Magnetic resonance imaging and histological classification of intracranial meningiomas in 112 dogs.

BACKGROUND: Intracranial meningiomas are the most common primary brain tumors in dogs. Classification of meningiomas by tumor grade and subtype has not been reported, and the value of magnetic resonance imaging (MRI) characteristics for predicting tumor subtype and grade has not been investigated. HYPOTHESIS: Canine intracranial meningiomas are a heterogenous group of tumors with differing histological subtypes and grades. Prediction of histopathological classification is possible based on MRI characteristics. ANIMALS: One hundred and twelve dogs with a histological diagnosis of intracranial meningioma. METHODS: Retrospective observational study. RESULTS: Meningiomas were overrepresented in the Golden Retriever and Boxer breeds with no sex predilection. The incidence of specific tumor grades was 56% benign (Grade I), 43% atypical (Grade II), and 1% malignant (Grade III). Grade I histological subtypes included meningothelial (43%), transitional (40%), microcystic (8%), psammomatous (6%), and angiomatous (3%). No statistically significant (P < .05) associations were found among tumor subtype or grade and any of the MRI features studied. CONCLUSIONS AND CLINICAL IMPORTANCE: Meningiomas in dogs differ from their counterparts in humans mainly in their higher incidence of atypical (Grade II) tumors observed. MRI characteristics do not allow for prediction of meningioma subtype or grade, emphasizing the necessity of histopathology for antemortem diagnosis. The higher incidence of atypical tumors in dogs may contribute to the poorer therapeutic response in dogs with meningiomas as compared with the response in humans with meningiomas.

Comparison of shunt fraction estimation using transcolonic iodine-123-iodoamphetamine and technetium-99m-pertechnetate in a group of dogs with experimentally-induced chronic biliary cirrhosis.

Portosystemic shunt fraction estimation using transcolonic iodine-123-iodoamphetamine (IMP) has been previously validated relative to portal vein macroaggregated albumin injections using an experimental model of cirrhosis. Transcolonic technetium-99m-pertechnetate (TcO4-) has been proposed as an alternative tracer to IMP to study portal circulation in cirrhotic patients. We compared shunt fraction estimates from paired transcolonic IMP and TcO4- studies performed on a group of dogs before and after common bile duct ligation surgery. Pertechnetate over-estimated shunt fraction in 6/7 postoperative studies relative to IMP. A good correlation between the two methods was demonstrated, however, the slope of the regression line was substantially less than 1.0 with TcO4- values reaching 100% at IMP shunt values of approximately 60%. This apparent inability to accurately assess high shunt flows may limit the quantitative aspects of TcO4- studies on patients with severe portosystemic shunting.

Portasystemic shunt fraction quantification using transrectal administration of iodine-123 iodoamphetamine in dogs with chronic bile duct ligation and after propranolol administration.

Following transrectal administration, 123I iodoamphetamine (IMP) has been shown in both animal and patient studies to be capable of detecting the presence of portasystemic shunting (PSS). However, the ability of this method to actually quantitate PSS in the presence of cirrhosis and propranolol has not been demonstrated. We studied nine dogs with hitologically proven cirrhosis induced by chronic bile duct ligation. After intravenous injection of propranolol, PSS were measured with both the IMP method and the standard of portal vein infusion of 99mTc macroaggregated albumin (MAA) given through a mesenteric vein catheter. Based on linear regression, a close relationship was seen, given by the equation: MAA = IMP 0.9 + 0.035, with correlation coefficient of 0.99. Thus, in dogs with cirrhosis secondary to chronic bile duct ligation and after propranolol administration, PSS can be quantitated with the transrectal IMP method.

Current status of immunoscintigraphy in the detection of thrombosis and thromboembolism.

