Tuberculosis. 
45 
of  the  herd.  By  accidental  infection  is  here  meant  the  con- 
veyance of  bacilli  from  the  premises  in  which  the  diseased 
animals  are  kept  into  those  set  apart  for  the  healthy  division. 
It  is  quite  impossible  to  ensure  that  this  will  not  take  place 
when  the  two  sets  of  buildings  are  contiguous,  or  even  when 
they  are  some  distance  apart,  if  there  is  only  one  set  of  milkers 
or  attendants  for  the  whole  of  the  animals.  If  the  diseased 
and  the  healthy  are  allowed  to  mix  at  grass  there  will  be  an 
added  risk  of  infection,  and  the  risk  becomes  serious  if  reacting 
animals  are  kept  on  after  they  have  developed  distinct  signs  of 
disease,  such  as  wasting,  cough,  or  discharge  from  the  genital 
passages.  It  cannot  be  too  strongly  insisted  on  that  a const  ant 
outlook  must  be  kept  for  symptoms  of  tuberculosis  in  the 
reacting  animals,  and  any  animal  presenting  such  symptoms 
should  be  immediately  destroyed.  And  in  this  connection  it 
may  also  be  stated  that  blind  reliance  should  not  be  placed  on 
non-reaction  to  tuberculin  ; the  healthy  section  of  the  herd  must 
also  be  carefully  watched,  in  order  that  any  animal  developing 
suspicious  symptoms  may  be  promptly  isolated  or  destroyed. 
In  conclusion  it  may  be  said  that  no  one  who  is  well 
acquainted  with  the  circumstances  will  venture  the  opinion 
that  for  the  average  British  farmer  the  elimination  of  tubercu- 
losis from  his  herd  is  an  easy  task.  The  fact  that  as  yet  few 
have  attempted  it  is  no  doubt  partly  due  to  obvious  difficulties, 
of  which  the  chief  are  inadequate  housing  accommodation  and 
inability  to  make  the  sacrifice  involved  in  selling  valuable 
breeding  or  milking  animals  at  butchers’  prices.  It  must  also 
be  confessed  that  in  many  cases  inability  to  see  any  promise  of 
adequate  reward  for  the  trouble  and  expense  necessary  to  stamp 
out  the  disease  is  largely  responsible  for  the  inaction.  The 
actual  loss  attributable  to  the  disease  is  often  not  very  great, 
even  in  herds  where  a considerable  proportion  of  the  adult 
animals  are  infected,  and  there  is  as  yet  a difficulty  in  obtaining 
a higher  price  for  the  milk  of  cows  proved  to  be  free  from 
tuberculosis.  But  the  valuable  pedigree  herds  of  this  country 
stand  on  a different  footing.  In  the  majority  of  them  sufficient 
housing  accommodation  to  make  possible  the  separation  of  the 
diseased  and  the  healthy  already  exists  or  could  be  provided 
without  serious  expense,  and  there  would  be  an  undoubted 
gain  in  the  higher  prices  obtainable  for  animals  sold  with  a 
guarantee  of  freedom  from  tuberculosis.  The  purification  of 
these  herds  could  not  fail  to  be  profitable  to  their  owners,  and 
it  would  provide  the  object  lesson  most  needed  to  encourage 
breeders  in  general  to  wage  systematic  war  against  this  wide- 
spread disease.  John  McFadyean. 
Royal  Veterinary  College, 
London,  N.W. 
