The Incidence of Liver Damage Found during Postmortem Examination at the Slaughterhouse

**Background:** The liver is the principal metabolic organ in animals, and its damage reflects poor health and welfare. While many studies have examined liver pathology in single species, few have compared incidence across multiple species and categories over a long period using standardized postmortem inspection. This study aimed to compare the incidence of liver damage (acute, chronic, parasitic, and other) across different species and categories of food animals slaughtered in the Czech Republic over 12 years.

**Methods:** Data were obtained retrospectively from the State Veterinary Administration of the Czech Republic information system. All animals reared on Czech farms and slaughtered for human consumption at any Czech slaughterhouse between 2010 and 2021 were included (n = 1,425,710,143). Animals were categorized as adult (cows, sows, ewes, does), fattening (heifers, fattening bulls, finishing pigs, lambs, kids), young culled from herd (calves, piglets), and poultry/rabbits (end-of-lay hens, broiler chickens, turkeys, ducks, geese, rabbits). Official veterinarians classified liver findings as acute (short-term inflammatory processes), chronic (long-term changes including fibrosis, steatosis, scarring), parasitic (invasion by parasites such as Fasciola, Ascaris, coccidia), or other (e.g., icteric changes). Incidence was expressed as percentages. Statistical analysis used chi-square tests with Yates' correction or Fisher's exact test for frequency comparisons, and Spearman's rank correlation for 12-year trends (p < 0.05 significant).

**Key Results:** Overall liver damage was highest in cows (46.38%), followed by piglets (32.39%), end-of-lay hens (20.32%), sows (17.51%), calves (17.6%), heifers (14.17%), ewes (12.97%), finishing pigs (11.26%), fattening bulls (7.97%), lambs (4.73%), does (4.26%), turkeys (3.38%), ducks (2.20%), geese (1.09%), kids (0.59%), broiler chickens (0.08%), and rabbits (0.04%). In all species, adult animals had higher liver damage than fattening animals. Chronic lesions dominated in most categories: cows (39.13% chronic vs. 5.23% acute), sows (15.93% vs. 1.00%), finishing pigs (7.35% vs. 0.22%), heifers (11.41% vs. 1.35%), fattening bulls (7.04% vs. 0.40%), end-of-lay hens (17.76% vs. 2.55%), turkeys (2.75% vs. 0.00%). Exceptions: piglets had more acute (15.97%) than chronic (15.21%) lesions; ducks had more acute (1.12%) than chronic (1.08%); ewes and lambs had predominantly parasitic lesions (7.51% and 3.51%, respectively). Parasitic damage was highest in ewes (7.51%), finishing pigs (3.68%), and lambs (3.51%). Spearman rank correlation showed significantly decreasing trends over 12 years for heifers (rSp = −0.8462, p = 0.0005), fattening bulls (rSp = −0.6923, p = 0.0126), ewes (rSp = −0.7552, p = 0.0045), lambs (rSp = −0.7902, p = 0.0022), kids (rSp = −0.7042, p = 0.0106), and end-of-lay hens (rSp = −0.9021, p = 0.0001). Significantly increasing trends were found for calves (rSp = 0.8951, p = 0.0001), piglets (rSp = 0.9161, p = 0.0000), rabbits (rSp = 0.6643, p = 0.0185), and turkeys (rSp = 0.6014, p = 0.0386).

**Clinical Implications:** The study provides a comprehensive baseline for liver health in food animals. The high prevalence in dairy cows (46.38%) reflects the metabolic burden of intensive milk production and negative energy balance postpartum. The high rate in piglets (32.39%) and calves (17.67%) culled from the herd indicates that poor liver health is associated with early culling. The dominance of chronic lesions across most species points to long-term nutritional and management factors rather than acute disease. The increasing trends in calves, piglets, rabbits, and turkeys are concerning and warrant targeted interventions. The high parasitic burden in grazing sheep (ewes 7.51%, lambs 3.51%) and finishing pigs (3.68%) highlights the need for improved parasite control strategies. The very low incidence in broiler chickens (0.08%) and rabbits (0.04%) suggests that current feeding and management practices for these species are appropriate for maintaining liver health. These findings can inform veterinary surveillance, animal welfare improvements, and targeted nutritional management in livestock production.