Masters Theses

Date of Award


Degree Type


Degree Name

Master of Science


Comparative and Experimental Medicine

Major Professor

Karen M. Tobias

Committee Members

Cassie N. Lux, Jan S. Suchodolski


Background: The GI microbiome has not been characterized in dogs being medically managed for congenital portosystemic shunts [CPSS].

Objectives: To characterize the fecal microbiome in a population of dogs being medically managed for CPSS.

Animals: 27 client-owned dogs.

Methods: Prospective cohort study enrollment of fecal samples was performed with follow-up data collected retrospectively. The overall fecal dysbiosis index [DI] and individual bacterial abundances were determined using real-time qPCR. Medical management, clinical findings, clinicopathologic, and outcome variables were collected, and logistic regression analyses were performed to evaluate associations between these variables and overall DI and bacterial abundances. Numerical variables were evaluated with general linear models.

Results: All dogs were administered a therapeutic hepatic diet and lactulose, while antibiotics were used in 22 (81.5%) and acid suppressants in seven (25.9%). Seventeen dogs (63.0%) had a DI > 2. The median DI in this population was 3.02 (range, 4.23-8.42), and the median DI in dogs receiving and not receiving antibiotics was 4.3 (range, -4.23 – 8.42) and 1.52 (range, -1.62 – 5.43), respectively.

No significant association between any of the analyzed variables and the DI was identified. The abundance of E. coli was positively significantly affected by the use of metronidazole (p = 0.024).

Conclusions and clinical importance: Dysbiosis appears to be common in dogs that are being medically managed for CPSS, though the clinical significance remains unclear.

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