Saturated salt solution: a further step to a formaldehyde-free embalming method for veterinary gross anatomy.

ABSTRACT

In the field of veterinary anatomy, most of the specimens used in practical sessions are perfused with fixatives. Thus, they can be used for a longer time, reducing the number of animals for educational purposes. Formalin is the most commonly used fixative, consisting of a 37% formaldehyde solution. However, formaldehyde is a powerful irritant of the eyes and airways and is considered carcinogenic, causing nasopharyngeal cancer in exposed workers and professionals. In the present study, we explored an alternative method to avoid the use of formaldehyde in specimens used for gross anatomy practical sessions. We propose an inexpensive, non-toxic fixative that is available worldwide, such as sea salt. This method consists of a continuous perfusion of saturated salt solution for a period of 6-8 h, enabling drainage of the solution to avoid a weight increase of the specimen, and allowing salt to be retained in the tissue. The method is based on recirculation of the saturated salt solution instead of maceration. Perfused specimens retained their natural consistency and joint mobility, with no blood, resembling a piece of meat from the slaughterhouse. They could be used immediately without a maceration period, or stored in the fridge until use and then kept in a bath of saturated salt solution for future conservation. In the case of the former, no refrigeration was needed. The specimens did not have an irritating or offensive smell, and could be used for long sessions (several hours per day) and stored for long periods. However, the blood vessels used for perfusion determine the results: a less invasive approach (through common carotid arteries) gave good preservation of the musculoskeletal system, whereas more invasive access to cannulate the abdominal aorta and vena cava caudalis was required to achieve better preservation of the viscera. In conclusion, we propose that perfusion followed by immersion in a saturated salt solution is a good alternative method for the preservation of specimens used in the practical teaching of gross veterinary anatomy. It is a very simple and inexpensive technique, and is much healthier for users than traditional formalin. Moreover, specimens can be preserved for prolonged periods, and maintain a similar appearance and consistency to fresh material.