Comparison of digitized and conventional radiographic images for assessment of hip joint conformation in dogs

OBJECTIVE: To determine agreement between assessments of canine hip joint conformation provided by board-certified radiologists after evaluation of digitized and conventional radiographic images. SAMPLE POPULATION: 200 pelvic radiographs previously evaluated by radiologists using the Orthopedic Foundation for Animals standard grading system for canine hip joint conformation. PROCEDURES: Each of 20 board-certified radiologists evaluated conventional and digitized pelvic radiographs from each of 200 dogs for hip joint conformation. A weighted kappa coefficient and intraclass correlation were used to determine agreement between assessments derived from digitized radiographic images and conventional radiographs and between the original Orthopedic Foundation for Animals conformation ratings and assessments derived from each image format. RESULTS: Overall, agreement between assessments derived from the digitized images and conventional radiographs was good, with all but 1 radiologist attaining a weighted kappa coefficient > 0.61. Intraclass correlation for each radiologist ranged from 0.75 to 0.98 (95% confidence interval, 0.67 to 0.984). On comparison of conformation assessments, 95.7% of those derived from conventional radiographs and digitized images were within 1 grade. On comparison of digitized radiographic conformation assessments and conformation ratings, 94.2% were within 1 grade. On comparison of conventional radiographic conformation assessments and conformation ratings, 92.3% were within 1 grade. CONCLUSIONS AND CLINICAL RELEVANCE: The use of digitized radiographic images does not appear to impact the radiographic assessments of canine hip joint conformation made by consultant radiologists. Compared with conventional radiographs, the use of digitized radiographic images decreases storage space requirements and enables more rapid reporting of assessment results for individual dogs.     

Relationships among measurements obtained by use of computed tomography and radiography and scores of cartilage microdamage in hip joints with moderate to severe joint laxity of adult dogs

OBJECTIVE: To evaluate correlations among measurements on radiographic and computed tomography (CT) images with articular cartilage microdamage in lax hip joints of dogs. ANIMALS: 12 adult mixed-breed hounds. PROCEDURES: Pelvic CT and radiography were performed. Hip joints were harvested following euthanasia. Orthopedic Foundation for Animals (OFA) and PennHIP radiograph reports were obtained. Norberg angle (NA) and radiographic percentage femoral head coverage (RPC) were determined. Center-edge angle (CEA), horizontal toit externe angle (HTEA), ventral acetabular sector angle (VASA), dorsal acetabular sector angle (DASA), horizontal acetabular sector angle (HASA), acetabular index (AI), and CT percentage femoral head coverage (CPC) were measured on 2-dimensional CT images. Femoral head-acetabular shelf percentage was measured on sagittal 3-dimensional CT (SCT) and transverse 3-dimensional CT (TCT) images. Light microscopy was used to score joint cartilage. Relationships of OFA confirmation and PennHIP osteoarthritis scores with radiography, CT, and cartilage variables and relationships of cartilage scores with radiography and CT measurements were evaluated with Spearman rank correlations. Pearson correlation was used for relationships of distraction index (DI) with radiography, CT, and cartilage variables. RESULTS: Significant relationships included PennHIP osteoarthritis score with cartilage score, CEA, HTEA, DASA, AI, CPC, and TCT; OFA confirmation score with cartilage score, NA, RPC, CEA, HTEA, DASA, AI, CPC, and TCT; cartilage score with NA, RPC, CEA, HTEA, DASA, HASA, AI, and TCT; and DI with cartilage score, CEA, HTEA, DASA, HASA, AI, and CPC. CONCLUSIONS AND CLINICAL RELEVANCE: CT appeared to be a valuable imaging modality for predicting cartilage microdamage in canine hip joints.     

Comparative assessment of bone mineral measurements obtained by use of dual-energy x-ray absorptiometry, peripheral quantitative computed tomography, and chemical-physical analyses in femurs of juvenile and adult dogs

