Correlation of cardiac enlargement as assessed by vertebral heart size and echocardiographic and electrocardiographic findings in dogs with evolving cardiomegaly due to rapid ventricular pacing

Vertebral heart size (VHS) has been proposed as a method for quantifying cardiomegaly in dogs. This study was designed to determine how well echocardiographic and electrocardiographic findings correlated with VHS. Dogs were rapid-paced into varying degrees of cardiomegaly and were monitored by thoracic radiography, echocardiography, and electrocardiography during development of cardiomegaly. Echocardiographic and electrocardiographic parameters were compared with VHS. VHS increased with increased duration or rate of pacing or both, and left atrium-to-aorta ratio, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, P wave duration, and QRS duration correlated significantly with VHS. VHS (a score obtained from routine thoracic radiographs) seems to correlate well with both echocardiographic and electrocardiographic parameters. When 9 veterinarians, experienced in interpretation of cardiac silhouettes on radiographs, measured VHS from 1 normal dog and 1 dog with severe cardiomegaly, coefficients of variation (ratio of standard deviation to the mean) for their measurements were 2.7% and 2.8%, respectively. Thus, VHS could be established with great uniformity by experienced interpreters.     

Prevalence of Radiographic Signs of Osteoarthritis in Lusitano Purebred Horses

Radiographic prevalence and correlation of radiographic findings has not been performed in Lusitano Purebred horses. The aim of this study was to (1) evaluate the prevalence of primary osteoarthritis radiographic findings in Lusitano Purebred horses; (2) to assess correlations between radiographic findings in different joints of the same limb and different limbs; and (3) elucidate the effect of age in the radiographic findings. A radiographic protocol of the stifle, tarsi, fetlocks and distal limbs was done in 98 Lusitanos and the classification of the radiographs was performed using a 0-4 scale developed and applied blindly by three veterinarians. The distal interphalangeal, proximal interphalangeal, metacarpophalangeal, metatarsophalangeal, tarsometatarsal, distal intertarsal, proximal intertarsal/, tibiotarsal and femorotibial-patellar joints were evaluated. Most joints presented no abnormal findings or minor abnormal radiographic findings (82.86% grade ≤1). The most affected joint was tarsometatarsal and more severe lesions were found in tarsometatarsal and distal intertarsal. Femorotibial-patellar radiographic changes were rare (2.13%). A strong/moderate correlation was found between contralateral joints with exception hindlimb fetlocks. A moderate correlation was found between fore and hindlimbs for distal limb joints. When analyzing ipsilateral as well as diagonal distal limbs, a strong/moderate correlation was also found. The total score progressed in 0.2 score points per each year of age, revealing that age can be a statistically significant predictor for radiographic changes. Overall, Lusitano horses presented a low prevalence of severe radiographic sings of primary osteoarthritis. Findings in contralateral joints tend to be correlated.     

Radiographic Differences Between Uneven Feet in Horses With Foot Lameness and Admitted for MRI Examination

Unevenness is an important feature of foot conformation and coincides with both kinetic and kinematic asymmetrical locomotor differences. It reportedly may lead to early retirement of elite horses from a warmblood population. The aim of this study was to evaluate the radiological consequences of an uneven feet conformation and on distal limb tissue development. In a retrospective study, the complete sets of good quality radiographs of both distal forelimbs were compared objectively for 121 “foot lame” horses that had been admitted for magnetic resonance imaging of one or both front feet (2003–2010). A chi-square test was used to test for significant radiometric differences between the upright and the lower angle foot (P < .05); 60% of the horses were unilaterally lame in the upright foot, whereas 40% were lame in the lower angle foot, which appeared to be a nonsignificant difference. In 84% of the horses, the navicular bone (NB) had a substantially more radiolucent, osteoporotic structure (P < .05). In 88% of the horses, the deep digital flexor tendon (DDFT) in the upright foot was significantly more radiodense and pronounced than in the lower angle foot (P < .05). The NB showed a significantly more osteoporotic structure as scored in the upright foot than in the lower angle foot, whereas the DDFT appeared was scored more compact in the upright foot than in the lower angle foot, suggesting less tension on the DDFT. In conclusion, radiological differences between uneven feet in foot lame horses seem to be related to differences in distal limb locomotor tissue development.