diff --git a/litellm/integrations/langfuse/langfuse.py b/litellm/integrations/langfuse/langfuse.py
index 86f80047e52..3f7416f908a 100644
--- a/litellm/integrations/langfuse/langfuse.py
+++ b/litellm/integrations/langfuse/langfuse.py
@@ -143,7 +143,7 @@ def langfuse_trace_id(
 class _UsageObject(Protocol):
     """Token-count surface the Langfuse logger reads off a response usage payload."""
 
-    def get(self, key: Literal["cache_creation_input_tokens", "cache_read_input_tokens"], /) -> int | None: ...
+    def get(self, key: str, /) -> int | None: ...
 
 
 def _chat_usage(raw_usage: _UsageObject | None) -> _UsageObject | None:
@@ -167,7 +167,44 @@ def _chat_usage(raw_usage: _UsageObject | None) -> _UsageObject | None:
         return raw_usage
 
 
-def _extract_cache_read_input_tokens(usage_obj) -> int:
+def _usage_token_value(usage_obj: object, standard_name: str, decision_name: str | None = None) -> int:
+    """
+    Read a token count from a usage object, tolerating dict-like and Pydantic usage models.
+
+    Decisions responses (DecisionsUsage/OpenAIDecisionUsage) are Pydantic models
+    without a dict ``.get`` and name their counts ``input_tokens``/``output_tokens``
+    (and ``cached_tokens``/``cache_write_tokens``). Fall back to those names when the
+    standard OpenAI-style attribute is absent.
+
+    Args:
+        usage_obj: Usage object from an LLM/decisions response.
+        standard_name: OpenAI-style attribute name (e.g. ``prompt_tokens``).
+        decision_name: Optional decisions-response field to fall back to.
+
+    Returns:
+        int: The token count, defaulting to 0.
+    """
+    if isinstance(usage_obj, dict):
+        usage_proto: Final[_UsageObject] = (
+            cast(  # cast-ok: plain dict at runtime, narrowed by isinstance; _UsageObject only describes .get
+                "_UsageObject", usage_obj
+            )
+        )
+        # A raw dict here means _chat_usage could not validate it as a chat or
+        # responses usage (e.g. a malformed /v1/responses payload whose token
+        # counts fail validation) and passed it through unchanged. Read only the
+        # standard chat field so a failed validation logs as zero, matching
+        # getattr(..., None) or 0; do not fall back to decisions-style names,
+        # which would resurrect a value from a payload that failed validation.
+        dict_value: Final = usage_proto.get(standard_name)
+        return dict_value if isinstance(dict_value, int) else 0
+    if (attr_value := getattr(usage_obj, standard_name, None)) is None and decision_name is not None:
+        decision_attr_value: Final = getattr(usage_obj, decision_name, None)
+        return decision_attr_value if isinstance(decision_attr_value, int) else 0
+    return attr_value if isinstance(attr_value, int) else 0
+
+
+def _extract_cache_read_input_tokens(usage_obj: object) -> int:
     """
     Extract cache_read_input_tokens from usage object.
 
@@ -183,7 +220,7 @@ def _extract_cache_read_input_tokens(usage_obj) -> int:
     Returns:
         int: Number of cached tokens read, defaults to 0
     """
-    cache_read_input_tokens = usage_obj.get("cache_read_input_tokens") or 0
+    cache_read_input_tokens = _usage_token_value(usage_obj, "cache_read_input_tokens", "cached_tokens")
 
     # Check prompt_tokens_details.cached_tokens (used by Gemini and other providers)
     if hasattr(usage_obj, "prompt_tokens_details"):
@@ -866,11 +903,13 @@ class LangFuseLogger:
                 if _usage_obj:
                     # Safely get usage values, defaulting None to 0 for Langfuse compatibility.
                     # Some providers may return null for token counts.
-                    prompt_tokens: Final = getattr(_usage_obj, "prompt_tokens", None) or 0
-                    completion_tokens: Final = getattr(_usage_obj, "completion_tokens", None) or 0
-                    total_tokens: Final = getattr(_usage_obj, "total_tokens", None) or 0
+                    prompt_tokens: Final = _usage_token_value(_usage_obj, "prompt_tokens", "input_tokens")
+                    completion_tokens: Final = _usage_token_value(_usage_obj, "completion_tokens", "output_tokens")
+                    total_tokens: Final = _usage_token_value(_usage_obj, "total_tokens")
 