This review describes the use of monoclonal antibodies (MoAbs) for immunoscintigraphic detection of thrombosis and thromboembolism. Two major groups of MoAbs have been tested: Antibodies directed against platelets and antibodies directed against fibrin. Several antiplatelet antibodies have been developed that are directed against either the platelet membrane glycoprotein complex, IIb/IIIa, which binds fibrinogen, or against two different proteins, alpha granule membrane protein GMP-140 and thrombospondin (TSP) that are expressed during platelet activation. Platelets labeled with radioactive antibody or antibody fragments have characteristics similar to platelets labeled in vitro with lipophilic complexes. Studies in animal models indicate that antiplatelet antibody and antiactivated platelet factor antibody imaging have a high sensitivity for clots less than 24 hours old and that images can be positive as early as one to two hours after antibody administration. A limited number of antiplatelet antibody studies have been performed in patients. This technique appears to yield accurate results provided that active platelet deposition is occurring at the time of the study. Several antifibrin MoAbs, specific for fibrin monomers, have been developed. Compared with antiplatelet antibodies, antifibrin antibodies and antibody fragments appear to be capable of detecting older experimental clots (up to five days old). Images in experimental thrombosis models are routinely positive within two hours of antibody administration. Recently reported clinical trials indicate a high sensitivity in all anatomic locations within the extremities whether or not patients were receiving heparin.

Short echo time magnetic resonance imaging of tendon.

RATIONALE AND OBJECTIVES: Current clinical magnetic resonance (MR) imaging studies provide almost no useful signal from normal tendon and have no clear advantage over other imaging modalities in the evaluation of tendon injuries. The authors believe that tendon MR signal may be T2-limited, and, if so, could be enhanced by short echo time (TE) pulse sequences. The relationship of tendon signal intensity and tendon infrastructure conspicuity to TE was assessed at three different field strengths. METHODS: Magnetic resonance imaging studies were performed on samples of normal equine tendon at 3 different field strengths with spin-echo or gradient-recalled-echo sequences of varying TE. Tendon signal-to-noise ratios (SNR) were determined for each study and images were evaluated for visual evidence of tendon infrastructure. RESULTS: Tendon SNR demonstrated a strong inverse relationship to TE at each field strength. Signal-to-noise ratio values of 10 to 40 were achieved on the shortest TE studies (TE < 3 msec). Tendon infrastructure could be visualized and was primarily dependent on in-plane resolution and to a lesser extent on SNR. CONCLUSIONS: Short echo time MR imaging enhances tendon signal. Under optimal imaging conditions, tendon infrastructure can be evaluated. As high-performance gradient coil systems become available for clinical imaging systems, the authors believe similar results will be achievable on routine diagnostic studies and foresee an expanding role for MRI in the evaluation of tendon disease.

Indirect computed tomography lymphography of subdiaphragmatic lymph nodes using iodinated nanoparticles in normal dogs.

RATIONALE AND OBJECTIVES: We evaluated the imaging characteristics of an iodinated particulate contrast agent for indirect computed tomography (CT) lymphography of normal subdiaphragmatic lymph nodes in dogs. METHODS: Four milliliters of a 15% (wt/vol) iodinated nanoparticle suspension was injected into the gastric, colonic, rectal, or cervical submucosa, loose paraprostatic fascia, or metatarsal subcutaneous tissues in 10 healthy beagles. Endoscopic, CT, or ultrasound guidance was used when necessary to facilitate contrast agent delivery. CT and radiographic images were obtained prior to contrast administration and at 4 hr, 24 hr, and 7 days postcontrast injection. Postmortem examinations were then conducted. RESULTS: CT images showed enhancement of regional lymph nodes draining the various injection sites. The mean attenuation of opacified nodes was 678 +/- 463 Hounsfield units 24 hr after injection and remained elevated 7 days later. Lymph node opacification on CT images correlated well with the node location observed on postmortem examinations. CONCLUSION: Subdiaphragmatic lymph nodes can be effectively opacified using an iodinated nanoparticle contrast agent for indirect CT lymphography.

Iodinated nanoparticles for indirect computed tomography lymphography of the craniocervical and thoracic lymph nodes in normal dogs.

RATIONALE AND OBJECTIVES: We evaluated the imaging characteristics of an interstitially or intraperitoneally delivered iodinated particulate contrast agent for computed tomography (CT) lymphography of the craniocervical and thoracic lymph nodes. METHODS: We injected 2-4 ml of 15% wt/vol iodinated nanoparticle suspension subcutaneously, submucosally, or intraperitoneally in eight normal dogs. CT and plain radiographic images were obtained prior to contrast administration and 4 hr, 24 hr, and 7 days after injection. Correlation was made to detailed postmortem assessment. RESULTS: CT images showed enhancement of regional nodes draining injection sites. Mean attenuation of opacified nodes was 313 +/- 297 (mean +/- standard deviation), 536 +/- 453, and 492 +/- 372 Hounsfield units at 4 hr, 24 hr, and 7 days postinjection, respectively. Lymph node opacification on CT images correlated well with node location found at postmortem. CONCLUSION: Craniocervical and thoracic lymph nodes can be effectively opacified from interstitial or intraperitoneal delivery of this iodinated nanoparticulate contrast agent.

