The time course of lymphatic routes emanating from the peritoneal cavity in rats

The lymph drainage routes from the abdominal cavity in rats were observed at 3 min, 1, 2 and 4 h after India ink was administered intraperitoneally. Four systems of lymph drainage routes from the peritoneal cavity were observed. Three minutes after injection, the drainage route travelled via the intrathoracic lymph vessels located along the internal thoracic artery and returned to the anterior mediastinal lymph nodes. One hour after injection, the drainage route travelled via the lymph vessel located along the left phrenic nerve in addition to the drainage route observed at 3 min. Two and four hours after injection, in addition to the above-mentioned routes, the drainage that had travelled via the thoracic duct continued along the right side of the aorta and was also observed in the lateral lymph vessel located on the vertebra. These findings suggest that lymph or cells absorbed into the peritoneal cavity at first travel towards the anterior mediastinal lymph nodes in the thorax via the ventral lymphatic channels, and then gradually course through the dorsal lymphatic channels. These routes may serve as a route for transporting cancer cells and other cells from the peritoneal cavity.     

Topographie des Collecteurs Lymphatiques Mammaires de la Chienne

The topography of the lymph drainage was examined by in vivo injections of india ink into the mammary parenchyma of 73 female dogs. Only one gland was injected at a time on each side. Only the cranial abdominal mammary gland had direct drainage to the axillary as well as to the superficial inguinal nodes. The principal routes of drainage differ for each gland. The glands on each side are completely independent as regards their lymph drainage. The cranial thoracic mammary glands on each side had their own collecting duct which led to the sternal lymph nodes. The results of this study suggest to develop a new model for the surgical extirpation of mammary tumors in the bitch.     

99mTc-labeled dextran for mammary lymphoscintigraphy in dogs

Lymphoscintigraphy is the technique of choice for sentinel lymph node detection in women with early breast cancer, but there is limited information evaluating the value of this technique in animals. We investigated mammary lymphatic drainage in 25 young female mongrel dogs by intramammary injection of 18.5 MBq of 99mTc-dextran (70,000 Da). Lymph node anatomical referencing was obtained using an external marker, bone scintigraphy, or scintiscanning the body contour. Cranial and caudal thoracic mammary glands drained into the cranial sternal lymph node and axillary lymph center. The cranial thoracic mammary gland also drained into the superficial cervical lymph node in two of five animals. The cranial abdominal gland was drained by the axillary lymph center. The caudal abdominal mammary gland was drained by the superficial inguinal lymph node in all animals and simultaneously by medial iliac lymph nodes in four of five animals. In one dog, this mammary gland was also drained by the mediastinal and the superficial cervical lymph nodes. The inguinal mammary gland was drained by superficial inguinal lymph nodes and simultaneously via the medial iliac lymph node in one animal. Lymphatic communications between lymph nodes were identified in 11 of 25 (44%) animals. 99mTc-dextran mammary lymphoscintigraphy was easy and rapid to perform and may provide valuable information for further studies.     

The lymph drainage of the neoplastic mammary glands in the bitch: a lymphographic study

The purpose of this investigation was to study the lymph drainage of the neoplastic mammary glands in the bitch using indirect lymphography. The main conclusions drawn from the study of 41 natural cases were as follows: the first or cranial thoracic and second or caudal thoracic neoplastic mammary glands usually drain into the ipsilateral axillary lymph nodes and rarely into the ipsilateral axillary and sternal lymph nodes, simultaneously. The third or cranial abdominal neoplastic mammary gland usually drains into the ipsilateral axillary and superficial inguinal lymph nodes simultaneously, but sometimes only cranially into the ipsilateral axillary lymph nodes. Rarely, it drains only caudally into the ipsilateral superficial inguinal and medial iliac lymph nodes, simultaneously. The fourth or caudal abdominal neoplastic mammary gland usually drains only caudally into the ipsilateral superficial inguinal lymph nodes. Rarely, it drains into the ipsilateral axillary and superficial inguinal lymph nodes simultaneously. The fifth or inguinal neoplastic mammary gland usually drains into the ipsilateral superficial inguinal lymph nodes but rarely, does it also drain into the ipsilateral popliteal lymph node and into a lymphatic plexus at the medial aspect of the ipsilateral thigh. Lymphatic connections between the neoplastic and adjacent normal mammary glands were demonstrated in only one case. The lymph drainage pattern of the neoplastic mammary glands is slightly different to that described in normal glands using the same radiographic method.     

