A COMPARISON OF NORMAL FELINE THORACIC RADIOGRAPHS MADE IN DORSAL VERSUS VENTRAL RECUMBENCY

Thoracic radiographs of 11 normal cats were made in dorsal (VD) and ventral (DV) recumbency with a vertically directed x-ray beam. These radiographs were compared subjectively and objectively with each other and with an additional pair of radiographs made with the cats in dorsal and ventral recumbency using a horizontally directed x-ray beam. Differences were found between VD and DV thoracic radiographs but they were minimal. In VD radiographs the caudal mediastinum and accessory lobe regïon of the lung were more clearly seen but cardiac shape varied somewhat. In DV radiographs, the appearance of the heart was more constant and caudal lobar pulmonary arteries more clearly seen. The results of this study indicated that both VD and DV radiographs are satisfactory for radiographic examination of the feline thorax     

RADIOGRAPHIC AND ECHOCARDIOGRAPHIC MEASUREMENT OF THE HEART IN OBESE CATS

A prospective study was undertaken to reconcile radiographic cardiomegaly and normal echocardiography in obese cats and to test a radiographic technique for better distinguishing between pericardial fat and the heart. Ten obese, but otherwise normal cats and 10 non-obese normal cats were used. A body condition scoring system was used to objectively group obese and non-obese normal cats. Two-dimensional echocardiograms were made to verify that all cats had a normal heart. Thoracic radiographs then were made using standard and altered exposure techniques. The hearts were measured on these radiographs using the metric and a vertebral scale system. Obese cats consistently had excessive fat around the heart especially if they also had a large amount of falciform fat. Altering exposure technique by increasing mAs and decreasing kVp sometimes enhanced the radiographic contrast between fat and myocardium. Enhanced radiographic contrast accentuated the double silhouette identifying the true cardiac silhouette within the fat expanded silhouette. Pericardial fat usually was distinguished more readily in lateral than in VD radiographs. In two cats, pericardial fat had a characteristic prominent square corner to the right cranial margin of the cardiac silhouette in VD radiographs. Obesity caused increased width and depth of the thoracic cage. 2D echocardiograms revealed normal cardiac dimensions in both groups of cats and increased precordial distance in the obese group.     

Vertebral scale system to measure heart size in radiographs of cats

OBJECTIVE: To determine absolute and relative heart size in clinically normal cats by correlating heart size and selected skeletal structures. DESIGN: Prospective radiographic study. ANIMALS: 100 cats that did not have thoracic radiographic abnormalities. PROCEDURE: Standardized measurements of the long and short axes of the heart, midthoracic vertebrae, and other structures were made. Measurements were recorded in millimeters and number of thoracic vertebral lengths spanned by each dimension, measured caudally from T4 in a lateral radiograph. The long- and short-axis measurements of the heart, expressed in vertebral lengths, were added to yield vertebral heart size. RESULTS: Mean +/- SD vertebral heart size in lateral radiographs was 7.5 +/- 0.3 vertebrae. The long-axis dimension correlated with the length of 3 sternebrae, measured from S2 to S4. The cardiac short-axis dimension correlated moderately with the length of 3.2 vertebrae, measured from T4 to T6. The cardiac short-axis dimension in ventrodorsal radiographs was 3.4 +/- 0.25 vertebrae. CONCLUSIONS AND CLINICAL RELEVANCE: The vertebral heart-size method is easy to use, allows objective assessment of heart size, and may be helpful in determining cardiomegaly and comparing heart size in sequential radiographs.     

