Comparison of clinical, radiographic, computed tomographic, and magnetic resonance imaging methods for early prediction of canine hip laxity and dysplasia.

The purpose of the study was to use two palpation methods (Bardens and Ortolani), a radiographic distraction view, three computed tomography (CT) measurements (dorsolateral subluxation score, the lateral center-edge angle, and acetabular ventroversion angle) and two magnetic resonance (MR) imaging hip studies (synovial fluid and acetabular depth indices) in the early monitoring of hip morphology and laxity in 7-9 week old puppies; and in a follow-up study to compare their accuracy in predicting later hip laxity and dysplasia. The MR imaging study was performed with the dog in dorsal recumbency and the CT study with the animal in a weight-bearing position. There was no association between clinical laxity with later hip laxity or dysplasia. The dorsolateral subluxation score and the lateral center-edge angle were characterized by a weak negative correlation with later radiographic passive hip laxity (-0.26 < r < -0.38, P < 0.05) but its association with hip dysplasia was not significant. There was an association between early radiographic passive hip laxity and synovial fluid index with later passive hip laxity (0.41 < r < 0.55, P < 0.05) and this was significantly different in dysplastic vs. nondysplastic hips (P < 0.05). There was no association between the remaining variables and later hip laxity or dysplasia. The overlapping ranges of early passive hip laxity and synovial fluid index for hip dysplasia grades and the moderate correlations with the later passive hip laxity make the results of these variables unreliable for use in predicting hip laxity and dysplasia susceptibility.

Passive hip laxity in Estrela Mountain Dog--distraction index, heritability and breeding values.

Two hundred and fifteen Estrela Mountain Dogs (EMD) were examined using the PennHIP method between 2002 and 2006. Passive hip laxity (PHL) was estimated calculating the distraction index (DI). Pedigree information was obtained from the Portuguese Kennel Club. The heritability and breeding values were estimated using the linear Animal Model. The DI, using as reference the worst joint of each animal, ranged from 0.15 to 1.12 (0.55 +/- 0.19). The PHL was equal in right and left sides, and was higher in females than in males (P > 0.05 and P <0.01 in the t-test, respectively). The estimated heritability was 0.83 +/- 0.11. The mean breeding values for PHL were stable in EMD born between 1991 and 2003, and showed an improvement in 2004 and 2005. The data confirm high PHL in breeds with high prevalence and severity of canine hip dysplasia. The high heritability indicates that the DI could be reduced in the breed if PHL were used as a selection criterion. The early favourable evolution of DI breeding values could be related with the increase of voluntary radiographic hip screening in the last years, and the subsequent introduction of hip quality as a breeding criterion.

Mechanical devices to help in PennHIP examination.

A modified PennHIP procedure (MPP), using specific mechanical holding devices, was used on 70 dogs and compared to the standard PennHIP method (SPM) used on 39 dogs, in terms of technical effectiveness and the mean number of essential individuals within the X-ray room (EIXRR). The data using the Chi-squared test were consistent with the null hypothesis that the technical effectiveness was equal in the groups under investigation (P > 0.05). On the contrary, using the two-sample unpaired t-test the null hypothesis, that the mean EIXRR was equal, was rejected (P < 0.001). The estimated EIXRR was 3.4 +/- 0.7 and 5.7 +/- 1.2 (mean +/- SD) for MPP and SPM, respectively. In conclusion, the MPP needs fewer EIXXR than the SPM and complies with the new recommendations in X-ray protection, which introduce the ALARA (as-low-as-reasonably-achievable) idea.