OBJECTIVE: To compare bone mineral measurements obtained by use of dual-energy x-ray absorptiometry (DEXA), peripheral quantitative computed tomography (pQCT), and chemical-physical analyses and determine effects of age and femur size on values obtained for the various techniques. SAMPLE POPULATION: Femurs obtained from 15 juvenile and 15 adult large-breed dogs. PROCEDURE: n each femur, 7 regions of interest were examined by use of DEXA to measure the bone mineral content (BMC) and bone mineral density (BMD), and 5 were examined by use of pQCT to measure BMD. Among these, 1 region was examined by both noninvasive methods and an invasive method. Volume of the femur was determined by water displacement. Volumetric bone density (VBD) was calculated. Calcium (Ca), phosphorus (P), total Ca, and total P contents were determined. RESULTS: DEXA- and pQCT-derived results revealed that all values increased with age in juvenile dogs. In adults, VBD and pQCT-derived BMD decreased significantly and DEXA-derived BMD increased with increasing femur length.The pQCT-derived BMD correlated well with VBD and Ca content, whereas DEXA-derived BMC was strongly correlated with Ca content. In juveniles, values correlated regardless of the technique used, whereas in adult dogs, DEXA-derived BMD did not correlate with pQCT-derived BMD, Ca concentration, or VBD unless data were adjusted on the basis of femur length. CONCLUSIONS AND CLINICAL RELEVANCE: DEXA-derived BMD adjusted for femur length yields approximately the same percentage variability in VBD as for pQCT-derived BMD. However, pQCT-derived BMD is still more sensitive for determining variability BMD in Ca concentration, compared with DEXA-derived BMD adjusted for femur length.     

Comparison of measurements of dorsolateral subluxation of the femoral head and maximal passive laxity for evaluation of the coxofemoral joint in dogs

OBJECTIVE: To determine whether dorsolateral subluxation (DLS) of the femoral head reflects osseous conformation of the coxofemoral (hip) joint and represents a property distinct from maximum passive laxity of the hip joint in dogs. ANIMALS: 14 Labrador Retrievers, 16 Greyhounds, 58 Greyhound-Labrador Retriever mixed-breed dogs, and 1 Rottweiler. PROCEDURES: DLS of the femoral head (DLS score) and passive laxity of the hip joint (distraction index) were determined radiographically in 3 groups of dogs: not treated (167 joints of 84 dogs); before and after injecting 2 ml of hyaluronan into 25 hip joints of 13 dogs; and before and after unilateral triple pelvic osteotomy in 5 dogs. Results of the 2 methods were compared for each group. RESULTS: In untreated dogs, the correlation coefficient (r) of DLS score versus distraction index was -0.73 and -0.69 for 84 left and 83 right hip joints, respectively. Mean coefficient of determination (r2) for both hips was 0.5. Mean DLS score did not differ before and after intra-articular injection of hyaluronan into either hip joint, whereas mean distraction index increased significantly after intra-articular injection. Unilateral triple pelvic osteotomy resulted in a significant increase in DLS score, compared with values obtained before surgery. However, distraction index before and after surgery did not differ significantly. CONCLUSIONS AND CLINICAL RELEVANCE: The DLS test assesses the congruity of the acetabulum and the femoral head in a canine hip joint and thus represents a characteristic distinct from maximum passive laxity. The DLS score and the distraction index evaluate different components of hip joint stability.     

Intraobserver and interobserver repeatability of ocular biometric measurements obtained by means of B-mode ultrasonography in dogs

OBJECTIVE: To assess intra- and interobserver repeatability of ocular biometric measurements obtained by means of high-resolution B-mode ultrasonography in dogs. Animals-6 Beagles without ocular abnormalities. PROCEDURES: B-mode ultrasonography was performed bilaterally with a 10.5-MHz broadband compact linear array transducer. All measurements were made on 2 different occasions by 2 observers. The Bland-Altman method was used to assess agreement between measurements obtained by the 2 observers and between the 2 sets of measurements obtained by each observer. RESULTS: Intra- and interobserver repeatability was highest for larger measurements, such as depth of the eye and depth of the anterior chamber. When repeatability was examined, bias was significantly different from 0 for only a few measurements, but the percentage difference between observations was as high as 180% for some measurements. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that most measurements of intraocular distances and structures obtained by means of high-resolution B-mode ultrasonography have acceptable intra- and interobserver repeatability. However, the percentage difference between observations can be high for smaller measurements.     

Comparison of the cognitive palatability assessment protocol and the two-pan test for use in assessing palatability of two similar foods in dogs

OBJECTIVE: To compare preferences of dogs for 2 similar foods by use of 2 distinct methods (the cognitive palatability assessment protocol [CPAP] and the 2-pan test). ANIMALS: 13 Beagles. PROCEDURE: 6 dogs were trained in a 3-choice object-discrimination-learning task in which their nonpreferred objects were associated with a reward of a lamb-based or chicken-based food. The number of choices for each object was used to determine food preferences. Preference of the same foods was also assessed by use of a 2-pan test in which all 13 dogs were provided the 2 foods in identical bowls. The amount of each food consumed in 10 minutes was used to determine food preference. RESULTS: All dogs had a noticeable preference for the chicken-based food during the CPAP. Once established, preferences remained consistent and were not affected by satiety. The 2-pan test identified a preference for the chicken-based food in dogs with previous exposure to the food but only a weak and nonsignificant preference for the same food in dogs without previous exposure. Food preferences in the 2-pan test varied considerably. Total food consumption and the ability to detect a preference were reduced when dogs were fed prior to testing. CONCLUSIONS AND CLINICAL RELEVANCE: The CPAP provides a reliable measure of food preference that requires few test subjects. The 2-pan test reveals similar preferences but with variability in data that requires larger numbers of subjects and is susceptible to effects from prior exposure and feeding of the test foods to the subjects.     

