Why is my chicken losing feathers in patches? Is it a disease?

It would be best to discourage mice being in the coop as much as possible, either by setting traps or making sure the grain fed to the chickens is hung out of reach and all grain-bins are closed. While they may not transmit much or anything to your hens, the droppings can transmit diseases to the humans cleaning the coop if not properly handled. Chickens should have feathers. It is possible your hen is molting (losing feathers while new ones grow in) which is normal and happens yearly for most chickens, and you will see pin (or short pin-like) feathers signaling new feathers regrowing. If your chicken is not regrowing the feathers or is being picked on, it may indicate an issue such as being bullied, parasites, illness, etc and should be checked out by a vet.

It is possible Penny is molting. This is normal and is the process of losing old feathers while new ones grow in. You may see pin feathers, or small feathers that look like little pins sticking out of the skin as they grow. It often looks like a mess because some birds tend to lose a lot of feathers all at once, while others have a slower, gradual molt. As long as she is otherwise healthy and active, making sure she is on a balanced diet to ensure good feather growth is best. If she seems ill or new feathers are not growing in, it could indicate she is ill, has some mites, or another skin condition which should be checked out by a vet.

Molting time is different for each individual bird, so yes, molting is possible if it is that time for Sheephony. You may see new feathers, called pin feathers, growing in to replace the old if this is the case (they look like little pins sticking out of the skin, hence the name). Other potential causes of feather loss can include nutritional issues, parasites on the skin, infections, illness, etc, so if she seems otherwise unhealthy or ill, or you aren't seeing new feathers growing in, scheduling an exam with your vet is best. In some cases, birds will also pluck feathers if bored or stressed, so adding some enrichment and making sure Sheephony is kept in an area with low stress may help as well.

Poor Mrs. Star! Loss of feathers can be due to a number of things, including mites or parasites, skin issues, or even learned behaviors/stress. Checking for any signs of mites (stuff attached to the feathers, crawling bugs on the body, excessive itching, etc) can alert you to this. If you are seeing any wounds, making sure to treat them and keep Mrs. Star separate until the wound is healed is best (as other chickens are likely to peck at the exposed area.) If the feather plucking has become a learned behavior, using a chicken apron to protect the area, or an Elizabethan (cone) collar to break the habit for a few days may help the area to start to heal. Making sure all of the hens have enough space, plenty of enrichment, etc is also a good idea to help decrease stress.

It looks like infection. You would need to have them examined by your veterinarian or a vet experienced in treating domestic fowl for confirmation and treatment. Causes include trauma, bacterial infection, fungal infection or parasites. Separate them from the flock to prevent potential spread. Keep them warm, fed, hydrated and as stress free as possible until you see the veterinarian.

It is most likely that your bird is either picking out her feather because of stress or boredom or that she is molting. Since she is eating well and otherwise acting like herself I think it is less likely that she is ill. Make sure you are feeding her a well balanced diet of pellets, small amounts of fruits and veggies and minimal amounts of seeds. If she continues to lose feathers for more than a couple weeks or if she stops eating, then I would recommend taking her in to be evaluated by your veterinarian. I hope this helps. Thanks for using Petco Pet Education Center, formerly Petcoach. Best of luck.

It's possible the chick is getting picked on or has parasites that are causing the feather loss and runny stool. A medicated feed, deworming, and treating for any external parasites is a good idea. If the other chicks are pecking at it, removing it to a hospital cage for a few days and then reintroducing it to the flock is best to allow for time to recover and heal. I would also make sure there is a heat lamp provided until the feathers have come in.