Technetium 99m sulfur colloid scintigraphy to evaluate reticuloendothelial system function in dogs with portasystemic shunts.

In a retrospective study, technetium 99m sulfur colloid scintigraphy was used to evaluate reticuloendothelial system function in 61 dogs with single congenital and 40 dogs with multiple acquired portasystemic shunts. Whole body reticuloendothelial function was measured by calculating the plasma clearance rate constant from a dynamic study of liver uptake of 99mTc sulfur colloid. Relative liver, spleen, and lung uptake, and a ratio of hepatic:extrahepatic uptake were measured on static equilibrium images. Results were compared with those of a group of 26 normal dogs. Compared with values for the group of normal dogs, the plasma clearance rate constant, relative liver uptake, and hepatic:extrahepatic uptake ratio were significantly decreased, and relative spleen and lung uptake were significantly increased in dogs with portasystemic shunts (P < .0001). The only significant difference between dogs with single congenital versus multiple acquired shunts was that the relative splenic uptake was higher in the former group (P < .0002). Based on these results, we concluded that dogs with portasystemic shunts have significantly impaired reticuloendothelial function. The primary cause of this dysfunction is likely a reduction in effective liver blood flow. Increases in spleen and lung reticuloendothelial activity did occur, but only partially compensated for the reduction of liver reticuloendothelial activity. Possible mechanisms for the increased spleen and lung uptake are discussed.

Endotoxin concentrations measured by a chromogenic assay in portal and peripheral venous blood in ten dogs with portosystemic shunts.

A chromogenic Limulus amebocyte lysate assay was used to measure portal and peripheral venous endotoxin concentrations in ten medically managed dogs undergoing surgery for correction of a single extrahepatic portosystemic shunt. In all dogs, both peripheral and portal venous blood samples were obtained at the time of surgical manipulation of the anomalous vessel. In six dogs, peripheral venous samples were obtained an average of 8.0 months after surgery. Five physically normal dogs without biochemical or histologic evidence of liver disease served as controls. Data analysis failed to demonstrate significant differences in peripheral and portal venous endotoxin concentrations between the control and study groups. Postoperatively five of six dogs showed a measurable reduction in peripheral venous endotoxin concentration over intraoperatively obtained values, but the differences were not statistically significant (P = 0.06). Based on results of this study it was concluded that systemic endotoxemia was not present in dogs with a single extrahepatic portosystemic shunt that were medically stable prior to surgery.

Diagnostic features of clinical neurologic feline infectious peritonitis.

Feline infectious peritonitis (FIP) is a fatal Arthus-type immune response of cats to infection with FIP virus, a mutant of the ubiquitous feline enteric coronavirus (FECV). The disease may occur systemically or in any single organ system, and primary neurologic disease is a common subset of such manifestations. We examined 16 domestic cats with clinical neurologic FIP and 8 control cats with nonneurologic FIP, with the intention of identifying the ante- and postmortem diagnostic tests that most contribute to accurate diagnosis. Of the 16 cats with neurologic FIP, 15 were less than 2 years of age and all 16 originated from large multiple-cat households. The most useful antemortem indicators of disease were positive anti-coronavirus IgG titer in cerebrospinal fluid, high serum total protein concentration, and findings on magnetic resonance imaging suggesting periventricular contrast enhancement, ventricular dilatation, and hydrocephalus. Postmortem diagnosis was facilitated by FIP monoclonal antibody staining of affected tissue and coronavirus-specific polymerase chain reaction. Most cats with neurologic and ocular forms of FIP had patchy, focal lesions, suggesting that recently developed technologies described in this report may be useful for evaluation of cats with suspected FIP.

Pulmonary lymphomatoid granulomatosis in seven dogs (1976-1987).

