Viruses common cause disease in canaries, just like they do in other birds and animals. This particularly so when large numbers are confined in a small area, such as a bird room.

The practice of swapping canaries between aviaries is very common, it can also lead to virus disease outbreaks if a carrier is introduced to a susceptible group. Many of these viruses are carried in birds that look perfectly normal but are shedding the virus in droppings, respiratory secretions, skin and feather dust.

Viral Disease of Canaries:

1 - Pox Virus ( avipoxvirus ). This infection is the most common and well known of the viruses that affect canaries. There are two forms of the pox virus - the skin form and the wet form ( or septicaemic form ). The wet form will cause high death rates as it attacks the windpipe ( trachea ) and the lungs. All age birds can be infected and 20 - 100% of infected birds may die. The most alarming clinical signs are forced respiration, weight loss and death.

The infection is introduced by insects and transmitted directly via the sores and indirectly via the food and water.

Diagnosis is not difficult, particularly in the skin form, treatment of the skin form is only necessary if the bird is having difficulty eating. In the wet form of the disease treatments are not very successful, and rely on keeping the bird alive long enough for it to fight off the virus.

2 - Herpesvirus Outbreaks of a disease causing conjunctivitis and respiratory distress with a high death rate ( 70% ) have been reported. Virus particles can be seen in tissues taken from the eyelids, windpipe and oesophagus.

As yet no known therapy or prevention is available.

In the case of outbreaks strict hygiene and quarantine must be applied to prevent further spread of the disease.

3 - Polyomavirus - Polyoma and papova like viruses have been seen in canary and finch aviaries across Australia and the US. The disease is probably more common than reports would suggest. The disease causes mortalities of nestlings and a chronic disease in older birds where poor development and beak abnormalities are seen. Most cases are complicated by secondary disease ( which are the easiest to diagnose ).

The most common sign on post mortem is an enlarged liver. Unfortunately enlarged livers are common in many bird diseases.

4 - Adenovirus - this has been reported overseas where it caused significant deaths in juvenile canaries which showed nervous signs before death. The virus was found in the blood vessels of the brain. Interestingly these outbreaks have been associated with severe megabacteria infections.

5 - Coronavirus - a newly recognised virus seen in overseas canary populations, all birds were adults up to 3 years old. At present we are unsure if the disease is in Australia.

The disease presented as skin and feather abnormalities, minor respiratory signs and only a few deaths. At post mortem ( after euthanasia ) the birds were in good condition. The feathers were malformed with blood pins present. The virus was found in tissues from the windpipe, lungs and skin. Again megabacteria were found in the proventriculus of most birds tested.

The presence of a series of viruses that circulate in the canary population, reinforce the need for quarantine procedures in aviaries. Any one of these diseases could decimate a canary population - and there is no treatment!