The figures emerged after it was revealed that two guard dogs used to protect the Duke of Cambridge were euthanised within days of him leaving his military base.
288 dogs were put down by the MoD from January 2010 to June this year.
Among those humanely killed, 81 were because of age, 61 due to osteoarthritis and 33 were related to dangerous temperament.
An MoD spokesman said: "Most animals are re-homed. Regrettably, due to the challenging nature of their work, some of our dogs get injured or contract illnesses and need to be put down. These decisions are taken only as a last resort following veterinary advice."