Comparison of serum and plasma taurine values in Bengal tigers with values in taurine-sufficient and -deficient domestic cats.

A white Bengal tiger was determined to have a central retinal lesion and a central visual defect. Because of the known association between feline central retinal degeneration (CRD) and taurine deficiency in domestic cats, plasma concentrations of taurine were measured in this tiger. Serum concentrations of taurine, methionine, and cystine also were measured in white Bengal tigers, orange Bengal tigers, taurine-sufficient domestic cats, and taurine-deprived and tissue-taurine-depleted visually impaired cats with CRD. Hepatic and brain enzymes responsible for taurine synthesis were identified in tissue specimens from an orange Bengal tiger. Serum taurine concentrations were lower in white vs orange tigers, but were not as low as those in cats with CRD. Thus, we concluded that taurine depletion did not account for the central retinal lesion in the white Bengal tiger.

Ligneous conjunctivitis in four Doberman pinschers.

Ligneous conjunctivitis (LC) was diagnosed in four unrelated Doberman pinschers. Thick, opaque membranes of the palpebral conjunctivae and nictitating membranes were present bilaterally. Three dogs had concurrent signs of multisystemic disease. A thick, amorphous, eosinophilic, hyaline-like material in the substantia propria of the conjunctiva--containing a moderate, mononuclear cell infiltrate--was evident on histological examination. A predominance of T lymphocytes, few macrophages, and weak positive staining for immunoglobulin G (IgG) and immunoglobulin A (IgA) were evident by immunohistochemical staining. The clinical and histological appearance of LC in Doberman pinschers and humans is similar.

Enrofloxacin-associated retinal degeneration in cats.

OBJECTIVE: The objective of this study was to evaluate the possible relationship between the administration of parenteral and/or oral [corrected] enrofloxacin and the onset of acute retinal degeneration in cats. The animals studied included 17 cats that received systemic enrofloxacin and developed retinal degeneration soon thereafter. PROCEDURES: In this retrospective clinical study, cats that received parenteral and/or oral [corrected] enrofloxacin and developed acute blindness were identified. Parameters recorded included breed, age, sex, enrofloxacin dosage (daily dose and number of days administered), medical condition for which the antibiotic had been prescribed, ophthalmic signs, examination results, and the visual outcome. Fundus photographs were obtained in seven cats, and electroretinography was performed in five cats. Histopathology was performed on two eyes from one cat (case 1) that received enrofloxacin 5 months previously and developed retinal degeneration. RESULTS: All cats were the domestic shorthair breed; seven were females (one neutered) and ten were males (seven castrated). Ages ranged from 3 to 16 years old (mean +/- SD; 8.8 +/- 4.6 years). The medical disorders for which enrofloxacin was administered ranged from lymphoma and pancreatitis to otitis and dermatitis, and eight cats had urinary diseases. The daily and total dosage of enrofloxacin and number of days of administration were also highly variable. Presenting clinical signs were most often mydriasis and acute blindness. All cats had diffuse retinal degeneration as evidenced by increased tapetal reflectivity and retinal vascular attenuation. Absence of recordable electroretinographic responses suggested diffuse and extensive outer retinal disease. Vision returned in a few cats, but the retinal degeneration persisted or even progressed. Histopathology of two eyes revealed primarily outer retinal degeneration, with diffuse loss of the outer nuclear and photoreceptor layers, and hypertrophy and proliferation of the retinal pigment epithelium. CONCLUSION: Parenteral and/or oral [corrected] enrofloxacin is potentially retinotoxic in some cats, and may result in acute and diffuse retinal degeneration. Blindness often results, but some cats may regain vision. Practitioners should adhere closely to the manufacturer's current enrofloxacin dosage recommendation (5 mg/kg q 24 h), and continue clinical observations for this drug toxicity in cats.