Lymphatic Drainage on Healthy and Neoplasic Mammary Glands in Female Dogs: Can it Really be Altered?

The purpose of this research was to study the mammary lymphatic drainage under a macroscopic and mesoscopic view, 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. However, the popliteal drainage is specific for the healthy caudal abdominal mammary gland. The inguinal gland can be drained 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%), than healthy glands (33.33%), and an increase in contralateral 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 arborization, thus forming new drainage channels and recruiting a larger number of lymph nodes. Lastly, some comments were made about the severity of a specific neoplasic mammary gland and conditions to be considered before making a decision in terms of the most adequate operative procedure, and suggestions for further investigations.     

USE OF COMPUTED TOMOGRAPHY TO EVALUATE THE INTESTINAL TRACT OF ADULT LLAMAS

In the llama, signs of colic are obscure and may be exhibited as persistent sternal recumbency and anorexia even in the presence of a surgical lesion. Diagnostic methods for evaluation of abdominal disorders are limited. As a result, surgical intervention may be prolonged and increase the risk of mortality and postoperative complications. The objective of this study was to determine the feasibility of computed tomography to evaluate the llama intestinal tract. Eighteen hours prior to the computed tomography scan, six llamas were given barium sulfate (15%) via an orogastric tube. Following induction of general anesthesia, the llamas were positioned in sternal recumbency, and 10 mm contiguous slices were obtained from the diaphragm to the tuber ischiadicum. Structures that were consistently identified included the first, second, and third compartments (C1, 2, and 3), small intestine, spiral colon, and ascending colon. C1 was easily identified in the cranial aspect of the abdomen due to its large size relative to the other compartments and characteristic saccules. C2 was located cranial, ventral, and to the right of Cl, while C3 was visualized as a tubular structure to the right and ventral to C1 and C2, C3 was traced caudally until it turned dorsally and continued cranially to a dilated ampulla in the right cranial abdomen delineating the entrance to the small intestine. The spiral colon was identified consistently in the left ventral caudal abdomen. Structures that could not be conclusively identified included the cecum and mesenteric lymph nodes. Computed tomography allowed a consistent evaluation of the major intestinal structures associated with colic in the llama. Thus, computed tomography is a potentially valuable noninvasive diagnostic tool to effectively evaluate the abdominal cavity and differentiate medical from surgical lesions in the llama.     

ULTRASOUND‐GUIDED MESENTERIC LYMPH NODE IOHEXOL INJECTION FOR THORACIC DUCT COMPUTED TOMOGRAPHIC LYMPHOGRAPHY IN CATS

Computed tomographic (CT) lymphography was performed in cats using percutaneous ultrasound‐guided injection of contrast medium into a mesenteric lymph node. The thoracic duct and its branches were clearly delineated in CT images of seven cats studied. The thoracic duct was characterized by anatomic variation and appeared as single or multiple branches. The thoracic duct and the cisterna chyli were identified along the ventral or left ventral aspect of the vertebrae from the level of the cranial lumbar to the caudal cervical vertebrae. The thoracic duct was identified in the central caudal mediastinum, deviated to the left in the cranial mediastinum, and finally moved toward the venous system. Small volumes of extranodal contrast medium leakage were identified in all cats. After injection, the mesenteric lymph nodes were cytologically normal. Ultrasound‐guided CT lymphography via percutaneous mesenteric lymph node injection appears safe and effective in cats.     