Seven dogs with pulmonary lymphomatoid granulomatosis were reviewed. The disease occurred in six large-breed and one small-breed dogs. The dogs were five to 14 years old (mean, 8.4; median, 7), and four of seven dogs were males. Three dogs had been previously treated with adulticide therapy for canine dirofilariasis. Clinical histories included a progressive respiratory disease characterized by varying degrees of cough, dyspnea, exercise intolerance, and weight loss. Thoracic radiographic features included hilar lymphadenopathy, pulmonary masses of varying sizes, and mixed pulmonary patterns of lobar consolidation with ill-defined interstitial and alveolar pulmonary infiltrates. Cardiovascular changes compatible with chronic dirofilariasis were present in three dogs. The clinical course was usually progressive and fatal. The survival time ranged from six days to four years (mean, 12.5 mos; median, 3 mos). Gross and histologic features included mass lesions with areas of necrosis that replaced normal pulmonary architecture. Cytologically, these lesions were characterized by infiltration with pleomorphic, angioinvasive mononuclear cells that often resulted in vascular obliteration. The infiltrating cells resembled large lymphoid cells that possessed large hyperchromatic nuclei and small amounts of cytoplasm. Systemic lymphoid neoplasia with peripheral lymphadenopathy was diagnosed in two dogs. In both cases, lymph-node cytology was similar to the cellular infiltrates found in the lungs and consistent with a diagnosis of lymphomatoid granulomatosis. These features are compared with previously reported cases of canine lymphomatoid granulomatosis and those features identified in a similar disease described in man.

Hepatic dearterialization in the dog.

Hepatic dearterialization was performed in 9 adult dogs. Evaluation of the technique was based on clinical and laboratory assessment of physiologic and pathologic changes related to the procedure. All dogs had hematologic and histopathologic evidence of transient hepatic ischemia that was reflected by minimal post-operative morbidity.

Modified in vitro method to label equine red blood cells with technetium 99m in concentrated whole blood.

An in vitro method to label equine RBC with technetium 99m was modified to achieve quantitative labeling of cells in concentrated whole blood. After a blood sample was incubated with a reducing agent (stannous citrate), an oxidizing reagent (NaOCl) and a chelating agent (EDTA) were added to inactivate residual Sn2+ in the plasma. This step prevented premature reduction of pertechnetate in plasma. Labeling of RBC from 9 healthy horses, using a standard whole blood protocol, resulted in only moderate labeling efficiency (44 to 85%) and indicated a linear relationship between labeling efficiency and PCV. Effects of increased incubation time, increased incubation temperature, prelabeling sedimentation, and double addition of NaOCl/EDTA were investigated in whole blood from 10 healthy horses. Labeling efficiency was improved by each independent factor and by combination of factors. Highest labeling efficiencies (96 to 97%) were achieved when blood samples were sedimented for 20 minutes before being labeled, regardless of incubation time or incubation temperature. Morphologic features of RBC were unaffected by labeling procedures. In vivo whole blood clearance time for labeled cells was determined in 5 healthy horses. Sedimented blood samples were labeled, using a standard 15-minute incubation time at 20 to 22 C. Mean clearance half-time for 5 horses was approximately 20 hours. More than 95% of 99mTc activity was associated with the cells during the 24 hours after reinjection.

Use of technetium-99m sulfur colloid to evaluate changes in reticuloendothelial function in dogs with experimentally induced chronic biliary cirrhosis and portosystemic shunting.

Technetium-99m sulfur colloid scintigraphy was used to study alterations of reticuloendothelial function in 7 dogs with experimentally induced biliary cirrhosis and portosystemic shunting. Scintigraphic studies were performed before and 6 weeks after common bile duct ligation. Radiocolloid plasma clearance rate was determined by measuring activity in plasma samples and by analyzing the rate of liver uptake on dynamic scintigraphic image sequences. Percentage of uptake in the liver, spleen, and lungs, as well as the ratio of hepatic-to-extrahepatic uptake, was determined from static equilibrium images. Relative to preoperative values, there were significant decreases in plasma clearance rate, percentage of liver uptake, and ratio of hepatic-to-extrahepatic uptake and significant increases in percentage of spleen and lung uptake on postoperative studies. The mechanism of technetium-99m-labeled sulfur colloid extraction by the liver is different from that of other radiocolloids; it does not require active phagocytosis or pinocytosis. Thus, liver uptake of this tracer principally reflects effective liver blood flow. Portosystemic shunting was documented in these dogs at the time of the postoperative radiocolloid scans, and we believed was responsible for the decrease in liver reticuloendothelial activity. Possible mechanisms for the increased splenic and pulmonary reticuloendothelial activities are discussed.

