Edible snails are kept in farms in many countries worldwide. As farm animals, they are an object of interest of veterinary studies and applied biology. There is a large demand for tests which would help identify their health and well-being. The objective of this study was to assess the usefulness of determining the concentration of urea in hemolymph as a marker of health of the Lissachatina fulica and Cornu aspersum edible snails. The observation covered snails from four farms marked from A to D, in which numerous deaths (farm A) and decreased body weight gain (farms B and C) were observed. In experimental farm D we observed a group of snails subjected to stress and a control group maintained in correct conditions. High concentrations of urea were found in the hemolymph of all farm animals from farms A, B and C, as well as in those subjected to food deprivation in farm D (on average from 96 mg/dl in farm D to 320 mg/dl in farm A). On the other hand, in controls from group D, the concentration of the parameter in question was much lower (< 2.0 mg/dl). The results obtained indicate that the urea concentration is a non-specific marker of pathological conditions in snails, and that the continuous monitoring of this parameter makes it possible to demonstrate irregularities in farming and introduce appro- priate and early measures to eliminate such disturbances.

The aim of the study was to establish normal ranges for chosen biochemical parameters of haemolymph of snails (Gasropoda: Mollusca), in the light of the use of these animals as experi- mental models in various types of studies. The study was conducted on 100 specimens of Cornu aspersum maxima (CAM) and 100 specimens of Cepaea nemoralis (CN). The haemolymph col- lected from the animals was analysed using colorimetry to assay aspartate transaminase (AST) activity, alanine transaminase (ALT) activity, amylase activity and the concentrations of urea and triglycerides. In the further part of the study, the influence of administering doxycycline with feed on the change of AST and ALT activity in snail haemolymph has been studied. The normal values established for CAM are as follow: AST activity: 26-38 u/l, ALT activity: 0-11 u/l, amylase activity 9-16 u/l, concentration of urea: 3-6 mg/dl, concentration of triglycerides: 16-20 mg/dl. For CN, the following data have been obtained: AST activity: 30-80 u/l, ALT activity: 0-15 u/l, amylase activity 12-15 u/l, concentration of urea: 5-8 mg/dl, concentration of triglycerides: 18-24 mg/dl. It has been shown that doxycycline presents a high workload on the hepatopancreas of snails, which is reflected by a statistically significant (p<0.05) increase of AST and ALT activity in the haemolymph of the specimens which obtained doxycycline in feed, as compared to the groups with antibiotic-free feed. The haemolymph activity of both studied parameters increased together with study time and tetracycline administration time.