BackgroundOtitis externa is a common inflammatory ear disease in dogs caused by a variety of pathogens, and coagulase-positive staphylococci are frequently isolated from such infections.ObjectiveTo identify antimicrobial susceptibility profiles and methicillin-resistant strains among coagulase-positive staphylococci isolated from otitis externa in dogs.MethodsA cross-sectional study was performed over 2 years on 114 client-owned dogs presented to the Veterinary Teaching Hospital with a primary complaint of ear infections. Swabs were obtained from both ears and cultured for staphylococci which were subsequently confirmed as coagulase-positive using rabbit plasma. Antimicrobial susceptibility assays were assessed on all isolates followed by subsequent genetic analysis for species identification and detection of the mecA gene.ResultsSixty-five coagulase-positive staphylococci were isolated from 114 client-owned dogs. The isolates exhibited resistance against neomycin (58.5%), streptomycin (49.2%), penicillin (49.2%), polymyxin B (44.6%), tetracycline (36.9%), sulphamethoxazole/trimethoprim (33.8%), kanamycin (33.8%), doxycycline (32.3%), norfloxacin (23.1%), amoxicillin/clavulanate (20%), ciprofloxacin (20%), enrofloxacin (18.5%), gentamicin (16.9%), and cephalothin (9.2%). Forty (61.5%) of the isolates were resistant to at least three or more antimicrobials and 10 were sensitive to all. Using a multiplex polymerase chain reaction assay based on species-specific regions of the thermonuclease (nuc) gene, 38/65 (58.5%) isolates were classified as Staphylococcus aureus, 23/65 (35.4%) as S. pseudintermedius, 2/65 (3.1%) as S. intermedius, and 2/65 (3.1%) as S. schleiferi. Analysis for the mecA gene revealed two positive isolates of S. pseudintermedius which were oxacillin-resistant, representing a first report of such organisms in the Caribbean.ConclusionDespite the relatively high prevalence of multidrug-resistant coagulase-positive staphylococci in Trinidad, these are largely susceptible to gentamicin consistent with use in clinical practice. The first detection of methicillin-resistant S. pseudintermedius (MRSP) in dogs is likely to have implications on the treatment options for otitis externa in dogs and potential public health significance.
The objective of this study was to document changes in echocardiographic variables of left ventricular size and function noninvasively during acute normovolemic anemia. This model was developed as a pilot study with the purpose of providing baseline information to investigate the pathophysiology, and more specifically the effect on the heart, of canine babesiosis-induced anemia. The study group comprised of 11 mature healthy Beagle dogs that weighed between 9 and 15 kg. Severe normovolemic anemia was induced over a 3-4-day period by serial bleeding while maintaining normovolemia by autotransfusing plasma and infusing crystalloids. The dogs were then allowed to recover. Preanemic (mean Hct 46.7%, standard deviation [SD] 2.4%) echocardiographic variables of left ventricular performance (Fractional shortening, ejection fraction, end-systolic and end-diastolic ventricular volumes, cardiac index, and heart rate) were compared with those in the severely (mean Hct 15.3%, SD 1.1%), moderately (Hct mean 24.7%, SD 1.5%), and mildly (mean Hct 33.5%, SD 2.5%) anemic states, and between the anemic states. With the exception of end diastolic volume, there was a statistically significant (P < 0.05) increase in all variables in the severely anemic state vs. the preanemic and the mild and moderate anemic states. In concordance with previous invasive models, a hyperdynamic state of the left ventricle develops in response to experimentally induced acute canine normovolemic anemia in the conscious dog. Echocardiography has promise as a noninvasive technique of evaluating the cardiac changes in dogs having canine babesiosis.
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