Scintigraphic biodistribution and plasma kinetics of indium 111-labeled transferrin in dogs.

OBJECTIVE: To determine plasma clearance kinetics and imaging biodistribution of indium 111-labeled transferrin (111In-TF) in dogs. ANIMALS: 7 adult dogs. PROCEDURE: After 30 minutes' incubation of 18.5 MBq (0.5 mCi) of 111InCl3 with 1 ml of serum (n = 3) or 1 ml of plasma (n = 4) at 37 C, dogs were given autologous 111In-TF i.v., and serial blood samples and right lateral and dorsal scintigraphic images were obtained immediately and 1, 3, 5, 9, 22, and 48 hours later. Blood and plasma clearance kinetics were determined from a least-squares, nonlinear fit of the sample radioactivity data. Blood radioactivity was compared with plasma radioactivity to determine the extent of cellular labeling. Imaging biodistribution was characterized by subjective and objective assessment of blood pool, liver, gastrointestinal (abdomen) tract, kidney, and bone marrow activity. RESULTS: 111In-TF plasma clearance was best described by a biexponential fit, with early and late clearance half-times of 6 and 49 hours, respectively. The 111In was not redistributed between transferrin (plasma proteins) and blood cells. Imaging studies documented progressive liver and bone marrow uptake of the 111In-TF over 48 hours. Some radioactivity was evident in the colon of 1 dog on 48-hour images. Decay-corrected count rates (counts/pixel/mCi/kg/min) within the abdominal region of interest increased over the 48-hour imaging period and exceeded the blood pool (cardiac) activity at 20 hours after injection. CONCLUSION: 111In-TF has a biexponential plasma clearance in clinically normal dogs, with early and late clearance half-time of 6 and 49 hours, respectively. Scintigraphically, 111In-TF localizes to sites of iron storage (bone marrow and liver) over time. Some loss of 111In-TF via the gastrointestinal tract may be seen on late 48-hour images. CLINICAL RELEVANCE: 111In-TF appears to be a viable radiopharmaceutical for use in dogs, with specific application for identifying those with protein-losing enteropathy.

Experimental definition of latissimus dorsi, gracilis, and rectus abdominus musculocutaneous flaps in the dog.

Dissection and injection studies in canine cadavers and in anesthetized dogs were conducted to determine the feasibility of using the latissimus dorsi, gracilis, and rectus abdominus muscles as musculocutaneous free flaps. Lengths of vascular pedicles for the latissimus dorsi (2 +/- 0.8 cm), gracilis (1.8 +/- 0.8 cm), and rectus abdominus (1.9 +/- 0.9-cm cranial deep epigastric, 1.7 +/- 0.5-cm caudal deep epigastric), as well as arterial diameters (1.28 +/- 0.31-mm thoracodorsal for the latissimus dorsi, 1.10 +/- 0.33-mm muscular branch for the gracilis, 1.25 +/- 0.25-mm cranial deep epigastric and 1.26 +/- 0.32-mm caudal deep epigastric for the rectus abdominus) were considered satisfactory for microvascular transfer. Fluorometry demonstrated overlying cutaneous perfusion in all flaps based on their muscle vascular pedicles, with the exception of the rectus abdominus flap based on the caudal deep epigastric artery. In this instance, up to 20% of the cutaneous element had questionable or no perfusion.

Radiographic/morphologic investigation of a radiolucent crescent within the flexor central eminence of the navicular bone in thoroughbreds.

The source of a previously described radiolucent crescent in the flexor cortex of the distal sesamoid (navicular) bone on the palmaro45 degrees proximal-palmarodistal oblique (Pa45 degrees Pr-PaDio) clinical radiographic projection was investigated in 48 forelimb navicular bones from 24 Thoroughbreds by use of high-detail radiography and x-ray computed tomography (CT). Twenty-five of these bones also were evaluated, using microradiography and histologic examinations. Of these 25 bones, 5 had been labeled in vivo with fluorochrome markers. Tetrachrome-stained 100-microns-thick nondecalcified sections of these 5 bones were examined, using epifluorescence microscopy. A reinforcement line of compacted cancellous bone, parallel and several millimeters deep to the flexor cortex in the region of the flexor central eminence, was visualized by CT in 42 of 48 navicular bones and by microradiography in 23 of 25 navicular bones investigated. Variable degrees of compaction were observed in the cancellous bone between the flexor cortex and the reinforcement line. High-detail skyline radiographic projections and reconstructed CT images indicated a crescent-shaped lucency within the flexor central eminence of the flexor cortex in the bones in which the reinforcement line was identified, but the cancellous bone between the reinforcement line and the flexor cortex had not been compacted. The radiolucent crescent seen in the flexor central eminence of the navicular bone on the Pa45 degrees Pr-PaDiO projection was not caused by the concave defect or synovial fossa of the flexor central eminence overlying the flexor cortex, as was described.(ABSTRACT TRUNCATED AT 250 WORDS)

