Page 1044 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

H aemolymphatic system 1019

VetBooks.ir 9.21

Infected horse

EIA virus

Acute form Subacute form Chronic, inapparent, carrier form
Fig. 9.21 Pathogenesis of equine infectious anaemia (EIA). Insect vectors transmit EIA virus from an infected
horse to susceptible horses. Iatrogenic infection through re-use of needles or other cross-contamination of
blood can also occur. Acute, subacute and chronic (carrier) forms may ensue.

Differential diagnosis An ELISA is also available; however, it has a lower
Other causes of anaemia and thrombocytopenia, specificity, which is of concern considering the
including equine viral arteritis (EVA), immune- consequences of a positive result. Typically, the
mediated disease, ehrlichiosis and purpura haemor- Coggins test will be positive within 45 days of
rhagica, need to be considered. Chronic forms may acute infection.
need to be differentiated from lymphocytic neopla-
sia and persistent inflammatory diseases. Management
There is no specific treatment available for EIA.
Diagnosis Supportive therapy may facilitate clinical recov-
When clinical infection is present, animals usually ery. EIA is a reportable disease in most countries.
have fever, haemolytic anaemia and thrombocyto- The consequences of a positive EIAV test may
penia. Anaemia is most severe during the subacute include euthanasia, permanent identification as
to chronic stages. Leucopenia, lymphocytosis and EIAV infected or life-long quarantine a minimum
monocytosis may be observed. The Coombs test distance (i.e. 200 metres) away from other equids.
may be positive. Definitive diagnosis is achieved Demonstration of EIAV-negative status is required
by detecting EIAV-specific antibody p26 in an for interregional transportation and for enter-
agar-gel immunodiffusion assay (Coggins test). ing sales or competitive events in most countries.