Volume 44 | Issue 1 Article 3 1982 Canine Ascites W. Michael Peden Iowa State University R. D. Zenoble Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/iowastate_veterinarian Part of the Gastroenterology Commons, and the Small or Companion Animal Medicine Commons Recommended Citation Peden, W. Michael and Zenoble, R. D. (1982) "Canine Ascites," Iowa State University Veterinarian: Vol. 44 : Iss. 1 , Article 3. Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol44/iss1/3 This Article is brought to you for free and open access by the Journals at Iowa State University Digital Repository. It has been accepted for inclusion in Iowa State University Veterinarian by an authorized editor of Iowa State University Digital Repository. For more information, please contact [email protected]. Canine Ascites by W. Michael Peden, DVM R. D. Zenoble, DVM* INTRODUCTION cirrhosis, and cholangitis. Most of the cardiac Canine ascites is an infrequently seen and hepatic diseases are associated with por­ clinical sign which is often the primary com­ tal hypertension as the direct cause of ascites. plaint for presentation of an animal to a vet­ Another cause of fluid accumulation in the erinarian. As in all cases a good history is a peritoneal cavity is hypoproteinemia due to priority as further questions may reveal renal loss of protein. Diseases such as behavioral changes, vomiting, anorexia, and amyloidosis and glomerulonephritis may other clinical signs which may be important cause massive proteinuria. Other causes of in defining the primary problem. Ascites itself abdominal fluid accumulation include can physically interfer with respiration, cause neoplasia of an abdominal organ, ruptured general discomfort, and disturb fluid and urinary bladder, and hemorrhage from electrolyte metabolism. The underlying cause trauma or neoplasia. must be determined and treated. Simply re­ The following steps need not necessarily be moving the ascitic fluid will only give short performed in any certain sequence, but a term relief. logical procedure should be followed in order A diagnostic evaluation of an animal to arrive at a diagnosis. For example, blood presented with ascites may include a complete work and radiographs or analysis of ab­ blood count (CBC), biochemical evaluation, dominal fluid may be done in a different abdominal paracentesis and biocheIll,ical and order than presented here, but all work cytologic analysis of the fluid obtained, should be done with the idea of ruling out the radiographs, biopsy, and organ function easiest and most obvious diseases first. Ascites tests. A physical exam always precedes any is most often due to cardiac disease which can further diagnostic aids. be ruled out relatively easily by a physical ex­ Ascites is a sign that something serious has am and thoracic radiographs. If these find­ gone wrong with the animal and the client ings are normal, more involved diagnostic should be appraised that diagnosis could be aids may be required to rule out liver disease expensive, the prognosis may be poor, and or neoplasia. A urinalysis may reveal the treatment difficult or unrewarding. In causes of hypoalbuminemia to be via the general the two main causes of ascites are car­ kidneys. In short, a logical pattern should be diac problems and liver disease, with the kept in mind in order to arrive at a reasonable greater percentage caused by cardiac prob­ diagnosis with a reasonable amount of time lems. and effort. Common cardiac problems associated with ascites are heartworms, congestive cardiomy­ PHYSICAL EXAM opathy, right heart failure, and congenital The animal is often presented with a com­ pulmonic stenosis. Hepatic diseases which plaint of abdominal enlargement. The causes cause ascites and/or hypoalbuminemia are of distension (gas, liquid, organomegaly) liver insufficiency, chronic-active hepatitis, should be determined. Intraabdominal gas will give a sharp rebound to percussion and a *From Iowa State University College of Veterinary Medicine. Dr. Peden is a 1981 graduate. Dr. Zenoble is higher pitched resonance when ausculated an assistant professor in Veterinary Clinical Sciences. than fluid. The ascitic abdomen has a charac- 12 Iowa State Veterz"narz"an teristic pear shape and percussion of the ab­ alerts the clinician to consider the heart more domen will result in a sharp fluid rebound on carefully. Specific examples include: 1) heart­ the opposite side. worm disease with enlarged right ventricle Fluid distensions may occur within the and enlarged pulmonary arteries, 2) biven­ gastrointestinal tract or any hollow organ. tricular enlargement with mitral and Palpation is used to rule out a palpable tricuspid insufficiency, 3) enlarged right ven­ obstruction such as an intussusception. tricle and poststenotic dilation of pulmonary However, the great volume of fluid may limit artery with congenital pulmonic stenosis, 4) a good physical examination. Ballotment marked generalized cardiomegaly with through the abdominal wall may indicate a idiopathic congestive cardiomyopathy