Comparison of deposition images obtained by use of an ultrafine 99m-technetium-labeled carbon dry aerosol with ventilation images obtained by use of 81m-krypton gas for evaluation of pulmonary dysfunction in calves.

OBJECTIVE: To characterize the accuracy of an ultrafine 99m-technetium-labeled carbon dry aerosol for use in assessment of regional ventilation in calves with pulmonary dysfunction. ANIMALS: 7 Belgian White and Blue calves. PROCEDURE: The ultrafine aerosol was assessed by comparing deposition (D) images with ventilation (V) images obtained by use of 81 m-krypton (81mKr) gas via D-to-V ratio (D:V) image analysis in calves during spontaneous breathing (SB) and during experimentally induced pulmonary dysfunction (ePD). RESULTS: Mismatching index (LrTot) calculated on the D:V images revealed a good match (LrTot, 0.96 +/- 0.01) between D and V distribution patterns in calves during SB. Calculation of the ultrafine aerosol penetration index relative to 81mKr (PIRel) revealed preferential distribution of the ultrafine aerosol in lung parenchyma (PIRel, 1.13 +/- 0.11). In ePD, heterogeneity in the D:V distribution was observed (LrTot, 0.78 +/- 0.10) as a result of ultrafine aerosol particles impaction in airways as indicated by PIRel (0.66 +/- 0.16) and a proportion of pixels more radioactive in D images, compared with V images, that was located in the central part of the lung (475 +/- 77% in ePD vs 32.8 +/- 5.7% in SB). However, this central deposition did not prevent visual examination of the entire ventilated lung. CONCLUSIONS AND CLINICAL RELEVANCE: The ultrafine aerosol appears suitable for use in examination of ventilated parts of lungs of cattle, even those with impaired pulmonary function. However, airway impaction of ultrafine aerosol particles impedes the quantification of regional ventilation in cattle with abnormal lung function.     

Comparison of two-dimensional echocardiographic measurements of the left atrium in healthy dogs

The aim of the study was to establish normal echocardiographic values of the left atrium just above the mitral annulus (LAama) in healthy dogs. In the first part of the study 20 dogs of various breeds were examined. The diameter of the left atrium just above the mitral annulus (LAama) was compared to the linear (left to right) dimension of the left atrium (LAr-l) as published earlier. There was a linear relationship between LAr-l and the body weight (LAr-l = 0.5061 BW (kg) + 22.206; R2 = 0.81), but the proportion of LAr-l/LAama was independent of the body weight (LAr-l/LAama = 0.0004 BW (kg) + 1.0833; R2 = 0.01). In the second part of the study the left atrial diameter just above the mitral annulus (LAama) was measured in 121 dogs of various breeds. There was a positive linear relationship (R2 = 0.697; p < 0.001) between body weight and LAama (LAama = 0.54 BW (kg) + 18.502+/-4.76), but there were no significant correlations between the age of animals and LAama (p = 0.45) as well as between the gender of animals and LAama (p = 0.78). Two-dimensional echocardiographic (2DE) determination of LAama as described in the present study can be recommended for use in those dogs where measurement of LAr-l encounters technical difficulties. In these cases LAr-l can be calculated from LAama using the formula LAr-l/LAama = 0.0004 BW (kg) + 1.0833, worked out in the first experiment.     

Quantitative assessment of nociceptive processes in conscious dogs by use of the nociceptive withdrawal reflex

