Epidemiologic factors associated with the anatomic location of intrahepatic portosystemic shunts in dogs

Objective - To determine whether breed, sex, country of origin, and age are associated with anatomic location of intrahepatic portosystemic shunts (IHPSS) in dogs. Study Design - Multi-institutional retrospective case series. Sample Population - Dogs (n=125) with IHPSS from the veterinary teaching hospitals of the University of Florida (21), Sydney University (44), and the University of California - Davis (60). Methods - Dogs with surgical/necropsy confirmation of single IHPSS were identified. Data were analyzed using logistic regression for associations between age, breed, sex, and country with the anatomic location of IHPSS. Results - Right (34%), left (34%), and central divisional IHPSS (32%) were prevalent with approximately equal frequency in Australia; in the United States, the prevalence of right (24%) and central divisional (26%) combined was similar to left divisional IHPSS (51%). Country (P=048), sex (P=.016), and Australian cattle dog ([ACD], P=.025) were significantly associated with IHPSS location. Dogs in Australia had 2.5-fold higher odds of having right versus left divisional IHPSS. Males and ACD had 2.8- and 5.6-fold higher odds of having right versus left divisional IHPSS. Australian dogs were significantly older than those in the United States (P<.0001) and ACD were significantly older than other breeds (P=.0067). Conclusions - Although country of origin, breed, and sex had significant associations with anatomic location of IHPSS, signalment does not appear to be a strong predictor of shunt location when used alone. Clinical Relevance - For the common breeds in this report, signalment is only occasionally helpful in predicting likelihood of anatomic division in IHPSS. Australian cattle dogs and male dogs have a statistical association with right (versus left) divisional IHPSS. If advanced imaging techniques are not available, veterinary surgeons should be prepared to locate and address any anatomic configuration of IHPSS in a dog.