Old timers called it "end of the summer sickness". Maybe it is the change in temperature. Maybe it's the vulnerable age of a juvenile bird when it seems most susceptible to illness. Or maybe it's a time of year when most breeders are at max capacity before culling down and our pens are not as tidy. Inevitably, if sickness rears its ugly head in your flock, it will be around this time.
There are many common poultry diseases. Perhaps the most common are MG (mycoplasma gallisepticum), MS (mycoplasma synoviae) and mareks. Sometimes MG and MS are combined to describe an ailment called CRD (chronic respiratory disease) but, the two are different. If left untreated, mycoplasma symptoms worsen sometimes to a point where that bird will never heal and always display symptoms (chronic). Symptoms include: nasal discharge (often fowl smelling), bubbly eyes, rattles or coughing/sneezing, unthriftiness, loss of appetite. MS can additionally include lameness and stunted growth.
Mycoplasma is transferred from bird to bird via waterer and dander. It is brought in from other farms by way of shoes and clothing. It can also be spread by wild birds. It is passed through the egg to offspring so management is difficult.
Mareks is also extremely common. Some estimate 80-90% of backyard flocks carry 1 or even all 3 of these common diseases. One reason for that is by being a carrier of one, that bird is now much more susceptible to falling ill to another. There are different types of mareks but, the classic symptom is paralysis. Often times a young chicken will begin having trouble walking. Symptoms worsen until the bird is completely paralyzed in the legs and then possibly the neck and wings. Mortality rates are high. Symptoms are common in the first 12-20 wks of age but, infection can begin at hatch if exposed. If exposed after 20 wks, the bird will most likely not get sick. This is why many breeders keep their juveniles separate from adult pens.
Up until recent years, most poultry keepers were breeding for production or for show and a level of care was necessary to breed healthy offspring. Sick birds were culled.
Cull (kul) 1)to select from a group 2) to reduce the size of a herd by removal of weaker animals by killing).
With the huge influx of backyard breeders (including myself) things are rapidly changing. Birds that would otherwise be "culled" for the health of the flock are now being treated medically or sold and then bred from. This practice weakens the entire flock and increases the chances of future offspring succumbing to disease by way of unnatural selection.
Your chicken does NOT have a cold. It has a disease, will forever be a carrier, and will pass on either that disease or the weak gene which made it susceptible. There is a huge responsibility that comes with breeding animals and though, culling does not always mean killing, (I sell pet quality birds by way of "culling") but, being able to put down a sick or injured bird is something every breeder should be able to do. If you choose to treat sick birds, they should not be bred or sold/given to another person to breed. There are many humane ways to put down a bird so research to see what you are comfortable with.
*Keep bedding clean and dry.
*Regularly treat birds for parasites which can weaken immune system.
*Feed birds a healthy diet and keep waterers clean.
*I like to add probiotics and vitamins to waterers.
*Immediately QT (quarantine) sick birds.
*Practice biosecurity (limit foot traffic into your coops. Be selective about adding in new birds and ALWAY QT new birds.
There is so much to learn and even old timers are learning more every day. The diseases change. The treatments change and there are new discoveries. Here are some great links to learn more and become proactive in the fight to keep your birds safe.
The Poultry Site
Chicken Illness for Dummies
The Poultry Keeper