VERTEBRAL HEART SIZE RANGES SPECIFIC FOR WHIPPETS

To assess the influence of breed, breeding lines, and training on heart size, the vertebral heart size (VHS) was evaluated on left-to-right lateral, right-to-left lateral, dorsoventral, and ventrodorsal thoracic radiographs from 44 whippets free from cardiac and pulmonary disease. In lateral views, the VHS was 11.0 +/- 0.5 vertebrae (mean +/- SD) on right-to-left lateral and 11.3 +/- 0.5 vertebrae on left-to-right lateral radiographs, being larger than the 9.7 +/- 0.5 vertebrae proposed by Buchanan (P<0.0001). The VHS on left-to-right lateral views was larger than on right-to-left lateral views (P<0.0001). The VHS was 10.5 +/- 0.6 vertebrae on dorsoventral radiographs and 11.1 +/- 0.6 vertebrae on ventrodorsal radiographs. Both values were larger than the 10.2 +/- 1.5 vertebrae (dorsoventral) (P<0.0082) or 10.2 +/- 0.8 vertebrae (ventrodorsal) (P<0.0001) proposed by Buchanan. In addition, the VHS on ventrodorsal views was larger than on dorsoventral views (P<0.0001). Dogs out of racing pedigree lines had a significantly larger VHS than those out of show pedigree lines, and trained dogs had a significantly larger VHS than nontrained dogs. Because most trained dogs came out of racing pedigree lines, and all nontrained dogs came out of show pedigree lines, however, it is difficult to determine whether the higher VHS for trained dogs is due to genetic influences or training, or both. In conclusion, it is important to take into account the breed and the radiographic view when evaluating heart size in thoracic radiographs of whippets to avoid overinterpretation of cardiac enlargement in these dogs.     

RADIOGRAPHIC MEASUREMENT OF CARDIAC SIZE IN NORMAL FERRETS

Right lateral, left lateral and ventrodorsal radiographs were obtained in 20 normal ferrets (11 male). Three independent observers recorded measurements of the cardiac silhouette and results for each parameter were averaged. Long axis (length), short axis (width) and total of length plus width (L+W) were recorded in each view. Comparative measurements were calculated, including the ratio of L+W/length of thoracic vertebrae 5-8, and a modified vertebral heart score (VHS) method, measuring the heart in vertebral units. Measurements made in ventrodorsal views were usually larger than corresponding measurements in lateral views. Weight and most absolute measurements differed significantly between male and female ferret (P<0.05), but the differences in absolute measurements were not apparent when related to measures of body size (Ratio and modified VHS methods). Given the variability in body weight and size in ferrets, measurements of the cardiac silhouette normalized for body size may be more universally applicable than absolute measurements.     

INFLUENCE OF CARDIAC CYCLE ON THE RADIOGRAPHIC APPEARANCE OF THE FELINE HEART

The effect of cardiac-cycle phase on the radiographic appearance of the feline heart was investigated. Results show that the size and shape changes in the cardiac silhouette due to the cardiac cycle were present in all three postural positions investigated. Cardiac size and shape changes were present more frequently and in more locations of the cardiac silhouette when patients were in ventral recumbency (DV) versus dorsal recumbency (VD). In most cases, the magnitude of differences was small and detection was facilitated by comparison viewing. It is suggested that these size and shape influences of the cardiac cycle on cardiac appearance should be kept in mind when interpreting feline radiographs for cardiac pathology.     

Vertebral scale system to measure heart size in growing puppies.

OBJECTIVE: To determine relative heart size in clinically normal puppies and assess whether relative heart size changes with growth. DESIGN: Prospective radiographic study. ANIMALS: 11 puppies without evidence of disease. PROCEDURE: Standardized measurements of the long and short axes of the heart, midthoracic vertebrae, and other structures were made at 3, 6, 12, and 36 months of age. Measurements were recorded in millimeters and number of thoracic vertebral lengths spanned by each dimension, measured caudally from T4 on lateral radiographic views. The long and short axis measurements of the heart, expressed in vertebral lengths, were added to yield vertebral heart size. RESULTS: Mean +/- SD vertebral heart sizes on lateral radiographic views at 3, 6, 12, and 36 months of age were 10.0 +/- 0.5, 9.8 +/- 0.4, 9.9 +/- 0.6, and 10.3 +/- 0.6 vertebrae, respectively. Significant differences were not detected. CONCLUSIONS AND CLINICAL RELEVANCE: Vertebral heart size measurements in puppies are within the reference range for adult dogs (9.7 +/- 0.5 vertebrae) and do not change significantly with growth to 3 years of age. Standards for determining cardiac enlargement are similar in puppies and adult dogs.     

