diff --git a/nirc_ehr/resources/queries/study/arrival.js b/nirc_ehr/resources/queries/study/arrival.js
index 0d31e16e..7f1d4366 100644
--- a/nirc_ehr/resources/queries/study/arrival.js
+++ b/nirc_ehr/resources/queries/study/arrival.js
@@ -10,6 +10,14 @@ function onInit(event, helper){
         skipAssignmentCheck: true,
     });
 }
+
+EHR.Server.TriggerManager.registerHandlerForQuery(EHR.Server.TriggerManager.Events.BEFORE_INSERT, 'study', 'Arrival', function(helper, scriptErrors, row, oldRow) {
+
+    if (triggerHelper.animalIdExists(row.Id)) {
+        EHR.Server.Utils.addError(scriptErrors, 'Id', 'Animal Id ' + row.Id + ' is already in use. Please use a different Id.', 'ERROR');
+    }
+});
+
 EHR.Server.TriggerManager.registerHandlerForQuery(EHR.Server.TriggerManager.Events.BEFORE_UPSERT, 'study', 'Arrival', function(helper, scriptErrors, row, oldRow) {
 
     if (row.eventDate) {
diff --git a/nirc_ehr/src/org/labkey/nirc_ehr/query/NIRC_EHRTriggerHelper.java b/nirc_ehr/src/org/labkey/nirc_ehr/query/NIRC_EHRTriggerHelper.java
index c423298f..0f86c196 100644
--- a/nirc_ehr/src/org/labkey/nirc_ehr/query/NIRC_EHRTriggerHelper.java
+++ b/nirc_ehr/src/org/labkey/nirc_ehr/query/NIRC_EHRTriggerHelper.java
@@ -264,6 +264,18 @@ public String saveBirthRecord(String id, Map<String, Object> row) throws QueryUp
         return null;
     }
 
+    public boolean animalIdExists(String id)
+    {
+        TableInfo ti = getTableInfo("study", "demographics");
+        if (ti != null)
+        {
+            SimpleFilter filter = new SimpleFilter(FieldKey.fromString("Id"), id);
+            TableSelector ts = new TableSelector(ti, PageFlowUtil.set("lsid"), filter, null);
+            return ts.exists();
+        }
+        return false;
+    }
+
     public boolean birthExists(String id)
     {
         TableInfo ti = getTableInfo("study", "birth");
@@ -275,6 +287,7 @@ public boolean birthExists(String id)
         }
         return false;
     }
+
     public boolean deathExists(String id)
     {
         TableInfo ti = getTableInfo("study", "deaths");