Generally, no. Under the rules of civil procedure, a subpoena to testify may be quashed if it "requires disclosing an unretained expert’s opinion or information that does not describe specific occurrences in dispute and results from the expert’s study not requested by a party."
expert witnesses are much different from a regular witness since they have an exception to the hearsay rule (can testify about things they didn't directly observe themselves), their credentials are examined, they make a report, they are required to be paid, etc. Because of this you cannot subpoena them like a regular witness.
If they were being subpoenaed - compelled to be a witness - I am sure the matter would be different.