Quick Answer: A chicken respiratory infection typically shows up as sneezing, wheezing or rattling breath, nasal or eye discharge, facial swelling, and a drop in egg production — caused most often by Mycoplasma gallisepticum (a bacterium that becomes a lifelong carrier state), infectious bronchitis (a fast-spreading virus), or infectious coryza (bacterial, known for facial swelling), with poor ventilation and ammonia buildup making all three worse. Isolate any symptomatic bird immediately since these spread through the flock in days, and call a vet or your state extension’s poultry specialist if breathing is labored or more than one bird gets sick at once.
A single sneeze rarely means anything — dust, a strand of bedding, or a gulp of water going down wrong can all trigger it. What actually matters is the pattern: repeated sneezing, any wheeze or rattle, discharge from the eyes or nostrils, or a hen that’s suddenly gone quiet and stopped laying. This guide covers how to tell a real respiratory infection from a passing irritant, what’s usually behind it, and the difference between a case you can support at home and one that needs a vet.
Symptoms at a glance
| Sign | What it looks/sounds like | Urgency |
|---|---|---|
| Sneezing | Occasional, no other symptoms | Watch — likely dust/irritant |
| Wheezing / rales | Clicking, rattling, or whistling on each breath | Isolate + monitor closely |
| Nasal/eye discharge | Clear, cloudy, or thick discharge, often crusted | Isolate + monitor closely |
| Facial swelling | Puffy sinuses, swollen wattles/eyes (classic coryza sign) | Isolate, consider vet |
| Open-mouth breathing | Stretching neck, gasping, visibly labored | Vet/extension call now |
| Off feed + multiple birds sick | Not eating/drinking, spreading within days | Vet/extension call now |
By the numbers
- 71% of backyard flock owners have no vet they can call, per a CDC MMWR survey of 638 flock owners across 48 states — which is why a state extension poultry specialist is often the more realistic first call than “find an avian vet” advice assumes.
- Roughly 1 square foot of vent opening per 10 square feet of floor space is the standard extension guideline for coop ventilation — the single biggest lever against the ammonia buildup that irritates airways and opens the door to infection.
- Mycoplasma gallisepticum infection is generally considered lifelong once a bird is exposed — there’s no cure, only management, and stress (molting, a move, a predator event) is what triggers a latent carrier into an actively shedding, symptomatic bird.
1. Isolate first, diagnose second
Wire Dog Crate / Isolation Pen
- Move a symptomatic bird to a separate space with its own food and water the moment you notice repeated sneezing, wheezing, or discharge — not after you've confirmed a diagnosis.
- Respiratory pathogens spread through airborne droplets and shared water, so distance and separate equipment matter more than which building it's in.
- The same wire crate setup covered in our broody breaker cage guide works as a dual-purpose isolation pen for sick or newly introduced birds.
Whatever ends up causing it, the first move is the same: get the symptomatic bird away from the flock. Most respiratory pathogens in chickens move bird-to-bird through respiratory secretions and shared water sources, and a coop can go from one sneezing hen to half the flock symptomatic within days once shedding starts. Isolating doesn’t require anything fancy — a wire dog crate, rabbit hutch, or the same setup our broody breaker cage guide covers works fine, and keeping it in a separate airflow path from the main coop (not just a divider inside it) matters more than the enclosure itself.
