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Myiasis 673

low-normal hematocrit; anecdotally, dar- • Serum biochemistry profile: at least q 2 ingestion of medications not intended for
veterinary use).
bepoetin (Aranesp) 0.45 mcg/kg SQ once months to monitor overall health • Management of MDS is focused on identify-
VetBooks.ir for maintenance (may be less antigenic than PROGNOSIS & OUTCOME ing and treating underlying diseases (espe- Diseases and Disorders
weekly at first, then q 2-3 weeks adjusted
recombinant erythropoietin), and/or throm-
cially immune-mediated hemolytic anemia,
bopoietin (currently experimental) may have
a role in treating refractory cytopenias. Some • In general, the prognosis for most animals immune-mediated thrombocytopenia, and
lymphoma) and supportive care of secondary
with MDS is poor, with survival times
recombinant human cytokines cause dogs ranging from a few days to a few months. cytopenias.
and cats to form cross-reactive neutralizing ○ Primary MDS is considered to be a • When considering these conditions, consulta-
antibodies to the recombinant products and preneoplastic condition, progressing to tions with a veterinary clinical pathologist
their own cytokines, especially with chronic acute leukemia in 40%-60% of cases. and a veterinary oncologist are highly
or repeated use. Animals may live a year or more but recommended.
• Immunosuppressive doses of prednisone/ eventually succumb to acute leukemia • Antineoplastic chemotherapy has not been
prednisolone 2 mg/kg PO q 24h have or bone marrow failure. shown to be beneficial for control of MDS
been effective for some dogs and cats with ○ The prognosis for animals with secondary or to prevent progression to leukemia.
refractory cytopenias. MDS depends on successful elimination • Although the overall prognosis for patients
• Low-dose cytosine arabinoside (LD-AraC) of the inciting disease or drug. with MDS is poor, there is substantial
2
0.7-1.4 mg/kg (or 100 mg/m ) SQ q 24h for • Cats with refractory anemia can enjoy long interindividual variability; some patients
2-4 days has been attempted as a differentia- survival times; however, cats with other respond well to therapy and enjoy longer
tion agent in the management of MDS in types of MDS are typically euthanized due survival times.
cats. A single complete response has been to cytopenias or may develop acute myeloid
described. LD-AraC administered to a dog leukemia (AML) in weeks to months. Prevention
2
with MDS-Er at 10 mg/m SQ q 12h for • The prognosis for cats with concurrent All cats should be tested for feline retroviruses
3 weeks was ineffective (p. 609). MDS and FeLV infection is especially grave; (FeLV; also FIV if > 6 months old) as kittens,
most do not survive 1 week after diagnosis. and FeLV vaccination should be considered.
Chronic Treatment The prognosis is better for cats with FIV-
• Patients responding to treatment will likely associated MDS because progression is more Technician Tips
require lifelong therapy and chronic monitor- chronic. • Because immunosuppression often accompa-
ing for progression to leukemia. • Dogs with MDS-RC may have a better nies MDS, nosocomial infection prevention
○ Supportive therapy as indicated (antibiot- prognosis than those with MDS-EB. In one protocols should be employed. This includes
ics, transfusions, hematopoietic cytokines) small study, dogs with refractory anemia lived handling patients with gloves, using antibi-
○ Hematopoietic cytokines should be reduced/ longer (>6 months) than dogs with other otic scrub technique for blood collection and
discontinued after cell counts are improved MDS (mean, 2 weeks). injections, and keeping patients away from
to reduce the risk of autoantibody formation. • In general, patients with high blast counts other hospital patients.
• Patients with concurrent MDS secondary and/or poor clinical condition have a worse • Blood collection should be performed using
to drug administration should never receive prognosis. peripheral venipuncture, rather than jugular
that drug again. • Breed-related macrothorombocytopenia vein collection due to risk of thrombocy-
is inconsequential and does not require topenia. Apply bandages and monitor for
Possible Complications treatment. swelling or bruising at collection sites.
Chronic administration of rh-Epo and/or
G-CSF can result in the production of anti- PEARLS & CONSIDERATIONS Client Education
bodies that cross-react with feline or canine • Retrovirus-negative cats should be kept inside
equivalent cytokines and have caused intractable Comments to prevent them from becoming exposed to
cytopenias. • MDSs are uncommon and can be challeng- cats harboring FeLV or FIV.
ing to accurately diagnose. When MDS • There is a high risk of progression of primary
Recommended Monitoring is suspected based on clinical signs and MDS to acute leukemia.
• Physical exams and CBC: q 1-2 weeks, more evidence of hematologic abnormalities, bone
frequently during initial therapy. Blood marrow evaluation is indicated for definitive SUGGESTED READING
smear review to monitor cytopenias, blasts diagnosis. Weiss DJ: Myelodysplastic syndromes. In Weiss DJ,
and other abnormal cell morphology, and • A thorough history is imperative to identify et al, editors: Schalm’s Veterinary hematology, ed
possible adverse effects of treatment. If lasting underlying causes of secondary MDS, espe- 6, Ames, IA, 2010, Wiley-Blackwell, pp 467-474.
response to therapy is noted, interval may cially in cases of environmental exposures AUTHOR: Jennifer E. Locke, DVM, DACVIM
be extended to monthly. and drug or medication reactions (including EDITOR: Jonathan E. Fogle, DVM, PhD, DACVIM

Myiasis

BASIC INFORMATION Synonym • Larvae are relatively species specific, but small
Maggot infestation animals may serve as aberrant hosts when
Definition housed near primary hosts.
An infestation of living animals with the larvae Epidemiology
(maggots) of dipteran (two-winged) flies, which SPECIES, AGE, SEX RISK FACTORS
may cause cutaneous, nasal, or other tissue • Dogs and cats may be affected; no age or Wounded, soiled, debilitated, or weak animals
lesions sex predisposition living in temperate, wet regions known to

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