Baytril is a popular and potent antibiotic used aginst bacterial infections in both dogs and cats to treat a wide variety of infections. It is available both in pill form and as an injectable.
Developed by Bayer specifically for veterinary use, Baytril was approved for use in the United States in 1989.
Over the years, Bayer Animal Health received sporadic but an increasing number of reports concerning altered vision in feline patients treated with Baytril Tablets and/or Baytril Injectable. (Baytril Injectable is only approved for use in dogs.)
These reports, while very rare, have linked Baytril to altered vision and even blindness in cats, according to a warning letter sent by Bayer to veterinarians in June 2000.
Preliminary investigation by the company revealed the dosage recommendations should be limited.
The increase in the number of reports appears to be temporally associated with the July 1997 label change for the oral dosage from a dose administration of 2.5 mg/kg bid to the flexible dose administration of 5-20 mg/kg as a single dose or two equally divided doses.
As a result of discussions with their ophthalmologists, a specific feline safety study was designed to assess any potential effects of Baytril on the eyesight of cats. This study was conducted with dosages both within and well above the label dose range.
Preliminary results suggests that the blindness problems are specifically related to higher doses of Baytril.
The dosage of Baytril given to a cat
must not exceed 5 mg/kg/day
The most severe observations of eyesight problems were in cats dosed at 50 mg/kg/day (2.5x the high-end of the approved dose range) and developed within one week.
No changes were observed in cats dosed at 5 mg/kg/day (the lower end of the approved dose range).
Bayer now strongly recommends that the dosage of Baytril given to a cat not exceed 5 mg/kg/day. Previously, the dosage had been thought to be safe at as high as 50 mg/kg/day.
Bayer is thoroughly documenting and monitoring all reported cases in order to collect as much salient information as possible. Please direct any questions about Baytril or any of the Bayer products to Bayer Veterinary Services, 800-422-9874.
No adverse effects were observed in cats that received 5 mg Baytril per kg body weight.
NOTE: The administration of doses of 20 mg/kg body weight or greater caused salivation, vomition and depression and additionally resulted in mild to severe fundic lesions on ophthalmologic examination, changes in electroretinograms (including blindness) and diffuse light microscopic alterations.
Baytril has been documented to interfere
Baytril has not been shown to be a problem in the growth
In contrast to cats there is no evidence that visual alterations can also occur in other species, e.g. dogs.