Interpretation of cardiac chamber size on canine thoracic radiographs is limited and may result in the false identification of right-sided cardiomegaly in the presence of severe left-sided cardiomegaly

The vertebral right heart index: A new radiographic method to assess right heart enlargement in dogs

In veterinary medicine, the radiographic assessment of right heart enlargement (RHE) is essentially subjective. The aim of this study was to evaluate the vertebral right heart index (VRHi) as a new quantitative radiographic method to detect RHE in dogs. This was a multicenter, retrospective, observational study, including dogs with RHE and control dogs. All dogs had to have a thoracic radiographic study and a complete echocardiography on the same day. Right heart enlargement was defined as the presence of right atrial enlargement, right ventricular enlargement, and/or hypertrophy based on echocardiography. For the radiographic study, all the radiographic views available for each case were considered for measurement: right lateral (RL), left lateral (LL), ventrodorsal (VD), and dorsoventral (DV). The VRHi was measured using LL, RL, VD, and DV views. A total of 204 dogs were included: 91 dogs with RHE and 113 control dogs. The VRHi (RL), the VRHi (LL), and the VRHi (VD) were significantly greater in dogs with RHE compared with controls (P < .0001). The best diagnostic accuracy was observed for VRHi (LL) (area under the curve [AUC] 0.86, P < .0001; cutoff ≥ 3.5 vertebrae, sensitivity [Se] 71%, specificity [Sp] 89%), followed by VRHi (RL) (AUC 0.85, P < .0001; cutoff ≥ 3.5 vertebrae, Se 68%, Sp 86%) and VRHi (VD) (AUC 0.80, P = .0004; cutoff ≥ 3.0 vertebrae, Se 57%, Sp 95%). In conclusion, the lateral VRHi in LL and RL and the VD VRHi could represent useful radiological tools for the detection of RHE in dogs.

ECHOCARDIOGRAPHIC MEASUREMENTS IN ANESTHETIZED CAPTIVE RED PANDAS (AILURUS FULGENS)

A recent review of mortality in captive red pandas (Ailurus fulgens) listed cardiac pathology as the most common cause of death in the adult age group. The aim of this study was to describe the standard echocardiographic variables in 13 captive, healthy, adult red pandas that underwent an elective health examination. In addition, differences between the two subspecies of red panda, A. f. styani than in A. f. fulgens, and association of these echocardiographic variables with age, sex, and body condition score, were examined. Anesthesia was induced and maintained with isoflurane inhalant anesthetic. All animals underwent a full physical examination and comprehensive echocardiogram including 2D, M-mode, and Doppler modes of ultrasound examination. Mean and SD of the echocardiographic variables are reported. Systolic performance was considered subnormal due to the effect of the anesthetic agent. The echocardiographic variables were similar for the two subspecies and sexes, with the exception of the left atrial dimension (2D), which measured larger (P= 0.03) in A. f. styani than in A. f. fulgens, and left ventricular internal diameter in diastole, which measured larger (P = 0.04) in males than females. Several echocardiographic measurements were correlated with age (P < 0.05), whereas the only measurement that significantly correlated with body condition score was end diastolic volume (P = 0.01). These results provide ranges that can offer guidance for predicting cardiac disease in red panda.

Caudal pulmonary artery to vein ratio on radiography can predict pulmonary hypertension in dogs with mitral regurgitation

Pulmonary hypertension (PH) is an important predictor of poor outcomes in dogs with mitral regurgitation (MR). The feasibility of radiography to predict PH in dogs with MR is unknown. This retrospective, observational, and analytic study aimed to identify a radiographic parameter to predict PH in dogs with MR. A total of 302 dogs diagnosed with MR on echocardiography were enrolled. Medical record and radiographic findings such as the size of the main pulmonary artery, left atrium, left ventricle, and right chamber, and cranial and caudal pulmonary arteries and veins were evaluated according to the presence of PH. The diameters of the cranial and caudal pulmonary vessels were compared to the fourth rib and the ninth rib, respectively, and the ratio of the pulmonary artery to the corresponding vein (CdPA/CdPV) was calculated. Pulmonary hypertension was diagnosed in 77 dogs (25.5%) and the prevalence of PH increased with MR grade. The CdPA/CdPV was significantly higher (P < 0.001) in the presence of PH. Multivariate analysis showed that the CdPA/CdPV was the only independent radiographic parameter that had a significant association with PH in dogs with MR (P = 0.028). The cut-off value of the CdPA/CdPV = 1.10 showed 90.6% specificity and 31.1% sensitivity for detecting PH in dogs with MR. In dogs with MR, PH can be predicted with high specificity when the caudal pulmonary artery is 1.1 times larger than the corresponding vein on radiographs.