Efficient computation of genotype probabilities for loci with many alleles: II. Iterative method for large, complex pedigrees

An algorithm for computing genotype probabilities for marker loci with many alleles in large, complex pedigrees with missing marker data is presented. The algorithm can also be used to calculate grandparental origin probabilities, which summarize the segregation pattern and are useful for mapping quantitative trait loci. The algorithm is iterative and is based on peeling on alleles instead of the traditional peeling on genotypes. This makes the algorithm more computationally efficient for loci with many alleles. The algorithm is approximate in pedigrees that contain loops, including loops generated by full sibs. The algorithm has no restrictions on pedigree structure or missing marker phenotypes, although together those factors affect the degree of approximation. In livestock pedigrees with dense marker data, the degree of approximation may be minimal. The algorithm can be used with an incomplete penetrance model for marker loci. Thus, it takes into account the possibility of marker scoring errors and helps to identify them. The algorithm provides a computationally feasible method to analyze genetic marker data in large, complex livestock pedigrees.     

Additional kinematic variables to describe differences in the trot between clinically normal dogs and dogs with hip dysplasia

OBJECTIVE: To describe the abnormal gait of dogs with hip dysplasia by use of kinematic gait analysis. ANIMALS: 19 large-breed dogs with moderate to severe clinical and radiographic evidence of hip dysplasia and 10 clinically normal dogs (controls). PROCEDURE: Kinematic and force plate data were collected, and degree of coxofemoral joint abduction-adduction, mediolateral foot movement, distance between hind feet, maximum hind foot elevation, mediolateral pelvic movement, and coxofemoral joint angular acceleration were calculated. Essential Fourier coefficients were determined and used to reconstruct mean angular acceleration curves. Fourier coefficients and foot and pelvic movement data were compared between groups. RESULTS: Dogs with hip dysplasia had a greater degree of coxofemoral joint adduction and range of abduction-adduction and greater lateral pelvic movement, compared with controls. Foot movement variables did not differ significantly between groups. Coxofemoral joint angular acceleration was greater in the middle to end of the stance phase, whereas deceleration was greater in the late stance to early swing phase and middle to end of the swing phase in dogs with hip dysplasia, compared with controls. CONCLUSIONS AND CLINICAL RELEVANCE: Differences in degree of coxofemoral joint abduction-adduction, amount of mediolateral pelvic movement, and coxofemoral joint angular acceleration between clinically normal dogs and dogs with hip dysplasia may indicate a compensation in gait of affected dogs as a result of discomfort or biomechanical effects attributable to hip dysplasia and degenerative joint disease. Information gained from kinematic and kinetic gait analyses may be useful in evaluating treatments for hip dysplasia in dogs.     

Nonreproductive surgery in reptiles.

As reptiles have gained popularity as pets, veterinarians are more frequently called on to perform surgical procedures on these pets. Veterinarians must have a basic understanding of the anatomic and physiologic differences between reptilian and mammalian companion animals. This article reviews some basic points about reptilian anatomy and physiology that are important to consider when performing surgery on reptilian patients. This article covers approaches to the coelomic cavity in the different groups of reptiles and some basic concepts regarding surgery on different, nonreproductive systems in these reptiles.     

Cold hardiness of interspecific hybrids between Pinus strobus and P. wallichiana measured by post-freezing needle electrolyte leakage

Interspecific hybrids between eastern white pine (Pinus strobus L.) and Himalayan blue pine (P. wallichiana A. B. Jacks.) were developed in Ontario, Canada, to introduce blister rust (Cronartium ribicola Fisch.) resistance genes to P. strobus. There is concern that introducing blister rust resistance has resulted in reduced cold hardiness of the progeny compared with non-hybridized eastern white pine. To test the efficacy of backcrossing with P. strobus to improve cold hardiness, 1-year-old seedlings from hybrid crosses differing in P. strobus genome composition were artificially freeze-tested. In Experiment 1, unhardened seedlings were allowed to acclimate to progressively lower temperatures in a growth room, whereas in Experiment 2, seedlings were hardened outdoors under natural weather conditions in Sault Ste Marie, Ontario. Needle cold injury was determined by calculating relative electrical conductivity based on post-freezing electrolyte leakage. Results indicated that needle fascicles from unhardened seedlings of all genotypes in the greenhouse tolerated -5 degrees C for 3 hours with little or no injury. Cold hardiness increased in parallel with declining growth room minimum temperature over the 7-week period of hardening. Cold hardiness was improved for hybrid crosses with increased Pinus strobus genome composition in Experiment 2, but the results were less conclusive in Experiment 1.