The topography of the lymph vessels of mammary glands in female cats

Malignant tumours of the mammary gland in the female cat metastasize, especially through the lymphatic system. However, the anatomical knowledge of this system in cats is not sufficient to develop a reasoned model for the extirpation of these glands in the case of malignant tumours. A study of the topography of the collector vessels in 50 female cats was conducted by indirect injection in vivo of India ink inside the mammary parenchyma. All the lymph nodes were controlled by microscopic examination and lymph vessels were examined after clearing. The success rate of the colouration of the lymph vessels was 76.4%. Clearing showed several principal routes of drainage, different for each gland. Contrary to the presentation observed in the bitch, no evidence existed in any of the 65 cases of lymphatic plexuses connecting the two mammary glands of each row in the female cat. The result of this study is in favour of the development of a new model for the surgical extirpation of mammary tumours in cats.     

THE EFFECT OF POSITIONING ON THE APPEARANCE OF SELECTED CRANIAL THORACIC STRUCTURES IN THE DOG

In this retrospective study the effect of thoracic positioning on the visibility and size of selected cranial thoracic structures in dogs was investigated. Dorsoventral (DV), ventrodorsal (VD) as well as left lateral recumbent (LLR) and right lateral recumbent (RLR) thoracic radiographs of 17 large, 15 medium, and 10 small skeletally mature dogs were evaluated. The craniodorsal and cranioventral mediastinum, the cupula pleura and sternal lymph nodes were examined. The effect of obesity was also evaluated. The craniodorsal mediastinum was better delineated on DV radiographs and was wider on VD radiographs. The craniodorsal mediastinal width: width of T2 cranial end-plate on VD radiographs was 2.41 for all groups combined and obesity significantly influenced this value. The cranioventral mediastinum was more visible in RLR and VD radiographs. A normal sternal lymph node soft tissue opacity was seen most commonly in RLR in large breed dogs and had a mean length of 30 mm. The pulmonary cupula extended beyond the first rib on all views and extended more cranially and was better visualised on VD than DV views.     

Morphological and immunological characteristics of the bovine temporal lymph node and hemal node

Anatomical dissection of the temporal regions of 62 cattle demonstrated that lymph nodes and hemal nodes are present in 89% of the animals (bilaterally in 65% and unilaterally in 24% of the cases). Lymph nodes accounted for 60% and hemal nodes for 40% of all examined nodes. They are nearly always round with diameters ranging from 1 to 9mm. Injections of India ink showed that their drainage area consists of the forehead, the upper eyelid, the base of the horn and the temporal muscle. Immunohistochemistry and flow cytometry revealed that the distribution and percentages of the different cell populations in the lymph nodes and hemal nodes are similar to other cranial lymph nodes. Based on its anatomical location the name temporal lymph node (lymphonodus temporalis) is proposed.     

Anatomical variations of the thoracic duct in the dog

Anatomical variations can be frequently found in the lymphatic system, which is also true for the shape and course of the thoracic duct (ductus thoracicus), the biggest lymph vessel in the body. From 2012 to 2019, the thoracic duct was successfully dissected in 43 dog carcasses that were used in the anatomy course at the Faculty of Veterinary Medicine, University of Zagreb. The thoracic duct originated from the cranial border of the cisterna chyli as one lymph vessel in 36 dogs (83.7%), as two vessels in six dogs (14%) and as three vessels in one dog (2.3%). We divided the observed thoracic duct variations into six groups according to their anatomical similarities. Considering the specific embryonic development, we can conclude that all observed variations are the result of minor deviations from the standard ontogenesis. However, the importance of thoracic duct variations is significant in surgical procedures done in the thoracic cavity to prevent or cure the chylothorax. Since this research showed variations in 39 out of 43 dogs (90.7%) throughout the whole course of the thoracic duct, great care must be taken while performing the ligation or embolization of the thoracic duct.     

Tracheal compression secondary to abscessation of cranial mediastinal lymph nodes in a horse

Respiratory distress and laryngeal paralysis were found to be caused by a Streptococcus equi abscess of cranial mediastinal lymph nodes, putting pressure on the trachea at the thoracic inlet. Surgical drainage was required to relieve the compression, and long-term antibiotic therapy was used to treat the bacterial infection. The trachea returned to normal diameter but left laryngeal hemiplegia persisted. Peritracheal abscesses should be considered in the differential diagnosis of inspiratory dyspnea of the horse.     