THE EFFECT OF MANUAL LUNG INFLATION VS. SPONTANEOUS INSPIRATION ON THE CARDIAC SILHOUETTE IN ANESTHETIZED DOGS

The purpose of this study was to assess radiographic heart size in anesthetized dogs, comparing radiographs made with the patient breathing spontaneously to radiographs obtained using positive pressure manual lung inflation. The hypothesis was that manual inflation would cause reduction in the cardiac size. With dogs in right recumbency a radiograph was made at peak spontaneous inspiration followed immediately a radiograph made with application of positive pressure manual inflation of the thorax. Cardiac size was assessed, both subjectively and objectively using the vertebral heart scale (VHS). Two hundred and six dogs were studied. Manual inflation resulted in a significantly greater degree of lung inflation assessed radiographically ( P <0.0001). The subjectively assessed heart size was significantly smaller in radiographs made with manual inflation, leading to different subjective categorization of heart size in 67 (32%) of dogs. The objectively measured VHS was also significantly smaller in the radiographs made using manual inflation by a mean of 0.24 of a vertebral length (95% CL of mean difference: −0.29, −0.19, P <0.0001). A statistically significant reduction in subjective heart size and in VHS occurred with manual inflation of the lungs, and these differences may be clinically significant. Thus, if serial radiographs are obtained to assess cardiac size, the radiographic technique used should be the same.     

Radiographic vertebral left atrial size: A reference interval study in healthy adult dogs

Thoracic radiography is a useful technique for the evaluation of cardiac dimensions, especially when echocardiography is not possible. The vertebral left atrial size (VLAS) has recently been proposed as a new radiographic method for quantifying left atrial dimensions in dogs. The aims of this retrospective, reference interval, observational study were to describe values for VLAS in a group of healthy adult dogs and to compare intraobserver and interobserver agreement for VLAS versus vertebral heart score (VHS) methods. Thoracic radiographs of 80 healthy adult dogs were evaluated. Normal left atrial size was determined based on an echocardiographic left atrial‐to‐aorta ratio < 1.6. The VLAS and vertebral heart score values were measured from right lateral radiographs. The correlations between VLAS, the vertebral heart score, and the left atrial‐to‐aorta ratio were evaluated. The effects of body weight, sex, and age were also tested using regression analyses. The median value of VLAS were 1.9, with a reference interval of 1.4‐2.2. A positive correlation was found between VLAS and vertebral heart score values (r = 0.53; P < .0001). No effect of body weight, sex, and age on VLAS was detected. Excellent intraobserver and interobserver agreements were found for both VLAS and vertebral heart score methods (intraclass correlation coefficients ≥ 0.91). Findings from this sample of healthy dogs indicated that VLAS is a repeatable radiographic method for quantifying left atrial size. Further studies are warranted to evaluate this measure in clinically affected dogs.     

Assessment of the value of the vertebral heart scale in the radiographic diagnosis of cardiac disease in dogs

In order to assess the influence of the vertebral heart scale (VHS) on the accuracy of the radiographic diagnosis of cardiac disease, thoracic radiographs of 50 dogs with proven cardiac disease, 26 with other thoracic diseases, and 50 with no clinical signs of cardiovascular or respiratory disease were mixed and examined by three independent, blinded observers chosen to represent a range of radiographic abilities. They first examined all the radiographs without making measurements of VHS and made a diagnosis. They then re-examined the radiographs, and measured VHS on both lateral and dorsoventral or ventrodorsal radiographs before again recording a diagnosis without reference to their original diagnoses. For all the observers, the dogs with cardiac disease had a higher mean VHS than the normal dogs. A VHS over 10.7 on the lateral radiograph was a moderately accurate sign of cardiac disease. The observers' accuracy of diagnosis did not change significantly as a result of using VHS as an adjunct to a subjective assessment of the radiographs.     

CORRELATION OF RADIOGRAPHIC, ECHOCARDIOGRAPHIC, AND ELECTROCARDIOGRAPHIC SIGNS OF LEFT HEART ENLARGEMENT IN DOGS WITH MITRAL REGURGITATION

Thoracic radiographs of 40 dogs with mitral regurgitation were evaluated for signs of left heart enlargement and classified into three groups based on the degree of left atrial enlargement (mild = group A, moderate = group B, and severe = group C). Echocardiographic enlargement ratios were calculated for the left atrium (LAE_echo), the left ventricle (LVE_echo), and the aorta (AOE_echo) by dividing the measured dimension with the expected dimension normalized for body weight. The incidence of LVH patterns and p-mitrale was recorded on electrocardiograms. With advanced stages of the disease, there was good agreement of the radiographs and echocardiograms with significant differences of the left atrial enlargement ratio between groups. Nine of the 16 dogs from groups A and B, however, had LAE_echo ratios within the normal range. Sixteen dogs with radiographic signs of left ventricular enlargement had normal LVEecho ratios. These disagreements were interpreted as either cardiac enlargement not manifest in the dimensional change measured by the echocardiogram or as overreading of radiographs. The left ventricular wall thickness did not vary significantly between groups. The incidence of p-mitrale was 30%, but this ECG abnormality, when present, reliably identified enlarged left atrial dimensions. Left ventricular hypertrophy patterns of the ECG did not correlate with either the radiographic diagnosis of left ventricular enlargement or the echocardiographic enlargement ratios.     

