Adenoviral infection of Arab foals with respiratory tract disease.

This research studied Arab foals and horses suffering from acute non-fatal respiratory disease, and found that adenoviruses were causing the illness. The adenoviruses showed similarities to previously studied strains, suggesting that these viruses can cause both fatal and non-fatal respiratory diseases in horses.

Study overview

• The study was conducted on 16 Arab foals and eight adult Arab horses, all of whom were suffering from an acute, non-fatal respiratory disease.
• The age of the foals ranged from 2.5 months to 6 months.
• Analysis of their viral load found adenoviruses in four of the foals.

Adenovirus properties

• The adenoviruses displayed a common group antigen specific to adenoviruses.
• The viruses were resistant to organic solvents, trypsin, heat exposure, and a pH of 3.
• The electronic microscopic examination revealed typical adenovirus particles.
• The isolated viruses caused cytopathic changes with intranuclear inclusions in EK 269 cell cultures.
• The viruses demonstrated aggravation of erythrocytes (red blood cells) in rats in high titers (concentrations), with lower titers for horse, cattle, sheep, and rabbit erythrocytes. Chicken erythrocytes were not aggravated.

Relationship to other strains

• The four isolated strains of adenovirus showed a close relationship to each other and to a previously isolated strain of equine adenovirus (EAM-1).
• This relationship was supported through neutralization tests, haemaglutination-inhibition tests, and precipitation tests.

Conclusions

• The study postulated that equine adenoviruses are not only capable of causing fatal disease in immunodeficient Arab horses but can also cause acute non-fatal respiratory diseases in normal horses.
• These findings add to knowledge about the pathogenic potential of equine adenoviruses, and could have implications for treatment and prevention strategies in equine health.