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This article was published in 1981
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Blindness in Pigs Attributed to Hygromycin B
(A Case Report)
Peter Green, B.V.Sc., Veterinary Inspector, Dubbo
Whilst I was visiting a piggery in October 1980 on another disease matter, the owner mentioned that a large proportion of his sows were blind.
The piggery in question runs approximately 110 sows. They are mainly Large White or Landrace and Crossbreds with some Berkshires. Before farrowing the sows are placed in individual stalls and are kept there until the piglets are weaned. The sows then go into the dry sow mob and are re-mated. The young pigs are generally sold as baconers.
The general feed mixture consists of 90% wheat and barley 10% meat meal with 'Tylan 20', 'Hydromix' plus a mineral and vitamin supplement. The housing of the pigs and management is well above average for our area.
On inspection of the pigs I found at least 30% of the sows showed obvious ocular lesions. None of the grower pigs showed any such lesions but the owner told me that an occasional boar had gone blind. The lesions generally first became obvious as a small 'Milky' spot which then spread until the whole lens was involved. The lesions were usually bilateral. Some of the sows appeared to be totally blind but seemed to be otherwise healthy. They farrowed normally and reared their piglets. The owner said that they were only a bother when taken to a strange area to load when being sent for slaughter.
In 1978 Sanford and Dukes in Canada reported the occurrence of widespread cataracts in sows on several farms. They eliminated hereditary, nutritional and environmental factors as well as infectious diseases. The only common factor appeared to be the feeding of hygromycin B.
The owner in my area, considers that ocular lesions appear about six months after first treating his sows for worms with hygromycin B at the manufacturer's recommended rate and regimen. As the mixed feed is held in bulk bins there would be times when the additive would be fed for somewhat longer periods than is recommended.
References
Sanford S.E., D.V.M. and Dukes T.W., M.S. D.V.M. J.A.V.M.A., Vol 173 No. 7, October 1, 1978 Pages 852-853