Experiments conformed to the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research. Dogs were 9-month-old male beagles (Marshall Farms USA Inc., North Rose, NY) individually housed in 0.9 × 2.7-m runs and fed a daily diet (Bioserve, Frenchtown, NJ) consisting of approximately 450 g of standard dog chow containing either 30% nonnutrient fiber or 30% galactose, as previously described.
15 Ten dogs received the control diet containing 30% fiber, and 50 dogs received the galactose diet. After 24 months, the galactose was removed from the diets of 15 randomly selected dogs in the galactose-fed group and at 31 months from the diets of an additional 15 randomly selected dogs in the galactose-fed group.
Enucleations in any given period were limited to one eye of each dog, so that all eyes in each group at the specified time points were from separate animals. In each group, dogs with two eyes underwent enucleation first, followed by dogs with one eye. All dogs were killed after the second enucleation. Based on this criterion, dogs were randomly selected for enucleation as follows: control group: two eyes at 24 months and three eyes at 30, 36, 42, 48, 55, and 60 months; galactose-fed group: two eyes at 24 months, five eyes at 30 and 36 months, six eyes at 42, 48, and 55 months, and three eyes at 60 months; 24-month reversal group: four eyes at 24 months, five eyes at 30 and 36 months, and four eyes at 42, 48, 55, and 60 months; and the 31-month reversal group: five eyes at 24, 30, 36, 42, 48, 55, and 60 months. Baseline data for the 31-month reversal group were obtained at the 30-month enucleation period, 1 month before removal of galactose from the diet.
Clinical blood chemistry profiles, conducted at 3-month intervals, included determinations of complete blood counts with differential, serum T3, thyroxine (T4), glucose, serum urea nitrogen, creatinine, sodium, potassium, chloride, calcium, phosphorus, uric acid, total proteins, albumin, globulin, aspartate aminotransferase, alanine aminotransferase, γ-glutamyl transferase, alkaline phosphatase, lactate dehydrogenase, total bilirubin, direct bilirubin, triglycerides, cholesterol, and glycosylated hemoglobin. Hb A1C levels were obtained by the high-pressure liquid chromatography (HPLC) method at 3-month intervals. All tests were conducted by Maryland MedPath (Rockville, MD). No significant abnormalities in blood chemistry profiles were observed.