Blindness due to eye abnormalities in piglets, a case report

Manon Houben, Lucía Dieste Pérez, Karlijn Eenink, Naomi de Bruijn Royal GD, Pig Health department, Deventer, The Netherlands

Introduction

Occasionally blind pigs can be found in pig herds, but normally blindness and/or eye abnormalities are not a herd problem. Ocular blindness can be caused by keratitis, uveitis or anatomic abnormalities.

Materials and Methods

Clinical signs:

In a 350 sow farrow to finish herd approximately five percent of weaned piglets in three or four weekly batches showed signs of blindness, without neurological disorders.

Clinical examination of affected animals revealed:

- glaucoma, - opacity of the cornea

- or microphthalmia

Pathophysiological ocular blindness can be caused by: - keratitis, - uveitis - or anatomic abnormalities.

The primary cause of these changes can be: - traumatic, - infectious - or nutritional.

Because sows which produced these piglets were fed a lactation feed with tenfold overdose of vitamin D, this vitamin D overdose was expected to cause the problems in these animals. An excess of vitamin D can cause abnormally high blood concentrations of calcium, which can result in calcification of soft tissues, heart and kidneys and calcification of the eyes, resulting in glaucoma.

Diagnostics

Unfortunately only blood samples were taken of acutely affected animals, no necropsies were performed. At the slaughterhouse, three blind pigs were collected for post mortem examination.

Results

Normal levels of calcium and APP and acute phase proteins were found in 10 week old pigs with typical clinical signs. Mean serum level of vitamin D was 158 nmol/Liter, which is within the normal range but much higher than expected. Post-mortem examination, three months later, revealed microphthalmia without depositions of minerals in de eyes. No microscopic alterations of the conjunctiva, nictitating membrane and other tissues around the eyes were seen.

Conclusion

Based on the sudden onset and cease of the clinical problems, an unproven association with the vitamin D overdose in the lactation feed is suspected in this herd.

Picture 1: macroscopic lesions of an affected pig. The eye is enlarged and rotated within the eye socket.

Picture 2: microphtalmia in a pig of approximately 10 weeks old.