Immunohistochemical identification of lymphatic vessels in the periodontium of equine cheek teeth

Immunohistochemical detection of lymphatic capillaries was performed in the periodontium of maxillary and mandibular cheek teeth from 6 horses (aged 3-23 years). Tissue sections of the periodontium were taken at 4 different horizontal levels along the long axis of the tooth. The specimens were processed for immunoreaction with anti-Prox1, in order to distinguish lymphatic endothelium from blood vascular endothelium. Lymphatic vessels were detected in all periodontal tissues except for the dental cementum. Lymphatic capillaries were most densely distributed in the gingiva compared to other tissues of the periodontium. Lymphatic capillaries were found most consistently in samples taken from the gingival and subgingival regions in all horses examined. Within these levels, the gingiva as well as the spongiosa of the maxillary and mandibular bone had the greatest incidence of lymphatic vessels. Considering the distinct distribution of the lymphatic capillaries in the periodontium of the maxillary and mandibular cheek teeth, two complementary lymphatic drainage pathways are proposed: (1) superficial lymph drainage via the gingiva, emptying into the mandibular lymph nodes; (2) deep lymph drainage via the mandibular and maxillary spongiosa, emptying into the mandibular and retropharyngeal lymph nodes, respectively.     

Lymph Drainage from the Ovine Tonsils: An Anatomical Study of the Tonsillar Lymph Vessels

Although the tonsils of sheep have gained much attention during the last decade, only few data are available on their lymph vessel architecture. Tonsillar lymph vessels are immunologically important as they form the efferent routes for locally activated immune cells to reach the draining lymph nodes. To gain insight into the tonsillar lymph drainage in the sheep, Indian ink and a casting polymer were injected into the interstitium of the five tonsils present in the heads of slaughtered sheep. This enabled us to determine the draining lymph node and to examine the microscopic organization of lymph vessels using light and scanning electron microscopy. No lymph vessels were observed within the tonsillar lymphoid follicles. The corrosion casts demonstrated that the lymphoid follicles are surrounded by numerous sacculated lymph sinuses that drain into a dense interfollicular lymph vessel network. From here, the lymph flows into single small lymph vessels that in turn drain into larger lymph vessels extending towards the medial retropharyngeal lymph node. The presented results can be valuable for immunological studies, for example during oral or intranasal vaccine development.     

Transformation of a thymic branchial cyst to a carcinoma with pulmonary metastasis in a dog

A 9-year-old, female neutered Dalmatian was evaluated for acute onset of dyspnoea. Thoracocentesis on presentation yielded 1300 ml sanguineous fluid, while thoracic radiology and ultrasonography showed a mixed-echoic cavitary cranial mediastinal mass, sternal lymph node enlargement and pleural effusion. Surgical exploration of the thorax revealed a multi-lobulated red/brown cranial mediastinal mass and multiple similarly coloured ovoid nodules within several lung lobes. Histopathology revealed thymic branchial cysts with neoplastic transformation and examination of the lung was consistent with metastasis. Despite initially recovering well, acute sepsis and pyothorax resulted in cardiac arrest 8 days postoperatively. This is the first veterinary report of neoplastic transformation of a thymic branchial cyst with pulmonary metastasis.     

The Lymph Drainage of the Mammary Glands in the Bitch: a Lymphographic Study. Part II: the 3rd Mammary Gland

The objective of this investigation was to study the lymph drainage of the 3rd mammary gland in the bitch using indirect lymphography. The main conclusions drawn after the study of 62 normal lactating mongrel bitches were as follows: lymph usually drains from the third gland to the axillary and superficial inguinal nodes simultaneously, but in some cases it drains only cranially to the axillary nodes. It may, rarely, drain only caudally to the superficial inguinal nodes. A lymphatic connection between the mammary glands could not be demonstrated. It was demonstrated that there is a connection between the superficial inguinal lymph nodes on either side. It is suggested that lymphatic connection between the axillary and sternal nodes and the axillary nodes of both sides should be possible in some cases. Lymphatics of the mammary glands that cross the midline were not demonstrated. No relationship between the number of lymph nodes and the body size of the dog could be demonstrated.