Mass-like lesions of the iris were evaluated in 15 horses or ponies of various ages and breeds. Breed or gender predilection was not found. These lesions were most often found in blue irides at the 12 o'clock region. Because the lesions transilluminated and changed shape rapidly with changes in pupillary size, they were hypothesized to be zones of iris hypoplasia. Histologic evaluation of one specimen supported this interpretation. The lesions were not associated with any other ocular or systemic abnormality.
Objective—To compare aesthesiometer-determined
corneal sensitivity between diabetic and nondiabetic
dogs and to investigate the correlation between
corneal sensitivity and duration of diabetes or status
of glycemic control, as estimated by use of glycated
blood protein concentrations.
Animals—23 diabetic and 29 nondiabetic normoglycemic
Procedure—A Cochet-Bonnet aesthesiometer was
used to measure corneal touch threshold (CTT) in 5
corneal regions of each dog. At the time of ocular
examination, duration of diabetes mellitus was estimated
from the history, and blood was drawn for
assessment of blood glycosylated hemoglobin and
serum fructosamine concentrations.
Results—Median CTT for central, nasal, dorsal, temporal,
and ventral corneal regions in nondiabetic dogs
(1.6, 2.3, 2.8, 2.8, and 5.1 g/mm2, respectively) was
significantly lower than in diabetic dogs (2.8, 4.0, 5.1,
5.1, and 6.6 g/mm2, respectively). Median regional
CTT in diabetic dogs was not significantly correlated
with estimated duration of diabetes mellitus or blood
glycated protein concentrations. No significant difference
was found in regional CTT between eyes of normoglycemic
dogs with unilateral cataracts.
Conclusion and Clinical Relevance—Diabetic dogs
have significantly reduced corneal sensitivity in all
regions, compared with nondiabetic normoglycemic
dogs. Regional variation in corneal sensitivity is similar
in diabetic and normoglycemic dogs. Neither
glycemic control nor duration of diabetes, as estimated,
is significantly correlated with corneal hyposensitivity.
Corneal nerve dysfunction may be associated
with recurrent or nonhealing ulcers in diabetic dogs
for which no other underlying cause can be found.
(Am J Vet Res 2003;64:7–11)