A comparative analysis of two unrelated outbreaks in Latvia and Australia of acquired idiopathic megaesophagus in dogs fed two brands of commercial dry dog foods: 398 cases (2014-2018).

CASE DESCRIPTION: In Latvia in 2014, acquired idiopathic megaesophagus (AIME) was observed in increased numbers of dogs that consumed varieties of 1 brand of dog food. Within 2 years, 253 dogs were affected. In Australia in November 2017, 6 working dogs that consumed 1 diet of another brand of dog food developed AIME. In total, 145 Australian dogs were affected. CLINICAL FINDINGS: AIME was diagnosed predominantly in large-breed male dogs (> 25 kg [55 lb]). Regurgitation, weight loss, and occasionally signs consistent with aspiration pneumonia (coughing, dyspnea, or fever) were noted. Most Latvian dogs had mild to severe peripheral polyneuropathies as evidenced by laryngeal paralysis, dysphonia, weakness, and histopathologic findings consistent with distal axonopathy. In Australian dogs, peripheral polyneuropathies were not identified, and histopathologic findings suggested that the innervation of the esophagus and pharynx was disrupted locally, although limited samples were available. TREATMENT AND OUTCOME: Investigations in both countries included clinical, epidemiological, neuropathologic, and case-control studies. Strong associations between the dog foods and the presence of AIME were confirmed; however, toxicological analyses did not identify a root cause. In Latvia, the implicated dietary ingredients and formulations were unknown, whereas in Australia, extensive investigations were conducted into the food, its ingredients, the supply chain, and the manufacturing facilities, but a cause was not identified. CLINICAL RELEVANCE: A panel of international multidisciplinary experts concluded that the cause of AIME in both outbreaks was likely multifactorial, with the possibility of individualized sensitivities. Without a sentinel group, the outbreak in Australia may not have been recognized for months to years, as happened in Latvia. A better surveillance system for early identification of pet illnesses, including those associated with pet foods, is needed.

Assessment of serum symmetric dimethylarginine and creatinine concentrations in hyperthyroid cats before and after a fixed dose of orally administered radioiodine.

BACKGROUND: Serum symmetric dimethylarginine (SDMA) is a sensitive renal biomarker for detecting early chronic kidney disease (CKD) in nonhyperthyroid cats, but knowledge regarding its performance in hyperthyroid cats remains limited. OBJECTIVES: To determine the relationship between serum SDMA, creatinine and total thyroxine (TT4) concentrations in hyperthyroid cats before (T0) and 3 months after (T1) receiving a PO fixed dose of radioiodine. ANIMALS: Eighty client-owned hyperthyroid cats. METHODS: Prospective cohort study. Serum TT4, and SDMA, creatinine concentrations, and urine specific gravity were measured at T0 and T1. Nonparametric tests were used to determine the relationship among SDMA, and creatinine and TT4 concentrations. Agreement between SDMA and creatinine regarding CKD staging at both time points was assessed using Goodman and Kruskal's gamma statistic. RESULTS: Mean serum SDMA concentration increased after treatment of hyperthyroidism. However, 21 of 75 cats experienced a decrease in SDMA between T0 and T1, whereas creatinine decreased in only 2 cats. A moderate correlation between SDMA and creatinine was seen at T1 (r = 0.53; P < .001) but not at T0 (r = 0.13; P = .25). Where assessable at T1, poor agreement was observed between SDMA and creatinine and CKD stage (Goodman and Kruskal's gamma 0.20; P = .29). CONCLUSIONS AND CLINICAL IMPORTANCE: Discordant outcomes between SDMA and creatinine after radioiodine treatment in cats with hyperthyroidism suggest extrarenal factors may interfere with the reliability of SDMA to adequately reflect renal function. As a result, SDMA should not be interpreted in isolation in hyperthyroid cats treated with radioiodine.

Assessment of treatment outcomes in hyperthyroid cats treated with an orally administered fixed dose of radioiodine.

OBJECTIVES: The aims of this study were to describe the treatment outcomes following oral administration of a fixed dose (138 MBq; 3.7 mCi) of radioiodine in hyperthyroid cats and to examine the correlation between total thyroxine (TT4) concentrations before and after treatment. METHODS: This was a retrospective cohort study that documented the TT4 concentration and clinicopathological parameters at the time of diagnosis and after treatment. Logistic regression was used to assess the relationship between TT4 concentrations before and after treatment. The difference in pre- and post-treatment variables between cats that had TT4 concentrations below or within the reference interval (RI) was compared by the Mann-Whitney U-test. RESULTS: Of 161 cats, 133 (82.6%) cats had TT4 concentrations within the RI, four (2.5%) cats had TT4 concentrations above the RI and 24 (14.9%) cats had TT4 concentrations below the RI after treatment. The severity of hyperthyroidism at diagnosis, as measured by the percentage of TT4 elevation above the upper limit of the RI, had no impact on the odds of cats having low TT4 concentrations after treatment (odds ratio 1.00; 95% confidence interval 0.96-1.05; P = 0.828). CONCLUSIONS AND RELEVANCE: When using an orally administered fixed dose of radioiodine for the treatment of feline hyperthyroidism, TT4 concentrations at diagnosis cannot be used to predict TT4 concentrations after treatment. The proportion of cats with TT4 concentrations below the lower limit of the RI after treatment was 14.9%. Further work is required to optimise oral radioiodine dosing to achieve maximal euthyroid outcomes.

Comparison of bronchoalveolar lavage fluid examination and other diagnostic techniques with the Baermann technique for detection of naturally occurring Aelurostrongylus abstrusus infection in cats.

OBJECTIVE: To evaluate the diagnostic sensitivity and specificity of bronchoalveolar lavage (BAL) fluid examination and other diagnostic techniques, compared with the use of the Baermann technique performed on fecal samples as the reference standard, for detection of naturally occurring Aelurostrongylus abstrusus infection in a population of cats. DESIGN: Cross-sectional study. SAMPLE POPULATION: Cadavers of 80 semiferal domestic cats. PROCEDURES: BAL fluid collection and analysis, necropsy, examination of fecal samples and minced lung tissue via the Baermann technique, fecal sedimentation-flotation, and histologic examination of lung tissue were performed. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for detection of A abstrusus infection were calculated. RESULTS: On the basis of fecal Baermann test results, prevalence of infection was 13.8%. Sensitivity (NPV) of tests was as follows: Baermann technique on minced lung tissue, 81.8% (97.2%); fecal flotation-sedimentation, 63.6% (94.5%); stereomicroscopic examination of BAL fluid combined with cytologic examination of BAL fluid, 54.5% (93.2%); stereomicroscopic examination of BAL fluid alone, 45.4% (92.0%); cytologic examination of BAL fluid alone, 36.4% (90.8%); histologic examination of lung tissue, 45.4% (91.8%); and gross lung appearance, 36.4% (90.8%). Specificity and PPV of all tests were 100%, with the exception of histologic examination of lung tissue (specificity, 97.1%; PPV, 71.4%), which identified infected cats that had negative fecal Baermann test results. CONCLUSIONS AND CLINICAL RELEVANCE: The Baermann technique was the most sensitive test for detection of A abstrusus infection. On the basis of the prevalence of 13.8% in this study, A abstrusus infection should be considered in pet cats.