68 SWINE PRACTICE 



incisors are covered with enamel. The canines, or tushes, are larger 

 in the boar. In extreme eases the upper canines maj^ reach a length 

 of i inches and the lowers 8 to 10 inches. These teeth are relatively 

 small in sows. 



The first premolars are separated })y a space from the canines and 

 are relatively small. The premolars increase in size from the first 

 to the fourth. The first and second molars are larger than the 

 fourth premolar, but the third molar is relatively small. 



The formula for the permanent teeth is as follows: 



2(ltC|PM|M I) =+4 



The average periods of eruption of the teeth of swine, according 

 to Sisson, is as follows: 



Temporary. Permanent 



Ij 2-4 weeks 12 months 



T [upper — 2-3 months 



' |lower— 1i/o-2 months 16-20 months 



I3 Before birth 8-10 months^ 



C Before birth '. f-10 months 



PM, 5 months.. 



PM, 5-7 weeks 



pjf Jupper — 4-8 daj^s 



I lower — 2-4 weeks 



pj^j r upper — 4-8 days 



1 lower — 2-4 weeks 



^Ii 4-6 months 



M2 8-12 months 



M3 18-20 months 



PHARYNX 



The pharynx is an irregular cavity common to the digestive and 

 respiratory system and is located posterior to the posterior nares 

 and mouth and anterosuperior to the larynx and esophagus. There 

 is a median fold of mucous membrane superiorly, on either side 

 of which is the opening of the eustachian tube. In the posterior 

 portion of the pharynx there is a cul-de-sac, which is the source 

 of much annoyance in the administration of capsules. 



12-15 months 



