Page 1198 - Cote clinical veterinary advisor dogs and cats 4th

Lymphadenopathy 599

Selected Lymph Nodes of the Dog and Associated Anatomic Regions of Lymphatic Drainage
VetBooks.ir Lymph Node (Alternative Location Distribution of Lymphatics Contributing Diseases and Disorders
to the Node
Name)
Ventral to the angle of the mandible; subcutaneous and mobile (vs.
Submandibular (mandibular)*
Most structures of the head, except for the external
Prescapular (superficial cervical)* mandibular salivary glands, which are deeper, fixed structures) ear and some parts of the skin of the dorsal muzzle
Skin of the head, neck, and forelimb
Medial and dorsal to the point of the shoulder
Axillary Dorsal to deep pectoral muscle and at the dorsal-most aspect of medial Thoracic wall, deep structures of the forelimb
forelimb
Inguinal (superficial inguinal) Caudoventral abdomen, immediately caudal to the fifth mammary gland Mammary glands, prepuce, scrotum, vulva, ventral
abdominal wall up to the umbilicus
Popliteal* Caudal surface of stifle (femorotibial joint) All parts of the hindlimb distal to the node
Sublumbar (medial or external iliac) Trifurcation of aorta (dorsal surface of pelvic canal/abdomen); may be Genital system, caudal part of the urinary and
palpable per rectum digestive systems, pelvis, hindlimbs, and dorsal half of
the abdomen
Sternal (internal thoracic) Medial to the second costal cartilage or intercostal space, cranioventral Peritoneal cavity, ribs, sternum, serous membranes,
to the internal thoracic blood vessels thymus, adjacent muscles, and mammary glands
Perihilar (tracheobronchial) Immediately adjacent to the mainstem bronchi, distal trachea and hilar Lungs, bronchi, heart, mediastinum; thoracic trachea,
vessels, dorsal to proximal portions of the pulmonary veins and main esophagus, and diaphragm
pulmonary artery
*Nodes that are normally palpable in the healthy dog and cat.

and urinalysis together with diagnostic imaging
are often needed to determine the underlying
cause. Lymph node biopsy may be necessary
if no cause is found.
Differential Diagnosis
A detailed differential diagnosis is provided
on p. 1251.
Initial Database
• Review history of travel to endemic infectious
disease areas.
• Fine-needle aspiration of lymph nodes
allows classification of the disease process
and frequently yields infectious etiologic
agents or neoplastic cells (e.g., lymphoma).
• CBC
○ Circulating blasts: lymphoma, acute
leukemia LYMPHADENOPATHY Lateral view of a bull terrier with evidence of severe submandibular (thick arrow)
and prescapular (thin arrow) lymph node enlargement. (Courtesy Dr. A. Zambelli, Inanda Veterinary Hospital.)
○ Neutrophilia: lymphadenitis, reactive
lymph node hyperplasia, or neoplasia
○ Eosinophilia: allergic, parasitic
○ Thrombocytopenia: rickettsiosis, Advanced or Confirmatory Testing Acute General Treatment
lymphoma • Excisional lymph node biopsy (usually Prompt therapy (based on cause) is neces-
○ Monocytosis: granulomatous disease, popliteal node) and histopathologic evalu- sary if lymph nodes obstruct the airway or
mycosis, neoplasia, or immune-mediated ation is ideal to confirm neoplasia and to vessels.
disease perform immunophenotyping in lymphoma
○ Anemia: ± depending on cause (e.g., for prognostication. PROGNOSIS & OUTCOME
anemia of inflammatory disease, anemia ○ Flow cytometry or PCR for antigen recep-
due to myelophthisis) tor rearrangement (PARR) testing may be Varies; determined by underlying cause
• Serum biochemistry profile useful when cytology is indeterminate for
○ Hypercalcemia: lymphoma, multiple lymphoma before excisional biopsy. PEARLS & CONSIDERATIONS
myeloma, anal sac adenocarcinoma • ± Aspiration and cytologic evaluation of
○ Hyperglobulinemia: neoplasia, rickettsio- spleen, liver, bone marrow Comments
sis, chronic inflammatory diseases • ± Serologic tests for suspected infectious • Lymphadenopathy is most commonly
• Test cats for feline leukemia virus and feline agents (e.g., Blastomyces, Ehrlichia) associated with lymph nodes that are firm,
immunodeficiency virus infections. irregular, painless, nonadherent to underlying
• Imaging: radiographs, ultrasound, and/or CT TREATMENT tissue, and not warm to the touch.
to search for nidus of infection or neoplasia • Nodes that are softer, warm, painful, and
and determine the extent of lymph node Treatment Overview adherent to underlying tissue typically denote
involvement Treat the underlying cause of lymphadenopathy lymphadenitis.

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