Craniological features of the American mink in south-eastern Belarus

Abstract

A series of skulls (n = 27) of the American mink (Neogale vison) from the south-east of Belarus (Gomel region, floodplain of the Sozh River) was studied. The animals were caught by different hunters in 2000–2004. The sex of individuals was not determined. When examining the skull, only the most pronounced morpho-anatomical changes that can be diagnosed confidently as deviations from the norm were taken into account. In all cases, lamellar deposition of calcium salts in the area of tentorium cerebelli osseum inside the cranial vault was detected. The growing plate length reached half of the arch height in some individuals. These traits (considerable area of bone plates; presence of a sharp spine growing in different plains) allow suggesting that the analysed growths are of pathological origin. This pathology can considerably affect the viability and physiological status of individuals as it disrupts the functioning of the central nervous system. It is difficult to identify the cause of intracranial calcifications due to the possible effect of factors of various nature. Some degree of calcification of the opisthion region of foramen magnum was found. The changes occurred in the foramen shape cannot be considered phenetic variability. In most individuals, the thinning of maxillary bone in the teeth roots area is observed. However, we believe that the identified degree of bone tissue thinning is not critical and therefore does not affect the life expectancy of individuals. Two adult individuals have swelling of the maxillary bone. In one case, an extensive bone tissue excavation was identified on the left lower jaw, which led to the loss of the canine tooth. The analysed pathomorphological change is not of traumatic nature because in case of post-traumatic osteomyelitis sequesters (separating fragments) are formed. It is necessary to further analyse the American mink skulls available at scientific collections of Belarus and to identify the degree of calcium salt deposits and their impact on the foramen magnum phenotypes. We consider it necessary to create an annotated catalogue of pathologies and anomalies of the skull of the American mink in the south-east of Belarus and adjacent territories of Ukraine, since the morphological method is essential in the diagnosis of bone tissue diseases.