Topical treatment of Pseudomonas sp-infected corneal ulcers in horses: 70 cases (1977-1994).

This research investigated the most effective antimicrobial agents against Pseudomonas sp-infected corneal ulcers in horses and sought to identify associated clinical conditions to improve treatment strategies. The study found that aggressive topical treatments were largely successful and that most horses maintained excellent vision.

Methodology

• The study is a retrospective case series, meaning it was a type of observational study that looked backwards in time, using previously collected data.
• The researchers looked at the records of 66 horses with a total of 70 corneal ulcers infected with the bacteria Pseudomonas sp. The cases used in the study came from the George D. Widener Hospital for Large Animals, University of Pennsylvania, collected over a period from July 1977 to December 1994.
• Any horse that had Pseudomonas sp isolated from a corneal ulcer, confirmed through a scraping or deep swab, was included in the research.

Findings

• Of the 70 ulcers, aggressive topical medical treatment was successful in 57 cases, with a likelihood that it would have been effective in 5 additional cases.
• Antimicrobial susceptibility testing was carried out to see how effective different antimicrobial agents would be against the bacteria. The bacteria showed susceptibilities of 87% to tobramycin, 85% to gentamicin, and 93% to amikacin.
• Fungal infections were found in only 2 of 35 ulcers examined. Despite this, around three-quarters of the ulcers were still treated with antifungal medications as a preventative measure.

Clinical Outcomes

• The outcomes for the 70 affected eyes were varied. The best outcome, which was excellent vision with minimal leukoma, was achieved in 73% of the cases.
• Enucleation or removal of the eye occurred in 19% of cases, while 4% resulted in a blind eye that was shrunken or atrophied (a condition known as phthisis).
• In 3% of the cases, only peripheral vision was maintained, while 1% of the cases ended with euthanasia of the newborn horse.

Conclusions

• The study concluded that aggressive topical treatment with antimicrobial agents that are effective against Pseudomonas sp could lead to excellent vision with minimal leukoma in most horses suffering from these corneal ulcers.