diff --git a/litellm/constants.py b/litellm/constants.py
index d02114f56b1..2f93ff6e8ad 100644
--- a/litellm/constants.py
+++ b/litellm/constants.py
@@ -1748,6 +1748,7 @@ AZURE_SPEECH_PASS_THROUGH_ROUTE_PREFIX: Final = "/azure_speech"
 AZURE_SPEECH_SHORT_AUDIO_PATH_PREFIX: Final = "/speech/"
 AZURE_SPEECH_BATCH_PATH_PREFIX: Final = "/speechtotext/"
 AZURE_SPEECH_FAST_TRANSCRIPTION_PATH: Final = "/speechtotext/transcriptions:transcribe"
+OPENSEARCH_PASS_THROUGH_ROUTE_PREFIX: Final = "/opensearch"
 AZURE_SPEECH_STT_DOMAIN: Final = "stt.speech.microsoft.com"
 AZURE_SPEECH_COGNITIVE_SERVICES_DOMAIN: Final = "api.cognitive.microsoft.com"
 AZURE_SPEECH_SUBSCRIPTION_KEY_HEADER: Final = "Ocp-Apim-Subscription-Key"
diff --git a/litellm/llms/opensearch/vector_stores/index_passthrough.py b/litellm/llms/opensearch/vector_stores/index_passthrough.py
index 4283532335d..a5c2346253d 100644
--- a/litellm/llms/opensearch/vector_stores/index_passthrough.py
+++ b/litellm/llms/opensearch/vector_stores/index_passthrough.py
@@ -87,6 +87,15 @@ INDEX_OPERATIONS: Final = (
 )
 
 
+_NDJSON_APIS: Final = frozenset(
+    operation.api for operation in INDEX_OPERATIONS if operation.body in ("bulk", "msearch")
+)
+
+
+def carries_ndjson_body(route: str, media_type: str) -> bool:
+    return media_type == NDJSON_CONTENT_TYPE or route.rpartition("/")[2] in _NDJSON_APIS
+
+
 def _endpoint_patterns(permission: IndexPermission) -> Iterator[tuple[IndexHttpMethod, str]]:
     for operation in INDEX_OPERATIONS:
         if operation.permission == permission:
diff --git a/litellm/proxy/auth/user_api_key_auth.py b/litellm/proxy/auth/user_api_key_auth.py
index 292a147d200..f7bde0e9f12 100644
--- a/litellm/proxy/auth/user_api_key_auth.py
+++ b/litellm/proxy/auth/user_api_key_auth.py
@@ -143,7 +143,7 @@ from litellm.proxy.common_utils.http_parsing_utils import (  # noqa: F401  # leg
     _safe_get_request_headers,  # pyright: ignore[reportPrivateUsage,reportUnusedImport]  # backwards-compatible package export
     _safe_get_request_query_params,  # pyright: ignore[reportPrivateUsage,reportUnusedImport]  # backwards-compatible package export
     _safe_set_request_parsed_body,  # pyright: ignore[reportPrivateUsage,reportUnusedImport]  # backwards-compatible package export
-    is_opaque_audio_pass_through_request,
+    is_opaque_pass_through_request,
     populate_request_with_path_params,
     read_raw_json_body,
     read_request_body,
@@ -2045,7 +2045,7 @@ async def _read_request_body_deferring_parse_failure(
     must run (resolving identity onto the request's trace) before the 400 goes
     out; the caller re-raises the returned exception once identity is seeded.
     """
-    if is_opaque_audio_pass_through_request(
+    if is_opaque_pass_through_request(
         route=get_request_route(request=request),
         content_type=safe_get_request_headers(request=request).get("content-type", ""),
     ):
diff --git a/litellm/proxy/common_utils/http_parsing_utils.py b/litellm/proxy/common_utils/http_parsing_utils.py
index 56cd14d987d..0c41b6bc2ad 100644
--- a/litellm/proxy/common_utils/http_parsing_utils.py
+++ b/litellm/proxy/common_utils/http_parsing_utils.py
@@ -19,6 +19,7 @@ from litellm.constants import (
     LITELLM_CLIENT_DISCONNECT_DETAIL,
     LITELLM_HTTP_STATUS_CLIENT_DISCONNECTED,
     MAX_REQUEST_BODY_SIZE_TO_REPAIR_MB,
+    OPENSEARCH_PASS_THROUGH_ROUTE_PREFIX,
 )
 from litellm.integrations.otel.runtime import phase_event
 from litellm.proxy._types import ProxyException
@@ -374,12 +375,18 @@ async def read_request_body(request: Request | None) -> dict:
 _read_request_body: Final = read_request_body
 
