Tuberculosis. 
43 
article  will  have  made  it  plain  that  such  a practice  involves 
no  risk  that  the  disease  will  be  handed  on  from  the  bull  to 
the  calves,  and  the  danger  to  the  cows  is  so  slight  that  it  may 
be  faced,  provided  always  that  the  bull  appeal’s  healthy  or  is 
kept  isolated  except  when  his  services  are  required. 
It  has  already  been  laid  down  as  a rule  that  the  first  step 
towards  elimination  ought  to  be  to  test  the  whole  of  the  herd 
in  order  to  ascertain  what  progress  the  disease  has  already 
made  in  it.  This  was  the  plan  originally  favoured  by  Professor 
Bang  in  Denmark,  but  he  subsequently  advised,  or  at  least 
sanctioned  as  an  alternative,  that  the  owner  should  refrain 
from  testing  the  adult  breeding  animals,  and  agree  to  regard 
them  as  all  infected.  The  reasons  assigned  for  this  plan  are — 
(1)  that  if  the  herd  is  tuberculous  to  any  extent  a very  large 
proportion,  or  even  a decided  majority,  of  the  adult  animals 
may  be  expected  to  react  ; (2)  that  a number  of  the  older 
animals  may  fail  to  react  although  actually  diseased  ; and 
(3)  that  the  discovery  that  a large  proportion  of  the  breeding 
animals  are  already  affected  is  apt  to  discourage  the  owner 
and  lead  him  to  abandon  all  hope  of  being  able  to  eliminate 
the  disease  entirely.  The  force  of  these  reasons  cannot  be 
denied,  and  it  is  even  possible  to  add  others  in  favour  of  the 
plan  of  leaving  the  older  animals  untested.  One  is  that  most 
owners  would  prefer  not  to  know  for  certain  that  animals 
which  they  cannot  afford  to  dispose  of  immediately  are 
tuberculous.  That  this  is  a consideration  likely  to  be  taken 
into  account  both  by  owners  of  milking  herds  and  by  those 
who  breed  pedigree  animals  is  sufficiently  obvious,  and  the 
ultimate  decision  as  to  whether  the  adult  animals  are  to  be 
tested  or  not  must  be  left  to  the  owner  himself. 
It  may,  however,  be  maintained  that  it  is  as  a rule  the 
wisest  plan  to  submit  the  entire  herd  to  the  tuberculin  test 
at  the  outset,  and  this  plan  will  find  immediate  justification 
when  the  result  of  the  test  is  to  show  that  only  a minority 
of  the  adult  animals  are  diseased. 
"What,  it  may  now  be  asked,  is  the  time  within  which  the 
owner  of  a tuberculous  herd  may  reasonably  expect  to  obtain 
a clean  bill  of  health  for  his  stock,  provided  the  disease  is 
resolutely  attacked  on  the  lines  laid  down  in  the  preceding 
pages  ? To  this  question  no  short  and  precise  answer  can  be 
given,  as  the  period  depends  upon  the  original  condition 
of  the  herd,  the  financial  position  of  the  owner,  the  separate 
housing  accommodation  available  for  the  reacting  and  the  non- 
reacting  animals,  and  the  intelligence  and  consistency  with 
which  the  preventive  measures  are  carried  out. 
It  is,  of  course,  a priori  obvious  that  when  a large  propor- 
tion of  the  breeding  animals  react  to  the  first  test,  and  financial 
