Page 1383 - Small Animal Internal Medicine, 6th Edition

CHAPTER 82 Anemia 1355

reported in this study, so the prevalence of true IDA is BOX 82.5
unknown. The last recorded PCV was significantly lower
VetBooks.ir than the admission PCV for both dogs (admission PCV, Bone Marrow Disorders in Cats and Dogs
42%; last recorded PCV, 34%, P < 0.0001) and cats (admis-
Marrow (or Erythroid) Aplasia-Hypoplasia
sion PCV, 31%; last recorded PCV, 26%, P < 0.0001). Patients
that developed anemia had significantly more blood samples • FeLV (C)
collected (nonanemic, 5 blood samples; anemic, 7 blood • Immune-mediated disorders (D, C)
samples, P < 0.0001). Hospitalized cats were significantly • Estrogen (D)
more likely to develop anemia than dogs (P < 0.0001), but • Phenylbutazone (D)
anemic dogs were significantly less likely to survive to dis- • Other drugs (D, C)
• Idiopathic (D, C)
charge (P = 0.0001). Surgical patients were at higher risk of
developing hospital-acquired anemia compared with medical Myelophthisis
patients (odds ratio [OR], 0.63; 95% confidence interval • Acute leukemias (D > C)
[CI], 0.4-0.9; P = 0.01). Blood products were administered • Chronic leukemias (D > C)
to 198 patients (158 dogs and 40 cats); packed RBCs were • Multiple myeloma (D, C)
the most commonly administered product in 129 cases (100 • Lymphoma (D, C)
dogs and 29 cats). • Systemic mast cell disease (C > D)
In my experience, the most common cause of symptom- • Malignant histiocytosis (D > C)
atic IDA in adult dogs that present for evaluation of signs • Metastatic carcinoma (rare D, C)
associated with anemia is GI neoplasia. • Histoplasmosis (rare D, C)
Dogs with IDA are typically evaluated because of the Myelodysplastic Syndromes
signs of the anemia or because of GI tract signs such as diar- • FeLV (C)
rhea, melena, or hematochezia. Mild IDA is occasionally • FIV (C)
recognized during the routine evaluation of heavily parasit- • Preleukemic syndrome (D, C)
ized dogs (mostly pups). Hematologically, most dogs with • Idiopathic (D, C)
IDA have microcytic hypochromic indices, mild reticulocy-
tosis, high RBC distribution width (RDW) with an occa- Myelofibrosis
sional bimodal population of RBCs, thrombocytosis, low • FeLV (C)
serum iron and TIBC (transferrin) concentrations, extremely • Pyruvate kinase deficiency anemia (D)
low percentage of saturation (usually <10%), low serum fer- • Idiopathic (D, C)
ritin concentration, and low iron stores in the bone marrow Osteosclerosis/Osteopetrosis
(see Box 82.5; Fig. 82.9). The typical tetrad of hematologic • FeLV (C)
abnormalities in dogs with IDA is microcytosis, hypochro-
masia, mild regeneration, and thrombocytosis. “Anemia of C, Cat; D, dog; FeLV, feline leukemia virus; FIV, feline
the elderly,” a progressive, age-related microcytic hypochro- immunodeficiency virus.
mic anemia documented in people, was recently described
in senior and geriatric dogs (Radakovich et al., 2017).
Because the most common cause of IDA in adult dogs is smear for hookworms and thorough physical examination
chronic GI tract bleeding, the stools should always be evalu- to search for fleas are mandatory because these are the two
ated for occult blood with commercially available kits (see most common causes of IDA in young dogs and cats.
Chapter 27); if the results are negative, they should be evalu- IDA usually resolves within 6 to 8 weeks after the primary
ated again two or three times during a period when the cause has been eliminated. Oral or intramuscular iron sup-
animal is not eating canned dog food; myoglobin in canned plementation is usually not necessary to hasten the resolu-
dog food can rarely result in false-positive reactions. If occult tion of the hematologic abnormalities; a sound commercial
blood is present in the stool, a GI tract neoplasm should be diet usually achieves the same effect. As a general rule, if the
ruled out. Tumors commonly associated with IDA in dogs cause can be eliminated, I do not use iron supplementation.
include GI stromal tumors (GISTs), leiomyomas and leio- The dietary iron requirement for adult dogs and cats is
myosarcomas, lymphomas, and carcinomas. In dogs with approximately 1.3 mg/kg/day.
weight loss, IDA, positive fecal blood test results, and lack of
clinical signs associated with the GI tract, the most likely
diagnosis is a jejunal tumor (usually a GIST or leiomyosar- TRANSFUSION THERAPY
coma); I refer to these tumors as the silent GI neoplasms.
Another condition that can lead to IDA is chronic upper Veterinary transfusion medicine has made great strides in
GI tract bleeding secondary to gastroduodenal ulceration, the past decade. Several commercial blood banks for pets are
although most of these dogs have overt clinical signs associ- now available; most of them store blood components derived
ated with the GI tract (e.g., vomiting, hematemesis, weight from processing units of whole blood or collected by apher-
loss). In pups or kittens with IDA, fecal flotation or a direct esis. In a typical situation, a unit of whole blood is spun