A DOG walker has told how she was left seriously ill after she was bitten by Britain's only native venomous snake.

Beau Avis, 26, was walking her cockapoo Bonnie in Upminster, Essex with her dad Kevin, 59, when she accidently trod on an adder which bit her ankle.

Her leg rapidly swelled and turned yellow and she suffered a life-threatening anaphylactic shock.

She was rushed to hospital where thankfully doctors, by chance, had an anti-venom shot to hand.

Echo: Close call - Beau Avis was walking her dog when she was bitten by a snakeClose call - Beau Avis was walking her dog when she was bitten by a snake (Image: SWNS)

She was kept in for two nights before being discharged in a wheelchair, and the incident has left her unable to walk.

Now Beau is on the mend, but she wants to warn others about the dangers of poisonous snakes in the UK and how to react if you're bitten by one.

Beau, from Brentwood, said: "The bite felt like someone had poured acid into my left leg.

"I panicked as I've been scared of snakes my whole life, but I found out later panicking makes the venom spread faster.

Echo: Ouch - the cuts left by the snake biteOuch - the cuts left by the snake bite (Image: SWNS)

"In that scenario you are supposed to stay calm - something I didn't do."

Beau was working from home on May 31 when her and Kevin headed out on her lunch break to walk her Bonnie at around 2pm.

They drove to a nearby woodland area, and were walking down a country path when Beau suddenly let out a scream.

The PR executive, who was wearing sandals at the time, immediately put her hand on her left ankle to find she'd been bitten.

Echo: Scary - Beau's leg changed colour following the biteScary - Beau's leg changed colour following the bite (Image: SWNS)

The bite left three teeth marks, and Beau says when she looked down, she saw the back end of a 50cm brownish, zig zagged snake slither off into the long grass.

She explained: "Me and Dad were engrossed in conversation, walking the dog like we often do. Then I felt this sharp bite on the inside of my left ankle.

"Almost immediately the skin under the bite started to swell and I looked frantically for the cause.

"That's when I saw the back end of a brownish, zig zagged creature slither into the long grass.

Echo:

"It suddenly hit me that I'd trodden on an adder snake and I started to panic.

"I was freaking out and dad was desperately trying to calm me down but the fear had already gripped a hold of me.

"We rushed back to the car and the pain and swelling was getting worse every second that went by, it was horrific."

Beau called her mum who rung an ambulance while they were in the car on the way home.

Paramedics were at her parent's house within 25 minutes, in which time Beau had gone into anaphylactic shock as a result of the bite.

She was drifting in and out of consciousness, vomiting and battling intense stomach pain which would frequently come and go.

After arriving at Queen's Hospital in Romford, Beau was fast tracked to the Resuscitation Department and administered with an anti venom adrenaline shot.

At first, doctors were unsure whether they had the right concoction of medicine on site - but thankfully they were able to form the right anecdote.

She was given the shot at 4pm, two hours after the incident and kept in hospital overnight.

But the swelling had travelled so far up her left leg and knee cap that she required a second shot at 6am the next morning.

It was only after another full day and night on an intervenes drip that she was allowed to continue her recovery at home.

Beau said: "Doctors called the The National Poisons Information Services who told them the shot they required to repel the adder venom.

"Thankfully they had the drugs they needed in the hospital and they blended a concentrate in to an intervenes drip which fed into a bag.

"Anti venom is most effective within four hours so it was vital they acted quickly.

"By the evening, my whole limb was bright red and had doubled in size - and I was being treated for cellulitis.

"The swelling travelled above my knee meaning I needed another shot at 6am the next morning to make sure all the venom had been flushed out.

"An ultra sound revealed three days later that I hadn't suffered any blood clotting in the leg, and it was only then they were comfortable with me going home.

Beau has been left relearning how to walk after her hospital stint, and is only just getting movement in her leg back.

Now, she wants to raise awareness about the real danger of poisonous snakes in the UK, and spread information on how to treat bite symptoms.

She added: "My consultant called this morning to check in and ask to use me as a case study so other hospitals know what to do in similar situations.

"An adder bite hasn't killed anyone in ages, but they were really concerned in the first 12 hours because of my low blood pressure.

"If I'd have known panicking spreads the venom, I would have done more to stay calm.

"That's why I want to share my story so others know how to react if they ever get in a similar situation."