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in Journal of the American Veterinary Medical Association

SUMMARY

The hepatobiliary dynamics of a 99mTc-labeled derivative of iminodiacetate were investigated in 29 healthy dogs. A 2-compartment model proved to be adequate to describe the hepatic time-activity curve. Model-derived variables for the hepatic accumulation and the biliary excretion and transport were used as a reference for evaluation of a number of commonly used measurements directly derived from hepatic and biliary time-activity curves (graphic variables). The difference between t50(ex) and t95(ex), representing the moments when 50 and 95%, respectively, of the maximal count rate during the hepatic excretory phase were measured, proved to be an adequate graphic variable to quantitate biliary excretion. The use of other graphic variables to quantitate hepatobiliary functions seemed unjustified.

Free access
in American Journal of Veterinary Research

SUMMARY

In 25 dogs with spontaneous cholestatic disease, the hepatobiliary dynamics were evaluated by use of scintigraphy and a 99mTc-labeled iminodiacetate (ida) derivative. Hyperbilirubinemia existed in all dogs, with serum total bilirubin concentration ranging from 6 to 262 (μmol/L. An appropriate compartmental model was used to characterize the liver time-activity curves. Model-dependent variables for hepatic uptake and biliary excretion of radiolabeled IDA were found to reliably represent the underlying physiologic processes. Measurements directly derived from the liver time-activity curves of IDA, representing the moments of accumulation of 50 and 95% of the maximal hepatic activity did not accurately represent the hepatic uptake by being significantly influenced by biliary excretion and by competition of renal excretion. The time-interval between 95% and 50% of the maximal activity in the excretory phase proved to be a quantitative characteristic of bile flow in all instances. Compartmental analysis of 99mTc-ida excretory scintigraphy characterized bile flow quantitatively in clinically normal dogs and in dogs with cholestasis. The method permitted the clinical evaluation of cholestasis based on quantitative, instead of the usual qualitative, and on functional, instead of phenomenologic, criteria.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To test validity of prediction for inherited portosystemic shunts (PSS) in Irish Wolfhounds, using nonselective clinical findings and a computerized database containing 5-generation pedigrees.

Animals

613 dogs in the first and 396 dogs in the second cohort.

Procedure

Preprandial venous ammonia concentration was measured at 6 to 8 weeks in all pups born between Jan 1, 1988 and Jan 1, 1997. Portosystemic shunts were confirmed in hyperammonemic pups, using radioisotope shunt index measurement, and diagnosis of shunting was confirmed at abdominal surgery or necropsy. Findings in dogs of the first cohort (born before Jan 1, 1992) were used to predict shunting in their offspring of the second cohort. Common ancestors of first-cohort dogs with shunts were tested for positive associations with the disease. Risk for a shunt in all second-cohort dogs was predicted on the basis of relatedness with founders and was compared with outcome of clinical screening.

Results

Prevalence of shunts in first and second cohorts was 3.1 and 2.3%, respectively. Fifteen highly related associated founders could be identified. Second-cohort dogs were classified into 6 groups of increasing predicted risk. Mean number of dogs per class was 60; number of clinically diagnosed cases ranged from 0 in the class with the lowest risk to 4 in the highest risk class.

Conclusions

Genetic risk for reproducing a PSS in Irish Wolfhounds was accurate, using the described method.

Clinical Relevance

Risk estimation provides a tool for genetic counseling, does not require knowledge of the mode of inheritance, and may be valid for any inherited disease. (Am J Vet Res 1998;59:1553-1556)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To analyze familial clustering and genetic risk for various forms of elbow dysplasia (ED) in Bernese Mountain Dogs (BMD) in The Netherlands and define possible means to select against ED.

Animals

98 BMD born in 1992 and 64 BMD born in 1995.

Procedure

Dogs were examined radiographically when 12 to 18 months old. The population was resolved into familial clusters, and distribution of ED for the clusters was analyzed. Common ancestors associated with each form of ED were identified, and risk for having ED in the 64 offspring born in 1995 was calculated by relatedness to common ancestors. Risk was compared with radiographic outcome.

