Peripheral Lymphadenopathy in Dogs: Differential Diagnoses

Following are differential diagnoses for dogs presented with peripheral lymphadenopathy.

• Neoplastic

  • Lymphoproliferative

    • Lymphoma

    • Chronic lymphocytic leukemia

    • Acute lymphoblastic leukemia

  • Metastatic neoplasia (common causes)

    • Carcinoma (eg, mammary gland carcinoma, thyroid carcinoma, oral squamous cell carcinoma) 

    • Sarcoma (eg, soft tissue sarcoma, histiocytic sarcoma)

    • Mast cell tumor

    • Melanoma (oral or digit)

• Reactive

  • Infectious 

    • Systemic fungal infection

      • Blastomycosis (ie, Blastomyces dermatitidis)

      • Histoplasmosis (ie, Histoplasma capuslatum)

      • Coccidioidomycosis (ie, Coccidioides immitis)

      • Sporotrichosis (ie, Sporothrix schenckii)

      • Aspergillosis (eg, Aspergillus fumigatus, A flavus)

      • Pythiosis (ie, Pythium insidiosum)

    • Bacterial infection

      • Brucellosis (ie, Brucella canis) 

      • Nocardiosis (ie, Nocardia spp)

      • Plague (ie, Yersinia pestis)

    • Vector-borne disease (coinfection is common)

      • Ehrlichiosis (eg, Ehrlichia canis, E chaffeensis, E ewingi, E equi)

      • Anaplasmosis (ie, Anaplasma phagocytophilum) 

      • Neorickettsiosis (ie, Neorickettsia risticii)

      • Salmon poisoning disease (ie, Neorickettsia helminthoeca)

      • Bartonellosis (eg, Bartonella henselae,¹ B clarridgeiae, B vinsonii) 

      • Rocky Mountain spotted fever (ie, Rickettsia rickettsii) 

      • Leishmaniasis (eg, Leishmania infantum, L donovani)

      • Babesiosis (ie, Babesia canis)

      • Hepatozoonosis (ie, Hepatozoon americanum)

  • Severe generalized pyoderma

    • Primary bacterial pyoderma

    • Secondary bacterial pyoderma

      • Atopy

      • Demodectic mange

      • Sarcoptic mange

      • Sebaceous adenitis

• Inflammatory, noninfectious 

  • Cutaneous lupus erythematosus²  

  • Juvenile sterile granulomatous dermatitis and lymphadenitis (ie, juvenile cellulitis, puppy strangles)    

  • Adult-onset sterile granulomatous dermatitis and lymphadenitis (ie, juvenile cellulitis)³

• Other

  • Phenobarbital-induced pseudolymphoma⁴