Hookworm Anthelmintic Resistance: Novel Fecal Polymerase Chain Reaction Ancylostoma caninum Benzimidazole Resistance Marker Detection in a Dog.

A 4 yr old castrated male greyhound presented with a history of chronic (>3 wk) intermittent diarrhea. Initial fecal analysis identified infection with Ancylostoma caninum. Despite treatment with routine anthelmintics, the dog remained persistently A caninum positive for several months. A novel fecal gastrointestinal real-time polymerase chain reaction (qPCR) parasite panel detected A caninum and the genetic benzimidazole (BZ) F167Y resistance marker in multiple samplings over 48 hr. This finding, together with the dog's clinical signs (diarrhea) and lack of response to routine anthelmintics, prompted treatment with cyclooctadepsipeptide emodepside, a drug currently not registered for dogs in the United States. The dog's clinical signs resolved and post-treatment fecal qPCR testing was negative. However, 5 mo later, retesting with fecal qPCR detected A caninum and concurrent BZ resistance marker, as well as Giardia. A presumptive diagnosis of re-infection was made and the emodepside treatment was continued. The dog again reverted to undetected (A caninum and the 167 resistance marker) on reassessment fecal qPCR. This case report describes the use of a novel fecal qPCR panel for gastrointestinal parasites, persistent hookworm and BZ F167Y resistance marker detection in a dog, and highlights the importance of a stepwise approach to clinical management, treatment, and retesting.

Left ventricular function quantified by myocardial strain imaging in small-breed dogs with chronic mitral regurgitation.

BACKGROUND: The presence of left ventricular (LV) systolic dysfunction may influence prognosis or therapy in dogs with chronic mitral regurgitation (MR). Assessment of LV function in MR by conventional echocardiography is confounded by altered ventricular loading. Myocardial deformation (strain) imaging might offer more sensitive estimates of LV function in this disease. OBJECTIVE: Prospectively measure myocardial strain in dogs with asymptomatic MR compared to a control group. ANIMALS, MATERIALS AND METHODS: Forty healthy dogs (3.5-11.5 kg): 20 Controls; 20 dogs with MR and LV remodeling (Stage B2), were evaluated in this study. LV size and function were assessed in a short-axis plane. Segmental radial strain and strain rate and global circumferential strain were measured using a 2D echocardiographic speckle-tracking algorithm (GE EchoPAC). Groups were compared using Bonferroni t-tests. Influences of heart rate and body weight were explored with linear regression. RESULTS: The MR group had significantly greater mean values for heart rate, LV size, and LV systolic function. Specifically, LV diastolic diameter, diastole area, shortening fraction, averaged peak systolic and early diastolic radial strain, global circumferential strain, and averaged radial strain rate were significantly greater in the MR group (p < 0.015 to p < 0.001). Strain was unrelated to weight, but weakly correlated with heart rate. CONCLUSIONS: Similar to conventional indices, Stage B2 dogs with MR demonstrate hyperdynamic deformation in the short-axis plane. Short-axis strain variables measured by 2D speckle tracking are greater than for controls of similar age and weight. These results imply either preserved LV systolic function or that LV dysfunction is masked by altered ventricular loading.

Comparison of echocardiographic indices of myocardial strain with invasive measurements of left ventricular systolic function in anesthetized healthy dogs.

OBJECTIVE: To compare echocardiographic indices of myocardial strain with invasive measurements of left ventricular (LV) systolic function in anesthetized healthy dogs. ANIMALS: 7 healthy dogs. PROCEDURES: In each anesthetized dog, preload and inotropic conditions were manipulated sequentially to induce 6 hemodynamic states; in each state, longitudinal, radial, and global strains and strain rate (SR), derived via 2-D speckle-tracking echocardiography, were evaluated along with conventional echocardiographic indices of LV function and maximum rate of rise (first derivative) of LV systolic pressure (LV+dp/dt(max)). Catheter-derived and echocardiographic data were acquired simultaneously. Partial and semipartial correlation coefficients were calculated to determine the correlation between LV+dp/dt(max) and each echocardiographic variable. Global longitudinal strain was compared with conventional echocardiographic indices via partial correlation analysis. RESULTS: All myocardial segments could be analyzed in all dogs. Significant semipartial correlations were identified between conventional echocardiographic strain indices and LV+dp/dt(max). Correlation coefficients for longitudinal deformation and global strain, segmental longitudinal strain, and segmental SR were -0.773, -0.562 to -0.786, and -0.777 to -0.875, respectively. Correlation coefficients for radial segments and strain or SR were 0.654 to 0.811 and 0.748 to 0.775, respectively. Correlation coefficients for traditional echocardiographic indices and LV+dp/dt(max) (-0.586 to 0.821) and semipartial correlation coefficients for global strain and echocardiographic indices of LV systolic function (-0.656 [shortening fraction], -0.726 [shortening area], and -0.744 [ejection fraction]) were also significant. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that LV systolic function can be predicted by myocardial strain and SR derived via 2-D speckle-tracking echocardiographic analysis in anesthetized healthy dogs.