 
-def is_opaque_audio_pass_through_request(route: str, content_type: str) -> bool:
-    """Azure Speech bodies (raw audio, multipart uploads) are forwarded byte for byte, so auth must not consume them."""
+def is_opaque_pass_through_request(route: str, content_type: str) -> bool:
+    """Azure Speech audio and OpenSearch NDJSON bodies are forwarded byte for byte, so auth must not parse them."""
     media_type: Final = _normalize_media_type(content_type)
-    return route.startswith(f"{AZURE_SPEECH_PASS_THROUGH_ROUTE_PREFIX}/") and (
-        media_type.startswith("audio/") or media_type == "multipart/form-data"
-    )
+    if route.startswith(f"{AZURE_SPEECH_PASS_THROUGH_ROUTE_PREFIX}/"):
+        return media_type.startswith("audio/") or media_type == "multipart/form-data"
+    if route.startswith(f"{OPENSEARCH_PASS_THROUGH_ROUTE_PREFIX}/"):
+        from litellm.llms.opensearch.vector_stores.index_passthrough import (  # noqa: PLC0415  # loaded only for OpenSearch routes, like the route itself
+            carries_ndjson_body,
+        )
+
+        return carries_ndjson_body(route, media_type)
+    return False
 
 
 async def read_raw_json_body(request: Request | None) -> bytes | None:
diff --git a/litellm/proxy/pass_through_endpoints/llm_passthrough_endpoints.py b/litellm/proxy/pass_through_endpoints/llm_passthrough_endpoints.py
index 2663f73fca1..19eae87880c 100644
--- a/litellm/proxy/pass_through_endpoints/llm_passthrough_endpoints.py
+++ b/litellm/proxy/pass_through_endpoints/llm_passthrough_endpoints.py
@@ -1015,8 +1015,8 @@ async def opensearch_proxy_route(  # noqa: ANN201  # returns create_pass_through
     `write` on it in `allowed_vector_store_indexes`, and LiteLLM signs the call with the vector store's AWS identity.
     """
     from litellm.llms.opensearch.vector_stores.index_passthrough import (
-        NDJSON_CONTENT_TYPE,
         IndexRefusal,
+        carries_ndjson_body,
         index_operation,
         parse_index_path,
         prepare_index_request,
@@ -1060,7 +1060,7 @@ async def opensearch_proxy_route(  # noqa: ANN201  # returns create_pass_through
     )
     setattr(request.state, LITELLM_PASS_THROUGH_RAW_BODY_STATE_KEY, prepared.body)
     setattr(request.state, LITELLM_PASS_THROUGH_CUSTOM_BODY_STATE_KEY, {})
-    if prepared.media_type == NDJSON_CONTENT_TYPE:
+    if carries_ndjson_body(endpoint, prepared.media_type):
         safe_set_request_parsed_body(request, {})
     return await endpoint_func(request, fastapi_response, user_api_key_dict)
 
diff --git a/tests/unit/proxy/pass_through_endpoints/test_llm_pass_through_endpoints.py b/tests/unit/proxy/pass_through_endpoints/test_llm_pass_through_endpoints.py
index ec305432672..9c9e418e615 100644
--- a/tests/unit/proxy/pass_through_endpoints/test_llm_pass_through_endpoints.py
+++ b/tests/unit/proxy/pass_through_endpoints/test_llm_pass_through_endpoints.py
@@ -9729,21 +9729,24 @@ class TestOpenSearchProxyRoute:
             pytest.param("_msearch", b'{}\n{"query":{"match_all":{}}}\n{"preference":"a"}\n{}\n', id="msearch"),
         ],
     )
+    @pytest.mark.parametrize("content_type", [NDJSON_TYPE, "application/json"])
     def test_an_ndjson_body_without_index_references_is_sent_byte_for_byte(
-        self, opensearch_client: TestClient, monkeypatch: pytest.MonkeyPatch, api: str, body: bytes
+        self, opensearch_client: TestClient, monkeypatch: pytest.MonkeyPatch, api: str, body: bytes, content_type: str
     ) -> None:
-        _act_as(monkeypatch, _opensearch_caller("read", "write"))
+        monkeypatch.setattr("litellm.proxy.proxy_server.master_key", SHARED_MASTER_KEY)
         with respx.mock(assert_all_called=True) as upstream:
             route = upstream.post(f"{DOCS_UPSTREAM}/{api}").mock(
                 return_value=httpx.Response(200, json={"errors": False, "items": []})
             )
             response = opensearch_client.post(
-                f"/opensearch/docs/{api}", content=body, headers={"Content-Type": NDJSON_TYPE}
+                f"/opensearch/docs/{api}",
+                content=body,
+                headers={"Content-Type": content_type, "Authorization": f"Bearer {SHARED_MASTER_KEY}"},
             )
 
         assert response.status_code == 200
         sent: Final = route.calls.last.request
-        assert (sent.content, sent.headers["content-type"]) == (body, NDJSON_TYPE)
+        assert (sent.content, sent.headers["content-type"]) == (body, content_type)
         assert _verified_sigv4_scope(sent) == ("aoss", "us-east-1")
 
     @pytest.mark.parametrize(