Infectious coryza isn’t just a seasonal nuisance - it’s a fast-moving bacterial disease that can derail the health and laying of your flock within days. For many Australian backyard chicken owners, the first signs of trouble appear quietly - a swollen face, a drop in egg numbers, or a quiet cluck where there used to be lots of happy chatter.
This article breaks down what every flock keeper needs to know, from the earliest symptoms to recovery strategies and long-term prevention. If you keep hens in suburban Victoria or on a bush block in NSW, this is essential reading - written in plain English, grounded in Australian experience, and backed by practical advice.
What Exactly Is Infectious Coryza?
Coryza is a bacterial respiratory disease caused by Avibacterium paragallinarum. It spreads rapidly among chickens through sneezing, shared feeders, or close contact, and symptoms can appear just days after exposure. Unlike viral colds, it often requires antibiotics to control, and even recovered birds may continue to spread the bacteria for life.
It’s most common in cooler months, particularly in coastal regions, and thrives in damp or crowded conditions. This means that our backyard flocks, with their close quarters and occasional wild bird visitors, are particularly vulnerable.
Recognising the Early Signs
The sooner you act, the better. Early signs can include:
- Facial swelling (often on just one side like in the image above)
- Watery or crusty eyes
- Nasal discharge with a sour or rotten odour
- Gurgling or raspy breathing
- Lethargy and isolation
- A sudden drop in egg laying
It’s easy to mistake the symptoms for dust irritation or a minor sniffle, but that delay can cost your flock. Once one hen shows symptoms, the rest could follow within 48 hours.
Case Example: Learning the Hard Way
In South East Melbourne, a customer told us the story of how they introduced two new hens from a friend without isolating them. Within three days, one of her original hens developed a swollen eye and stopped laying. The others followed soon after. A poultry vet confirmed infectious coryza. While the birds recovered with antibiotic treatment, egg production took weeks to recover and one hen never returned to full health.
The lesson? Always quarantine new arrivals for at least 21 days and monitor carefully for any issues or signs of trouble.
Why Biosecurity Matters
Prevention is not about perfection - it’s about establishing good habits. You don’t need a highly controlled laboratory setup, but you do need consistency.
Here’s how to reduce the risk:
- Quarantine new birds in a safe but separate place with their own feeder and drinker etc
- Disinfect boots and tools if you visit other flocks
- Clean feeders and waterers weekly
- Use netting or tight mesh to keep wild birds out of coops and runs
- Keep a close eye on your flock for changes in behaviour
At Talking Hens, we recommend using Coop Clean - a veterinary-grade disinfectant safe for backyard chickens as part of your cleaning routine. It’s proven in agricultural settings and ideal for small-scale use.
Supporting Your Flock Through Recovery
Once diagnosed, treatment typically includes vet-prescribed antibiotics such as tylosin or oxytetracycline. Supportive care can make all the difference, including fresh water, good ventilation, extra nutrition and dry bedding to speed recovery.
Many chook keepers use apple cider vinegar or garlic in small amounts to support immunity, but these won’t replace antibiotics where infection is established.
Important: Do not attempt to treat coryza without consulting a vet experienced in poultry. Inappropriate treatment can lead to bacterial resistance and ongoing issues in your flock.
The Hidden Costs
Even with successful treatment, infectious coryza can leave a lasting mark:
- Weeks of lost egg laying
- Deformed or soft-shelled eggs
- Delayed development in young hens (pullets)
- Stress-induced moulting
- Reduced laying in older hens
That’s why prevention is always cheaper and more humane than cure.
Should Backyard Keepers Consider Vaccination?
Vaccines are available for infectious coryza but are rarely offered to backyard keepers due to batch size and cost. However, if you’ve had a confirmed outbreak, speak to your poultry vet about options. At Talking Hens, we normally vaccinate for infectious coryza among a range of other diseases that have a high chance of affecting backyard chickens.
Myths That Need Busting
“It’s just a cold.” No - coryza is a bacterial infection that often requires antibiotics and proper isolation.
“Natural remedies are enough.” They help support, but they don’t eliminate infection.
“If they recover, they’re safe.” Recovered birds may still transmit the bacteria to new flock members.
“Vinegar disinfects everything.” Not true. Vinegar is ineffective against many poultry pathogens. Use a proven/tested disinfectant like Coop Clean.
The Emotional Toll of Coryza
Our backyard chickens aren't just birds, they’re family. The stress of seeing your favourite hen unwell, the guilt of not catching it sooner, and the heartbreak of needing to isolate or even euthanise a sick bird can be overwhelming.
Protect Your Flock With Knowledge and Action
Infectious coryza isn’t inevitable, and it’s not unbeatable. With early detection, sound hygiene, good nutrition, and a bit of proactive care, your flock can stay happy, healthy, and productive — even in the face of this disease.
Need help setting up a safer coop? Looking for proven poultry products? We’re here to help.
Comments (1)
Thanks you for this information. Are you also able to recommend an appropriate medic to treat a sick bird?