OBJECTIVE: To investigate the feasibility of evoking the nociceptive withdrawal reflex (NWR) from fore and hind limbs in conscious dogs, score stimulus-associated behavioral responses, and assess the canine NWR response to suprathreshold stimulations. ANIMALS: 8 adult Beagles. PROCEDURE: Surface electromyograms evoked by transcutaneous electrical stimulation of ulnaris and digital plantar nerves were recorded from the deltoideus, cleidobrachialis, biceps femoris, and tibialis cranialis muscles. Train-of-five pulses (stimulus(train)) were used; reflex threshold (I(t train)) was determined, and recruitment curves were obtained at 1.2, 1.5, and 2 x I(t train). Additionally, a single pulse (stimulus(single)) was given at 1, 1.2, 1.5, 2, and 3 x I(t train). Latency and amplitude of NWRs were analyzed. Severity of behavioral reactions was subjectively scored. RESULTS: Fore- and hind limb I(t train) values (median; 25% to 75% interquartile range) were 2.5 mA (2.0 to 3.6 mA) and 2.1 mA (1.7 to 2.9 mA), respectively. At I(t train), NWR latencies in the deltoideus, cleidobrachialis, biceps femoris, and cranial tibialis muscles were not significantly different (19.6 milliseconds [17.1 to 20.5 milliseconds], 19.5 milliseconds [18.1 to 20.7 milliseconds], 20.5 milliseconds [14.7 to 26.4 milliseconds], and 24.4 milliseconds [17.1 to 40.5 milliseconds], respectively). Latencies obtained with stimulus(train) and stimulus(single) were similar. With increasing stimulation intensities, NWR amplitude increased and correlated positively with behavioral scores. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs, the NWR can be evoked from limbs and correlates with behavioral reactions. Results suggest that NWR evaluation may enable quantification of nociceptive system excitability and efficacy of analgesics in individual dogs.     

Comparison of radiographic and anatomic femoral varus angle measurements in normal dogs

Objective— To determine if the clinically practiced method of radiographic femoral varus angle (R-FVA) measurement is repeatable, reproducible, and accurate.
Study Design— Radiographic and anatomic study.
Animals/Sample Population— Normal Walker hound cadavers (n=5) and femora (n=10).
Methods— Cadavers were held in dorsally-recumbent and torso-elevated positions as 3 craniocaudal radiographs were made of each femur, by each of 2 different technicians. Femora were then harvested for direct measurement of anatomic femoral varus angle (A-FVA). R-FVA was measured on each radiograph by each of 3 examiners on 3 separate occasions. Intra-observer (repeatability) and inter-observer (reproducibility) variance in R-FVA measurement and the strength of relationship between R-FVA and A-FVA (accuracy) were determined.
Results— Mean (±SD) A-FVA was 5.2±2.1° (range, 2.4–8.2°). Mean (±SD) R-FVA was 5.8±1.0° (range, 2.7–9.6°). Intra-observer variance (range: 11–16%) and inter-observer variance (16%) were acceptable. The strength of relationship between measured R-FVA and A-FVA (maximum adjusted R²<0) was unacceptably low regardless of observer, patient position, or radiographic technician.
Conclusion— R-FVA measurement was repeatable and reproducible, but not statistically accurate in predicting A-FVA in these 5 normal Walker hounds. The detected inaccuracy may be real or the result of a selection bias for normal dogs obscuring the true relationship.
Clinical Relevance— R-FVA may not be an accurate method of femoral varus measurement in dogs with A-FVA<10°. Using Slocum's criteria for distal femoral osteotomy (R-FVA>10°), the procedure would not have been erroneously performed in any of the normal dogs of this study.     

Comparison of direct and indirect blood pressure measurements in anesthetized dogs.

The precision and accuracy of an indirect oscillometric blood pressure measurement technique (Dinamap 8100) was assessed in 11 anesthetized Beagle dogs weighing 8 to 11.5 kg. Direct blood pressure measurements were made by catheterization of the lingual artery, and simultaneous indirect measurements were determined by placing a cuff over the median artery (midradial area). Blood pressure measurements at 2 different planes of anesthesia (light and deep) were recorded in triplicate. At a light plane of anesthesia, the Dinamap 8100 underestimated diastolic and mean arterial pressure, and at a deep anesthetic plane overestimated systolic pressure. The indirect technique had good repeatability of systolic pressures. Regression analysis for the 2 techniques showed excellent correlation (r = 0.93). The results indicate that the indirect oscillometric blood pressure measurement technique provides a good estimate of systolic, diastolic, and mean arterial pressure in dogs weighing 8-11.5 kg.     

Comparison between invasive hemodynamic measurements and noninvasive assessment of left ventricular diastolic function by use of Doppler echocardiography in healthy anesthetized cats

