Bannasch et al. 2021 genetic heterozygosity findings by breed:
A large dataset (227 breeds; dataset 1) of median heterozygosity values (H) was obtained through commercial DNA testing of 49,378 dogs. The mean number of individuals per breed was 217.5 (95% Confidence Interval 162ā273.1) and the range of individual dogs/breed was 30ā4728. Since the H values do not provide a simple relationship to pedigree, we wanted to determine what their equivalency was to the coefficient of inbreeding (F). The genotype-based coefficient of inbreeding was determined in 19 breeds with 8ā20 individuals in each breed (dataset 2) for comparison to dataset 1. Dreger at al [8] used 10 individuals per breed and calculated F based on genotypes and the correlation with dataset 2 was 0.85 (12 breeds in common). Yordy et al. [9] used 6ā724 individuals per breed and the correlation with dataset 2 was 0.75 (15 breeds in common). F from dataset 2 was highly correlated with H from dataset 1 (Pearson correlation coefficient of āā0.8899 (PĀ <ā0.0001) for the same 19 breeds. Linear regression (r2Ā =ā0.79) was performed to obtain adjusted F values (Fadj) for the dataset 1 breeds. Based upon linear regression, an H value of 33.1% was equivalent to F of 0.25. The H values were adjusted based on the regression to provide breed estimates of inbreeding for the 227 breeds in dataset 1 (Fadj). These adjusted values from dataset 1 were compared to adjusted values from [9] which included 97 breeds in common and the Pearson correlation was 0.883 and [8] which included 75 breeds in common and was 0.89. The mean of the Fadj values for 227 breeds was 0.249 (95% CI 0.235ā0.263) (Fig.Ā 1). Strikingly few breeds (NĀ =ā12) had low inbreeding values (<ā0.10). The breeds with the lowest levels of inbreeding were mostly landrace breeds or breeds with recent cross breeding. To put the inbreeding values in context, the breeding of two first cousins produces Fā=ā0.0625, two half siblings Fā=ā0.125 and two full siblings or parent-offspring Fā=ā0.25.
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Generally there was a correlation between higher inbreeding and higher morbidity but there were a few outlier breeds. Border terrier, Basenji, Collie, and English setter scored high on inbreeding but below average morbidity, on the flip side Malinois, Pomeranian, and Russian Tsvetnaya Bolonka were low inbreeding but relatively higher morbidity.
There was also a correlation found between brachycephalylic dogs and more veterinary care. sorted by FCI groups, Group 2 (molossoid, pinschers, mountain dogs) scored the highest for amount of visits to the vet while Group 5 (spitz and primitive) scored the lowest.
Overall the highest rates of morbidity tended to be dogs with high rates of inbreeding and a large body size, lower morbidity was associated with less inbred smaller dogs.
