diff --git a/h/static/scripts/app.coffee b/h/static/scripts/app.coffee
index 47dfad07cc7..88c6e654a2b 100644
--- a/h/static/scripts/app.coffee
+++ b/h/static/scripts/app.coffee
@@ -147,7 +147,6 @@ module.exports = angular.module('h', [
 .service('host', require('./host'))
 .service('localStorage', require('./local-storage'))
 .service('permissions', require('./permissions'))
-.service('pulse', require('./pulse'))
 .service('queryParser', require('./query-parser'))
 .service('render', require('./render'))
 .service('searchFilter', require('./search-filter'))
diff --git a/h/static/scripts/directive/annotation.coffee b/h/static/scripts/directive/annotation.coffee
index b7afd99614f..5325e99ead9 100644
--- a/h/static/scripts/directive/annotation.coffee
+++ b/h/static/scripts/directive/annotation.coffee
@@ -387,11 +387,6 @@ AnnotationController = [
         # Discard saved drafts
         drafts.remove model
 
-        # Propagate an update event up the thread (to pulse changing threads),
-        # but only if this is someone else's annotation.
-        if model.user != session.state.userid
-          $scope.$emit('annotationUpdate')
-
       # Save highlights once logged in.
       if this.isHighlight() and highlight
         if model.user and not model.id
diff --git a/h/static/scripts/directive/test/annotation-test.coffee b/h/static/scripts/directive/test/annotation-test.coffee
index d666e98570d..4452c66160e 100644
--- a/h/static/scripts/directive/test/annotation-test.coffee
+++ b/h/static/scripts/directive/test/annotation-test.coffee
@@ -486,24 +486,6 @@ describe 'annotation', ->
         $document.click()
         assert.notOk(dialog.hasClass('open'))
 
-  describe 'annotationUpdate event', ->
-    beforeEach ->
-      createDirective()
-      sandbox.spy(isolateScope, '$emit')
-      annotation.updated = '123'
-      $scope.$digest()
-
-    it "does not fire when this user's annotations are updated", ->
-      annotation.updated = '456'
-      $scope.$digest()
-      assert.notCalled(isolateScope.$emit)
-
-    it "fires when another user's annotation is updated", ->
-      fakeSession.state.userid = 'acct:jane@localhost'
-      annotation.updated = '456'
-      $scope.$digest()
-      assert.calledWith(isolateScope.$emit, 'annotationUpdate')
-
   describe "deleteAnnotation() method", ->
     before ->
       sinon.stub(window, "confirm")
diff --git a/h/static/scripts/directive/test/thread-test.coffee b/h/static/scripts/directive/test/thread-test.coffee
index 0287b78cc2b..722bc796577 100644
--- a/h/static/scripts/directive/test/thread-test.coffee
+++ b/h/static/scripts/directive/test/thread-test.coffee
@@ -6,7 +6,6 @@ describe 'thread', ->
   $scope = null
   controller = null
   fakeGroups = null
-  fakePulse = null
   fakeRender = null
   fakeAnnotationUI = null
   sandbox = null
@@ -29,7 +28,6 @@ describe 'thread', ->
     fakeGroups = {
       focused: sandbox.stub().returns({id: '__world__'})
     }
-    fakePulse = sandbox.spy()
     fakeRender = sandbox.spy()
     fakeAnnotationUI = {
       hasSelectedAnnotations: ->
@@ -38,7 +36,6 @@ describe 'thread', ->
         selectedAnnotations.indexOf(id) != -1
     }
     $provide.value 'groups', fakeGroups
-    $provide.value 'pulse', fakePulse
     $provide.value 'render', fakeRender
     $provide.value 'annotationUI', fakeAnnotationUI
     return
@@ -351,31 +348,3 @@ describe 'thread', ->
         controller.container = {}
         assert.isFalse(controller.matchesFilter())
         assert.calledWith(check, controller.container)
-
-  describe 'directive', ->
-    beforeEach ->
-      createDirective()
-
-    it 'pulses the current thread on an annotationUpdated event', ->
-      $element.scope().$emit('annotationUpdate')
-      assert.called(fakePulse)
-
-    it 'does not pulse the thread if it is hidden (parent collapsed)', ->
-      fakeParent = {
-        controller: -> {collapsed: true}
-      }
-      sandbox.stub(angular.element.prototype, 'parent').returns(fakeParent)
-      $element.scope().$emit('annotationUpdate')
-      assert.notCalled(fakePulse)
-
-    it 'does not pulse the thread if it is hidden (grandparent collapsed)', ->
-      fakeGrandParent = {
-        controller: -> {collapsed: true}
-      }
-      fakeParent = {
-        controller: -> {collapsed: false}
-        parent: -> fakeGrandParent
-      }
-      sandbox.stub(angular.element.prototype, 'parent').returns(fakeParent)
-      $element.scope().$emit('annotationUpdate')
-      assert.notCalled(fakePulse)
diff --git a/h/static/scripts/directive/thread.coffee b/h/static/scripts/directive/thread.coffee
index 6268830f16b..b42c0383b28 100644
--- a/h/static/scripts/directive/thread.coffee
+++ b/h/static/scripts/directive/thread.coffee
@@ -219,8 +219,8 @@ isHiddenThread = (elem) ->
 # Directive that instantiates {@link thread.ThreadController ThreadController}.
 ###
 module.exports = [
-  '$parse', '$window', '$location', '$anchorScroll', 'pulse', 'render',
-  ($parse,   $window,   $location,   $anchorScroll,   pulse,   render) ->
+  '$parse', '$window', '$location', '$anchorScroll', 'render',
+  ($parse,   $window,   $location,   $anchorScroll,   render) ->
     linkFn = (scope, elem, attrs, [ctrl, counter, filter]) ->
 
       # We would ideally use require for this, but searching parents only for a
@@ -239,15 +239,6 @@ module.exports = [
         counter.count 'message', 1
         scope.$on '$destroy', -> counter.count 'message', -1
 
-      # Flash the thread when any child annotations are updated.
-      scope.$on 'annotationUpdate', (event) ->
-        # If we're hidden, we let the event propagate up to the parent thread.
-        if isHiddenThread(elem)
-          return
-        # Otherwise, stop the event from bubbling, and pulse this thread.
-        event.stopPropagation()
-        pulse(elem)
-
       # The watch is necessary because the computed value of the attribute
       # expression may change. This won't happen when we use the thread
       # directive in a repeat, since the element will be torn down whenever the
diff --git a/h/static/scripts/pulse.coffee b/h/static/scripts/pulse.coffee
deleted file mode 100644
index 0a171fb362b..00000000000
--- a/h/static/scripts/pulse.coffee
+++ /dev/null
@@ -1,12 +0,0 @@
-###*
-# @ngdoc service
-# @name pulse
-# @param {Element} elem Element to pulse.
-# @description
-# Pulses an element to indicate activity in that element.
-###
-module.exports = ['$animate', ($animate) ->
-  (elem) ->
-    $animate.addClass elem, 'pulse', ->
-      $animate.removeClass(elem, 'pulse')
-]
diff --git a/h/static/styles/threads.scss b/h/static/styles/threads.scss
index bb750a13350..5fcc760eb41 100644
--- a/h/static/styles/threads.scss
+++ b/h/static/styles/threads.scss
@@ -28,14 +28,6 @@ $thread-padding: 1em;
     margin-left: -$thread-padding;
   }
 
-  @keyframes pulse {
-    10% { background-color: #ffc; }
-  }
-
-  &.pulse {
-    animation: pulse 1200ms ease-in-out;
-  }
-
   .thread {
     border-left: 1px dotted $gray-light;
     padding: 0;