The comet assay has become one of the methods of choice for the evaluation and
measurement of DNA damage. It is sensitive, quick to perform and relatively affordable for
the evaluation of DNA damage and repair at the level of individual cells. The comet assay can
be applied to virtually any cell type derived from different organs and tissues. Even though
the comet assay is predominantly used on human cells, the application of the assay for the
evaluation of DNA damage in yeast, plant and animal cells is also quite high, especially in
terms of biomonitoring. The present extensive overview on the usage of the comet assay in
animal models will cover both terrestrial and water environments. The first part of the review
was focused on studies describing the comet assay applied in invertebrates. The second part of
the review, (Part 2) will discuss the application of the comet assay in vertebrates covering
cyclostomata, fishes, amphibians, reptiles, birds and mammals, in addition to chordates that
are regarded as a transitional form towards vertebrates. Besides numerous vertebrate species,
the assay is also performed on a range of cells, which includes blood, liver, kidney, brain, gill,
bone marrow and sperm cells. These cells are readily used for the evaluation of a wide
spectrum of genotoxic agents both in vitro and in vivo. Moreover, the use of vertebrate models
and their role in environmental biomonitoring will also be discussed as well as the
comparison of the use of the comet assay in vertebrate and human models in line with ethical
principles. Although the comet assay in vertebrates is most commonly used in laboratory
animals such as mice, rats and lately zebrafish, this paper will only briefly review its use
regarding laboratory animal models and rather give special emphasis to the increasing usage
of the assay in domestic and wildlife animals as well as in various ecotoxicological studies