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Q: All about Coryza disease


Coryza is the chicken equivalent of the "common cold" - but interestingly enough, colds in humans are caused by viruses, while coryza is caused by a bacteria in chickens. Thankfully, this disease is rarely fatal, and chickens recover from it within a matter of weeks. But it can look like many other respiratory diseases, so you will want your vet to diagnose any ailing members of your flock to be sure you're treating them correctly. Read on for more information about this common chicken ailment:

Coryza Also called
Cold, Infectious Coryza, IC, Roup


General signs -
Loss of appetite, drop in laying, loose poo, wheezing, sneezing, or other general respiratory symptoms
Cardinal or diagnostic signs -
Bad-smelling discharge of various colors (often yellow, grey, brown or red) from eyes and nares, facial swelling

Bacterial - Haemophilus paragallinarum

Yes. It can be passed from bird to bird in much the same way humans can pass colds to one another.

Communicability to humans
No. Although it is referred to as a cold, it’s actually caused by a bacteria that is not known to affect humans. (Human colds are caused by various viruses.)

Incubation period
Up to 3 days

Yes. Some chickens can be symptom-less carriers.

The bacteria that causes Coryza is only thought to persist about 3 weeks in the environment outside a carrier.

Home treatment and/or prevention
Prevention: Disinfect; practice good biosecurity, including a 30-day quarantine when bringing new birds into your flock.

Treatment: Coryza generally runs its course in 3 weeks, but if the flock is stressed or dealing with other illnesses or issues, it may take longer to recover. Weak birds may need veterinary care. There is a vaccine for Coryza, but it’s fairly uncommon to have your flock vaccinated. If your flock has had coryza in the past, you may want to vaccinate new birds before adding them to your established flock, since some chickens can be asymptomatic carriers of coryza. Veterinary care
Contact your veterinarian for vaccination information. Veterinarians may also prescribe antibiotics for chickens suffering from coryza.

Coryza is not often fatal, and not usually serious. Even so, it can easily be mistaken at home for other, more serious, respiratory illnesses. It’s recommended to contact a vet for a firm diagnosis.

Other conditions, illnesses and/or diseases with similar signs:
Other respiratory illnesses can be easily mistaken for coryza, including infectious bronchitis, Newcastle, influenza, mycoplasmosis, and others. Vitamin A deficiency can sometimes cause similar signs of illness.

Also consider browsing through this list of other chicken illnesses with respiratory symptoms.