Backyard Chickens / Health

The Real Chicken Pox

Chickens get chicken pox, too

Not surprisingly, chickens get chicken pox too. Except in their case, it’s called fowl pox and like the human version, it’s a contagious viral disease with no cure and no treatment, other than trying to keep morale up.

Chickens in molt

Both of my chickens are in the middle of their molts, so I didn’t think too much of it when they started foraging less, playing less, and laying less (until the eggs ceased completely two weeks ago).

Molting chicken

A molt takes a lot out of a chicken and my poor Kimora is going through a pretty rough patch this year. She’s dropping feathers much more heavily than she did last year, and the only thing that will get her to run and jump is a handful of dried mealworms (which I’ve been giving more often, as well as black oil sunflower seeds and scrambled eggs). Otherwise, she spends the day lounging in the sun, partaking in the occasional dust bath, waiting for me to bring more treats. She is not a happy camper right now.

Molting chicken

A couple weeks ago, I noticed little black bumps of what looked like dried-up blood on her comb and dismissed them as battle wounds from possible pecking. She was quiet and lethargic, but I attributed it to a very hard molt. She had also stopped laying, which didn’t seem unusual considering the season, though last year she would still lay an egg or two a week through the dark days of winter.

Healing dry pox scabs

Healing dry pox scabs

I noticed her scabs were starting to heal last week, becoming less prominent, and she seemed to regain her energy a bit. But… I also noticed that Iman was getting those same bumps on her comb! The warty-looking nodules started appearing around the same time Kimora’s were clearing.

Lesions caused by fowl pox

Lesions caused by fowl pox

Unfortunately for Iman, her case of fowl pox seems much more intense. In a span of just three days, the bumps had multiplied and become larger in size. The first ones are starting to crust and scab over, leaving black bumps on her comb, wattle, ear, and face. She’s moodier and lazier, though she’ll still skip up to me when she hears the “special door” on the coop opening… you know, the door where yummy treats magically fall out.

Aside from the heavy molting and scabby pox (poor girls just can’t catch a break this season!), both chickens seem to be in decent health and average spirits… as much as a couple of sick chickens can be healthy and spirited, that is.

Fowl pox runs its course in two to four weeks and the best treatment is to let it do its thing. You can dab some iodine on the lesions to make them dry up faster, but I’ve found that they scab pretty readily. Once the fowl pox has fully cleared, infected birds get partial immunity from the same viral strain (just like humans do). They usually won’t get fowl pox again, but if they do, subsequent cases are likely to be less severe.

My only worry is secondary infection, when lesions appear inside the mouth and the respiratory tract, affecting the esophagus, pharynx, larynx, and trachea. This type of infection is called wet pox, or diphtheritic fowl pox. Advanced wet pox can interfere with feeding or breathing as the lesions become enlarged, blocking the airways.

My chickens have dry pox, or cutaneous fowl pox. These round, raised lesions (usually with dark scabby centers) only appear on areas of the body with no feathers, generally the comb, wattle, face, or feet. Dry pox is a nuisance, but rarely fatal. Neither forms of fowl pox are contagious to humans or other animals.

The virus is transmitted by mosquitoes, but can sometimes pass from bird to bird by mites or lice. Once a chicken is bitten by a mosquito carrying the virus, it’s almost certain that the rest of the flock will be infected as well. This usually happens if a mosquito continues to bite the other chickens, or if the infected chicken drinks from a water fountain and backwashes the virus into it. Other chickens then pick up the virus by drinking from the same water.

Infected chickens also drop infected feces, so the virus can enter a food or water source that’s been contaminated by droppings. This includes the droppings from pigeons, sparrows, and other wild birds that may be infected, as they all carry related strains of the pox virus.

Fowl pox virus can survive in the environment for at least a year (through dander or dried scabs that have fallen off). It’s a resistant and slow-moving virus, infecting an entire flock over a period of a month or more. Just as you think your chickens are getting well, others start to show symptoms. They’ll slow or stop their egg laying, become lethargic, probably eat less… but they’ll always have those telltale warty bumps.

While there’s no real treatment for fowl pox, you can try to prevent reinfection by cleaning and changing out the water supply every day; removing and replacing the bedding; disinfecting nests, roosts, and other places where your chickens spend a lot of time; and generally keeping the surroundings neat and sanitary. Eliminate any standing water, and pay special attention after a rain for puddles that mosquitoes might be breeding in.

I always add a little food-grade diatomaceous earth to the sand in their run (raking it in evenly), as well as dust the nests and pine shavings with it. Diatomaceous earth (also known simply as DE) controls mites and lice by drying out their exoskeletons as they scratch their way through the fine powder (made from the crushed-up fossils of hard-shelled algae).

DE is a cheap and easy preventative measure that any chicken-keeper should take, even without signs of infestation. Make sure you use food-grade DE — usually found in garden nurseries or feed stores — and not the DE intended for swimming pools.

Prevention of fowl pox comes in the form of a live virus vaccine. You can ask an avian vet for it, or purchase the vaccine from a poultry supplier and administer it yourself. Only healthy birds should be vaccinated, and birds that have already gone through fowl pox will not need the vaccination as they’ll develop immunity from it. The Merck Veterinary Manual offers more information about fowl pox (which also affects turkeys).

As for my girls, Kimora seems to be healing well and I hope she’ll recover fully in another week or so (and maybe even start laying again… fingers crossed). Iman might have another couple weeks to go with her dry pox, but so far the lesions don’t seem to be bothering her, despite one being very close to her eye.

I’m not doing anything out of the ordinary for them, other than keeping them comfortable through their molts and upping their protein intake. (Find out how to help your chickens grow back beautiful feathers before the cold sets in.)

Oh, chickens… always keeping me on my toes, that’s for sure.

About Author

I'm a plant lover, passionate road-tripper, and cookbook author whose expert advice and bestselling books have been featured in TIME, Outside, HGTV, and Food & Wine. The No-Waste Vegetable Cookbook is my latest book. Garden Betty is where I write about modern homesteading, farm-to-table cooking, and outdoor adventuring—all that encompass a life well-lived outdoors. After all, the secret to a good life is... Read more »