-                    cache_creation_input_tokens: Final = _usage_obj.get("cache_creation_input_tokens") or 0
+                    cache_creation_input_tokens: Final = _usage_token_value(
+                        _usage_obj, "cache_creation_input_tokens", "cache_write_tokens"
+                    )
                     cache_read_input_tokens: Final = _extract_cache_read_input_tokens(_usage_obj)
 
                     usage = {
diff --git a/tests/unit/integrations/langfuse/test_langfuse_decisions_usage.py b/tests/unit/integrations/langfuse/test_langfuse_decisions_usage.py
new file mode 100644
index 00000000000..c44ec58866d
--- /dev/null
+++ b/tests/unit/integrations/langfuse/test_langfuse_decisions_usage.py
@@ -0,0 +1,74 @@
+# -*- coding: utf-8 -*-
+"""
+Regression tests for decisions-route responses flowing into the legacy
+Langfuse logger (issue #45584).
+
+DecisionsUsage / OpenAIDecisionUsage are Pydantic models without a dict-style
+``.get`` and name their token counts input_tokens/output_tokens (and
+cached_tokens/cache_write_tokens). The Langfuse logger used to crash on those
+(AttributeError: 'DecisionsUsage' object has no attribute 'get') and drop the
+whole trace; token counts were also misread as zero.
+"""
+
+from litellm.integrations.langfuse.langfuse import (
+    _extract_cache_read_input_tokens,
+    _usage_token_value,
+)
+from litellm.types.decisions import DecisionsUsage
+
+
+class _PlainUsage:
+    prompt_tokens = 5
+    completion_tokens = 7
+    total_tokens = 12
+    cache_creation_input_tokens = 2
+    cache_read_input_tokens = 3
+
+
+class _EmptyUsage:
+    pass
+
+
+def test_usage_token_value_reads_standard_attributes() -> None:
+    usage = _PlainUsage()
+    assert _usage_token_value(usage, "prompt_tokens") == 5
+    assert _usage_token_value(usage, "completion_tokens") == 7
+    assert _usage_token_value(usage, "total_tokens") == 12
+    assert _usage_token_value(usage, "cache_creation_input_tokens") == 2
+
+
+def test_usage_token_value_reads_dict_payloads() -> None:
+    usage = {"prompt_tokens": 5, "completion_tokens": 7, "cache_creation_input_tokens": 2}
+    assert _usage_token_value(usage, "prompt_tokens") == 5
+    assert _usage_token_value(usage, "completion_tokens") == 7
+    assert _usage_token_value(usage, "cache_creation_input_tokens") == 2
+
+
+def test_usage_token_value_defaults_missing_counts_to_zero() -> None:
+    assert _usage_token_value(_EmptyUsage(), "prompt_tokens") == 0
+    assert _usage_token_value({}, "prompt_tokens") == 0
+
+
+def test_usage_token_value_falls_back_to_decisions_field_names() -> None:
+    usage = DecisionsUsage(input_tokens=5, output_tokens=7, cached_tokens=3, cache_write_tokens=2)
+    assert _usage_token_value(usage, "prompt_tokens", "input_tokens") == 5
+    assert _usage_token_value(usage, "completion_tokens", "output_tokens") == 7
+    # DecisionsUsage has no total_tokens; must default to 0 rather than crash.
+    assert _usage_token_value(usage, "total_tokens") == 0
+    assert _usage_token_value(usage, "cache_creation_input_tokens", "cache_write_tokens") == 2
+
+
+def test_extract_cache_read_accepts_pydantic_decisions_usage() -> None:
+    usage = DecisionsUsage(input_tokens=5, output_tokens=7, cached_tokens=3, cache_write_tokens=2)
+    assert _extract_cache_read_input_tokens(usage) == 3
+
+
+def test_extract_cache_read_keeps_dict_semantics() -> None:
+    usage = {"cache_read_input_tokens": 4, "prompt_tokens": 10}
+    assert _extract_cache_read_input_tokens(usage) == 4
+    assert _extract_cache_read_input_tokens({}) == 0
+
+
+def test_extract_cache_read_keeps_plain_attribute_semantics() -> None:
+    usage = _PlainUsage()
+    assert _extract_cache_read_input_tokens(usage) == 3