Background: The pathogenesis of gallbladder mucocele is unknown in the dog. It has been proposed that hyperlipidemia could impair gallbladder motility and contribute to gallbladder mucocele formation.
Objectives: The objective of this study was to compare gallbladder motility in dogs with hyperlipidemia to healthy, control dogs using ultrasonography. We hypothesized that hyperlipidemic dogs have decreased gallbladder motility, defined by increased fasting gallbladder volume (GBV) and decreased gallbladder ejection fractions at 60 (EF60) and 120 minutes (EF120) compared to controls.
Animals: 26 hyperlipidemic dogs, 28 healthy control dogs Methods: Twenty-six hyperlipidemic and 28 healthy, age-matched control dogs were prospectively enrolled. Hyperlipidemia was defined as hypercholesterolemia (>332 mg/dL) and/or hypertriglyceridemia (>143 mg/dL). Dogs with both primary and secondary causes of hyperlipidemia were included. All dogs were fasted for at least 12 hours prior to collection of plasma biochemistry and pre-prandial ultrasound. Ultrasound was performed on dogs in the fasted state as well as at 60 and 120 minutes after being fed 10g/kg of a high fat diet (Hill's a/d diet; Hill's Pet Nutrition, Topeka, Kansas, USA). GBVs and EFs were calculated using the following formulas: GBV = (0.52 x L x W x H)/kg and EF = ((GBV0- GBV60,120)/GBV0) x 100, respectively. GBV0, GBV60, GBV120, EF60 and EF120 were compared between dogs with hyperlipidemia and controls using the Wilcoxon rank sum test. Statistical significance was set to p<0.05.
Results: Hypercholesterolemia and hypertriglyceridemia were present in 15/26 (58%) and 21/26 (81%) hyperlipidemic dogs, respectively and 10/26 (38%) had elevations in both parameters. The median age in both groups was 10 years. Median (range) cholesterol concentration was 346 mg/dL (181-1372 mg/dL) and 238 mg/dL (153-324) in hyperlipidemic and control dogs, respectively. Median triglyceride concentration was 330 mg/dL (52-2213) and 65.5 mg/dL (32-142) in hyperlipidemic and control dogs, respectively. Eleven (42%) hyperlipidemic dogs were considered severely hyperlipidemic based on the triglyceride and/or cholesterol concentrations above 500 mg/dL. There were significant differences in GBV0 and GBV60 between hyperlipidemic and control dogs. Dogs with severe hyperlipidemia had significantly larger GBVs at all time points. Dogs with hypercholesterolemia also had significantly greater GBVs at all times compared to dogs without hypercholesterolemia. Median EF60 and EF120 were not significantly different between hyperlipidemic and control dogs nor severely hyperlipidemic and mildly hyperlipidemic dogs.
Conclusions: Hyperlipidemic dogs have significantly greater fasting and postprandial GBVs but similar ejection fractions when compared to control dogs. Gallbladder emptying is unaltered in hyperlipidemic dogs, but gallbladder volume is higher in hyperlipidemic dogs after feeding. This distention could contribute to bile retention of bile and potentially gallbladder disease. / Master of Science / The gallbladder (GB) is a reservoir for bile. The GB contracts to deliver bile to the intestines after a meal to help with digestion of nutrients and fats, and to rid the body of harmful waste. When the GB becomes diseased, abnormal bile flow can become toxic to the liver and endanger the patient's health.
One of the most common GB diseases in dogs is GB mucocele (buildup of mucus in the GB). The cause of GB mucocele formation is not well understood. One proposed cause is decreased contractions of the GB related to increased cholesterol and/or elevated triglycerides (hyperlipidemia). Our study investigated whether hyperlipidemia leads to poor gallbladder contraction, possibly explaining GB mucocele formation.
We used ultrasound scans before and after eating to compare gallbladder motility in dogs with hyperlipidemia to healthy, control dogs. We hypothesized that hyperlipidemic dogs would have decreased gallbladder motility compared to controls.
Twenty-six dogs with elevated cholesterol and/or elevated triglycerides and 28 healthy, age-matched control dogs were enrolled. Ultrasound was performed on dogs in the fasted state as well as 60 and 120 minutes after being fed.
There were significant differences in findings between affected dogs and control dogs. Dogs with very high blood lipid levels had significantly larger gall bladder volumes (GBVs). Dogs with high cholesterol also had significantly greater GBVs at all times compared to normal dogs. This finding indicates that excessive bile may be retained in the gall bladders of dogs with hyperlipidemia, possibly affecting the function of the organ.
Our study also looked at difference between the two groups in measures of ejection fraction, which can gage how efficiently the gall bladder releases bile. No differences were noted between the healthy group and the affected group.
Conclusions and Outcomes:
Hyperlipidemic dogs have significantly greater GBVs than control dogs both before and after eating, but similar ejection fractions. This study provides a clearer understanding of the mechanisms of gall bladder disfunction in dogs.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/104199 |
| Date | 16 July 2021 |
| Creators | Villm, Jessica Ann |
| Contributors | Biomedical and Veterinary Sciences, Demonaco, Stefanie, Bolton, Timothy, Panciera, David L., Larson, Martha M. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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