EFFECTS OF EXPERIMENTALLY-INDUCED HYPOTHYROIDISM ON THE EYE AND OCULAR ADNEXA OF DOGS

Citation
Pe. Miller et Dl. Panciera, EFFECTS OF EXPERIMENTALLY-INDUCED HYPOTHYROIDISM ON THE EYE AND OCULAR ADNEXA OF DOGS, American journal of veterinary research, 55(5), 1994, pp. 692-697
Citations number
24
Categorie Soggetti
Veterinary Sciences
ISSN journal
00029645
Volume
55
Issue
5
Year of publication
1994
Pages
692 - 697
Database
ISI
SICI code
0002-9645(1994)55:5<692:EOEHOT>2.0.ZU;2-8
Abstract
Schirmer tear test (STT), intraocular pressure (IOD) measurement, slit -lamp biomicroscopy, and indirect ophthalmoscopy were performed on 8 d ogs with I-131-induced hypothyroidism and 4 euthyroid control dogs at weeks 0, 9, 13, 17, immediately prior to treatment with levothyroxine, after 5 weeks of levothyroxine administration (0.022 mg/kg of body we ight, PO, q 12 h), and at euthanasia 7 weeks after discontinuation of replacement therapy. Although the control group had higher baseline ST T values than the hypothyroid group after randomization of dogs into t he 2 groups (P < 0.01), STT values remained unchanged from their respe ctive baseline values at all time intervals for both groups. Hypothyro id and control dogs had significant (P < 0.05) reduction in IOP from b aseline values at all subsequent time points, but differences were not observed when hypothroid dogs were compared with controls. Goblet cel l indices determined from biopsy samples of the inferior-nasal conjunc tival fornix obtained before induction of hypothyroidism (baseline), i mmediately prior to and at conclusion of levothyroxine therapy, and at euthanasia were not significantly different when values for hypothyro id dogs were compared with their own baseline values or with values fo r control dogs. Histologic examination of the globes and adnexa at eut hanasia also failed to indicate consistent qualitative differences bet ween hypothyroid and control dogs. Marked reduction in serum thyroid h ormone concentrations had little effect on the eye and ocular adnexa o ver the course of the study.