diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index a4046061aa3779cdd5249c590615cf8f41a2b971..be7eba5b0c58ad4dc996948850ebab057da4baac 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Added support for pluralization with a different starting letter than the singular version (cow/kine) #4929 [norri_b/hasmanyjosh]
+
 * Demote Hash#to_xml to use XmlSimple#xml_in_string so it can't read files or stdin.  #8453 [candlerb, Jeremy Kemper]
 
 * Backport clean_logger changes to support ruby 1.8.2 [mislav]
diff --git a/activesupport/lib/active_support/inflections.rb b/activesupport/lib/active_support/inflections.rb
index f53ef53ca453452bded676194607e43fa02f4593..967722c2bfa3f4a1b9e4ed7d985bfa709f7d0c49 100644
--- a/activesupport/lib/active_support/inflections.rb
+++ b/activesupport/lib/active_support/inflections.rb
@@ -47,6 +47,7 @@
   inflect.irregular('child', 'children')
   inflect.irregular('sex', 'sexes')
   inflect.irregular('move', 'moves')
+  inflect.irregular('cow', 'kine')
 
   inflect.uncountable(%w(equipment information rice money species series fish sheep))
 end
diff --git a/activesupport/lib/active_support/inflector.rb b/activesupport/lib/active_support/inflector.rb
index 084c58d38918896cce97b2597be6f6f9288eba5f..db6e44e91b9fb93fa8c1875c742a388909727ace 100644
--- a/activesupport/lib/active_support/inflector.rb
+++ b/activesupport/lib/active_support/inflector.rb
@@ -47,8 +47,15 @@ def singular(rule, replacement)
     #   irregular 'octopus', 'octopi'
     #   irregular 'person', 'people'
     def irregular(singular, plural)
-      plural(Regexp.new("(#{singular[0,1]})#{singular[1..-1]}$", "i"), '\1' + plural[1..-1])
-      singular(Regexp.new("(#{plural[0,1]})#{plural[1..-1]}$", "i"), '\1' + singular[1..-1])
+      if singular[0,1].upcase == plural[0,1].upcase
+        plural(Regexp.new("(#{singular[0,1]})#{singular[1..-1]}$", "i"), '\1' + plural[1..-1])
+        singular(Regexp.new("(#{plural[0,1]})#{plural[1..-1]}$", "i"), '\1' + singular[1..-1])
+      else
+        plural(Regexp.new("#{singular[0,1].upcase}(?i)#{singular[1..-1]}$"), plural[0,1].upcase + plural[1..-1])
+        plural(Regexp.new("#{singular[0,1].downcase}(?i)#{singular[1..-1]}$"), plural[0,1].downcase + plural[1..-1])
+        singular(Regexp.new("#{plural[0,1].upcase}(?i)#{plural[1..-1]}$"), singular[0,1].upcase + singular[1..-1])
+        singular(Regexp.new("#{plural[0,1].downcase}(?i)#{plural[1..-1]}$"), singular[0,1].downcase + singular[1..-1])       
+      end
     end
 
     # Add uncountable words that shouldn't be attempted inflected.
diff --git a/activesupport/test/inflector_test.rb b/activesupport/test/inflector_test.rb
index 9849e0b52b5cc6ec5f9ff32d5125c911ff9ca15c..684150a9255304b42a7c645657b9b2e2e1a50e8e 100644
--- a/activesupport/test/inflector_test.rb
+++ b/activesupport/test/inflector_test.rb
@@ -104,7 +104,9 @@ class InflectorTest < Test::Unit::TestCase
 
     "horse"       => "horses",
     "prize"       => "prizes",
-    "edge"        => "edges"
+    "edge"        => "edges",
+
+    "cow"         => "kine"
   }
 
   CamelToUnderscore = {