Detection of feline herpesvirus 1 DNA in corneas of cats with eosinophilic keratitis or corneal sequestration

Abstract

SUMMARY Objective To determine whether feline herpesvirus 1 (FHV-1) DNA is in the corneas of clinically normal cats and cats with eosinophilic keratitis or corneal sequestration. Sample Population Corneal biopsy specimens obtained from cats referred for treatment of corneal sequestration or eosinophilic keratitis. Procedure Corneal scraping or keratectomy specimens collected from clinically normal cats, cats with eosinophilic keratitis, and cats with corneal sequestration were evaluated for FHV-1 DNA by use of polymerase chain reaction (PCR). DNA was extracted from the tissue, and 1 μg was assayed for FHV-1 by use of a single-round (40 cycles) PCR assay with primers directed at a 322-bp region of the thymidine kinase gene. Polymerase chain reaction positivity for clinically normal and affected cats of various breeds was compared by χ2 analysis at α = 0.05. Results The FHV-1 DNA was detected in 5.9% (1/17) of corneas from clinically normal cats, in 55.1% (86/156) of corneal sequestra, and in 76.3% (45/59) of scraping specimens from cats with eosinophilic keratitis. Prevalence was significantly (P < 0.001) greater for cats with corneal sequestration or eosinophilic keratitis than for clinically normal cats. For cats with corneal sequestration, prevalence of FHV-1 DNA was significantly lower in Persian and Himalayan, compared with domestic shorthair and longhair breeds. Conclusion Data strongly imply involvement of FHV-1 in the pathogenesis of eosinophilic keratitis and corneal sequestration. In Persian and Himalayan breeds, however, other nonviral factors also appear to be involved. Clinical Relevance Feline herpesvirus 1 must be considered when treating cats with corneal sequestration or eosinophilic keratitis. (Am J Vet Res 1998;59:856–858)