CARDIAC INDICES IN THORACIC RADIOGRAPH EVALUATION OF DOGS WITH HEARTWORM INFECTION
Friday, October 18, 2019, 1:45 pm – 2:30 pm
Arville Mar Gregorio A. Pajas
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, University of the Philippines, Los Baños
One of the most common cardiac assessment tools using thoracic radiography in small animal practice is the vertebral heart scoring (VHS). VHS is a system used for evaluation of the canine cardiac silhouette to determine the size of the heart. Although VHS is an objective tool for assessment, this method can only assess the size of the heart; dilatation of the chambers, thickening of the walls and pericardial effusion cannot be determined using this method. Sphericity index (SI) is the ratio between the maximal long and short axes of the cardiac silhouette. The SI value gives an index for a rounded/globoid shape of the heart (Guglielmini et al., 2012). However, a moderate correlation was observed for SI in dogs with pericardial effusion. Lemkuhl (1997) devised a method for determining right-sided heart failure in the left lateral thoracic radiographs of dogs using the caudal vena cava ratios. The authors reported that the ratio between the caudal vena cava and aorta (CdVC/Ao) is a good index for right-sided heart enlargement.
Pajas and Acorda (2018) investigated the values of these indices in dogs, with a modification of the procedure of the vena cava ratios by Lemkuhl. Canine patients with heartworm infection were subjected to thoracic radiography and the resulting lateral and dorsoventral x-ray films were used for evaluation of the cardiac indices.
The findings of the study showed that Class II and III heartworm patients had a DV and right lateral VHS that was above the normal dog VHS. SI was not able to show any significant findings among heartworm classifications. The decreasing ratio of CdVC/Ao and CdVC/T4 was observed as heartworm classification became more severe while the increasing ratio was seen for CrVC/Ao and CrVC/T4.
VHS is still a valuable tool for cardiac size evaluation in patients with heartworm. Modified vena cava ratios can be potential indices for assessment in cardiac patients.