To understand the practical applications in food, we must consider the digestive physiology and focus on the basics.Two types of mechanisms are important for digestion. This is the transit (through which food can advance in the gut) and digestive secretions (which will allow the digestion of food).The digestive tract consists of the oral cavity,pharynx,esophagus,stomach,small intestine consists of the duodenum, jejunum,ileum,large intestine consists of the cecum, rectum, colon and anus.
The dog takes the food with his teeth and chews it more or less time. This phase of food intake is very important for proper digestion. Food is coarsely ground, soaked with saliva, and this facilitates their assimilation.The nature of the food ingested will influence the speed of grasping and chewing. The dog then swallowed. However, occasionally incidents:
– The animal “sucks” the food
– It does not chew and swallowed immediately after grasping
Both cases involve poor digestion, and a risk of regurgitation. The causes of these incidents may be, for the wrong grip:
– Pain in the mouth or jaw
– A puppy too “pressed”
The absence of chewing is rather due to:
– Tooth pain
– The dilapidated state of jaw (old dog without teeth)
– Teething (puppies and young dogs)
Accordingly, as the case requires:
– “Teach” the puppy chewing by dividing the ration to calm
– Check the condition of the mouth and teeth
– Give a soft diet during teething problems
This is a mechanism that will allow the passage of food into the esophagus and not into the trachea, causing a false swallowing.
It proceeds as follows:
1. Chewing stops.
2. The tongue is pressed against the palate and hunt the food back.
3. The soft palate rises to close the communication with the nasal cavities.
4. Pharyngeal contraction brings food to the entrance of the esophagus.
5. The epiglottis tips over and obstructs the larynx (already partially obstructed by the tongue base).
6. Respiration is inhibited.
Once food is in the esophagus, a wave of contraction will take them forward. Coordination is achieved by the swallowing center,located in the bulb up to the central nervous system. During anesthesia, there may be “wrong ways”,that is to say an orientation of saliva or vomit into the trachea.Therefore,it is important to animals fasted before anesthesia.When everything goes smoothly, the animal swallows every bite chewed by lifting his head slightly and stretching his neck.The incidents are possible:
– A false swallowing food passes into the trachea
– Regurgitation, if swallowing is difficult
Causes can be considered for:
– Anatomical problems of birth (megaoesophage, malformations)
– Ingestion too fast
– A “sore throat”
– A tumor that compresses the esophagus
How to react? As the case may require:
– Raise the bowl so that the transit in the esophagus easier
– How to check a barium swallow radiograph then with where the food is “stuck”
Once in the stomach, food will undergo a number of movements brewing to blend with the gastric secretions and to advance towards the pylorus that will enter the intestine.The malfunction of the pylorus may cause vomiting.In dogs, the stomach is highly developed and the residence time of food is very high. In a man weighing 70 kg the volume of the stomach is 1 l to 1.4 l while in a dog of 20 kg is 3 s.
It is provided by the muscles of the intestinal wall. Defecation marks the end of transit. It is both an activity of the intestine itself and by activity of abdominal press (contraction of the abdominal muscles). The bad gastric transit may cause vomiting and poor bowel causes diarrhea or constipation.
Saliva is secreted in the oral cavity. It is essentially aqueous, colorless and shooting.It contains enzymes, particularly amylase attacking starch.Saliva will soak foods, contribute to the formation of “bolus” through mucus in it and encourage swallowing. Saliva is essential for proper digestion. The secretion of saliva is permanent, but is significantly reduced during sleep. The volume of saliva secreted per day in dogs is 0.4 l.
Some cells produce mucus that will line the gastric mucosa in order to protect others secrete hydrochloric acid, and others secrete pepsin, the enzyme attacks the food protein and digestion begins. Then, cells secrete a hormone called gastrin, which regulates a number of digestive mechanisms, in particular those involving the stomach.
Gastric juice is dangerous in large quantities, so there is a control system. Flavors and odors arrive very early: at meal time the dog. This causes the secretion of hydrochloric acid. This stimulation causes secretion of gastrin, which also activates the secretion of hydrochloric acid.Then, a distension of the stomach in turn stimulates the secretion of gastrin. Then chemical stimulation by certain foods will cause gastric secretion. Moreover, histamine is released locally and also stimulates the secretion of hydrochloric acid.The role of gastric digestion is to begin protein digestion by pepsin and acid. Its importance is paramount in dogs whose diet is rich in protein. Poor secretion of these enzymes prevents proper digestion of proteins.
It comes from the pancreas. This is a very important digestive juice because it contains a large number of enzymes capable of digesting all the constituents of the diet of the dog:
– Glucolytiques enzymes (specific carbohydrate), especially amylase attacking the starch
– Lipolytic enzymes such as lipases attack fats
– Proteolytic enzymes: trypsin, chymotrypsin continuing the digestion of protein that was started in the stomach by pepsin
Bile is secreted by the liver. This is a very bitter liquid, greenish yellow, stringy, which occurs in the duodenum by the bile duct either directly or after being stored in the gallbladder.Bile contains bile salts formed from cholesterol and bile pigments, in particular bilirubin, which comes from the degradation of hemoglobin. The main role of bile is to promote the digestion of lipids.
In fact, that lipids can be digested by the lipase of pancreatic juice, it is necessary that these lipid molecules have been previously divided by bile salts. When bile secretion is insufficient, the fats are not or are poorly digested, the other constituents of the chyle are coated with these undigested fats and in turn, promoting the development of micro-organisms, fecal fat and will nauseous.If the digestive secretions are suffering from a malfunction, the digestion of basic constituents is not assured. We will solve this problem by a specific treatment and / or adaptation of the diet: no starch, or no protein, or fat-free.The absorption of various nutrients.It is mainly during the passage in the small intestine, which has a large mucosal number of folds each forming delimited by villus cells. The various constituents of the diet are digested and absorbed as follows.
• For carbohydrates, eg starch:
– In the mouth, salivary amylase attack
– In the stomach: no processing for starch
– In the duodenum: attack by pancreatic amylase
• For proteins:
– In the stomach by pepsin attack favored by the acidic
– In the duodenum: attack by the enzymes of pancreatic juice
• For lipids:
– In the duodenum: attack (when bile salts are present) by pancreatic lipase and penetration into the intestinal cells.