Page 1943 - Cote clinical veterinary advisor dogs and cats 4th

972 Thrombocytopenia, Immune-Mediated

it rostrally. This should be done when invaluable in aiding veterinarians in establish- AUTHOR: Lucien V. Vallone, DVM, DACVO
attempting to look for a cause of corneal ing an underlying diagnosis for third eyelid EDITOR: Diane V. H. Hendrix, DVM, DACVO
VetBooks.ir • Third eyelid flaps are not indicated in cases SUGGESTED READING
abnormalities.
ulceration.
of infected ulcers, melting ulcers, descemeto-
celes, or corneal perforations.
Multari D, et al: Pocket technique or pocket technique
combined with modified orbital rim anchorage
Technician Tips for the replacement of a prolapsed gland of the
Technicians skilled at performing the Schirmer third eyelid in dogs: 353 dogs. Vet Ophthalmol
tear test, fluorescein stain, and tonometry are 19:214-219, 2016.

Thrombocytopenia, Immune-Mediated Client Education
Sheet

BASIC INFORMATION • Pale mucous membranes Initial Database
• Fever in < 20% of cases • CBC with manual differential:
Definition ○ Bleeding may cause anemia (regenerative
Thrombocytopenia resulting from immune- Etiology and Pathophysiology after 3-5 days)
mediated platelet destruction in the absence • Occurs when a stimulus triggers a ○ By definition, severe thrombocytopenia:
of an identifiable cause patient with the appropriate susceptibility platelet count usually < 25,000/mcL; may
genes be few to no visible platelets (p. 1373)
Synonym • Identification and inheritance of predisposing • Serum biochemical profile: usually normal
Idiopathic thrombocytopenic purpura (ITP) genes are unknown. • Urinalysis (voided)
• Triggering factors may include vaccination, ○ Usually normal or may show hematuria
Epidemiology drug administration, stress, or infection. ○ Avoid cystocentesis in severely thrombo-
SPECIES, AGE, SEX • Bleeding does not occur until the platelet cytopenic patients.
Dogs > cats; either sex, 8 months to 15 years count is < 25,000/mcL, although bleeding • Coagulation profile: usually normal, but
of age, with middle-aged females predisposed may occur in the face of higher platelet activated clotting time (ACT) may be
counts if there is platelet dysfunction prolonged.
GENETICS, BREED PREDISPOSITION (thrombocytopathia). • Thoracic radiographs: usually normal
Cocker spaniels, Old English sheepdogs, German • Abdominal ultrasonography: usually normal
shepherds, and poodles are overrepresented. DIAGNOSIS or may show mild splenomegaly
• Serum titers for tick-borne diseases in
ASSOCIATED DISORDERS Diagnostic Overview endemic areas
Immune-mediated diseases may affect multiple The diagnosis is suspected in patients showing
body systems; immune-mediated thrombo- overt signs of bleeding in the history, physical Advanced or Confirmatory Testing
cytopenia (IMT) may be associated with exam, or both, and it is confirmed by dem- • Bone marrow cytologic exam is rarely
polyarthritis or proteinuria. Anemia may be due onstrating repeatable, severe thrombocytopenia necessary (e.g., if there is concurrent
to blood loss (especially gastrointestinal [GI]) (<25,000/mcL) in the absence of an identifiable leukopenia or nonregenerative anemia):
or concurrent immune-mediated hemolytic cause. may show increased (peripheral platelet
anemia (Evans syndrome). destruction; more common) or decreased
Differential Diagnosis (marrow-based destruction) megakaryocyte
Clinical Presentation • Breed-associated physiologic thrombocyto- numbers
DISEASE FORMS/SUBTYPES penia (greyhounds, Cavalier King Charles • Testing for platelet-bound antibody is usually
Primary IMT is idiopathic. Secondary IMT spaniels, Norfolk terriers) unnecessary.
occurs in association with infection, drug • Tick-borne disease (e.g., ehrlichiosis, • Antinuclear antibody testing only if there are
therapy, or neoplasia. anaplasmosis, Rocky Mountain spotted multiple systems involved to suggest systemic
fever) lupus erythematosus.
HISTORY, CHIEF COMPLAINT • Splenic disease (neoplasia, torsion, infarction)
Owners commonly notice bleeding in the • Drug administration (antineoplastic chemo- TREATMENT
skin, from the nose or mouth, or associated therapy, antibiotics, estrogen, nonsteroidal anti-
with minor trauma. Hematochezia, melena, or inflammatory drugs [NSAIDs], albendazole, Treatment Overview
hematuria may be observed. The patient may griseofulvin, propylthiouracil, ketoconazole) Stable patients can be treated as outpatients,
continue to act normally, although some present • Bacterial sepsis, vasculitis, disseminated with therapy aimed at raising the platelet count
with lethargy and weakness. Signs caused by intravascular coagulation into the normal range. If signs of anemia or
bleeding into vital organs (brain, spinal cord) • Bone marrow disease (e.g., myelofibrosis, severe bleeding are apparent, hospitalization
are uncommon. myelodysplasia, necrosis, myelophthisis) and transfusion are required.
• Thrombocytopathia (e.g., drug-related,
PHYSICAL EXAM FINDINGS inherited such as von Willebrand disease) Acute General Treatment
• Petechiae, ecchymoses • Severe hemorrhage (e.g., anticoagulant • Prednisone/prednisolone 2.2 mg/kg PO q
• Ocular hemorrhage/hyphema rodenticide, trauma) 24h or divided q 12h; for large-breed dogs
2
• GI bleeding manifesting as melena or • Cats: feline leukemia virus (FeLV), feline 40 mg/m /day (alternative: dexamethasone
hematochezia immunodeficiency virus (FIV) infections 0.3 mg/kg IV q 24h or divided q 12h)
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