But the microlight flying instructor says after meeting Biggles he really felt he had no choice other than to pay for the vet bills, kennel fees and transportation costs.
Mr McCafferty, from Great Horwood, runs a microlight school at Finmere Airfield and also leases an airfield on the Spanish island.
It was during a working trip last summer that Biggles turned up at the airfield.
He said: "He was just there one morning sitting outside the hangar and returned three or four mornings running.
"Eventually the penny dropped and although he wasn't in too bad a condition, I realised he was a stray.
"It looked to me like he had been abandoned rather than being a long-term stray because he was used to people."
What really made up the dog lover's mind was hearing that Biggles had run down the road chasing after his car as he left one evening.
After discussing the situation with his wife, Susanne, the couple agreed to give the little Spanish dog a new life in north Bucks.
Although he admits he didn't expect the costs to be so high, Mr McCafferty remains happy with his decision.
"Spain is like a lot of European countries with lots of strays walking around which can easily be killed or captured and put down," he said.
"If you are a person who loves animals then there really is no choice."
Following months of quarantine, Biggles eventually flew into Gatwick at the end of May and has since settled in well with the family, including Mr McCafferty's wife, daughters Sara, 22, Heidi, 19, and pet Labrador Sweep, a rescue dog taken in by the McCaffertys six years ago.