Transcolonic sodium pertechnetate Tc 99m scintigraphy for diagnosis of macrovascular portosystemic shunts in dogs, cats, and potbellied pigs: 176 cases (1988-1992).

Medical records of 176 animals that underwent transcolonic sodium pertechnetate Tc 99m scintigraphy between September 1988 and June 1992 were reviewed. The study included 162 dogs, 10 cats, and 4 potbellied pigs. Whenever possible, scan results were confirmed during exploratory surgery or necropsy. For animals that did not undergo surgery or necropsy, additional medical information, (ie, results of histologic examination of hepatic biopsy specimens, clinicopathologic testing, abdominal ultrasonography, and clinical outcome) was evaluated to estimate the likelihood that the scan interpretation was correct. Interpretations were classified as confirmed true, probable true, possible false, or unconfirmed results. Of the 97 scans interpreted as positive for portosystemic shunting, 85 were classified as confirmed true-positive results, 5 were classified as probable true-positive results, and 7 were classified as unconfirmed results. None were classified as confirmed or possible false-positive results. Of the 79 scans interpreted as negative for portosystemic shunting, 3 were classified as confirmed true-negative results, 54 were classified as probable true-negative results, 1 was classified as a possible false-negative result, and 21 were classified as unconfirmed results. Our results suggest that transcolonic pertechnetate scintigraphy has satisfactory performance as a diagnostic test for macrovascular portosystemic shunting.

Use of transcolonic portal scintigraphy to monitor blood flow and progressive postoperative attenuation of partially ligated single extrahepatic portosystemic shunts in dogs.

Transcolonic portal scintigraphy was used to evaluate immediate and long-term changes in shunt blood flow after partial ligation of single extrahepatic portosystemic shunts in 8 dogs. Scintigraphy was performed before surgery, within the first 7 days after surgery, and 3 to 9 months after surgery. Shunt fraction values for this group of dogs before surgery ranged from 67 to 87% (normal reference range, < or = 15%). On the basis of postoperative scintigraphy, 4 dogs had immediate and lasting occlusion of shunt blood flow (shunt fraction, < or = 15%). One dog had a shunt fraction value within the reference range immediately after surgery, had evidence of recurrent shunt blood flow (shunt fraction, 23%) at 3 months after surgery, and again had a shunt fraction value within the reference range 9 months after surgery. Persistent, though reduced, shunt blood flow (shunt fractions, 23 and 27%) was evident immediately after surgery in 2 dogs. One of these dogs had a shunt fraction within the reference range 3 months after surgery, whereas shunt blood flow in the other dog had increased to 41%. One dog had no appreciable change in shunt blood flow immediately after surgery (shunt fraction, 70%), but the shunt fraction value had decreased to 41% at the time of the final scintigraphic examination. As assessed by transcolonic portal scintigraphy, partial single extrahepatic portosystemic ligation caused a significant decrease in mean shunt blood flow in this group of 8 dogs and resulted in eventual shunt occlusion in a majority of the dogs (6 of 8 dogs).(ABSTRACT TRUNCATED AT 250 WORDS)

Radiocolloid scintigraphy as an aid to the diagnosis of congenital portacaval anomalies in the dog.

Five clinically normal dogs and 5 dogs in which portacaval anomalies were diagnosed angiographically were utilized to evaluate differences in the appearance of the radiocolloid liver scan between the 2 groups. The liver was clearly visualized in all dogs, allowing subjective evaluation of size. In the dogs with portacaval shunts, scintigraphy revealed an obviously small liver as well as pulmonary uptake of radiocolloid. The utility of this technique was then tested in a group of dogs with liver disease and was shown to be of value in differentiating dogs with primary portacaval shunts from other types of liver disease.