diff --git a/src/animaltrack/web/routes/actions.py b/src/animaltrack/web/routes/actions.py
index 16025f6..153f908 100644
--- a/src/animaltrack/web/routes/actions.py
+++ b/src/animaltrack/web/routes/actions.py
@@ -426,10 +426,13 @@ async def animal_promote(request: Request):
     form = await request.form()
 
     # Extract form data
+    # Note: "-" is used as sentinel for "no change" because FastHTML omits empty value attributes
     animal_id = form.get("animal_id", "")
     nickname = form.get("nickname", "") or None
-    sex = form.get("sex", "") or None
-    repro_status = form.get("repro_status", "") or None
+    sex_raw = form.get("sex", "")
+    sex = None if sex_raw in ("", "-") else sex_raw
+    repro_raw = form.get("repro_status", "")
+    repro_status = None if repro_raw in ("", "-") else repro_raw
     distinguishing_traits = form.get("distinguishing_traits", "") or None
     notes = form.get("notes", "") or None
     nonce = form.get("nonce")
@@ -1034,10 +1037,14 @@ async def animal_attrs(request: Request, session):
     form = await request.form()
 
     # Extract form data
+    # Note: "-" is used as sentinel for "no change" because FastHTML omits empty value attributes
     filter_str = form.get("filter", "")
-    sex = form.get("sex", "").strip() or None
-    life_stage = form.get("life_stage", "").strip() or None
-    repro_status = form.get("repro_status", "").strip() or None
+    sex_raw = form.get("sex", "").strip()
+    sex = None if sex_raw in ("", "-") else sex_raw
+    life_stage_raw = form.get("life_stage", "").strip()
+    life_stage = None if life_stage_raw in ("", "-") else life_stage_raw
+    repro_raw = form.get("repro_status", "").strip()
+    repro_status = None if repro_raw in ("", "-") else repro_raw
     roster_hash = form.get("roster_hash", "")
     confirmed = form.get("confirmed", "") == "true"
     nonce = form.get("nonce")
@@ -1277,7 +1284,9 @@ async def animal_outcome(request: Request, session):
     nonce = form.get("nonce")
 
     # Yield item fields
-    yield_product_code = form.get("yield_product_code", "").strip() or None
+    # Note: "-" is used as sentinel for "no selection" because FastHTML omits empty value attributes
+    yield_product_raw = form.get("yield_product_code", "").strip()
+    yield_product_code = None if yield_product_raw in ("", "-") else yield_product_raw
     yield_unit = form.get("yield_unit", "").strip() or None
     yield_quantity_str = form.get("yield_quantity", "").strip()
     yield_weight_str = form.get("yield_weight_kg", "").strip()
diff --git a/src/animaltrack/web/templates/actions.py b/src/animaltrack/web/templates/actions.py
index c3c63ab..69dd138 100644
--- a/src/animaltrack/web/templates/actions.py
+++ b/src/animaltrack/web/templates/actions.py
@@ -443,8 +443,9 @@ def promote_form(
     action_text = "Renaming" if is_rename else "Promoting"
 
     # Build sex options (optional - can refine current value)
+    # Note: Use "-" sentinel instead of "" because FastHTML omits empty value attributes
     sexes = [
-        ("", "Keep current"),
+        ("-", "Keep current"),
         ("female", "Female"),
         ("male", "Male"),
     ]
@@ -453,8 +454,9 @@ def promote_form(
         sex_options.append(Option(label, value=code, selected=code == selected_sex))
 
     # Build repro status options (optional) - must match ReproStatus enum
+    # Note: Use "-" sentinel instead of "" because FastHTML omits empty value attributes
     repro_statuses = [
-        ("", "Keep current"),
+        ("-", "Keep current"),
         ("intact", "Intact"),
         ("wether", "Wether (castrated male)"),
         ("spayed", "Spayed (female)"),
@@ -1032,24 +1034,27 @@ def attrs_form(
     )
 
     # Build sex options
+    # Note: Use "-" sentinel instead of "" because FastHTML omits empty value attributes
     sex_options = [
-        Option("No change", value="", selected=True),
+        Option("No change", value="-", selected=True),
         Option("Female", value="female"),
         Option("Male", value="male"),
         Option("Unknown", value="unknown"),
     ]
 
     # Build life stage options
+    # Note: Use "-" sentinel instead of "" because FastHTML omits empty value attributes
     life_stage_options = [
-        Option("No change", value="", selected=True),
+        Option("No change", value="-", selected=True),
         Option("Hatchling", value="hatchling"),
         Option("Juvenile", value="juvenile"),
         Option("Adult", value="adult"),
     ]
 
     # Build repro status options (intact, wether, spayed, unknown)
+    # Note: Use "-" sentinel instead of "" because FastHTML omits empty value attributes
     repro_status_options = [
-        Option("No change", value="", selected=True),
+        Option("No change", value="-", selected=True),
         Option("Intact", value="intact"),
         Option("Wether (castrated male)", value="wether"),
         Option("Spayed (female)", value="spayed"),
@@ -1293,7 +1298,8 @@ def outcome_form(
     ]
 
     # Build product options for yield items
-    product_options = [Option("Select product...", value="", selected=True)]
+    # Note: Use "-" sentinel instead of "" because FastHTML omits empty value attributes
+    product_options = [Option("Select product...", value="-", selected=True)]
     for code, name in products:
         product_options.append(Option(f"{name} ({code})", value=code))