Telomeres are specialized structures at the ends of chromosomes that preserve genome integrity and prevent their improper fusions. Their role is crucial in protecting chromosome ends from the action of cellular nucleases and DNA repair mechanisms. Telomerase is an enzyme that adds telomeric sequences to the ends of chromosomes, thereby compensating for their shortening during cell division. ALT is used for homologous recombination. Telomere shortening during cell division leads to senescence or apoptosis when they reach a critical length. Malignant cells use telomerase for unlimited replication potential, which allows them immortality. Research has shown that telomeres in long-lived birds and mammals shorten more slowly compared to short-lived species, suggesting evolutionary mechanisms that extend lifespan. Key proteins TRF1 and TRF2 play vital roles in regulating telomere length and protecting against DNA damage. The study of telomere dynamics in animals faces numerous challenges, including technical limitations and insufficient understanding of factors affecting telomere length. The development of advanced technologies for measuring TL and researching the impact of environmental factors is crucial for improving animal health and productivity.