Petechiation & Ecchymoses

Petechiae and ecchymoses are red to purple discolorations of the skin or mucosa and occur due to blood vessel disruption. Petechiae are generally <3 mm in diameter and form as a result of capillary bleeding. Ecchymoses are larger lesions caused by arteriolar and venular bleeding. Most cases of petechiation or ecchymoses tend to be multifactorial with multiple mechanisms contributing to their presence. 

Following are differential diagnoses for patients presented with petechiation and/or ecchymoses.

Thrombocytopenia

• Immune-mediated thrombocytopenia (ie, platelet destruction)

  • Primary or idiopathic (most common cause in dogs, rare in cats)

  • Secondary  

    • Infectious (eg, Angiostrongylus vasorum, Leishmania infantum, Anaplasma phagocytophilum [dog])

    • Inflammatory (eg, meningoencephalitis of unknown origin [cat], African bee envenomation [dog])

    • Neoplasia (eg, mast cell tumor, disseminated carcinoma, lymphoma, osteosarcoma [dog])

    • Drug-related (eg, gold salts [auranofin], carprofen, cephalosporins, chlorambucil, trimethoprim/sulfadiazine [dog])

• Platelet consumption

  • Disseminated intravascular coagulation

  • Vasculitis

  • Hepatic failure

  • Pancreatitis

• Myelosuppression

  • Myelodysplasia (eg, myelodysplastic syndrome with excess blasts [MDS-EB], myelofibrosis, myelophthisis [dog])

  • Drug-induced (eg, carbimazole, linezolid [cat], azathioprine, vincristine, chloramphenicol, cephalosporins, estrogen [dog])

  • Infection (eg, FeLV/FIV [cat], ehrlichiosis, parvovirus [dog]) 

  • Neoplasia (eg, lymphoma, lymphoid leukemia, histiocytic sarcoma)

• Sequestration (rare; although this mechanism is frequently considered as a cause for thrombocytopenia, it is unlikely to result in petechiae or ecchymoses) 

  • Hepatomegaly

  • Splenomegaly

  • Hypotension

  • Endotoxemia 

  • Hypothermia

Thrombopathia

• Inherited (rare in cats)

  • Glanzmann thrombasthenia (Great Pyrenees, otterhound, crossbreed dogs)

  • Canine thrombopathia (basset hound thrombopathia, spitz, Landseer Newfoundland)

  • Platelet P2Y12 receptor disorder (Greater Swiss mountain dog)

  • Leukocyte adhesion deficiency (LAD)-III (LAD-I variant; German shepherd dog)

  • Delta-storage pool deficiency (American cocker spaniel)

• Acquired

  • Infectious disease (eg, Ehrlichia canis, E platys [dog])

  • Snake envenomation (eg, copperhead, other pit vipers) 

  • Hepatic disease

  • Anticoagulant rodenticides

  • Uremia

  • Neoplasia (eg, essential thrombocythemia, acute megakaryocytic leukemia, chronic myeloid leukemia)

  • Disseminated intravascular coagulation 

  • Monoclonal gammopathies (eg, multiple myeloma, Ehrlichia canis) 

  • Platelet-inhibiting medications (aspirin, clopidogrel, heparin, dextran) 

  • Idiosyncratic drug reaction (carprofen, hydroxyethyl starch, omega fatty acids)

Von Willebrand disease

• Rarely causes petechiation

Vascular disorders

• Vasculitis

  • Immune-mediated

    • Primary

    • Secondary to medication, infection, neoplasia

• Infectious (eg, Rickettsia rickettsii) 

  • Hyperadrenocorticism (dog)