Chromosome analyses in dogs

Abstract

SummaryCytogenetics is the study of normal and abnormal chromosomes. Every species is characterized by a given number of chromosomes that can be recognized by their specific shape. The chromosomes are arranged according to standard classification schemes for the respective species. While pre-and postnatal chromosome analyses investigate the constitutional karyotype, tumor cytogenetics is focused on the detection of clonal acquired, tumor-associated chromosome aberrations. Cytogenetic investigations in dogs are of great value especially for breeders dealing with fertility problems within their pedigrees, for veterinarians and last but not least for the dog owners. Dogs and humans share a variety of genetic diseases, including cancer. Thus, the dog has become an increasingly important model for genetic diseases. However, cytogenetic analyses of canine cells are complicated by the complex karyotype of the dog. Only just 15 years ago, a standard classification scheme for the complete canine karyotype was established. For chromosome analyses of canine cells the same steps of chromosome preparation are used as in human cytogenetics.There are few reports about cytogenetic changes in non-neoplastic cells, involving predominantly the sex chromosomes. Cytogenetic analyses of different entities of canine tumors revealed that, comparable to human tumors, tumors of the dog are often characterized by clonal chromosome aberrations, which might be used as diagnostic and prognostic markers. The integration of modern techniques (molecular genetic approaches, adaptive computer programs) will facilitate and complete conventional cytogenetic studies. However, conventional cytogenetics is still non-replaceable.

Direct preparation protocol to obtain mitotic chromosomes from canine mammary tumors

“…Inadequate tissue dissociation can form aggregate cell that can mask the presence of mitotic metaphase. A solution for this problem would be treating the tissue with the enzyme collagenase prior to cell cultivation (Reimann-Berg et al, 2012), which should provide improved cell breakdown and increase the chances of viewing mitotic chromosomes.…”

“…There is great interest in expanding the work on chromosomal changes that occur in canine tumor cells because these studies can offer benefits to human disease as well (Reimann-Berg et al, 2012). In this sense, the contribution of cytogenetics to the identification of chromosomal changes that are associated with the occurrence of tumors promotes the improvement of diagnostic and prognostic techniques (Sumner, 2003;Sargan et al, 2005;Breen, 2008;Devitt et al, 2009;Ferguson-Smith, 2013).…”

“…In addition, these tissues are capable of generating a lineage bearer of chromosomal changes that do not reflect the constitution of the individual tumor karyotype (Sandberg, 1988). Despite these limitations, short or long term cell cultivation is still the most commonly used technique in obtaining chromosomes from solid tumors (Sargan et al, 2005;Devitt et al, 2009;Reimann-Berg et al, 2012).…”

Cytogenetic aspects of a canine breast carcinosarcoma - a case report

“…Recently, Reimann-Berg et al (2012) have also revealed the relevance of chromosome 13 in tumor disorders in dogs. These authors claim that this chromosome is high homology with regions 4 and 8 of human chromosomes that harbor the proto-oncogene c-kit and c-MYC.…”

“…However, in dogs, the cytogenetic study of tumors is a major challenge because the canine karyotype is the most complex among domestic mammals (Reimann-Berg et al, 2012). Among the chromosomal identification, difficult factors in dogs highlight the high diploid number (2n = 78) associated with the similarity of size and banding patterns of smaller autosomes (Breen et al, 2001).…”