11 Digestive tract J. Rothuizen, E. Schrauwen, L.F.H. Theyse and L. Verhaert Chapter contents Abdominal lymph nodes96 Percussion 96 11.1 History87 Auscultation 97 11.2 Physical examination88 Generation of splashing sounds97 11.2.1 Head88 Undulation test97 Introduction 88 11.2.4 Anus and circumanal 97area Chewing musculature88 Introduction 97 Oral cavity88 Inspection 98 Pharynx, tonsils, and soft Fig.palate 11.1 ) 90 ( Palpation 98 Salivary glandsFig. ( 11.2) 90 11.2.5 Rectum and adjacent structures99 Hyoid bones90 Introduction 99 Technique 90 Technique and interpretation99 Teeth 91 Anus 99 Hard palate93 Rectum 99 Tongue 93 Coccygeal and levator ani muscles99 Pharynx 94 Internal iliac lymph nodes100 11.2.2 Esophagus94 Pelvic bones100 Introduction 94 Prostate 100 Technique and interpretation94 11.3 Notation100 11.2.3 Abdomen94 11.4 Further examination100 Introduction 94 Inspection 94 Palpation 95 Superficial palpation95 In addition to the symptoms described by the owner in Deep palpation95 the general history (Chapter 6), such as dysphagia (difficult swallowing or complete inability to swallow), Palpation of the kidneys and urinary vomiting, abnormal feces, and abnormal defecation, tract 95 several other symptoms may originate from the Palpation of the 95liver digestive tract. These will be discussed below in the Palpation of the spleen96 specific history. When there is suspicion of aspiration Palpation of the pancreas96 pneumonia, as can occur with swallowing disorders, Palpation of the ovary, uterus, and the history and physical examination must be extended prostate 96 to include the respiratory tract (Chapter 9). Palpation of the stomach96 The examination of the digestive tract is usually Palpation of the intestinal 96tract limited to that part relevant to the problem which has now been formulated (Chapter 3). Rectal examination 86 History is not needed when the problem is dysphagia, nor is retrograde expulsion of vomitus. This is often preceded by examination of the upper digestive tract necessary swallowing, salivation, and restlessness (symptoms of when the problem is tenesmus alvi (painful, repeated nausea). Active vomiting is a reflex phenomenon. urgency to defecate). If a complete examination of the Neurogenic stimuli which lead to vomiting stimulate the digestive tract is indicated, then the examination vomiting center in the brainstem. Humoral stimuli that proceeds in sequence: mouth, pharynx, esophagus, lead to vomiting stimulate the chemoreceptor center, from abdomen, anus and perineum, and rectum. which the vomiting center is then stimulated. Stimulation of the vomiting center leads to coordinated muscle 11.1 History activity, of which the contractions of the muscles of the abdominal wall are the most striking. The best known manifestations of abnormal functioning of The term diarrhea is used when the characteristics the digestive tract are vomiting and diarrhea. These of the feces are changed by an increase in the volume symptoms will be discussed in detail below and a series of and/or percentage of water. Diarrhea is also often specific questions will be presented together with examples. used to describe an increased defecation frequency, with These questions also illustrate the importance of a careful or without an increase in volume or water content. history for further specifying the problem definition. Similar to the important distinction between vomiting In ‘vomiting’ animals, questions must be asked to and regurgitation, it is essential to distinguish between differentiate between regurgitation and active vomiting. small bowel diarrhea and large bowel diarrhea. Regurgitation is the passive, retrograde expulsion of A small bowel diarrhea occurs when the effluent contents from the throat, esophagus, or stomach. The act from the small bowel to the large bowel is so changed of regurgitation is ‘passive’ in the sense that it is not a in volume and composition that in spite of the reserve recognizable, reflex-determined phenomenon. Expulsion capacity of the colonic mucosa to absorb water, the occurs under the influence of the position of the head final contents and hence the feces are too voluminous and neck, gravity, the intrathoracic pressure, the and/or too watery. This form of diarrhea can be caused pressure relation between the thorax and abdomen, and by an increased osmotic value of the intestinal the pressure in the abdomen. The manifestation of contents, or by increased secretion and/or exudation of regurgitation can vary greatly with regard to the nature of the intestinal mucosa, and/or by abnormal motility. the regurgitated material, the amount, and the time after Large bowel diarrhea occurs as the result of abnormal eating. Regurgitation of food during eating can indicate an colon motility, reduction of the absorptive surface of the inability to relax the proximal esophageal sphincter colonic mucosa, or increased secretion and/or exudation (cricopharyngeal achalasia) or the presence of pharyngeal in the colon. The most characteristic features are paralysis. Regurgitation of large amounts