Attention: SmallpoxCanary pox has been occurring more frequently again in breeding stock for some years and often causes high losses. An overview of special features. prophylaxis of this serious disease.
Table of contents
– The pathogen – The spread – The symptoms – Measures for prophylaxis – Three questions to bird specialist Dietmar Steinmetz
From Dr. med. vet. Simone Bellair
Smallpox diseases occur in humans, mammals and birds. Human smallpox is considered eradicated worldwide. This was also hoped for canary pox. In the last few years, however, outbreaks in herds have increased again. The death rate in the affected herds is often high. Involves major financial losses in addition to animal losses. Since there is no specific therapy for sick animals, effective prophylactic measures are the best protection.
Canary pox (synonym: snap disease, diphtheria) occurs worldwide and is caused by the canary pox virus (Avipox serinae). Other birds of the order Passeriformes can also become infected, e.g., canary pox. B. Sparrows. Finch birds. Sparrows and finches. Poxviruses have a very high species specificity, a transmission from birds to humans or to other mammals and vice versa is therefore excluded. Even different bird species are infected only by specific avipox virus types.
Transmission occurs through contact with infected birds or indirectly through dust, drinking water, feed, as well as animate vectors (e.g. B. breeders and veterinarians). Spread is also possible through symptomless permanent carriers. Purchases from pet stores, pet fairs and after exhibitions pose a particular danger. Also bloodsucking ectoparasites. Insects spread the smallpox virus. The disease therefore often occurs in summer or early autumn. Can affect animals of all ages.
The virus is extremely resistant in the environment, special disinfection measures to kill it are necessary.
There are three clinical courses that can occur in parallel in a flock:
Peracute course: sudden deaths without conspicuous organ changes.
Skin form: Yellowish crusty changes in the corners of the beak, on the nose and eyelids, under the lower beak, on the feet and legs, and on the feather follicles ("pox"). Fallen crusts are contagious for months. Acute courses with respiratory distress as well as alopecia with nodular skin growths in the head and neck area have also been described.
Diphtheroid and pulmonary form (mucosal form): severely reddened, inflamed pharyngeal mucosa covered with yellow, diphtheroid deposits. Acute to peracute course: birds show respiratory distress gasping for breath. Often associated with conjunctivitis, blepharitis and rhinitis. Within two to three days 80 % of a group of canaries can die.
A therapy of the virus infection is not possible. Currently, no commercially licensed vaccine against canary pox is available in Germany either. Prophylactic measures are therefore of great importance: Exhibition animals or new acquisitions should be examined by a veterinarian. Suspicious animals must be kept spatially separated from the rest of the stock (selection). Feeding and care of sick birds should, of course, only take place after the healthy birds have been cared for. Protection against stinging insects. Ectoparasites also reduce the risk of infection.
Three questions for bird specialist Dietmar Steinmetz
Why is canary pox on the increase again?? The disease progresses in waves. Occurs more frequently every few years. Climate change has also increased the activity of biting insects that transmit the virus. Mosquitoes and the red bird mite, for example, serve as virus reservoirs. In certain areas, the disease is therefore endemic (e.g. B. River lowlands, Rhine-Main area, Danube valley). Increased travel by breeders, but also flight activities of affected wild birds such as bullfinches, siskins and chaffinches between Central and Southern Europe, contribute to the spread of the virus.
What makes canary pox so dangerous?
Steinmetz: In the mucosal form that affects the throat and airways, the birds die peracutely to acutely: the animals show high-grade respiratory distress with gasping and simply fall off the perch. With the skin form whole toes can die off. From own experience there are more and more transitional forms, e.g. the tarsal joint can be affected. The birds then have reddened limbs. Spare the affected leg. If symptomatic treatment of these animals is not successful, they should be euthanized for animal welfare reasons. In mixed populations, bird species that do not themselves become ill can serve as vectors, z. B. Gouldamadines.
How to prevent a stock infection?
Stonecutter: Very critical is effective insect protection (fly screens). A thorough purchase exam by a veterinarian is important when making acquisitions. Personal movement in a herd should be minimized to eliminate this route of transmission. In summer, when the disease is more frequent and the birds are weakened by the change of feathers, optimal nutrition and care are of great importance.
The gold standard for prophylaxis would be to vaccinate the entire population, but unfortunately no vaccine is currently licensed in Germany. Veterinarians would have to import the vaccine from neighboring European countries via exemption under Section 11(6) of the Animal Health Act through an application to the appropriate state supreme authority. This is usually too time-consuming and expensive for the individual flocks.
As a specialist journalist, Simone Bellair researches and writes about current topics related to veterinary medicine. The veterinarian, who holds a doctorate, also oversees the technical articles in our journal Der Praktische Tierarzt.