OBJECTIVE: To compare Doppler echocardiographic variables of left ventricular (LV) function with those obtained invasively via cardiac catheterization under a range of hemodynamic conditions. ANIMALS: 7 healthy anesthetized cats (1 to 3 years of age). PROCEDURE: Cats were anesthetized and instrumented to measure the time constant of isovolumic relaxation (tau [tau]), LV end-diastolic pressure (LVEDP), peak negative and positive rate of change of LV pressure, arterial blood pressure, and cardiac output. Echocardiographic variables of diastolic function (isovolumic relaxation time [IVRT], early LV flow propagation velocity [Vp], transmitral and pulmonary venous flow velocity indices, and LV tissue Doppler imaging indices) were measured simultaneously over a range of hemodynamic states induced by treatments with esmolol, dobutamine, cilobradine, and volume loading. Correlation between invasive and noninvasive measures of LV filling was determined by univariate and multivariate regression analyses. RESULTS: Significant correlations were found between tau and IVRT, peak Vp, peak late transmitral flow velocity, and peak systolic pulmonary venous flow velocity. A significant correlation was found between LVEDP and early diastolic transmitral flow velocity (peak E) and the ratio of peak E to peak Vp, but not between LVEDP and peak Vp. CONCLUSIONS AND CLINICAL RELEVANCE: IVRT and Vp can be used as noninvasive indices of LV relaxation; Vp was independent of preload and heart rate in this study. The E:Vp ratio may be useful as an indicator of LV filling pressure.     

Comparison of two caudolateral approaches to the scapulohumeral joint for treatment of osteochondritis dissecans in dogs

Two caudolateral approaches to the canine scapulohumeral joint that do not require myotomy, tenotomy, or osteotomy were used to expose the humeral heads of both scapulohumeral joints in 10 clinically normal dogs. One approach (method 1) was used on the left shoulder of 5 dogs and on the right shoulder of the other 5 dogs. The other approach (method 2) was used on the opposite joints. The amount of humeral head articular cartilage that could be exposed with each approach was measured. The amount of articular cartilage exposed with method 1 was significantly greater than that exposed with method 2 (P less than 0.0001). Method 1 also provided for exposure of the caudomedial aspect of the scapulohumeral joint. Method 1 was used unilaterally in 20 dogs with osteochondritis dissecans. This approach provided excellent exposure of the humeral head and osteochondritis dissecans lesion. Of the 16 dogs that were available for follow-up evaluation, 1 developed a seroma after surgery. Other complications were not observed or reported.     

Evaluation of ammonia measurements in dogs with two analysers for use in veterinary practice.

The measurement of ammonia in biological fluids is the only way to diagnose and evaluate hepatic encephalopathy, but samples for ammonia measurement cannot be stored or sent by post. Two analysers for use in veterinary practice have recently become available, the VetTest and the Blood Ammonia Checker II; the reliability of ammonia measurements in canine blood with these two analysers has been evaluated by comparing the results with a standard automated enzymatic assay. Blood samples from 39 dogs, with a range of ammonia concentrations from 5 to 589 microM, were used simultaneously in the three assays. The blood samples were placed immediately on ice, and the measurements were made in duplicate. The intra-assay coefficients of variation were 13.7 per cent for the VetTest, 4.7 per cent for the Blood Ammonia Checker, and 2.8 per cent for the enzymatic assay. The correlation coefficients over the entire range of concentrations were 0.79 between the VetTest and the enzymatic assay, and 0.98 between the Ammonia Checker and the enzymatic assay. The ammonia concentrations recorded in the enzymatic assay were divided into 12 samples within the normal range (0 to 50 microM), 18 samples with moderately increased concentrations (51 to 150 microM), and nine samples with concentrations above 150 microM. No correlation or a poor correlation was found between the results from the VetTest and those from the enzymatic assay from 0 to 50 microM (R = 0.27) and from 50 to 150 microM (R = 0.51; P = 0.05). The results from the VetTest were only reliable in samples with the highest concentrations (R = 0.93; P < 0.05). In contrast, the results from the Ammonia Checker correlated well with the results from the enzymatic assay over all the ranges: R = 0.79 (P < 0.05) from 0 to 50 microM, R = 0.86 (P < 0.05) from 50 to 150 microM, and R = 1.00 (P < 0.05) in samples exceeding 150 microM.     

Comparison of femoral inclination angle measurements in dysplastic and nondysplastic dogs of different breeds

In this study, inclination angle of the femoral head and neck was measured on 484 limbs of 242 dogs belonging to 7 breeds, examined for hip dysplasia. These inclination angles were compared according to age, sex and joint laxity, evaluated with Subluxation Index (SI) and Norberg angle (NA) results. The findings indicate that (a) there was a minimal (nonsignificant) difference in femoral inclination angle between the dysplastic and nondysplastic dogs belonging to 7 breeds; (b) although there was no significant difference in femoral inclination angle between the nondysplastic dogs belonging to 4 breeds (Pointer, Irish Setter, Golden Retriever and German Shepherd), a significant difference was observed between Doberman and Labrador, and between Anatolian Karabash and the other six breeds (p < 0.001). Age and sex did not affect the femoral neck angle.