of mucus or summarized in Table 11.1.Thetableoncemoreillustrates food, independent of food intake (thus both before that the distinction between small bowel diarrhea and and after), is usually related to esophageal paralysis. large bowel diarrhea relies on findings in the history. Regurgitation of large amounts of food may occur with pyloric stenosis. Occasionally, regurgitation is Questions that can be asked about problems that may characterized by belching of fluid, which can be due to involve the digestive tract are given below, with a few dysfunction of the cardia or it can be due to pyloric stenosis. examples to illustrate their relevance. We speak of active vomiting when there are active Development. After determining the age at which the contractions of the abdominal muscles before the animal was acquired by the present owner, the next step Table 11.1 Most characteristic differences between small bowel diarrhea and large bowel diarrhea. This distinction is only important in chronic diarrhea. Not all of the criteria have to be present for either type and there can be some overlapping small bowel diarrhea large bowel diarrhea Defecation frequency Low High Tenesmus Rare Often (persisting) Volume of feces Large Small Mucus in feces Rare Often Blood in feces Rare Often Polydipsia Often Rare Polyphagia Often Rare Borborygmi and flatulence Often Rare Weight loss Often Rare 87 Chapter 11: DIGESTIVE TRACT is to ask when gastrointestinal problems were first through the pharynx and esophagus to the stomach. noticed. Food intolerance generally appears at a young Dogs and cats hold large pieces of food with the front age, whereas enteritis is most often seen in young adult feet and then tear off pieces mainly with the incisor to middle-aged animals. Neoplasia is more likely to be and canine teeth. Larger pieces can be cut off with the involved in gastrointestinal problems in older animals. carnassials (fourth premolars in upper jaw and first Course. Knowing whether the problem is continuous molars in lower jaw). The incisor teeth are used to or episodic is often helpful. Enteritis is often episodic, pick up smaller pieces of food or to tear them loose. while exocrine pancreatic insufficiency (EPI) results in Dogs and cats only marginally chew their food. The continuous problems without spontaneous remission. premolars are mainly suited for holding the food (prey). Further characterization of the problem. The iatrotropic The teeth of cats are characteristic of a real carnivore, problem (} 3.1.1) is documented and further described. whereas those of dogs have some characteristics of an Apart from vomiting and/or diarrhea (see above) there omnivore. In dogs the upper and lower molars have a may be associated problems such as anorexia, dysphagia grinding occlusal surface. (swallowing problems), or bloody feces. By means of the short ‘catching’ movements of the Additional symptoms may include: head, which are very noticeable in the dog, the food, – Decreased appetite, which is considered to be very which is held and guided by the hard palate, cheeks serious if associated with weight loss. Malignancy and tongue, is moved caudally. Saliva is added while (gastric carcinoma, malignant lymphoma) should the food is broken or ground into slightly smaller be considered. pieces by the molars. The bolus of food formed in this – Weight loss may not only be caused by decreased way is pressed against the hard palate by the tongue food intake, but may also be the result of and then by contraction of the muscles of the pharynx maldigestion/malabsorption. it is brought into the esophagus. – Pica is the tendency to eat things that are The soft palate closes off the nasopharynx in this inedible for dogs and cats, such as potato process. The larynx is pulled more or less under the peelings or cloth. It may be the result of extreme root of the tongue and together with tension on the hunger, as can occur in EPI. Eating grass or vocal folds, the airway is closed off. other plants may be a prodrome (forerunner) of vomiting and may be one of the manifestations Chewing musculature of nausea. Of these muscles the masseter and temporal muscles are – General signs of illness. Lethargy associated with a accessible for physical examination. The masseter gastrointestinal problem usually indicates a serious muscle is on the lateral surface of the ramus of the disorder. It can also be secondary to one of the mandible, ventral to the zygomatic arch. The temporal consequences of gastrointestinal disease, such as muscle is the largest and strongest muscle of the head dehydration. Conversely, a problem outside the and lies in the temporal fossa. Both muscles are gastrointestinal tract may lead to general illness important in opening and closing the mouth. with vomiting, as occurs in renal disease when accumulating waste products trigger the vomiting Oral cavity center. – Manifestations of abdominal pain. Conditions such The mouth or oral cavity lies between the mouth opening as acute pancreatitis and intestinal foreign body and the entrance to the throat.