The claim significantly understates the actual magnitude of losses - available data shows losses in the hundreds of millions, not just millions of euros.
The specific period is not mentioned in the claim; the 350 million euro figure refers to losses over a 14-month period from sheep pox alone.
Source is journalistic (secondary source citing official/unofficial estimates) rather than a primary statistical source.
Sources
SecondaryKathimerini (English edition)Economic losses from the spread of small pox in sheep and goats are estimated at more than 350 million euros in the past 14 months