Avian Pox, sometimes referred to as Fowl Pox, often causes problems in exhibition, backyard and hobby poultry flocks. The pox virus is also capable of causing disease in almost any avian species including pigeons, wild birds, turkeys, ducks, quail, pheasant and all breeds of chickens. Infected birds exhibit poor growth, reduced egg production and weight loss. Pox can cause death in severely infected birds. While this disease was first reported in birds as early as the 17th century, it still remains a problem in many parts of the world today.
What is Avian Pox?
Avian pox is a viral disease that can occur in two forms: dry or skin (cutaneous) and the wet (or diphtheritic) form. Mortality is usually low (1%- 5%), however, severe cases of wet pox can result in much higher mortality.
The dry form of avian pox causes lesions (Figures 1- 4) on areas of the head, legs and body that contain no feathers. These lesions start as small blisters that become yellowish as they grow. The lesions then progress into wart-like nodules and later become dry scabs. At times, generalized lesions on the feathered skin may also be seen.
Figure 1. Pox lesions on a turkey become yellowish as they grow
Wet pox causes throat and upper respiratory tract lesions (Figure 5) that usually begin as white nodules and may become large patches that appear as yellow cheesy masses or growths. These growths can become severe enough to interfere with eating, drinking and breathing. The wet form of pox, when severe enough, is likely to cause death in infected avian species. Both forms of the disease can be observed in a flock, and occasionally a bird can be infected with both forms. Birds infected with either form of the disease will usually have a depressed appetite, some weight loss, and a drop in egg production. Infected young birds may have slower growth and poor feed conversion. Birds infected with the dry form usually recover in 2 to 4 weeks, but it can take several weeks to months for a flock to recover since the disease can spread slowly through the flock.