Investigation of Neurokinin-1 Receptor Antagonism as a Novel Treatment for Chronic Bronchitis in Dogs.

BACKGROUND: Canine chronic bronchitis (CCB) results in cough lasting ≥2 months and airway inflammation. Adverse effects include risk of secondary infection associated with lifelong corticosteroid administration and prompt investigation into alternative therapies. Neurogenic pathways mediated by tachykinins that bind neurokinin (NK) 1 receptors may induce cough and airway inflammation. Maropitant, a NK-1 receptor antagonist, has been advocated for treatment of CCB based on anecdotal improvement, but without scientific evidence. HYPOTHESIS/OBJECTIVES: Maropitant will blunt clinical signs and airway inflammation associated with CCB. ANIMALS: Client-owned dogs (n = 8) with cough >2 months, thoracic radiographic evidence of airway disease and sterile airway inflammation (>7% non-degenerate neutrophils, >7% eosinophils or both) on bronchoalveolar lavage (BAL) enrolled. METHODS: Maropitant (2 mg/kg) administered q48h for 14 days. Study endpoints included client perception of clinical signs (surveys at baseline and 14 days, and visual analogue scale [VAS] at baseline, 7, and 14 days), and BAL % neutrophils and eosinophils (baseline and 14 days). One-way repeated measures ANOVA (VAS) and Wilcoxon-signed rank-sum tests (BAL cells, cough frequency) used with P < .05 considered significant. RESULTS: Maropitant significantly decreased cough frequency (P < .001) and VAS scores (P = .005). No differences in BAL % neutrophils or % eosinophils noted with treatment (P = .279 and P = .382, respectively). CONCLUSIONS AND CLINICAL IMPORTANCE: Preliminary results suggest that although maropitant may have antitussive properties leading to perceived clinical improvement, its failure to diminish airway inflammation makes it unsuitable for treatment of CCB. Future studies could evaluate maropitant as a cough suppressant for other respiratory disorders in dogs.

Seroepidemiology of Mycoplasma hyopneumoniae in pigs from farrow-to-finish farms.

A prospective study was carried out on three intensive farrow-to-finish farms. The aims were to estimate the incidence of Mycoplasma hyopneumoniae infection, to determine when pigs become infected and the pattern of transmission of infection and to verify the relationship between seroconversion and clinical signs. One batch of pigs per farm was followed from farrowing-to-slaughter. Blood samples were taken at 10, 27, 70, 94, 125 and 147 days of age, from 44, 48 and 44 pigs per farm. Colostrum and blood samples were also taken from the sows. Animals were checked clinically once a week and coughing rates were recorded. Antibodies against M. hyopneumoniae were detected by a blocking ELISA. At 27, 70 and 94 days of age most pigs on the three farms were seronegative, suggesting that no circulation of M. hyopneumoniae occurred during the growing period. Thereafter, a high proportion of pigs seroconverted, indicating that infection occurred soon after the transfer of the animals to the finishing houses. Differences were detected between farms in the incidence of seroconversion. Seropositive pigs were widely distributed among the finishing pens, suggesting that in addition to direct contact, other methods of transmission, such as indirect or airborne transmission, may have been important. Coughing started at around the same time as seroconversion. The results showed that the critical period for the transmission of M. hyopneumoniae is around the beginning of the finishing period, when pigs have low concentrations of antibodies against the agent.

A simple non-invasive method to measure the cough reflex in dogs.

INTRODUCTION: This study describes a method to measure the cough reflex in dogs that is simple to perform, requires no surgical intervention and can be used to profile efficacy and side-effect liabilities of antitussive drugs. METHODS: Experiments were performed in propofol-anesthetized dogs in which cardiopulmonary functions were non-invasively monitored before and after the induction of cough produced by spraying 0.75 ml of distilled water into the trachea. RESULTS: The magnitude of the cough response, measured by the frequency and amplitude was not different for individual dogs performed with repeated trials on different days. Treatment with the opioid antitussive drug, torbutrol (0.055-0.0055 mg/kg, s.c.) inhibited the cough frequency but not the amplitude induced by the water challenge. Furthermore, side effects of torbutrol were identified as mild respiratory depression and an anesthetic-sparing effect with propofol. DISCUSSION: This method offers many distinct advantages to evaluate efficacy of antitussive drugs including the fact that no surgery is required, it takes only 15-20 min to complete an experiment, and it can be used to simultaneously profile antitussive and side effect liabilities of drugs developed for the treatment of cough.