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- Author or Editor: Gregory B. Daniel x
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Abstract
Objective—To evaluate the usefulness of serum biochemical variables and scintigraphic study results for differentiating between dogs and cats with complete extrahepatic biliary obstruction (EHO) and those with partial EHO or patent bile ducts.
Study Design—Retrospective case series.
Animals—17 dogs and 1 cat.
Procedure—Animals that underwent hepatobiliary scintigraphy and had either surgical or postmortem confirmation of the degree of bile duct patency were included. Scintigraphic images were evaluated and biliary tracts were classified as patent, partially obstructed but patent, or obstructed. Surgery or postmortem examination was considered the gold standard for diagnosis, and compared with those findings, sensitivity and specificity of scintigraphy were calculated.
Results—With absence of radioactivity in the intestinal tract as the diagnostic criterion for EHO, the sensitivity and specificity of scintigraphic diagnosis were both 83% when final images were acquired at 19 to 24 hours, compared with 100% and 33%, respectively, when 180 minutes was used as the cutoff time. Animals with partial biliary obstruction had less intestinal radioactivity that arrived later than that observed in animals with patent biliary tracts.
Conclusions and Clinical Relevance—Animals in which intestinal radioactivity has not been observed after the standard 3 to 4 hours should undergo additional scintigraphic imaging. Findings in animals with partial biliary obstruction include delayed arrival of radioactivity and less radioactivity in the intestine. Distinguishing between complete and partial biliary tract obstruction is important because animals with partial obstruction may respond favorably to medical management and should not be given an erroneous diagnosis of complete obstruction. (J Am Vet Med Assoc 2005;227:1618–1624)
Abstract
Objective—To standardize techniques for renal scintigraphy in birds, to use scintigraphy to assess gentamicin nephrotoxicosis in birds, to compare nuclear medicine assessments with histologic assessment of gentamicin nephrotoxicosis and serum uric acid concentrations, and to determine the radiopharmaceutical that best quantifies avian renal function.
Animals—12 domestic pigeons (Columba livia domestica).
Procedure—Serum uric acid concentrations were determined for all birds. Renal scintigraphy techniques that used technetium-m99 (99mTc)-dimercaptosuccinic acid (DMSA; 4 hours after injection) and 99mTc-diethylenetriamine pentaacetic acid (DTPA; 15- minute dynamic study) were evaluated in all birds. Renal biopsy specimens were collected following baseline scans. Number and size of renal tubule granules positive for periodic acid-Schiff stain were scored for severity (scale of 0 to 4). Nephrotoxicosis was induced by administration of gentamicin. Serum uric acid concentrations were measured, and 99mTc-DMSA and99mTc-DTPA scans were repeated after gentamicin administration. Birds were euthanatized, and complete necropsies were performed.
Results—Standard avian renal scintigraphy techniques were developed for 99mTc-DMSA and 99mTc- DTPA. Decreased renal radiopharmaceutical uptake for 99mTc-DMSA and 99mTc-DTPA indicated nephrotoxicosis. Cloacal accumulation of 99mTc-DTPA was significantly decreased after administration of gentamicin. Histologic grading of renal tissue before and after gentamicin administration confirmed nephrotoxicosis. Inconsistent serum uric acid concentrations could not be used to assess nephrotoxicosis.
Conclusions and Clinical Relevance—Renal nuclear scintigraphy is a useful, noninvasive means to determine renal function in birds. Although 99mTc-DMSA may prove useful in the evaluation of renal morphology, 99mTc-DTPA is the radiopharmaceutical agent of choice for the assessment of renal function in avian species. (Am J Vet Res 2003;64:453–462)
Abstract
Objective—To evaluate the use of scintigraphy involving technetium Tc 99m diethylenetriamine pentaacetic acid (99mTc-DTPA) or technetium Tc 99m dimercaptosuccinic acid (99mTc-DMSA) for the determination of kidney morphology and function in green iguanas ( Iguana iguana ).
Animals—10 healthy iguanas weighing > 1.6 kg.
Procedure—Renal scintigraphy was performed by use of 99mTc-DTPA in 6 of the iguanas and by use of 99mTc-DMSA in all 10 iguanas. After the injection of 99mTc-DMSA, scans were performed for each iguana at intervals during a 20-hour period. Renal biopsies were performed in all 10 iguanas after the final scintigraphic evaluation.
