Just after midnight on Wednesday 8 March a car was forced to stop in Ongar Road, Chigwell, after the occupants came across a dog in the road.
After the woman passenger, 50s, got out of the car, she was bitten by the dog and sustained serious wounds to her arm and leg.
PC Jack Witney, investigating said: “I’d like any witnesses to come forward and help our investigation and we’d be particularly interested in any footage of the incident.
“We understand that the incident may have been recorded by a member of the public in a dark coloured security van.”
If you have any information, CCTV, dash cam or other footage in relation to this incident, then please get in contact with us.
You can let us know by submitting a report on our website or by using our online Live Chat service available Monday to Friday (excluding public holidays) between 10am-9pm.
Visit www.essex.police.uk/digital101 to find out more about our website reporting services.
Alternatively, you can call us on 101.
In an emergency always call 999.
If you would like to make an anonymous report, you can contact independent charity on Twitter at @CrimestoppersUK, by visiting their website or by calling 0800 555 111.
Please quote crime reference 42/41398/23 when providing any information to make sure it gets to the right person as quickly as possible.