Recognise and prevent fowl pox 

Fowl pox is a viral infection that is common in chickens. Although it sounds a bit like chicken pox, fowl pox is not transmissible to humans, so you can't catch it from your flock. 

Although the severity of infection varies, chickens recover easily from the milder forms of fowl pox.

How to recognise fowl pox in chickens – signs and symptoms of fowl pox

There are two main forms of fowl pox that occur in chickens. Chickens can have both forms of the disease at once and outbreaks in a flock may not be limited to one form. Because fowl pox is often transmitted by mosquitoes, outbreaks are more common in the warmer months but can occur at any time. Chickens of any age can catch this disease.

Symptoms of both forms of fowl pox include: 

• A decrease in egg production
• Poor growth or weight gain 
• A loss of appetite

The milder form of fowl pox is referred to as the dry form. Dry fowl pox:

• Affects featherless areas such as the wattles, comb, eyes, face and, sometimes, the feet
• Causes dry, crusty scabs on featherless areas
• Scabs usually start out as blisters, before turning yellow and then brown or black
• Can look like warts or skin growths
• Occasionally causes lesions can occur on feathered skin too, but this is uncommon

It is important not to confuse the dry form of fowl pox with scabs or scars caused by pecking or fighting, with frostbite or with scaly leg mites.

The more severe form of fowl pox is known as wet fowl pox. Wet fowl pox:

• Affects the mouth and throat, including the windpipe
• Causes lesions in the mouth and throat that look like infected ulcers
• Can prevent eating and drinking, or cause obstructions that interfere with breathing, in severe cases
• Has a high mortality rate in chickens 

It is important not to confuse wet fowl pox with thrush, which causes white or cream patches in the mouth

Chickens usually recover from fowl pox, particularly the dry form, within 2-3 weeks. Although most birds seem to develop immunity to the disease after having it, some chickens will have reoccurrences of fowl pox symptoms in times of stress. This suggests that even healthy birds without symptoms can potentially carry the disease.

How do chickens get fowl pox?

Fowl pox can be transmitted in two ways: by mosquitoes and by infected chickens.

Fowl pox is most often transmitted by mosquitoes. This spreads the disease between chicken coops and properties. A mosquito that has bitten an infected chicken can carry fowl pox in its saliva for 8 weeks.

Fowl pox can also be spread by infected chickens. Chickens with fowl pox shed the disease in their feathers, dander, saliva, blood and scabs. Because dander is almost impossible to avoid, the disease spreads easily between birds. It can also remain in the environment for years. In order to become infected, chickens must inhale or eat infected material, or have it come into contact with a skin wound.

Symptoms of fowl pox usually appear 10 to 14 days after infection.

How to prevent fowl pox in chickens

In areas where fowl pox is common, it is difficult to prevent. But there are a few things that you can do to protect your birds:

• Even healthy chickens can carry fowl pox, so always quarantine new birds. 
• Vaccinate your chickens if you live in an area where fowl pox is common. Vaccination is usually performed on chicks, although a yearly booster may also be recommended. Consult with your veterinarian.
• If there is an outbreak, quarantine sick birds immediately, with mosquito netting, and vaccinate unaffected members of the flock. Also clean and disinfect the coop, and sanitise the drinking water with iodine (1 teaspoon of 1 % iodine per gallon of drinking water).
• In warmer areas, screen the coop to prevent mosquitoes and close chickens in early, as mosquitoes are most active at dawn, dusk and in the evening.
• Prevent mosquitoes from breeding by removing sources of standing water.

How to treat fowl pox in chickens

Unfortunately, there is no treatment for birds infected with fowl pox. However, there are some measures that lessen the severity of the disease and improve recovery. These include:

• Treating dry form lesions with Vetericyn, iodine or another antiseptic to prevent infection and promote healing
• Providing antibiotics in the drinking water to prevent secondary infection in sick birds, in particular in birds affected by the wet form of the disease
• Treating drinking water with iodine at a rate of 1 teaspoon of 1 % iodine solution per gallon of drinking water can also promote recovery, in particular from the wet form of the disease

Happy chicken keeping!

Rachael at Dine a Chook