2016 ACVIM Forum Research Abstract Program

FISH detected the presence of bacteria in 28% of mucoceles evaluated. FISH was more sensitive than bacterial culture, which was positive in only 1/8 cases with visible bacteria. Our results reveal that bacterial infection is more common than previously thought, and support the need for further studies to examine the relationship between gallbladder mucoceles, cholecystitis, and bacterial infection. After cholecystectomy a median of 27% of dogs die before hospital discharge. The cause of GBM formation is unknown. Retrospective studies identify 14-17% of dogs with GBM have a diagnosis of hypothyroidism compared to 5-9% of normal dogs. Whether hypothyroidism is an independent risk factor for GBM formation or the consequence of an underlying metabolic syndrome is unknown. This distinction has important implications regarding the cause of GBM formation and may establish a rationale for diagnosis or treatment of hypothyroidism in these dogs. We undertook a prospective case controlled study of dogs newly diagnosed with GBM formation and lacking clinical signs of hypothyroidism to test a hypothesis that occult hypothyroidism exists at a high prevalence in these dogs and that the cause may differ from classic lymphocytic thyroiditis. Dogs diagnosed with GBM by ultrasound and healthy, age, breed and sex-matched dogs with normal gallbladder ultrasound were enrolled. Exclusion criteria included clinical evidence, prior diagnosis or treatment for hypothyroidism; drugs interfering with thyroid function, intact reproductive status, or emergent disease. Testing included a CBC, chem panel, UA, thyroid function testing including serum total T4, total T3, free thyroxine by equilibrium dialysis (FT 4 ), free triiodothyronine (FT 3 ), thyrotropin (TSH) and autoantibodies to T4AA, T3AA and TGAA. Dogs were stratified by disease severity into 1) no clinical signs, 2) mild clinical disease, 3) moderate to require hospitalization, and 4) severe requiring intensive care (incl. emergent surgery). Thyroid histology of GBM dogs and controls was examined by a pathologist blinded to the diagnosis. Parametric data were analyzed by t-test and non-parametric data by Mann-Whitney U test. P < 0.05 was considered significant. Of 106 screened dogs, 38 with GBM met study inclusion criteria and ranged in age from 6-16 years (median 10.5 yrs). Breeds included 11 Shetland sheepdogs, 4 Cocker Spaniels, 3 Chihuahuas, 3 Beagles, and 16 other pure breeds. Illness severity scores were: 37% absent; 21% mild; 21% moderate; and 21% severe. Of 18 healthy dogs screened, 12 were enrolled. Dogs with GBM had significantly lower serum T 4 (median 11, range 0-44 nM), T 3 (median 0.7, range 0-1.7 nM), FT 4 (median 15, range 1-27 pM), and FT 3 (median 3, range 0-10.5 pM) compared to control dogs. Relative to control dogs, dogs with GBM frequently had severely low individual thyroid hormone concentrations. Serum T4 was below reference range (RR) in 50% of GBM dogs compared to 8% controls. Four (10.5%) GBM dogs had a T4 = 0. Serum T3 was below RR in 47% of GBM dogs compared to 25% controls. Three (8%) GBM dogs had a T3 = 0. Serum FT4 was below RR in 12% of GBM dogs compared to 0% controls. Serum FT3 was below RR in 17% of GBM dogs compared to 0% controls. Significant differences in T4AA, T3AA or mean TSH were not identified. However 23.5% of GBM dogs and only 8% control dogs had an elevated TSH. Serum TGAA was elevated in 17% of control dogs and 0% of GBM dogs. No inflammation was detected in the