Better Pork - April 2007

Nutrition

Swine dentistry 101 – What you should know about a pig’s teeth

The process of digestion starts in a pig’s mouth and is one of the keys to its health. Test your knowledge with this handy quiz

by JANICE MURPHY

We are a long way from having mainstream pig dentists, but recent research has highlighted the important role dental health can play in our modern swine production systems. While nutritionists are concerned with getting properly balanced rations into the mouths of pigs, the reality is that it is up to the pig and its digestive system to take it from there.

The process of digestion starts in the mouth, where chewing performs two important functions. First, the grinding action of the teeth breaks down the feed into smaller particles to make it easier to swallow and increase the surface area that is exposed to enzymes. Second, chewing mixes the feed with saliva, which lubricates it and adds the cocktail of enzymes that begins to break down the feed.

Pigs are not known for chewing their feed much. They take feed into their mouths and crunch it down with their molars, then mix it around to get it sufficiently lubricated to swallow.

So, what happens when pigs are unable to chew properly to begin that process of digestion? Testing our knowledge of the dentistry of pigs may unlock some important pieces to the puzzle.

1. At market weight, pigs have already shed their baby teeth and are eating with their mature, permanent teeth.
a) True b) False

2. Producers have traditionally clipped needle teeth in newborn piglets to:
a) Limit facial lesions in littermates
b) Limit udder lesions on the sow
c) Eliminate problems with greasy
          pig disease
d) All of the above
e) None of the above

3. Some producers are abandoning teeth clipping in order to:
a) Spend more time cleaning and disinfecting
b) Decrease the number of poor-doing pigs and joint infections
c) Eliminate problems with greasy pig disease
d) All of the above
e) None of the above

4. The most common dental problem observed in mature sows is:
a) Tartar build-up/gingivitis
b) Periodontal disease with gum recession and root exposure
c) Tooth wear (molars and incisors)
d) Tooth loss
e) Sows do not experience any significant dental issues

5. Pig’s teeth can be grown in rats.
a) True b) False

Answers
1. (b) In pigs, the transition from baby, or deciduous, teeth to permanent teeth occurs between eight and 20 months. The mature pig’s mouth houses 44 teeth (see Table 1), with three incisors, one canine, four pre-molars and three molars on each side of the jaw (both upper and lower).

2. (d) Piglets are born with eight sharp needle teeth which they use to establish pecking order within the litter and lay claim to one or more teats. The fighting that ensues may result in lesions on the face of littermates and the udder itself.

Research in Michigan followed 318 litters and found that, during the first three days of life, facial lesions were nearly twice as severe in litters with intact teeth as in litters with clipped teeth, compared to 10 per cent in clipped litters at 13 days of age. A Canadian study reported that facial lesions in their intact-teeth group were severe enough to have nine of the 19 litters removed from their experiment.

The facial lesions themselves can also favour development of greasy pig disease in some herds. Greasy pig disease is caused by Staphylococcus hyicus, bacteria that lives on the skin’s surface. When the skin is cut, this allows the bacteria to enter the body. There are reports that some producers who stopped teeth clipping noticed more piglets with greasy pig disease and, as a result, resumed clipping.

3. (b) If teeth clipping is not done properly, it can result in damage to the gums or roots of the teeth. For example, when teeth are clipped too close to the gum, the gums can be cut in the process and open the door to infection. If the clipper is dull or broken, the teeth can splinter or split down into the roots instead of neatly cutting off the sharp points of the teeth.

Any infection that gets into the roots of the teeth is extremely painful and can prevent the piglet from eating. Quite often the first sign of a tooth infection is a poor-doing piglet. Joint infections in piglets can be caused by Streptococcus suis, bacteria which can enter the piglet’s bloodstream through damaged gums or broken teeth.

4. (c) Research by veterinarian E. Wayne Johnson, working with swine behaviour specialist Stanley Curtis at the University of Illinois, examined the teeth of 82 culled sows in two packing plants. In their ground-breaking work, they discovered that 62-63 per cent of culled sows experienced tooth wear and 85 per cent had more than one abnormality that they presumed would cause a problem (see Table 2). Other common problems included tartar build-up, gingivitis and periodontal disease with gum regression and root exposure, as well as tooth loss.

As for an explanation of what may cause these dental problems in sows, the finger often points to bar-biting. But the fact that these problems exist in sows without anything to bite, like pastured sows, suggests that this is not the issue. Teeth grinding could be another possibility. And then there’s nutrition.

Johnson questions whether the culprit may be the diet that is fed during the critical four to six months of age, when permanent molars are erupting. He suggests that further research needs to focus on minerals such as molybdenum, which has been shown to improve tooth hardness, and boron. Calcium-phosphorus balance could also play a role. Johnson himself hopes to study the role that vitamin C deficiency might play in periodontal disease in sows, as it has also been shown to have an effect in people.

5. (a) In 2002 researchers in Boston succeeded in growing new pig's teeth in the body of rats.  The team at the Forsyth Institute managed to produce molars from cells extracted from the tooth buds of six-month-old pigs. The researchers seeded the cells onto biodegradable scaffolds, which were then transplanted into rat abdomens and allowed to develop for 30 weeks. The goal of this research was to develop a method for growing mature tooth crowns for humans. BP

Janice Murphy is the former Swine Nutritionist with the Ontario Ministry of Agriculture, Food and Rural Affairs.

Sources:
Johnson, W.E., S. E. Curtis and M. Ellis. 2003. Dental disease in sows: early findings. Allen D. Leman Swine Conference 2003, University of Minnesota. Miller, D. 2006. Sow dentistry 101. National Hog Farmer. January 15, 2006. Reese, D.E and B.E. Straw. 2005. Teeth Clipping - Have You Tried to Quit? Nebraska Swine Report 2005, University of Nebraska - Lincoln. Young, C.S., S. Terada, J.P. Vacanti, M. Honda, J.D. Bartlett and P.C. Yelick. 2002. Tissue engineering of complex tooth structures on biodegradable polymer scaffolds. Journal of Dental Research 81(10): 695-700.