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The Premier Online Magazine
devoted to Persian & Exotic Shorthair Cats

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The Premier Online Magazine devoted
to Persian & Exotic Shorthair Cats

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Baytril Warning

Baytril is a popular and potent antibiotic used to fight bacterial infections in cats and dogs. 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, 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 suggested that the blindness problems are specifically related to higher doses of Baytril.

  • No adverse effects were observed in cats that received 5 mg Baytril per kg body weight.
  • 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.
  • Eye problems included mild to severe fundic lesions on ophthalmologic examination, changes in electroretinograms (including blindness) and diffuse light microscopic alterations.
  • The administration of doses of 20 mg/kg body weight or greater caused salivation, vomiting and depression.

Bayer 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.

The dosage of Baytril given to a cat MUST NOT EXCEED 5 mg/kg/day

Baytril has been documented to interfere with the long bone grown in PUPPIES of large breeds of dogs.

Baytril has NOT BEEN SHOWN to be a problem in the growth of kittens,
so Baytril is safe to use on young kittens at the proper dosages.

In contrast to cats there is no evidence that visual alterations can also occur in other species, e.g. dogs.

Final Words

  • Baytril is a “big gun” antibiotic that is effective against serious bacterial infections in cats.
  • When using Baytril it is important not to over-dose your cat because of the risk of damaging its vision.
  • The maximum dosage of Baytril must not exceed 5 mg/kg/day.
  • Baytril is safe to use with young kittens.

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