Polydactyl canine case: Exploring possible linkage between anomalies, secondary infertility and SHH/ALX4 mutations

This case report details an unusual manifestation of polydactyly in a litter of purebred Caucasian puppies, where the dam exhibited polydactyl traits while the sire is suspected to have an incomplete penetrance of the trait. All littermates, except one, manifest severe postnatal mortality and displayed polydactyl at birth. Out of a litter of six puppies, only Luna survived, resulting in a mortality rate of approximately 83.33%. Luna, the surviving pup, presented with anomalies including polydactyly on both pelvic limbs, short limb development, double row teeth, thoracolumbar tenderness, anaemia and babesiosis. Furthermore, the dam also exhibited secondary infertility, which prompted a literature review on probable genetic influences. However, we suspect SHH and ALX4 mutations due to their possible interference with sonic hedgehog and Wnt/beta‐catenin signalling pathways as being causal for the observed clinical signs, particularly the role of Wnt/beta‐catenin signalling, which is crucial for reproductive organ development.