Tissue and genetic marker of mammary tumours in canines: modern diagnostic approaches

The study was conducted in 72 clinical cases of canine mammary neoplasms (CMN'S) presented at IVRI referral polyclinic. Different modern diagnostic tools were used in this study. The aim of this study was to determine whether these tools have potential to be used as an early diagnostic aid in tumour cases particularly in mammary tumours. Apart from normal histological examination, special stains were used in confirmation of tumour diagnosis. Among them, Argyrophilic Nucleolar Organizer Region (AgNOR) stain was found very useful technique. The histopathological technique of one-step staining of Argyrophilic proteins associated with nuclear organizer regions, appearing as black dots. In benign tumours, the AgNORs were few in number but larger in size, whereas in malignant counter part, it was numerous but smaller in size. Detection of Proliferative Cell Nuclear Antigen (PCNA) by immunohistochemical methods was also a valuable tool in tumour diagnosis. Telomerase Repeat Amplification Protocol (TRAP) was also tested on tissue lysates prepared from frozen tumour samples in some selected tumour cases. Hela cell line was used as the control. Alternatively canine Telomerase enzyme reverse transcriptase (cTERT) estimation in a few representative samples by Reverse transcriptase-Polymerase chain reaction (RTPCR) or its demonstration in tissue sections by in situ hybridization technique (ISH) was attempted. Telomerase activity of neoplastic tissue was compared with control. We also tried to explore genetic polymorphism at ZuBeCa₃ microsatellite and to estimate association between microsatellite polymorphism and mammary cancer in dog. Three genotypes namely AA, AB and BB were observed in mammary cancer affected as well as non-affected dogs. In affected group, frequency of genotype and allele were 0.59 for AA, 0.29 for AB and 0.12 for BB genotype, and 0.74 forA and 0.26 for B allele. In non-affected group, the frequency of AA, AB and BB genotype was 0.32, 0.41 and 0.26 and the frequency of A and B allele were 0.53 and 0.47, respectively. Statistical tests showed significant differences of allelic distribution between tumour affected and non-affected groups, which revealed the effect of polymorphism on occurrence of mammary cancer in dogs. These gene sequences are very much important in diagnostic point of view. This marker will aid the veterinarians to diagnose whether the animal is prone to mammary cancer or not. This diagnosis can also be performed at the time of birth of the animal, which will help the dog owners to take the preventive measures (breeding etc).