Weight loss, anorexia, abdominal pain
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WEIGHT LOSS OR ANOREXIA OF UNKNOWN CAUSE
Weight loss has many causes (Table 9-11 ). Concurrent problems with fewer potential causes (e.g., regurgitation, vomiting, diarrhea, icterus) should be considered first. If a patient had a reasonable appetite when weight loss began, major differential diagnoses are intestinal disease, maldigestion, increased use of calories (e.g., hyperthyroidism, lactation), or increased loss of calories (e.g., diabetes mellitus). If no other identifiable problems (other than weight loss or anorexia) can be pursued, a systematic search is indicated (Figure 9-9 ). One should first preclude as many causes as possible with the history and physical examination (i.e., lack of food, calorie-deficient food, inability to eat, regurgitation, vomiting and diarrhea). Next, extensive clinicopathologic screening is indicated. Imaging is considered an extension of the physical examination, and abdominal and thoracic radiographs are appropriate. Thoracic radiographs may be very revealing, even if a patient does not have coughing or abnormal lung sounds. Abdominal ultrasonography is particularly desirable and often more useful than radiographs if the operator is accomplished. If laboratory or radiographic abnormalities are not present or are unconvincing, one may repeat the tests at 1 to 3 week intervals, depending on the clinical condition of the patient, or immediately proceed to function tests, biopsies, or both. Certain hepatic and adrenal gland diseases may require such function tests. It is noteworthy that severe gastric or intestinal disease may cause anorexia or severe weight loss without vomiting or diarrhea.
TABLE 9-11
Major Causes of Weight Loss in Dogs and Cats
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Diagnostic approach to chronic weight loss in dogs and cats when no other abnormalities are found on history or physical examination and the animal is not ingesting adequate calories (see Table 9-11). ACTH, Adrenocorticotropic hormone; ANA, antinuclear antibodies; CBC, complete blood count; CSF, cerebrospinal fluid; EMG, electromyogram; FeLV, feline leukemia virus; FIV, feline immunodeficiency virus; TLI, trypsin-like immunore-activity; WBC, white blood cell.
Gastroduodenoscopy and ileoscopy plus biopsy are reasonable in patients with severe weight loss of unknown cause. Some cases with gastric neoplasia may present only for anorexia and weight loss. Clinicians without access to endoscopic equipment may consider exploratory laparotomy. If surgery is performed, gastric, duodenal, jejunal, ileal, mesenteric lymph node, and hepatic biopsies are usually appropriate, regardless of a normal gross appearance of the organs. In cats, the pancreas should also be biopsied.
Cancer cachexia can be particularly difficult to diagnose. It is a poorly defined, multifaceted syndrome that may involve loss of taste, malabsorption, increased metabolism with energy wasting, and other mechanisms. Almost any tumor can cause cancer cachexia, and no consistent laboratory findings exist. The causative cancer may be large or small, focal or diffuse; lymphomas and carcinomas are probably the most common causes.
Anorexia of unknown cause is similar to weight loss in being difficult to evaluate if no other identifiable abnormalities are seen. The diagnostic approach is similar to that for chronic weight loss (see Figure 9-9; Table 9-12 ). Anorexia can be divided into three categories: (1) pseudoanorexia associated with inability to eat (oral, pharyngeal, or esophageal disease), (2) primary anorexia (rare) associated with a primary CNS disorder, and (3) secondary anorexia (the most common), which is the result of systemic or metabolic disease.
TABLE 9-12
Categories of Diseases That Cause Anorexia
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If necessary, one may elect a therapeutic trial to treat for a suspected problem in a patient in whom a diagnosis cannot be made. It is vital that one design such therapy so that it is safe and extremely likely to succeed if the presumptive disease is present. Then, if the trial fails, one may rule out that disease and go on to treat for something else. To do this, the clinician must be sure that the dose and duration of the treatment is sufficient.
ABDOMINAL PAIN
History, physical examination, radiographs, and ultrasonography are the initial tools in diagnosing the cause of abdominal pain (Figure 9-10 ). Extra-abdominal diseases such as spinal problems and patients predisposed to nonsurgical diseases (e.g., pancreatitis) must be identified early.
Diagnostic approach to abdominal pain in the dog and cat. CBC, Complete blood count.
In patients with severe, progressive, acute abdomen (severe unrelenting pain or shock or stupor in a deteriorating patient), surgery is often indicated as soon as fluid, electrolyte, and acid-base status are acceptable for anesthesia. Imaging is desirable, but extensive laboratory testing is unlikely to identify the more common causes of acute abdomen (e.g., intestinal obstruction, gastric dilation and volvulus, peritonitis, organ ischemia, tumor, sepsis, or bleeding) and usually only delays surgical resolution of disease. Abdominal exploration offers a good chance for definitive diagnosis plus resolution of the disease process.
NOTE:
These maladies do not always present as surgical emergencies.
If a patient is not in severe pain and the disease is not progressing rapidly, one must differentiate between problems that ultimately necessitate surgery and those that usually do not (e.g., pancreatitis, hepatitis, cholecystitis, upper urinary tract infection, prostatitis, pansteatitis, heavy metal intoxication, Rocky Mountain spotted fever [RMSF]). Abdominal ultrasonography is useful to examine the liver, spleen, pancreas, kidneys, and prostate, as well as to detect peritoneal fluid. If abdominal fluid is present, abdominocentesis or abdominal lavage with cytologic analysis is indicated. If these procedures are not revealing and the problem continues, exploratory surgery may be necessary. Contrast radiographs are rarely useful because thorough abdominal exploration should diagnose almost anything they reveal; finding an abnormality on radiographs simply is an indication for surgery. In rare situations the exhibited abdominal pain may be referred from other causes such as pulmonary disease or disk disease.
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Reference:
Published online 2009 May 15. doi: 10.1016/B0-72-168903-5/50014-8
Gastrointestinal, Pancreatic, and Hepatic Disorders
Michael D. Willard and David C. Twedt