Page 2663 - Cote clinical veterinary advisor dogs and cats 4th

1366 Monocytes (Monocytosis, Monocytopenia) Mycobacterial Culture

sodium gluconate (e.g., Plasma-Lyte) causing plastic screw-cap tube. Plasma samples (1.2 mL) • A negative result for any fungal antigen test
does not rule out fungal disease.
false-positive results. should be collected in EDTA and spun for 15 • At present, alternative serodiagnostic tests
VetBooks.ir Specimen Collection and Handling tube. Samples are stable at 2°C-8°C for 2 weeks, are preferred over galactomannan assay for
minutes. Transfer plasma to plastic screw-top
sino-nasal aspergillosis, C. immitis and C.
For B. dermatitidis and H. capsulatum, urine
or 5 months if frozen.
antigen determination is more sensitive than is
neoformans.
serum/plasma. Fluids other than blood should Relative Cost: $$$ • Utilize the diagnostic laboratory website for
be collected in a sterile screw-top tube. CSF test-specific information relating to appropri-
specimen requirement is 0.8 mL; other fluids Pearls ate sample, collection technique, sample sta-
(BAL, urine specimen) requirement is 0.5 mL. • Cytologic or histopathologic identification bility, and submission (http://miravistalabs.
Treatment of the sample with mucolytic and of fungal elements is preferred, but serology com/veterinary-fungal-infections/).
keratolytic agents can degrade most fungal is valuable for support of diagnosis when
antigens. BAL samples that are too viscous to organism cannot be identified. AUTHOR: Sharon M. Dial, DVM, PhD, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
pipette are rejected. For blood samples, collect • Urine antigen tests can be serially monitored
serum (1.2 mL) in a red top tube, allow to clot to assure clinical response to antifungal
for 30 minutes, centrifuge, transfer serum to a therapy.

Monocytes (Monocytosis, Monocytopenia)

Definition Reference Interval Specimen Collection and Handling
3
Largest leukocyte on blood smear. They have Dogs: 0.1-1.5 × 10 monocytes/mcL; cats: 0-1 EDTA whole blood (lavender top tube) and
3
lobulated to occasionally indented, oval nuclei × 10 monocytes/mcL freshly prepared blood smear for laboratory
and gray basophilic cytoplasm with fine azuro- to stain
philic granules and occasionally clear vacuoles. Causes of Abnormally High Levels
Monocytes become macrophages upon entering • Inflammation, acute or chronic Relative Cost: $$ (reported as part of CBC)
tissues and fluids. • Stress leukogram, from endogenous or
exogenous glucocorticoids Pearls
Physiology • Monocytic leukemia, myelomonocytic After acute onset of neutropenia caused by
Monocytes are produced in the marrow, with a leukemia, hemophagic histiocytic sarcoma transient suppression of hematopoiesis (e.g.,
short transit time from monoblast to monocyte, anticancer chemotherapy), monocytes return
which quickly enters blood. Monocytes and Next Diagnostic Steps to Consider to high levels in blood sooner than neutrophils
macrophages are involved in killing bacteria if Levels are High since monocytopoiesis is more rapid than
and fungi, presenting antigens to lymphocytes, Evaluate for given causes, depending on signal- granulopoiesis. Therefore, in neutropenic
removal of necrotic and apoptotic cell debris, ment, history and physical exam. patients, even mild monocytosis can signal
and destruction of senescent or abnormal hematopoietic recovery and impending resolu-
erythrocytes. Dendritic cells (antigen-presenting Causes of Abnormally Low Levels tion of neutropenia.
cells in tissue) also derive from monocytic Monocytopenia is not considered a clinically
precursors in marrow. significant abnormality, because monocytes AUTHOR: Stephen D. Gaunt, DVM, PhD, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
often occur in very low numbers naturally.

Mycobacterial Culture

Definition Reference Interval Important Interspecies Differences
Laboratory growth, isolation, and identification Reported as growth or no growth, with • Feline leprosy (M. lepraemurium) and atypical
of Mycobacterium spp. identification of organisms mycobacteriosis (M. avium, M. fortuitum,
M. thermoresistibile, M. xenopi, M. phlei,
Physiology Causes of Abnormally High Levels and M. smegmatis) are considered unique to
Mycobacterium spp. cause uncommon but Infection with Mycobacterium spp. Common the cat.
important opportunistic infections in dogs and sites of infection include skin (leproid) and • Dogs, especially basset hounds, are sus-
cats. Organisms may be shed intermittently respiratory tract. Infections may become ceptible to systemic disease caused by M.
in respiratory specimens (tracheal exudate) or systemic, involving lymphatics and bone avium.
present constantly in solid tissue specimens marrow. • Dogs are not a reservoir for Mycobacteria sp.
(skin, lymph node) during infection. The Rare infection with M. bovis and very rare
organism must be grown in specific media, Next Diagnostic Steps to Consider infection with M. tuberculosis is attributed
and growth and identification of these fastidious if Levels are High to contact with infected people.
organisms may take 2-4 months. See p. 670.

www.ExpertConsult.com