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Clinical signs of Avian Influenza - made simple

It’s really important vets and owners are familiar with the clinical signs of avian influenza in hens.

A list of clinical signs and photos are available at


Different species can show different signs, or different combinations of signs. If you are not sure, please contact your vet.

Please don't transport birds with suspect Avian Influenza to vets. Ask your vet for a video consult and show them your birds if you are unsure. Show them this blog too if they are not used to seeing cases.

If you suspect any type of avian influenza in your birds you must report it immediately by contacting APHA

Flock signs - Signs seen in birds sharing housing

1. Unresponsive, quiet birds, unwell, don’t want to come out and engage as usual. Don’t come for treats as usual. Sitting around, fluffed up. They may rally temporarily, but will soon tire.

2. Huddling with each other or against coop furniture/equipment like in nests or around drinkers.

3. Unexpected deaths, with other birds looking unwell.

Individual bird signs typical with notifiable disease:

1. Neurological signs – severe e.g. shaking, twitching, struggling to balance or just falling asleep & head nodding.

2. Twisted heads or necks leaving birds looking up at the sky or sideways.

3. Swollen, bruised appearance to heads. Facial feathers may stick up in swollen areas.

4. Weak, unable to remain standing for long. Look drunk and may struggle to control their wings.

5. Shivering, actually tremors as birds don’t shiver when they are cold like we do.

6. Bruising or blood spots of the leg, neck or chest. Check in between the feathers.

Bird signs typical of many other common diseases in hens. Individual birds with these symptoms, in an otherwise well flock are very unlikely to be affected by Highly pathogenic AI. However, these signs are very suspicious of AI when combined with those previously mentioned or when multiple birds are suddenly affected all at once which is rare in a pet flock.

1. Coughing sneezing or gaping, esp. in birds recently wormed for gapeworm

2. Focal facial swelling e.g. around the eyes.

3. Reduction in laying

4. Lethargy

5. Diarrhoea – dark or excessively watery faeces

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