Departamento de Cirurgia, Universidade de Sa˜o Paulo (USP), Sa˜o Paulo, Brazil Lymphatic Drainage on Healthy and Neoplasic Mammary Glands in Female Dogs: Can it Really be Altered? C. T. Pereira 1 ,S.C. Rahal 2 ,J.C. de Carvalho Balieiro 3 andA.A.C.M. Ribeiro 4, * Addresses of authors: 1 Paulista University (UNIP); 2 Department of Surgery and Anaesthesiology, College of Veterinary Medicine, Sa˜o Paulo State University (UNESP)-Botucatu; 3 Faculdades Integradas da Fundacao de Ensino Octavio Bastos-Sao Joao da Boa Vista; 4 Department of Surgery, College of Veterinary Medicine, Sa˜o Paulo University (USP), Brazil; *Corresponding author: fax: 00 55 11 30917805; e-mail: guto@usp.br With 3 figures and 4 tables Received May 2002; accepted for publication December 2002 Summary The purpose of this research was to study the mammary lymphaticdrainageunderamacroscopicandmesoscopicview, comparing the vascular pattern of healthy and neoplasic mammary glands injected with drawing ink alcoholic and fluorescein solutions, in 46 mongrel female dogs. The results pointed out that the thoracic gland is drained by the axillary lymph centre, but in mammary neoplasia either superficial cervical or ventral thoracic lymph centres can be involved. Cranial and caudal abdominal glands may be drained by the axillary, inguinofemoral and popliteal lymph centres. How- ever, the popliteal drainage is specific for the healthy caudal abdominalmammarygland.Theinguinalglandcanbedrained by both inguinofemoral and popliteal lymph centres in both neoplasic and healthy conditions. Regarding the mammary lymphatic communications, this research demonstrated that neoplasic glands present more types of anastomosis (40.9%), thanhealthyglands(33.33%),andanincreaseincontralateral anastomosis (50%) compared with healthy ones (33%). Given the data, the mammary neoplasia can change the lymphatic drainage pattern in terms of lymph centres and vascular arb- orization,thusformingnewdrainagechannelsandrecruitinga larger number of lymph nodes. Lastly, some comments were madeabouttheseverityofaspecificneoplasicmammarygland and conditions to be considered before making a decision in terms of the most adequate operative procedure, and sugges- tions for further investigations. Introduction Thelymphaticsystemisananatomicentitythatplaysarolein localtumourcontrolandalsoonthetransportoftumourcells representing the most common route of metastases on neoplasias (Hartveit, 1990; Rubert et al., 1990; Patsiska et al., 1996; Stewart and Lyster, 1997; Liu and Zhang, 1998; Haigh and Giuliano, 2000). Lymphangiogenic factors induce the formation of new lymph vessels in early development and certainly in the pathological setting such as tumorigenesis (Graham and Myerers,1999; Olofsson et al., 1999; Veikkola et al., 2000). Yet, Else and Hannant (1979) affirmed that there is a relationship between the occurrence of metastases and the malignancy of the neoplasia. It is current practice that dogs and human beings who present mammary neoplasia are generally sent for surgical treatment, where both affected mammary gland and its lymphatic vascularization are removed (Fidler and Brodey, 1967; Moulton et al., 1970; Wilson and Hayes, 1980; Sautet et al., 1992; Vollmerhauss et al., 1997; Haigh and Giuliano, 2000; Imoto et al., 2000; Schrenk et al., 2000). However, there is little anatomic data concerning lymphatic vascularization of the neoplasic mammary glands in large animals, and no comparative studies have been published focusing on this subject in healthy and neoplasic glands. Given the existence of the lymphangiogenic factors during the neoplasic conditions, the lymphatic vascularization must be altered and it is necessary to acquire knowledge of these possible differences in terms of lymphatic vascular patterns in order to carry out the most adequate operative procedure. As there is lack of information in the specialized literature and the possibility of female dogs being used as an animal model to study the mammary lymphatic vascular pattern in humans(Nerurkaretal.,1989),inthispaperwehaveanalysed the lymphatic drainage channels of each dog’s mammary gland: healthy and neoplasic, and describe the different vascular patterns which were found in these two specific conditions. The present findings shed light on lymphvascular invasion of breast tumour cells and also give anatomical support for manual lymphatic drainage and for further functional inves- tigations focusing on this subject in the canine species. Materials and Methods We studied 46 (43 dead and three alive) adult mongrel female dogs separated into two groups according to the absence (group 1 with 24 animals) or presence of mammary neoplasia inaccordancewithbothclinicalandsurgicaldiagnoses(group 2with22animals).ThefemaledogscamefromtheVeterinary Hospital of the College of Veterinary Medicine (University of Sao Paulo-USP) and from the College of Veterinary Medicine (Sao Paulo State University-UNESP-Botucatu). Group1wasseparatedintotwosubgroups:1A(21animals) and 1B (three animals), depending on the lymphotechnique used(10%drawinginkÓ (RotringProdutosparaDesenho,Av This research was carried out at the College of Veterinary Medicine, Sa˜o Paulo University (USP), Brazil. U. S. Copyright Clearance Center Code Statement: 0340–2096/2003/3205–0282$15.00/0 www.blackwell.de/synergy Anat. Histol. Embryol. 32, 282–290 (2003) Ó 2003 Blackwell Verlag, Berlin ISSN 0340–2096