Summary
Eight control and 8 asymptomatic COPD‐affected horses were given, on separate occasions, inhalation challenges with extracts of Micropolyspora faeni, Aspergillus fumigatus and Thermoactinomyces vulgaris. All horses were also given nebulised phosphate‐buffered saline (PBS) challenges and ‘;natural challenges’ (NCs), i.e. exposure to hay and straw, as control challenges. Responses were assessed by clinical, pulmonary mechanics, arterial blood gas tensions, arterial blood pH and bronchoalveolar lavage fluid cytological examinations.
PBS challenges had no effect on control or COPD‐affected horses, while NC induced COPD only in the COPD‐affected horses. Pulmonary disease, similar to naturally occurring COPD, was induced, only in the COPD‐affected horses, by M. faeni and A. fumigatus challenges, thus implicating these organisms in the aetiology of equine COPD. The role of T. vulgaris in the aetiology of equine COPD could not, however, be determined because the T. vulgaris challenges, in addition to inducing pulmonary disease in 4 COPD‐affected horses, induced pulmonary disease in 2 control horses which had been unaffected by NC.
The absence of pulmonary disease in control horses after M. faeni, A. fumigatus and NC challenges suggests that equine COPD is a pulmonary hypersensitivity, rather than a non‐specific toxic response.
The clinical records of 277 cases of canine atopy treated with specific allergen immunotherapy were reviewed. A good response was defined as control with immunotherapy either alone or with topical agents, a partial response as control with immunotherapy and other systemic agents, and a poor response as no perceived benefit and the immunotherapy discontinued. The mean follow-up period was 29.2 months (range 10 to 85 months). Ninety-one cases (33 per cent) were lost to follow-up or failed to comply with the therapeutic protocol. Of the remaining 186 cases, 40 (21.5 per cent) had a good response to immunotherapy, 74 (39.8 per cent) had a partial response, and 72 (38.7 per cent) had a poor response. Immunotherapy was therefore of long-term benefit in 114 dogs (61.3 per cent). No significant differences in response rates were associated with the breed or sex of the dog, or the age of onset of the disease, or with the type or number of allergens included in a vaccine. Dogs which had clinical signs for more than 61 months before immunotherapy had a significantly poorer response rate (23.5 per cent, P < 0.05). In-house cases had a significantly better response rate (95.2 per cent, P < 0.05) than externally managed cases.
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