The company has been targeted for years because of its use of animals such as rabbits and mice in research.
Now some hardline animal rights leaders warn of a campaign similar to that which closed down Darley Oaks guinea pig farm in Newchurch, Staffs last week.
And a growing number of messages on extremists' website that describe Wickham staff as 'murdering scum' have added to the menace.
Two firms with connections to Wickham Labs have been attacked in recent days.
The militant Animal Liberation Front admitted slashing tyres and pouring paint-stripper over the cars of three workers at the White Rose incineration complex in Nottingham.
And they also broke windows at Cleanaway Ltd, a haulage firm in Leicestershire, and daubed ALF on the front door.
Local activists who have protested outside Wickham Labs for 30 years said they did not agree with the terror tactics but expect to see extremists becoming increasingly involved.
Dave Thompson, of the Southern Animal Rights Coalition, said: 'There is likely to be a step-up in action against Wickham Labs.
'The closure of the guinea pig farm has been a big morale booster for the whole movement.'