THE EFFECT OF DEXMEDETOMIDINE ON RADIOGRAPHIC CARDIAC SILHOUETTE SIZE IN HEALTHY CATS

Dexmedetomidine, an alpha₂‐adrenergic agonist, may be used in companion animals for chemical restraint, including cardiac evaluation. Echocardiographic changes associated with alpha₂‐adrenergic agonists have been described; however reports of radiographic changes in cats were not found at the time of this study. Aims of this observational, prospective, experimental study were to describe the effects of dexmedetomidine on the radiographic appearance of the cardiac silhouette in healthy, adult cats. Fourteen healthy adult cats received dexmedetomidine 40 mcg/kg IM. Right lateral, left lateral, ventrodorsal, and dorsoventral thoracic radiographs were obtained for each cat at three time points: presedation, intrasedation, and postsedation (≥ two hours after reversal with atipamezole). Radiographs were evaluated in a blinded, randomized fashion by two independent observers using the vertebral heart score on all four views, the number of intercostal spaces on lateral projections, and the percent width of thorax on ventrodorsal and dorsoventral projections. Median vertebral heart score on right lateral view was significantly increased intrasedation (median = 7.8; range = 7.25–8.25) compared to presedation (median = 7.5; range = 7–8 [P = 0.001]). Median percentage width was significantly higher intrasedation (70% on VD; range 65–80 [P = 0.001], and 75% on DV; range 65–80 [P = 0.006]) compared to presedation (65%; range 65–75 on both projections). Dexmedetomidine was associated with a small but significant increase in cardiac silhouette size on right lateral (vertebral heart score), ventrodorsal (percentage width), and dorsoventral (percentage width) radiographs in healthy adult cats. This effect should be taken into consideration for future interpretation of thoracic radiographs in dexmedetomidine‐sedated cats.     

Thoractic radiographic appearance during lung inflation in neonatal calves

The effect of lung inflation on thoracic radiographic anatomy was determined in seven anesthetized calves less than one week of age. Radiographs were taken with the calves in dorsoventral (DV), ventrodorsal (VD), left and right lateral recumbency at functional residual capacity (FRC), at half inflation of the lung and at total lung capacity (TLC). Lung volumes were maintained by positive pressure ventilation. Increases in areas and linear dimensions during lung inflation were not uniform, being greatest in the caudal and especially the caudal ventral regions of the thorax. With inflation, heart size decreased and the heart shadow moved cauded as the diaphragm flattened. When the calf was shifted from the DV to the VD position, the heart displaced toward the left thoracic wall. Lung areas were larger on VD than on DV projections with the right lung being larger than the left. On lateral radiographs the most reliable, easily observed indication of the stage of lung inflation was the area bounded by the vena cava, the caudal heart border and the diaphragm. On the DV or VD radiographs the transthoracic width at the diaphragm was the best indicator of the degree of lung inflation.     

Vertebral heart size in healthy Australian cattle dog

The vertebral heart score or size (VHS) measurement is routinely used to provide a more objective measurement of cardiomegaly in dogs. However, breed or body conformation can influence the VHS. To assess the specific VHS for the Australian Cattle Dog, left‐to‐right lateral, right‐to‐left lateral, dorsoventral and ventrodorsal thoracic radiographs from 20 individuals free from cardiac and pulmonary disease were obtained. The mean VHS was significantly higher in Australian Cattle Dog (10.5 ± 0.4 vertebrae), when compared with the average VHS for 100 normal dogs of different breeds that had been initially published (9.7 ± 0.5 vertebrae). This emphasizes the importance of breed‐specific VHS ranges. In our study group of normal Australian Cattle Dogs, the mean VHS was 10.5 ± 0.5 vertebrae (mean ±SD) on right lateral and 10.3 ± 0.5 vertebrae on left lateral radiographs. The VHS on right lateral views was significantly larger than on left lateral views. The VHS was 10.5 ± 0.6 vertebrae on dorsoventral and 11.1 ± 0.6 vertebrae on ventrodorsal radiographs. The VHS on ventrodorsal views was significantly larger than on dorsoventral views.     

