Neoplasms in Domestic Ruminants and Swine: A Systematic Literature Review

SIMPLE SUMMARY: Given the scarcity of information and the lack of comprehensive studies on neoplasms in domestic ruminants, i.e., cattle, sheep, and goats, and domestic pigs, the aim of the present study was to systematically review the scientific literature to verify the occurrence, type, organ system, and organs most affected by neoplasms in domestic cattle, sheep, goats, and pigs. Based on the results, the bovine species was the most affected by the neoplasm and also the most studied in relation to small ruminants and pigs. In all species, the most affected organ system was the integumentary system, and the most frequent neoplasms were squamous cell carcinomas for cattle, goats, and sheep, while melanoma was the most frequent for pigs. Few studies were carried out in slaughterhouses, and those found to be in the majority referred to cattle and pigs, none of them mentioned goats and sheep. No studies were found that measured the economic losses associated with the condemnation of carcasses of the studied species. The results reinforce the need to carry out studies on farms and slaughterhouses, which would provide more information such as the total number of animals and the origin of the samples. ABSTRACT: Background: Due to the limited information and lack of studies on neoplasms in domestic ruminants, i.e., cattle, sheep, and goats, and domestic swine, the objective of the present study was to systematically review the scientific literature to verify the occurrence, type, organ system, and organs most affected by neoplasms in these animals. Methods: The recommendations of the PRISMA methodology were followed for the elaboration of this study. The research consisted of a systematic review of neoplasms in domestic cattle, sheep, goats, and swine. Results: The number of neoplasms found was 1873. The most affected organ system was the integumentary system with 35.0%, followed in descending order by the alimentary system with 16.90%, the hematopoietic system with 13.50%, the special senses (i.e., eyes and ears) with 10.51%, the female and male genital systems with 7.31%, the urinary system with 4.38%, the liver and biliary system with 3.152%, the endocrine glands with 3.91%, the respiratory system with 2.67%, the nervous system with 2.35%, bones and joints with 0.43%, muscles and tendons with 0.37%, the cardiovascular system with 0.21%, and the pancreas with 0.16%. Of the animals with neoplasms studied, cattle were affected in 69.80% of cases, goats in 10.52%, sheep in 10.46%, and swine in 9.18%. In all species, the most frequent neoplasms were squamous cell carcinomas in ruminants, while melanoma was the most frequent in swine. Few studies carried out in slaughterhouses were found, and the existing ones referred to cattle and swine. No data were found on economic losses with carcass condemnation. Conclusions: In view of the above, it is necessary to carry out extensive and detailed studies that provide knowledge about the impact of neoplasms on the production and condemnation of carcasses in domestic cattle, sheep, goats, and swine and the respective risk factors.