Oral Anatomy and Physiology in the Companion Animal
This chapter provides a synopsis of the anatomy and physiology of the gastrointestinal tract of small animals, specifically cats and dogs. The stomach is both a grinding organ and a reservoir, metering foodstuffs into the small intestine for further proce
- PDF / 271,402 Bytes
- 10 Pages / 439.37 x 666.14 pts Page_size
- 30 Downloads / 216 Views
Oral Anatomy and Physiology in the Companion Animal Steven C. Sutton
Abstract This chapter provides a synopsis of the anatomy and physiology of the gastrointestinal tract of small animals, specifically cats and dogs. The stomach is both a grinding organ and a reservoir, metering foodstuffs into the small intestine for further processing and absorption. The small intestine is the primary site of absorption. On the one hand, the gastrointestinal tracts’ acidified stomach contents may result in the precipitation of pharmaceuticals. On the other hand, in response to food, the secretion of pancreatic fluid, bile salts and lecithin in the small intestine may result in a fine emulsion that facilitates the aqueous solubility and subsequent absorption of the pharmaceutical ingredient (API). The large intestine (cecum and colon) completes the processing and absorption of nutrients. Absorption of the API in this region is balanced by its solubility and residence time in this organ. This chapter shows that there appear to be many similarities in the anatomy and physiology of mammals.
4.1
Introduction
The diversity of companion animal species and breeds has exploded in recent years. The Humane Society lists the following categories for pets: dogs, cats, hamsters, gerbils, guinea pigs, rabbits, ferrets, horses, pet birds, rats, mice, and fish [1]. Despite these broad definitions of companion animals this chapter will focus on dogs and
S.C. Sutton (*) College of Pharmacy, University of New England, 716 Stevens Avenue, Portland, ME 04103, USA e-mail: [email protected] M.J. Rathbone and A. McDowell (eds.), Long Acting Animal Health Drug Products: Fundamentals and Applications, Advances in Delivery Science and Technology, DOI 10.1007/978-1-4614-4439-8_4, © Controlled Release Society 2013
59
60
S.C. Sutton
cats, as these are the most common species seen by veterinarians. But since the American Kennel Association lists hundreds of breeds—from the Affenpinscher to the Yorkshire Terrier [2]—it would not be accurate to generalize physiologic properties to all dogs. For example, canine body weights range from the 2 pound Chihuahua to the 120 pound Great Dane [3]. In some respects, cats and dogs are more different than the differences among dog breeds. While a ten pound Papillon dog may seem the same size as a ten pound Maine Coon cat, their eating habits are quite different. Diversity aside, in this chapter, an attempt will be made to provide some careful generalizations, while keeping in mind the most notable exceptions. As we will see, it is tempting to speculate that the carnivorous cat, accustomed to numerous small daily meals, evolved a smaller stomach and shorter intestine, since that was all that the animal required to process food. In contrast, the omnivorous dog—accustomed to eating fewer, larger meals—would have to use a larger stomach and a much longer intestine for its digestive needs.
4.2
Stomach
Very little absorption of nutrients or pharmaceuticals takes place in the stomach: it is both a mixing/grinding organ a
Data Loading...
