Annual  Report  for  1909  of  Royal  Veterinary  College.  335 
Usually,  the  lesions  in  lambs  are  confined  to  the  lips  and 
mouth,  and  in  ewes  to  the  udder  and  teats,  though  sores  may 
form  on  the  lips  and  mouths  of  ewes  also.  Unless  a very 
sharp  look  out  be  kept,  these  lesions  usually  escape  detection 
until  they  have  been  converted  into  raised  sores  covered  by 
brownish  crusts  or  scabs,  but  the  earliest  stage  on  the  skin  of 
the  nose  or  lips  is  one  in  which  the  part  becomes  swollen,  hot, 
and  tender,  while  at  one  or  more  circumscribed  raised  spots  the 
epidermis  becomes  rough  and  slightly  moist  from  escaping 
liquid.  This  liquid  tends  to  dry  up  between  and  around  the 
roots  of  the  hair,  and  in  this  way  a distinct  scab,  or  crust,  is 
soon  produced.  Forcible  detachment  of  the  scab  exposes  a 
wart-like  elevation  with  a raw  red  surface,  which  readily  bleeds 
but  soon  becomes  covered  again  with  a second  scab.  It  has  not 
been  possible  to  follow  with  the  same  precision  the  course  of 
the  much  rarer  lesions  on  the  tongue.  On  the  teats  and  udder 
the  course  is  the  same  as  on  the  lips,  but  the  sores  here  are 
often  larger  and  may  be  converted  into  ulcers,  while  healing 
is  retarded  by  the  displacement  of  the  crusts  in  the  act  of 
sucking.  The  lesions  usually  attain  their  full  development 
within  a few  days  or  a week,  and  healing  gradually  takes  place 
under  cover  of  the  scab,  which  eventually  falls  off,  leaving  a 
hairless  spot. 
Although  the  common  seats  of  the  disease  are  those 
mentioned  above,  sores  are  occasionally  formed  on  other  parts 
of  the  skin  in  young  lambs,  and  in  ewes  inside  the  thighs. 
The  uncomplicated  disease  is  seldom  or  never  fatal,  but  it 
often  occasions  a serious  loss  of  condition  through  interference 
with  sucking  and  mastication.  When  the  disease  makes  its 
appearance  in  a flock  it  may  spread  rapidly,  and,  although  it 
is  not  certain,  it  appears  to  be  probable,  that  it  is  transmitted 
solely  by  contact  between  a sore  and  healthy  skin  or  mucous 
membrane.  In  this  way  it  may  spread  by  the  mutual  rubbing 
of  noses,  or  by  feeding  of  diseased  and  healthy  out  of  a common 
trough.  The  lesions  on  the  teats  and  udders  in  the  ewes 
appear  to  be  always  ascribable  to  contact  with  sores  on  the 
noses  and  lips  of  the  previously  diseased  lambs. 
During  the  past  year  an  exceptionally  severe  outbreak  of 
this  disease  occurred  in  a flock  of  Hampshire  Down  ewes  and 
lambs  on  the  Home  Farm  of  Mr.  E.  W.  Stanyforth,  Kirk 
Hammerton  Hall,  York,  and  as  the  reported  symptoms  were 
in  some  respects  unusual,  a visit  was  paid  to  the  flock  by 
Professor  Macqueen.  His  investigations  showed  that  the 
disease  was  undoubtedly  malignant  aphtha,  but  that  the 
mouth  and  lip  lesions  were  exceptionally  severe  in  the  ewes, 
and  in  a considerable  number  of  cases  were  accompanied  by 
foot  lesions.  The  latter  usually  set  in  about  a week  or  ten 
