Clinical features and outcomes of phacoemulsification in 39 horses: a retrospective study (1993-2003)

OBJECTIVE: To identify visual outcome and postoperative complications following phacoemulsification of equine cataracts. ANIMALS: Records of 39 horses (55 eyes) with cataracts were reviewed. METHODS: Eyes with cataracts removed by phacoemulsification were included in the study. Data collected included age, breed, sex, stage and etiology of cataract, unilateral vs. bilateral involvement, and ultrasound findings. Horses were grouped by etiology of the cataract. Visual outcome and complications were evaluated for each group and the overall population. RESULTS: Immediately postoperatively 46 out of 47 eyes (98%) were sighted. Four weeks postoperatively 23 of 29 operated eyes (79%) were sighted [13/18 (72%) eyes with congenital/juvenile onset, 6/6 (100%) eyes with traumatic and 4/5 (90%) eyes with uveitis-induced cataracts], with 18 eyes lost to follow-up. The most common postoperative complications included corneal edema (19 eyes/40%), fibrin in the anterior chamber (11 eyes/23%), postoperative ocular hypertension (9 eyes/19%), synechia/dyscoria (9 eyes/19%), and hyphema (7 eyes/15%). CONCLUSIONS: Prognosis for vision is favorable for horses following phacoemulsification and planned posterior continuous tear circular capsulorrhexis. Success rates depend on age of patient, cause of cataract and pre-existing intraocular disease. The highest success rate occurred in eyes with traumatic cataracts.     

Comparison of a low carbohydrate-low fiber diet and a moderate carbohydrate-high fiber diet in the management of feline diabetes mellitus

This study compared the effects of a moderate carbohydrate-high fiber (MC-HF) food and a low carbohydrate-low fiber (LC-LF) food on glycemic control in cats with diabetes mellitus. Sixty-three diabetic cats (48 male castrated, 15 female spayed) were randomly assigned to be fed either a canned MC-HF (n = 32) food or a canned LC-LF (n = 31) food for 16 weeks. Owners were blinded to the type of diet fed. CBC, urinalysis, serum chemistry panel, fructosamine concentration and thyroxine concentration were determined on initial examination, and a complete blood count, serum chemistry panel, urinalysis and serum fructosamine concentration were repeated every 4 weeks for 16 weeks. Insulin doses were adjusted as needed to resolve clinical signs and lower serum fructosamine concentrations. Serum glucose (P = 0.0001) and fructosamine (P = 0.0001) concentrations significantly decreased from week 0 to week 16 in both dietary groups. By week 16, significantly more of the cats fed the LC-LF food (68%, 22/31), compared to the cats fed the MC-HF food (41%, 13/32), had reverted to a non-insulin-dependent state (P = 0.03). Cats in both groups were successfully taken off of insulin regardless of age, sex, type of insulin administered or duration of clinical disease before entering the study. There was no significant difference in the initial or final mean body weights or in the mean change in body weight from week 0 to week 16 between dietary groups. Diabetic cats in this study were significantly more likely to revert to a non-insulin-dependent state when fed the canned LC-LF food versus the MC-HF food.     

Diagnosis of congenital and adult-onset hypothyroidism in cats

Whereas hyperthyroidism is the most common endocrine disorder in the cat, hypothyroidism is the least common feline endocrine disorder. This is a the result of several factors including low index of suspicion, rarity of the naturally occurring hypothyroidism in cats, and a lack of species specific tests for endogenous TSH and antithyroglobulin antibodies. Nonetheless, hypothyroidism does occur in cats, especially in kittens and after radioactive treatment for hyperthyroidism. The clinician should become familiar with the common presentations of congenital and adult-onset hypothyroidism in cats. In addition, some of the tests specific to dogs (such as endogenous canine TSH) may be utilized to diagnose subclinical hypothyroidism in cats. Fortunately, the treatment of feline hypothyroidism with synthetic levothyroxine is both straightforward and effective.     

Alfaxalone alone or combined with midazolam or ketamine in dogs: intubation dose and select physiologic effects

Objective

To determine the intubation dose and select physiologic effects of alfaxalone alone or in combination with midazolam or ketamine in dogs.

Homology modelling of Drosophila cytochrome P450 enzymes associated with insecticide resistance

BACKGROUND: Overexpression of the cytochrome P450 gene Cyp6g1 confers resistance against DDT and a broad range of other insecticides in Drosophila melanogaster Meig. In the absence of crystal structures of CYP6G1 or complexes with its substrates, structural studies rely on homology modelling and ligand docking to understand P450–substrate interactions. RESULTS: Homology models are presented for CYP6G1, a P450 associated with resistance to DDT and neonicotinoids, and two other enzymes associated with insecticide resistance in D. melanogaster, CYP12D1 and CYP6A2. The models are based on a template of the X‐ray structure of the phylogenetically related human CYP3A4, which is known for its broad substrate specificity. The model of CYP6G1 has a much smaller active site cavity than the template. The cavity is also ‘V’‐shaped and is lined with hydrophobic residues, showing high shape and chemical complementarity with the molecular characteristics of DDT. Comparison of the DDT–CYP6G1 complex and a non‐resistant CYP6A2 homology model implies that tight‐fit recognition of this insecticide is important in CYP6G1. The active site can accommodate differently shaped substrates ranging from imidacloprid to malathion but not the pyrethroids permethrin and cyfluthrin. CONCLUSION: The CYP6G1, CYP12D1 and CYP6A2 homology models can provide a structural insight into insecticide resistance in flies overexpressing P450 enzymes with broad substrate specificities. Copyright © 2010 Society of Chemical Industry