Beyond the antimicrobial: what's the evidence for adding another drug for infectious diseases? (Proceedings)

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Beyond the antimicrobial: what's the evidence for adding another drug for infectious diseases? (Proceedings)

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Aug 01, 2011

In this session we will take an evidence-based medicine approach to ancillary therapy of bovine respiratory disease, bovine toxic mastitis, bovine neonatal enteric disease, and retained placenta/metritis. The literature reviewed here is not presented as being all-inclusive, but rather as a summary of many commonly cited articles on these subjects. The citations are primarily peer reviewed, but some are from freedom of information (FOI) summaries and a few are proceedings papers or abstracts. The depth of the information is beyond the scope of this proceedings paper, so references and discussion are provided here only for the respiratory disease portion. References and discussions will be available for toxic mastitis, enteric disease, retained placenta/metritis from the author.

Bovine respiratory disease

No published data could be found to support the use of Vitamin B or C, vaccines (at the time of therapy), antihistamines, anthelmintics, probiotics, or oral electrolytes in the ancillary therapy of bovine respiratory disease. For the purposes of this presentation, we will examine the published data concerning the use of steroidal and non-steroidal anti-inflammatory drugs as ancillary therapy for respiratory disease.

Glucocorticosteroids?



Decades after publication of the study described here, there is still only one published clinical trial addressing the use of steroids for ancillary therapy of BRD as you would encounter it clinically in the United States. One of two treatments was administered to animals identified as displaying clinical signs of BRD. Common drugs for the two treatment groups included IV oxytetracycline (5 mg/lb) and IM pyrelamine (250 mg total dose) on a daily basis for 3 days. Treatment group 1 also received 20 mg dexamethasone every day while treatment group 2 received a 10 ml placebo injection. The same treatments for each group were continued through day 9, as needed, for non-responders. Response was significantly different at P ≤ 0.05 and relapse rate was significantly different at P ≤ 0.01.

These findings aren't that surprising since dexamethasone, at 0.04 mg/kg daily (0.9 ml/100 lbs of a 2 mg/ml solution) for 3 days, is used as a research model to suppress neutrophil function in cattle. This model was utilized in small Holstein calves in conjunction with induced Haemophilus somnus pneumonia to demonstrate that this dexamethasone regimen increased lung lesions. An IBR latency model in rabbits demonstrated that a single high-dose injection of dexamethasone (2.8 mg/kg) could bring about reactivation of latent BHV-1. Other studies have failed to show significant differences in treatment response using prednisone acetate, methyl prednisolone, or methyl-prednisolone-succinate in natural and induced respiratory disease.