La microphtalmie chez le porc : anomalie congénitale d’origine génétique ou syndrome oculo-auriculo-vertébral ?

In native pig breeds at risk of extinction, the birth of a piglet affected by hereditary congenital abnormality raises questions: should all the other piglets in the litter, one or both parents also be excluded from breeding? In small size herds, to take the right decision matters. A male piglet (C) born from a primiparous sow (A) and an unrelated boar kept in a boar stud caught our attention because of severe bilateral microphthalmia. The litter consisted of four piglets, three of which were weaned. One male (C) and two females (D and E). A thorough clinical examination of the sow (A) and boar (B) revealed a slight similar defect of the left ear and suspected unilateral left vertical strabismus (or hypertropia). The significance of these abnormalities had gone unnoticed until then.
The question was then: is piglet C an isolated case of bilateral microphthalmia or is it an
oculoauricular syndrome, as described in human medicine? With the approval of the Animal Ethics Committee, the three pigs were raised and bred, giving birth to piglets presenting eye, ear, and/or spinal lesions, suggesting an oculo-auriculo-vertebral syndrome (OAVS). In humane, autosomal dominant as well as autosomal recessive types of inheritance have been described. In pigs, the inheritance of the defect is unknown. So, facing with a case of bilateral microphthalmia in a piglet, a prudent genetic advice should be to exclude all piglets from the litter and both parents from breeding.