Clinical, haematological and biochemical findings in foals with neonatal Equine herpesvirus-1 infection compared with septic and premature foals.

The study retrospectively analyzes the clinical, hematological, and biochemical results of foals infected by the Equine herpesvirus-1 (EHV-1) compared with septic and premature foals. The goal was to discern if it’s possible to diagnose EHV-1 in foals early on by distinguishing it from septicemia or premature symptoms.

Research Design and Methodology

• The study is retrospective and multicentre in nature, looking back at historical data gathered from multiple centres.
• The total number of foals studied was 53. They were categorized into two groups; 14 were herpes positive, and 39 were herpes negative. The herpes negative group consisted of 20 septic foals, 11 premature foals, and 8 foals that were both premature and septic.
• The presence of herpes antigen in the foals was confirmed using immunoperoxidase histochemical staining, a technique used to localize specific antigens in tissues, on tissues from necropsied foals.
• The information gathered was then subjected to a nonparametric statistical analysis followed by a backwards elimination logistic regression. The goal was to establish a statistical model for identifying the herpes infection — a P-value of less than 0.05 was considered statistically significant.

Findings and Analysis

• All the foals tested positive for herpes died, whereas 47% (or 9 out of 19) of the septic foals survived.
• From the analysis, it was found that the foals tested positive for herpes were more inclined to have a total white blood cell count of less than 3 x 10(9)/l. Also, they were more likely to be icteric—a yellowish pigmentation of the skin, tissues, and certain body fluids caused by jaundice—as opposed to septic and premature foals.
• Although the herpes positive foals demonstrated profound hepatic necrosis, or death of liver cells, the study found that their liver enzymes were not elevated and did not significantly differ from the control group. This suggests that routine liver function tests may not be reliable in diagnosing EHV-1 infection.

Implications and Conclusions

• The study gives some insight into early identifying indicators for EHV-1 infection, namely a low white blood cell count and icterus. This can allow for a more timely diagnosis, leading to more efficient treatment strategies.
• The lack of a significant difference in liver enzyme levels between infected and control foals highlights the limitations of relying only on liver function tests to diagnose EHV-1. This may justify the need for more specific diagnostic procedures for EHV-1 infection.