Results

The 2 forms of ED identified were fragmented coronoid process (FCP) and elbow joint incongruity (INC). Incidence of ED decreased from 63/98 (64%) in 1992 to 29/64 (45%) in 1995. None of the familial clusters was free of FCP or INC. Common ancestors associated with FCP differed from those associated with INC. There was more potential variation in risk for FCP and INC in the 64 offspring than was achieved by breeders, indicating a decrease in population heterogeneity.

Conclusions and Clinical Relevance

FCP and INC had differing familial sources; thus, they most likely are different genetic traits. Although Incidence of ED decreased from 1992 through 1995, we did not detect variation among pedigrees in genetic risk for ED remaining in the offspring born in 1995; thus, selection among families cannot further improve ED health status of BMD in The Netherlands. Phenotypic selection within families remains the only alternative. [Am J Vet Res 1999;60:1082-1087)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine portal hemodynamic changes associated with surgical shunt ligation and establish ultrasonographic criteria for determining the optimal degree of shunt narrowing and predicting outcome.

Design—Case series.

Animals—17 dogs, each with a single congenital extrahepatic portosystemic shunt.

Procedure—Pre- and postligation flow velocities and flow directions were determined by Doppler ultrasonography intraoperatively in the shunt and in the portal vein cranial and caudal to the shunt origin. Outcome was evaluated 1 month after surgery by measuring blood ammonia concentration and performing abdominal ultrasonography.

Results—Hepatofugal flow was detected in 9 of 17 dogs before shunt attenuation in the portal segment that was between the shunt origin and the entering point of the gastroduodenal vein. If hepatofugal flow became hepatopetal after shunt ligation, hyperammonemia resolved. Hepatofugal portal flow was caused by blood that flowed from the gastroduodenal vein toward the shunt. Shunt attenuation converted hepatofugal flow to hepatopetal in the shunt in 12 of 17 dogs. Chronic portal hypertension developed or perioperative death occurred when the portal congestion index caudal to the shunt origin increased by > 3.6 times.

Conclusions and Clinical Relevance—After hepatopetal flow in the cranial portal vein and the shunt is established, further shunt narrowing is contraindicated. Increase of the portal congestion index caudal to the shunt > 3.5 times should be avoided. Poor outcome because of severe hypoplasia of the portal branches can be expected if the flow direction remains hepatofugal after shunt occlusion cranial to the shunt origin. ( J Am Vet Med Assoc 2004;224:395–402)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine ultrasonographic abnormalities in dogs with hyperammonemia.

Design—Retrospective study.

Animals—90 client-owned dogs with hyperammonemia.

Procedure—Ultrasonography of the abdominal vessels and organs was performed in a systematic way. Dogs in which the ultrasonographic diagnosis was a congenital portosystemic shunt were included only if they underwent laparotomy or necropsy. Dogs in which the abdominal vasculature appeared normal and dogs in which the ultrasonographic diagnosis was acquired portosystemic shunts and portal hypertension were included only if liver biopsy specimens were submitted for histologic examination.

Results—Ultrasonography excluded portosystemic shunting in 11 dogs. Acquired portosystemic shunts were found in 17 dogs, of which 3 had arterioportal fistulae and 14 had other hepatic abnormalities. Congenital portosystemic shunts were found in 61 dogs, of which 19 had intrahepatic shunts and 42 had extrahepatic shunts. Intrahepatic shunts originated from the left portal branch in 14 dogs and the right portal branch in 5. Extrahepatic shunts originated from the splenic vein, the right gastric vein, or both and entered the caudal vena cava or the thorax. Ultrasonography revealed splenic-caval shunts in 24 dogs, right gastric-caval shunts in 9 dogs, splenic-azygos shunts in 8 dogs, and a right gastric-azygos shunt in 1 dog.

Conclusions and Clinical Relevance—Results suggest that ultrasonography is a reliable diagnostic method to noninvasively characterize the underlying disease in dogs with hyperammonemia. A dilated left testicular or ovarian vein was a reliable indicator of acquired portosystemic shunts. (J Am Vet Med Assoc 2004;224:717–727)

Full access
in Journal of the American Veterinary Medical Association