BLINDNESS IN CANARIES

BLINDNESS IN CANARIES  Extracts from an article in the Hunter Bulletin.  Additional material from ‘Every bird’.

Over a period of about eighteen months I noticed a few of my birds were going blind. This occurred at first in a young cock bird and then later in a number of breeding hens who were losing young in the nest. The initial observation showed a grey speck occurring in the eye of the affected bird, first in one eye then sometimes in the other eventually leading to total blindness.

A local veterinarian was asked to help. The birds were initially treated using the usual antibiotic creams and ointments without any response. He then decided more specimens should be sent off to a research laboratory. After many months little progress had been made. A New Zealand expert was consulted and it eventuated that it was some form of protozoal infection. Finally a further examination of tissue indicated a protozoal infection of the eye, choroid/retina and lens. Electron microscopic examination of these organisms revealed they were of the apidomplesus type, i.e. toxoplasma-like. These results were followed up with blood tests of myself and my wife revealing that at some time we had contracted toxoplasmosis.

Toxoplasmosis is a relative common occurrence in humans and animals and it is estimated that in the United States more than one quarter of the population has been exposed to this infection. The infection can be caught by eating raw or undercooked beef, or through contact with cat excreta. It is particularly dangerous to pregnant women causing birth defects and blindness in unborn children, the parasite can also cause lesions in the eyes of cats.

The parasite was thought to have been contacted by our canaries after eating greens from our garden which had been in contact with either cat faeces or urine. Our family cats were also blood tested but at the time of writing no results had been received.

The parasite can travel through the body of the bird forming a cyst within the brain. This can initially cause loss of balance and sudden blindness. An autopsy of the brain would be hit and miss and may not even detect anything. Always were rubber gloves when handling a bird that has died from unknown causes.

Lead poisoning can also show similar signs as toxoplasmosis. Loss of balance, diarrhoea, and sudden death. Canaries are very sensitive to even low levels of lead, and if you have a bird with the above symptoms, then it is more likely to be lead poisoning than toxoplasmosis. Paints produced several years ago contained lead and parts of their cage may be painted with this old paint. Lead is also contained in solder which is used in the manufacture of a lot of equipment such as cage fronts, seed hoppers, hang-on baths to name a few.

 Canaries are curious creatures, and to avoid boredom, they will often resort to chewing on the broken edge of a cage divider or something similar and so pick up lead.

If you are having problems check your cages, sanding and repainting the item using a modern non-toxic paint. Soldered joints should be cleaned of any loose material and painted over with the same non-toxic paint.

Common sense is the main requirement and all greens from the garden must be washed, especially if you or the neighbours have cats. Greens can be rinsed in a 1:100 solution of common bleach and water (10ml to 1ltr of water) for 10 minutes. This will prevent many nasties on green food being transferred to your birds.