Results—In iguanas, the use of 99mTc-DTPA for renal scintigraphy was nondiagnostic because of serum protein binding and poor renal uptake of the isotope; mean ± SD 99mTc-DTPA bound to serum proteins was 48.9 ± 9.9%. Renal uptake of 99mTc-DMSA produced distinct visualization of both kidneys. Renal uptake and soft tissue clearance of 99mTc-DMSA increased over the 20-hour imaging period; mean ± SD renal uptake of 99mTc-DMSA was 11.31 ± 3.06% at 20 hours. In each of the 10 iguanas, ultrasonographic and histologic examinations of biopsy specimens from both kidneys revealed no abnormalities.
Conclusions and Clinical Relevance—Results indicate that the kidneys of iguanas can be evaluated scintigraphically by use of 99mTc-DMSA; this technique may be potentially useful for the diagnosis of renal failure in iguanas. (Am J Vet Res 2005;66:87–92)
Abstract
CASE DESCRIPTION A 7-year-old castrated male Havanese was evaluated at a veterinary teaching hospital because of a 12-week history of hyperactivity, aggression, and progressive weight loss despite a healthy appetite.
CLINICAL FINDINGS Tachycardia was the only remarkable finding during physical examination. Serum 3,5,3′-triiodothyronine (T3) and free T3 concentrations were markedly increased, and thyroxine (T4), free T4, and thyroid-stimulating hormone concentrations were at or decreased from the respective reference ranges. Thyroid scintigraphy revealed suppressed uptake of sodium pertechnetate Tc 99m by the thyroid gland but no ectopic thyroid tissue, which was indicative of thyrotoxicosis induced by an exogenous source of T3.
TREATMENT AND OUTCOME The dog was hospitalized for 24 hours, and its diet was changed, after which the clinical signs rapidly resolved and serum T3 and free T3 concentrations returned to within the respective reference ranges. This raised suspicion of an exogenous source of T3 in the dog's home environment. Analysis of the commercial beef-based canned food the dog was being fed revealed a high concentration of T3 (1.39 μg/g) and an iodine (82.44 μg/g) concentration that exceeded industry recommendations. No other source of T3 was identified in the dog's environment.
CLINICAL RELEVANCE To our knowledge, this is the first report of clinical thyrotoxicosis in a dog induced by exogenous T3, although the source of exogenous T3 was not identified. This case highlights the importance of measuring serum T3 and thyroid-stimulating hormone concentrations in addition to T4 and free T4 concentrations when there is incongruity between clinical findings and thyroid function test results.
Abstract
Objective—To identify ventilatory protocols that yielded good image quality for thoracic CT and hemodynamic stability in cats.
Animals—7 healthy cats.
Procedures—Cats were anesthetized and ventilated via 4 randomized protocols (hyperventilation, 20 seconds [protocol 1]; single deep inspiration, positive inspiratory pressure of 15 cm H2O [protocol 2]; recruitment maneuver [protocol 3]; and hyperventilation, 20 seconds with a positive end-expiratory pressure of 5 cm H2O [protocol 4]). Thoracic CT was performed for each protocol; images were acquired during apnea for protocols 1 and 3 and during positive airway pressure for protocols 2 and 4. Heart rate; systolic, mean, and diastolic arterial blood pressures; blood gas values; end-tidal isoflurane concentration; rectal temperature; and measures of atelectasis, total lung volume (TLV), and lung density were determined before and after each protocol.
Results—None of the protocols eliminated atelectasis; the number of lung lobes with atelectasis was significantly greater during protocol 1 than during the other protocols. Lung density and TLV differed significantly among protocols, except between protocols 1 and 3. Protocol 2 TLV exceeded reference values. Arterial blood pressure after each protocol was lower than before the protocols. Mean and diastolic arterial blood pressure were higher after protocol 3 and diastolic arterial blood pressure was higher after protocol 4 than after protocol 2.
Conclusions and Clinical Relevance—Standardization of ventilatory protocols may minimize effects on thoracic CT images and hemodynamic variables. Although atelectasis was still present, ventilatory protocols 3 and 4 provided the best compromise between image quality and hemodynamic stability.