Effect of various thoracic radiographic projections on the appearance of selected thoracic viscera

OBJECTIVES: To assess the effect of different radiographic projections on thoracic width, as well as position and visibility of the trachea, principal bronchi, cardiac silhouette, aorta, caudal vena cava (CVC) and oesophagus. METHODS: Right lateral recumbency (RLR), left lateral recumbency (LLR), dorsoventral (DV) and ventrodorsal (VD) thoracic radiographs of 42 dogs were reviewed retrospectively. RESULTS: In 78 per cent of cases the thoracic width was significantly larger on the VD projection than on the DV projection. The angle of divergence formed by the principal bronchi was significantly larger on the VD projection than on the DV projection in 80 per cent of dogs. A cardiac silhouette bulge at 1 to 2 o'clock was apparent on the VD projection in 22 per cent of dogs but was never seen on DV projections. The descending aorta was more visible at the 4 to 5 o'clock cardiac silhouette level on the DV projection and laterally at the T8 level on LLR projections. The CVC was better seen on VD and LLR projections. The oesophagus was visible as a soft tissue opacity in LLR in large dogs with normal thoracic conformation in 35 per cent of cases. CLINICAL SIGNIFICANCE: The DV projection appears to be more reliable for assessing the cardiac silhouette, the descending aorta and the angle of divergence of the principal bronchi. The VD projection should be considered for evaluating the CVC. LLR should be used for assessing the descending aorta and CVC.     

Use of routine ventrodorsal radiographic views of the pelvis to assess inclination of the wings of the sacrum in dogs

OBJECTIVE: To determine the ratio of ventral-to-dorsal transverse diameters between the wings of the sacrum on ventrodorsal radiographic views of the pelvis in large dogs and to validate the reliability of this morphometric analysis for functional interpretation. SAMPLE POPULATION: Pelvic specimens from 40 large-breed dogs and radiographs of 113 large-breed dogs. PROCEDURE: In an anatomic and radiographic evaluation, the transverse dorsal diameter (TVDS) and transverse ventral diameter (TVV) between the wings of the sacrum were evaluated in sacrum specimens and on corresponding radiographs of the pelvis and sacrum. The ratio between TVV and TVDS (VD ratio) was calculated. Intraobserver reliability was determined by calculation of the coefficient of variation. In a retrospective radiographic evaluation, the VD ratio was determined in Rottweilers, Golden Retrievers, and German Shepherd Dogs. Correlations between VD ratio and breed, age, and sex were tested. RESULTS: The VD ratio was significantly higher in Rottweilers than in Golden Retrievers and German Shepherd Dogs, denoting an oblique alignment of the sacral wings in Rottweilers (ie, the dorsal aspects of the sacral wings were located more medially than the ventral aspects) and an almost sagittal alignment in the other breeds. The VD ratio was significantly associated with age but not with sex. CONCLUSIONS AND CLINICAL RELEVANCE: Sagittal alignment of the wings of the sacrum is considered to be biomechanically less efficient. These results provide a basis for further studies to evaluate radiographic assessment of the sacroiliac joints similar to the evaluation for hip dysplasia.     

Comparison of different radiographic scores with associated echocardiographic measurements and prediction of heart enlargement in dogs with and without myxomatous mitral valve disease

