Chinchilla

　　Digestive System

　　The incidence of dental diseases increases with age. With the formation of tartar, many oral diseases gradually appear, including gingivitis, gingival hyperplasia, periodontal disease, gingival recession, and bone loss, even tooth loosening and loss. Of course, old cats may also suffer from alveolar demineralization due to calcium deficiency, which leads to tooth loss. Periodontal disease causes chronic absorption of bacterial toxins, which may induce airway constriction and eventually lung disease; intermittent bacteremia may also occur, leading to endocarditis or nephritis.

　　With aging, the number of neurons in the sympathetic ganglia of the esophagus and the enteric plexus decreases gradually, leading to loss of esophageal muscle tone and reduced motility. The gastric mucosa gradually atrophies and becomes fibrotic, and the incidence of spontaneous megacolon also increases, possibly due to relative decrease or degeneration of intestinal ganglia.　　The number of liver cells decreases, fat proportion in the liver increases, and mild fibrosis appears; liver function gradually declines, which is very important for drug metabolism. Bile and intestinal secretions decrease, and pancreatic enzyme release also reduces; the height and width of intestinal villi gradually decrease, and renewal capacity of intestinal epithelial cells reduces. This series of changes leads to reduced calcium and lipid absorption, resulting in a deficiency of fat-soluble vitamins.