective, randomized, double-blinded, placebo-controlled multicenter trial involving 14 centers in Scandinavia. Two hundred twenty-nine Cavalier King Charles (CKC) Spaniels with MR attributable to MVD but no signs of CHF were randomly allocated to treatment with enalapril 0.25-0.5 mg daily (n ϭ 116) or to placebo groups (n ϭ 113). Each dog was evaluated by physical examination, electrocardiography, and thoracic radiography at entry and every 12 months (Ϯ30 days). The number of dogs developing heart failure was similar in the treatment and placebo groups (n ϭ 50 [43%] and n ϭ 48 [42%], respectively; P ϭ .99). The estimated means, adjusted for censored observations, for the period from initiation of therapy to heart failure were 1,150 Ϯ 50 days for dogs in the treatment group and 1,130 Ϯ 50 days for dogs in the placebo group (P ϭ .85). When absence or presence of cardiomegaly at the entrance of the trial was considered, there were still no differences between the treatment and placebo groups (P ϭ .98 and .51, respectively). Multivariate analysis showed that enalapril had no significant effect on the time from initiation of therapy to heart failure (P ϭ .86). Long-term treatment with enalapril in asymptomatic dogs with MVD and MR did not delay the onset of heart failure regardless of whether or not cardiomegaly was present at initiation of the study.
Journal of Veterinary Internal Medicine, 2009
The contribution of right heart (RH) chamber enlargement to general heart enlargement seen on tho... more The contribution of right heart (RH) chamber enlargement to general heart enlargement seen on thoracic radiographs in mitral regurgitation (MR) is not known. To determine the size and shape of the RH chambers in normal dogs and dogs with varying degrees of MR. Fifty-four privately owned dogs: 13 normal, 41 with varying degrees of MR including 25 with congestive heart failure (CHF). Archived first pass radionuclide angiocardiograms were used to produce static images of the RH and left heart (LH) chambers. Indexes of size and shape of the RH and LH chambers were related to severity of MR determined by heart rate-normalized pulmonary transit time (nPTT), vertebral heart scale (VHS), and clinical status. RH shape was measured by a circularity index of RH short axis/long axis. A 2nd degree polynomial fit best described the ratios; RH/LH dimension to nPTT (R(2)= 0.62) and to VHS (R(2)= 0.43), RH/LH area to nPTT (R(2)= 0.64) and to VHS (R(2)= 0.58), all P < .001. RH circularity was decreased in CHF, P < .001. In CHF, the RH chambers of 16 dogs were both flattened and enlarged, whereas 9 had convex septal borders. RH chambers are not significantly dilated in dogs with mild to moderate MR without CHF. In CHF, RH chambers enlarge and also may be compressed by the LH chambers. Pulmonary hypertension probably is present in some dogs with CHF. Increased sternal contact is not a useful sign of right-sided heart dilatation in MR.
Journal of Veterinary Internal Medicine, 2003
Pulmonary transit time (PTT) normalized to heart rate (nPTT) is a measure of the pulmonary blood ... more Pulmonary transit time (PTT) normalized to heart rate (nPTT) is a measure of the pulmonary blood volume (PBV) to stroke volume ratio (PBV/SV). It is an index of cardiac performance. To determine the effect of compensated mitral regurgitation (CMR) and decompensated mitral regurgitation (DMR) caused by valvular endocardiosis on the index nPTT, we measured nPTT by first-pass radionuclide angiocardiography and ECG in 13 normal dogs, 18 dogs with CMR, and 13 dogs with DMR. PTT was measured as time between onset of appearance of activity at the pulmonary trunk and the left atrium. In the normal dogs, the relationship between PTT and mean R-R interval (mRR) was PTT = 4.08 x mRR + 0.15 (R2 = 0.71). Normal nPTT was 4.4 +/- 0.6 (SD) (range. 3.6-5.3). in CMR, 6.3 +/- 1.6 (SD) (range, 4.0-9.7). and in DMR, 11.9 +/- 3.4 (SD) (range, 8.0-18.8). The differences among all groups were significant. Heart rates were 110 +/- 22 bpm in normal dogs, 111 +/- 20 in dogs with CMR, and 144 +/- 18 in dogs with DMR (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .001 for difference between DMR group and normal and CMR groups). Increased nPTT in CMR indicates preclinical heart pump dysfunction. Heart rate-normalized pulmonary transit times may be a useful index of heart function in mitral regurgitation.
Journal of Small Animal Practice, 2003
Journal of Small Animal Practice, 2009
Equine Veterinary Journal, 2010
Osteoarthrosis (OA) in the distal tarsal joints, bone spavin, is a well known condition which is ... more Osteoarthrosis (OA) in the distal tarsal joints, bone spavin, is a well known condition which is common in Icelandic horses age 6-12 years. To determine the nature, location and age of appearance of early radiographic and histological changes in the centrodistal tarsal joint (CD) of young Icelandic horses. Slab sections from the CD of young Icelandic horses were examined by high detail radiography (age 6 months to 6 years, n = 111) and histology (age 6 months to 4 years, n = 82) to detect and describe the early changes indicative of OA. Horses younger than 5 years were unridden. Chondronecrotic lesions histologically similar to those described in the early pathogenesis of OA were seen in 33% of the joints, located both medially and laterally. Radiographic sclerosis of the subchondral bone was recorded in 60% of the specimens, most often medially. Medial location was not associated with chondronecrosis, but was strongly related to age. Sclerosis was an infrequent finding on the lateral side, and was probably secondary to chondronecrosis in the corresponding part of the joint. Small defects in the subchondral bone were considered to be the most specific radiographic sign of OA as they were strongly associated with chondronecrosis. The high prevalence of chondronecrosis in the young horses indicates an early onset and slow progression of the disease. The early appearance also shows that the initiation of the disease is unrelated to the use of horses for riding. As clinical manifestation of OA in the distal tarsal joints is most often described in mature or old horses, the first stages of the disease are not likely to result in clinical signs. Subchondral bone sclerosis did not appear to be a primary factor in the development of OA in the CD but was considered to reflect an uneven distribution of biomechanical forces within the joint. The development of OA in the CD of young Icelandic horses seems to be due to poor conformation or joint architecture rather than trauma or overloading. These aetiological factors are likely to be of importance for OA in the distal tarsal joints in other breeds as well. The influence of hindlimb conformation and the architecture of the distal tarsal joints on the biomechanics of joints need to be investigated, preferably by locomotion analysis in young horses.