Assuming that the table or query is named "Matchups" and that the field names are "Owner", "Dog", "Breed", and "Recommendation Descrip", here is the SQL code for the modified query:
```
SELECT Owner, Dog, Breed, [Recommendation Descrip]
FROM Matchups
WHERE Owner Like "*Smith*" AND (Breed="Greyhound" OR [Recommendation Descrip]="Service dog")
```
In this modified query, the OR criteria have been added to the WHERE clause to select only those records where the Breed field value is "Greyhound" OR the Recommendation Descrip field value is "Service dog".
Note that the parentheses are used to group the OR criteria together, so that the database software evaluates them as a single expression. The Like operator is used to filter for records where the Owner field contains the string "Smith" (with any characters before or after the string).
You can run this query in Datasheet view by opening the query in Access and selecting the "Datasheet View" option from the View menu, or by clicking the "Datasheet View" button on the toolbar.