Despite the widespread use of vaccines, Bordetella bronchiseptica (Bb) infection is still commonly diagnosed in dogs with lower airway infection. As fatal pneumonia or chronic presentation may be observed, efficient treatment is required. Aerosolized gentamicin was historically described to maximize local drug delivery with minimal systemic absorption but clinical response to standardized protocols has not been reported.
The objective of this study was to compare clinical response to two different protocols of aerosolized gentamicin in dogs with confirmed respiratory Bb infection.
Diagnosis of Bb infection was based on compatible clinical signs and positive bacterial culture or PCR on bronchoalveolar lavage fluid. Dogs were recruited over a 5 years’ period (2012-2017). In all dogs, gentamicin was aerosolized for ³10 minutes twice daily for ³3 weeks, using a face mask and various types of ultrasonic nebulizers. Either a dose of 4 mg/kg of gentamicin diluted with 1-4 parts of saline was used (protocol 1, n=13) or a fixed amount of undiluted 5% gentamicin (protocol 2, n=24). At first recheck after 3 to _4 weeks, treatment was either stopped or pursued in 3-week increments until clinical cure. Clinical cure was defined as resolution of clinical signs (absence of cough) and radiographical lesions improvement/resolution. Proportion of dogs clinically cured at first recheck and median total duration of treatment were compared between treatment protocols; additionally, the effect of some factors (age, breed, co-infections with other bacteria including M. cynos, presence of alveolar lesions, previous steroid therapy and severity of neutrophilia of the lavage) on cure and treatment duration was analysed (Chi-square and Mann-Whitney tests).
Thirty-seven dogs were recruited (18 males, 19 females). Median age was 6 months [5weeks–7years] and median BW was 6.8 kg. Brachycephalic breeds, Yorkshires and Chihuahuas were over-represented (20/37 dogs (54%)) and 35/37 dogs (95%) had previously been treated with oral antimicrobial therapy with poor or no response. Twenty dogs (54%) had alveolar pattern on thoracic radiographs suggestive of bronchopneumonia. There was no difference in demographic and clinical data between dogs included in both protocols. Treatment was well tolerated in all dogs and no undesirable effect was observed. Clinical cure at first recheck tended to be more frequently observed in dogs treated with protocol 2 (13/24 [54%] dogs) compared with protocol 1 (3/13 [23%] dogs) (p=0.06). The median duration of treatment was shorter with protocol 2 (4 weeks, range 3-9) compared with protocol 1 (6 weeks, range 3-8) (p=0.03). None of the clinical or pathological parameter studied was associated with clinical response.
In conclusion, while being more time-consuming than oral antimicrobial therapy, aerosolized gentamicin appears safe and promising for treating dogs with Bb infection, particularly for cases refractory to oral antimicrobial therapy. Protocol 2 using undiluted 5% solution for ³10 minutes, that allows delivery of gentamycin in amounts proportional to the individual minute volume, could offer shorter duration of treatment.
Clinician Teacher and Researcher
Ecole National Vétérinaire de Maisons Alfort, France
Friday, June 15
8:30 AM – 8:45 AM
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