Congenital Ocular Abnormalities in Free-Ranging White-Tailed Deer

Abstract

Congenital ocular abnormalities in cervids have been previously reported as individual cases from various regions of the United States and include microphthalmia, anophthalmia, congenital cataracts, dermoids, and colobomata. A common underlying cause for these abnormalities, such as nutritional deficiencies, environmental toxin exposures, or genetic mutations, has not been established. This retrospective study summarized and compared cases of suspected congenital ocular abnormalities in free-ranging white-tailed deer ( Odocoileus virginianus) submitted to the Southeastern Cooperative Wildlife Disease Study (SCWDS) in Athens, Georgia, to the preexisting literature. Of 3645 accessions of white-tailed deer submitted to SCWDS, 15 qualifying case records were found. An additional 15 cases were reported previously in the literature. Conditions described in SCWDS cases included microphthalmia (8/15), congenital cataracts (3/15), anophthalmia (2/15), colobomata (1/15), anterior segment dysgenesis (1/15), ectopic lacrimal gland tissue (1/15), and congenital blindness with corneal opacity (1/15). Most (11/15; 73%) of the SCWDS cases were male fawns with an average age of 4 months at presentation, consistent with previously described cases. Most animals had bilateral abnormalities with few extraocular congenital abnormalities, also consistent with existing reports. Cases were variably tested for various infectious agents at the time of submission; 2 cases were seropositive for bluetongue virus. Spatiotemporal clustering of cases was not evident. This study provided a concise and systematic summary of known existing cases of congenital ocular defects in fawns but did not identify a cause.

Congenital Cataracts and Microphakia with Retinal Dysplasia and Optic Nerve Hypoplasia in a Calf

“…Differential diagnoses in ruminants or cattle, based on the described gross and histologic findings, should consist of epizootic hemorrhagic disease virus (EDV) and/or blue tongue virus (BTV), hypovitaminosis A, and underlying genetic abnormalities [ 23 ]. Ideally, a full postmortem examination of the carcass would have been performed to look for additional evidence of in utero BVDV infection (i.e., cleft palate, cerebellar hypoplasia, possible limb deformities, and perifollicular immunoreactivity to BVDV in the dermis).…”

Congenital cataract and spherophakia leading to starvation in a free-ranging muskox neonate from the Northwest Territories, Canada

“…Reports include a harbor seal ( Phoca vitulina richardsi ), a coyote ( Canis latrans ), and white-tailed deer ( Odocoileus virginianus ), with no identified cause. 4,7,10 Among domestic species related to muskoxen, congenital cataracts are best described in cattle and have been associated with multiparous dams, birth in warmer months, hypovitaminosis A, BVDV infection, inbreeding, and genetic mutations. 2,9,12–14 In an investigation of congenital cataracts in Ayrshire dairy cattle, the highest prevalence occurred in bull calves, which suggests the potential for X-linked inheritance.…”