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2. Know what’s actually behind it
| Cause | Type | Hallmark sign | Long-term outcome |
|---|---|---|---|
| Mycoplasma gallisepticum | Bacterial | Chronic sneezing, nasal discharge, rales, often triggered by stress | Lifelong carrier — no cure, only management |
| Infectious bronchitis | Viral | Fast-spreading, hits young birds hardest, drops egg quality in layers | Often recoverable; usually not a permanent carrier |
| Infectious coryza | Bacterial | Dramatic facial/sinus swelling | Recoverable with treatment; reinfection possible |
| Ammonia/dust irritation | Environmental, not infectious | Mild sneezing/watery eyes tied to poor ventilation, clears with airflow | Fully resolves once ventilation/cleaning is fixed |
It’s tempting to lump every sneeze into “my chicken has a cold,” but these have real differences that matter for how you respond. Mycoplasma gallisepticum is the one to take most seriously long-term: it’s a bacterium that, once introduced, generally stays with an infected bird for life — the bird can look completely healthy for months and then flare up the moment it’s stressed by a molt, a move to a new coop, or a predator scare, and it can shed the bacteria to flockmates during that window. Infectious bronchitis moves fast and hits chicks and young pullets hardest, and in laying hens it can also show up as misshapen or thin-shelled eggs even without dramatic symptoms. Infectious coryza is the one with the most visually obvious sign — swollen, puffy faces around the eyes and wattles — and while it responds to treatment, a flock can get reinfected later. And a real share of “respiratory” cases aren’t an infection at all: ammonia and dust buildup from a poorly ventilated coop irritate the same airways and produce similar early symptoms, which is exactly why our chicken coop fan and coop insulation guides both flag ventilation as a health issue, not just a comfort one.
3. Support breathing while you sort out the cause
VetRx Poultry Aid
- A menthol-and-camphor-based liquid keepers reach for to ease wheezing or congestion in a bird that's breathing audibly.
- Supportive care only — it eases symptoms, it doesn't treat the underlying bacterial or viral cause.
- Covered in more depth in our chicken first aid kit guide alongside wound care and hydration support.
While you’re figuring out whether it’s a passing irritant or something more serious, supportive care keeps a struggling bird more comfortable without masking the signs you need to keep watching. VetRx applied under the wing or on the beak can ease audible wheezing or congestion, and electrolytes in the water help a bird that’s off its feed keep hydrated — the same support covered in our chicken electrolytes guide for any stressed or under-the-weather bird. None of this treats Mycoplasma, infectious bronchitis, or coryza directly; it buys the bird comfort while you watch for the signs that tip a case from “monitor at home” to “call for help.”
4. Fix the ventilation, not just the symptom
Ammonia from droppings and wet bedding is one of the most common, and most overlooked, contributors to respiratory problems in a backyard coop. It doesn’t cause Mycoplasma or infectious bronchitis on its own, but it inflames the same airways those pathogens attack, which is why a poorly ventilated coop tends to have more respiratory cases even when no outside pathogen has been introduced. The extension guideline of roughly 1 square foot of vent opening per 10 square feet of floor space, placed high on the walls so moisture and ammonia can escape without drafting roosting birds, is the standard fix — our chicken coop fan guide covers active airflow options, and chicken coop cleaner covers the ammonia-neutralizing products that reduce the load between full cleanings.
5. Know when it’s time to call for help
A single sneeze with nothing else going on rarely needs intervention beyond watching for a repeat. Escalate to a vet or your state extension’s poultry specialist if you see open-mouth or labored breathing, a bird that’s stopped eating or drinking, thick or discolored discharge, or more than one bird showing symptoms within a few days of each other — that clustering is the strongest sign you’re dealing with something transmissible rather than one irritated bird. The reality for most backyard keepers is that a dedicated avian vet isn’t around the corner: a CDC MMWR survey found 71% of flock owners have no vet to call at all, which is why most land-grant university extension offices keep a poultry specialist on staff specifically to fill that gap — often free, and usually faster to reach than a general exotic-animal vet.
Stress is also worth watching for on its own, separate from any specific illness. A bird coming out of a hard molt, one recently added through the flock integration process, or a flock that just survived a predator scare are all more likely to show a respiratory flare-up in the days that follow — not because the stress causes an infection from nothing, but because it’s exactly the kind of trigger that turns a silent Mycoplasma carrier symptomatic.
The bottom line
Most respiratory issues in a backyard flock come down to three things: an actual pathogen (Mycoplasma, infectious bronchitis, or coryza), an environmental irritant (ammonia and dust from poor ventilation), or stress tipping a silent carrier into a symptomatic one. Isolate any bird showing repeated sneezing, wheezing, or discharge right away, fix ventilation as a standing preventive measure rather than a reaction, and don’t wait to call a vet or your state extension’s poultry specialist once you see labored breathing or more than one bird getting sick at the same time.