of mass or enlargement of an organ. large breed dogs. Physical findings along with Since cardiac disease is a major cause of radiographic findings may add support to ascites, particular care should be paid to cardiac cause of ascites. auscultating the heart. Murmurs may be in­ If there is no indication for cardiac disease dicative of a number of problems and the as the cause of ascites, abdominal radio­ location of the murmur may be a clue to the graphs may be helpful. Abdominocentesis particular problem. A murmur on the right prior to radiographing the abdomen is benefi­ side, third to fifth intercostal space may in­ cial as the amount of fluid in the abdomen dicate a tricuspid insufficiency due to car­ will obscure any detail in most cases. Removal diomyopathy or valvular fibrosis. In con­ of the fluid will give better definition and gestive heart failure both mitral and tricuspid possibly enable visualization of the abdominal insufficiency may be noted. Severe heartworm organs and relative positions. For example, disease can cause right sided heart failure and caudal displacement of the stomach gas a positive Knott's test and characteristic shadow may indicate hepatomegaly. Dorsal thoracic radiographs will support the diagno­ displacement of the intestines may indicate a sis. Delayed heart sounds such as late closure splenic tumor or mass. Pneumoperitoneogra­ of the pulmonary valve may also indicate phy may help in visualizing the abdominal heartworms. organs. Cystography may be used to evaluate Congenital pulmonic stenosis may be in­ the bladder if paracentesis shows urine in the dicated by a murmur on the left side near the fluid. cranial sternum. This condition may lead to right ventricular enlargement and right heart CBC and BLOOD CHEMISTRY failure. A CBC should be done on all animals Idiopathic congestive cardiomyopathy may presented with ascites even though the in­ be suspected when a large breed dog with formation will not give a definitive diagnosis. ascites is showing a deficit between the heart An eosinophilia may be a further indication and pulse rate. If atrial fibrillation is present of heartworm disease. An inflammatory (> 80 %) the heart rate can be greater than leukogram may indicate an inflammatory 200 beats per minute. process such as peritonitis. Hepatomegaly or spenomegaly are often Protein levels should be determined and a noted with cardiac problems due to venous specific check for albumin levels should be congestion. These signs may also indicate made. Hypoalbuminemia rarely is the pri­ neoplasia or hyperplasia. It is important not mary cause of ascites but definitely con­ to be led astray by signs which may indicate tributes to the continuation of the problem. more than one disease. Icterus is another In order for hypoalbuminemia to cause clinical sign which could be confusing as it is ascites the albumin level must be less than 1.5 usually associated with hepatic disease or g/dl. Decreased hepatic synthesis will con­ hemolytic disease. tribute to hypoalbuminemia but a more likely cause is expansion of the plasma volume and 2 7 RADIOGRAPHS subsequent dilution of albumin • The most important ancillary test used in A Knott's test for D'ioroj'ilar'ia 'imm'itzs diagnosing the cause of ascites is radiography. should also be performed. It should be Cardiac causes of ascites are easy to rule out remembered that a significant percentage of with a thoracic radiograph. In most in­ animals suffering from heartworms are stances, cardiomegaly will be seen which negative with the Knott's test. If all other Vol. 44, Issue No. 1 13 signs indicate heartworm disease, a negative hepatocellular necrosis, fibrosis, or Knott's test should not be the basis for biochemical lesions. Levels of significance for discarding that diagnosis. these enzymes can be found in most clinical Evaluation of the serum may reveal ab­ pathology references. It is important to normal chemical values which may be ex­ remember that the magnitude of the increase tremely helpful in diagnosing the primary in enzyme levels is proportionate to the problem after cardiac disease has been ruled damage, but no evaluation of the reversibility out. A urinalysis may yield information on of the damage can be made from these levels. bilirubin levels, urobilinogen, and renal loss The persistence of high levels of these enzymes of protein. is a poor prognostic sign, as the half-life is 2-4 In general, biochemical analysis of serum is days, and persistent high levels mean con­ primarily aimed at determining the status of tinuing damage. Other enzymes which can be the liver by 1) measuring substances excreted used to detect hepatocellular disease include or produced in the normal liver, 2) measuring isocitrate dehydrogenase, glutamate de­ enzymes which are associated with abnormal hydrogenase, and arginase.2 liver function, and 3) measuring the rate of Reduced functional hepatic mass can be removal of certain dyes such as BSP (sulfabro­ measured by a BSP excretion test or an am­ mophthalein).8 monia tolerance test.