92 ESSENTIALS OF VETERINARY LAW 
be added on either side there should be a definite 
agreement in writing. For example: It is not 
ordinarily understood that there is any warranty 
on the part of the physician or surgeon as to the 
results of his services, not even that they will be 
beneficial! A conditional contract between a 
patient and his physician, that if the physician 
effect a cure he should receive a reasonable com- 
pensation, is valid.? 
71. Competency. Where there is no law regu- 
_lating the practice of veterinary medicine it has 
been held, in an action to recover for professional 
services, that the plaintiff must prove his quali- 
fications as a veterinarian.? In other words, where 
the law imposes no restriction or qualification in 
the practice of the profession, the fact that a 
man renders a service is not of itself evidence that 
he is entitled to compensation as a veterinarian. 
He might be regarded as simply entitled to com- 
pensation for his labor, and not for professional 
opinion and knowledge. 
Where the law regulates the practice, by re- 
quiring either registration or license, there has 
been some difference of interpretation as to re- 
quirements in suits for professional fees. Thus, 
in England it has been held that the fact that an 
apothecary’s assistant had been paid for medi- 
cines could not be considered as proof that he was 
1Tefft v. Wilcox, 6 Kas. 46; 7 Carr. & P. 81; Patten v. 
Styles v. Tyler, 64 Conn. 432, Wiggin, 51 Me. 594. 
30 Atl 165; McCandless v. 2 Mock v. Kelly, 3 Ala. 387. 
MeWha, 22 Harris (Pa.) 261; 3Conkey v. Carpenter, 106 
Gallaher v. Thompson, Wright Mich. 1, 63 N. W. 990. 
(Ohio) 466; Hancke v. Hooper, 