IntroductionStaging of myxomatous mitral valve disease (MMVD) requires an echocardiographic examination along with thoracic radiographs. The aims of this study were to calculate mean values for radiographic scores vertebral heart size (VHS), left atrial width (LA_Width), radiographic left atrial dimension (RLAD), and vertebral left atrial size (VLAS) in conventional and grayscale inverted images in healthy dogs and dogs with different stages of MMVD, and to find cutoff values for a stage assignment.AnimalsOne hundred fifty dogs in different stages of MMVD and 50 unaffected dogs were evaluated.MethodsRadiographic scores, echocardiographic left atrium-to-aorta ratio and normalized left ventricular internal dimension at end-diastole, and results of a clinical examination were obtained. Analyses were performed to evaluate the correlation between radiographic scores and echocardiographic values, to determine cutoff values for a radiographic stage assignment, and to compare measurements in conventional and inverted radiographs.ResultsAfter excluding breed-specific higher VHS, the means of VHS, LA_Width, RLAD, and VLAS were similar in the control group and stage B1. All radiographic scores increased in stages B2 and C. The cutoff values identifying heart enlargement, and therefore differentiating stages B1 and B2, were 11.0 for VHS, 1.8 for LA_Width, 2.0 for RLAD, and 2.3 for VLAS. Besides RLAD, scores were similar in conventional and inverted radiographs.ConclusionCutoff values for the different radiographic scores for stage assignment were calculated. Radiographic cardiac scores using either conventional or inverted grayscale could be a tool to differentiate between different stages of MMVD when echocardiography is unavailable.     

PLEURAL FLUID MOVEMENT

The present study was an attempt to illustrate the differences between ventrodorsal (VD) and dorsoventral (DV) radiographs that result from the movement of free pleural fluid. A volume of 25 ml/kg of normal saline was introduced into the pleural space of a normal dog, and radiographs of the thorax were produced in ventral and dorsal recumbency using a vertical (overhead) x-ray beam and a laterally directed horizontal x-ray beam. On the DV projection (ventral recumbency) the heart, cranial mediastinum, cranial lung lobes, and the ventral aspect of the diaphragm were submersed in fluid, which resulted in the loss of radiographically detectable borders. On the VD projection (dorsal recumbency) radiographic visualization of these structures was improved due to movement of the free pleural fluid away from them, toward the dependent caudodorsal aspect of the thorax. Radiographs of three dogs with spontaneous pleural effusion are presented to illustrate the differences in radiographic appearance of the thorax with pleural effusion when radiographed in DV and VD projections. The movement of fluid to the dorsocaudal thoracic cavity in dorsal recumbency caused lesions that were obscured on the DV projection to be revealed on the VD projection. the authors therefore recommend the use of the VD projection of the thorax in patients with pleural fluid when clinical status permits.     

PNEUMOPERICARDIOGRAPHY IN THE NORMAL DOG

To define the normal radiographic anatomy of the canine heart and pericardial space as outlined by air, pneumopericardiography was performed in ten normal, anesthetized dogs using a percutaneously introduced pericardial catheter. Room air was injected to produce pneumopericardiums without causing cardiac tamponade, and radiographs were obtained using a vertical beam with the dogs positioned in right lateral (RLAT), left lateral(LLAT), dorsal (VD), and ventral (DV) recumbency. Selective and nonselective angiocardiography was used to confirm the identity of the outlined structures. The RLAT and LLAT positions provided more information than the DV or VD positions. Pericardial air consistently outlined a distinct interventricular sulcus and the recesses around the aorta and pulmonary artery. The right auricle, outlined along the cranial heart border ventral to the ascending aorta in both RLAT and LLAT positions, varied considerably in size. The RLAT position best outlined structures to the left of midline, including the left auricle, interventricular sulcus, outflow region of the right ventricle, and the origin of the pulmonary artery. The LLAT position best demonstrated structures to the right of midline, including the right atrium, proximal part of the cranial and caudal vena cavae, and ascending aorta. The considerable range of normal variation between dogs in this study must be considered in the interpretation of clinical pneumopericardiograms.     

THORACIC RADIOGRAPHIC APPEARANCE IN THE NORMAL LLAMA

The goal of this study was to collect quantitative and qualitative radiographic information of the normal adult llama thorax. Standing right-left lateral radiographs of the thorax of 16 normal llamas were made. Normal ratios of cardiac height, width, and height plus width to thoracic vertebrae 3-5 and thoracic height were calculated. Normal values determined for tracheal angle of divergence from the thoracic spine, cardiophrenic and cardiosternal contact are additional potential indicators of cardiac enlargement. Ratios of normal pulmonary artery and vein, caudal vena cava and trachea to the height of the fourth thoracic vertebra should allow identification of pathology of these structures. Observations regarding pulmonary vessels and airways, thoracic spine, sternebrae and portions of the gastrointestinal tract observed on thoracic radiographs are also included. It is proposed that these normal values and observations can be used to better evaluate diseases of the cardiovascular and respiratory systems of adult llamas.