Abstract
Background:
Hemomycoplasmosis caused by Hemotropic mycoplasmas, or Hemoplasma, previously classified as Eperythrozoon spp., is an uncultivable parasite that can be transmitted to humans by infecting the cell wall of erythrocytes in many susceptible mammals, including cattle, buffalo, goats, sheep, horses, cats, dogs, and even camels.

Aim:
This study aimed to display and evaluate the different diagnostic criteria for detecting the most precise method for diagnosing H. mycoplasma in horses.

Methods:
Different diagnostic methods were used to diagnose equine HMP caused by Mycoplasma haemofelis. Including cytological examinations (Giemsa stain blood smears and fluorescent microscopical diagnosis using acridine orange staining) as well as evaluation of the acute phase response reaction, molecular diagnosis via qPCR, and postmortem examination of dead carcasses

Results:
The cytological diagnosis revealed an infection rate of 88% (88/100), whereas the molecular diagnosis via qPCR confirmed infection in 79% (79/100) of the samples. The agreement between the two diagnostic methods was analyzed using Cohen’s kappa statistic. The observed agreement was 91% (91/100), and the chance-expected agreement was 72.04%. The calculated Kappa coefficient was κ = 0.678 (95% CI, confidence interval), indicating substantial agreement between cytological and qPCR diagnoses according to the Landis and Koch benchmark. The findings also showed that infected horses exhibit significant differences in the acute phase response; additionally, dead carcasses displayed general emaciation, paleness of internal organs, obvious splenomegaly, and enlarged liver, kidneys, and heart, which showed white patches. Furthermore, histopathological changes indicate degeneration and necrosis in cardiac muscles, atrophic glomeruli, dilatation of renal tubules in the kidneys, a marked reduction in the proportion of white pulp of splenic tissue, and degenerative changes in the cytoplasm of hepatocytes, accompanied by nuclear alterations characterized by loss of chromatin content in the hepatic tissue.

Conclusion:
Evaluating different tests for diagnosing equine hemomycoplasmosis is crucial to identify the most accurate one and use it confidently in the future. Additionally, although the diagnostic criteria and accuracy of each test vary, each test has its advantages and disadvantages. Moreover, cytological diagnosis is still advised for field screening, whereas quantitative polymerase chain reaction is for confirmatory diagnosis.

Key words: Acute phase response; Cytology; Equine diagnosis; Hemoplasma; qPCR.