PREVALENCE OF HYPOSEGMENTATION/PELGER-HUËT ANOMALY IN DIFFERENT CANINE BREEDS: A BAYESIAN APPROACH

Pelger-Huët anomaly (PHA) is a benign congenital hematological disorder in which granulocytes (especially neutrophils) are characterized by hyposegmentation of the nuclei and mature coarse chromatin patterns. It was first described in humans and was reported sporadically in domestic animals. In dogs, it has been mostly reported in Australian Shepherd Dog (9.8%-13%) were, based on genetic study, it was recently renamed as hyposegmentation (HG). Very limited evidence was available for some other canine breeds, based only on case reports and case series. The objectives of this study were: 1) to estimate the overall of HG/PHA in various canine breeds, 2) to use a Bayesian approach to quantify the uncertainty of the estimated values, and 3) to describe, for the first time, breeds affected by the anomaly that have not been previously reported in the literature. A cross-sectional study was conducted by searching the electronic database of the S. Marco Veterinary Clinic and Laboratory (Padua, Italy) during the period between April 2001 and February 2024 to obtain data from dogs of breeds with a diagnosis of HG/PHA and from dogs belonged to one of the breeds reported in the literature as possibly affected by HG/PHA. The results of the CBC and blood smear microscopic evaluations were used as a proxy measure of the prevalence of HG/PHA. A Bayesian analysis was performed to estimate the prevalence of the anomaly and its uncertainty by comparing posterior probabilities from broad to informative prior models. The analysis adhered to the Bayesian Analysis Reporting Guidelines (BARG). Dogs (n=5716) included in the study were German Shepherd (GS, n=2286, 40%), Dachshund (DA, n=1293, 22.6%), Cocker Spaniel (CS, n=990, 17.3%), Border Collie (BC, n=541, 9.5%), Australian Shepherd Dogs (ASD, n=338, 5.9%), Samoyed (SA, n=126, 2.2%), Boston Terrier (BT, n=91, 1.6%), Australian Cattle Dog (ACD, n=41, 0.7%), and Basenji (n=10, 0.2%). HG/PHA was observed in 0.45% of overall dogs belonging to ASD (7.1%), DA (0.08%) and SA (0.8%) and was absent in the other breeds. The prevalences were estimated as 6.47% (95% credible interval [95% CrI]: 4.21%, 9.18%) in ASD, 0.30% (95% CrI: 0.04%, 1.11%) in SA, 0.2% (95% CrI: 0.02%, 0.86%) in BA, 0.18% (95% CrI: 0.02%, 0.77%) in ACD, 0.16% (95% CrI: 0.02%, 0.64%) in BT, 0.11% (95% CrI: 0.02%, 0.30%) in DA, 0.10% (95% CrI: 0.02%, 0.37%) in BC, 0.08% (95% CrI: 0.01%, 0.25%) in CS, 0.05% (95% CrI: 0.01%, 0.15%) in GS. The anomaly was described for the first time in DA. The study is based on data from a conspicuous laboratory database over a 20-years period and could be representative of the prevalence of the HG/PHA in different canine breeds in the real-world setting.