Sodium Iodide As A Preventive Strategy For Respiratory Disease in Pre-weaned Dairy Calves

Problem: Innate airway defenses are crucial to preserving the health of bovine lungs. Stress, coupled with viral infections, compromises natural host defenses and allow bacteria to reach the lower airways and cause pneumonia. Innate defenses include airway mucus and ciliated epithelium, that trap and physically remove pathogens from the respiratory tract, and secreted antimicrobial peptides that neutralize pathogens. An additional mechanism of innate airway defense system has been described in cattle; it consists of lactoperoxidase (LPO), hydrogen peroxide (H2O2), and halide ions [1]. Lactoperoxidase catalyzes the oxidation of halide ions using hydrogen peroxide to form potent antimicrobial products. Typically, thiocyanate serves as the physiologic substrate for this reaction but our recent work has shown potent antiviral and antibacterial properties of hypoiodous acid, the product of iodide ion oxidation by LPO and hydrogen peroxide, in vitro [2-4]. The LPO/H2O2/iodine system could
be a powerful preventative strategy to augment innate airway defenses and prevent airway acquired infections. Additional work by our group has shown that oral dosing of adult cattle with Sodium Iodide (NaI) achieves concentrations of Iodide in airway secretions that correspond to effective concentrations in vitro and that these levels persist for at least 72 hours after a single dose [5].The overall goal of this study is to investigate the potential for NaI in preventing respiratory disease in pre-weaned dairy calves. Two knowledge gaps exist; the kinetics of iodine in airway fluid following oral supplementation of pre-ruminant calves, and whether strategically timed NaI supplementation can decrease respiratory disease in a production setting.Justification: BRD is an important cause of animal welfare issues and economic losses in dairy production worldwide. The 2011 NAHMS study found that 18% of pre-weaned heifers are affected by respiratory disease and 16.4% receive antimicrobials.
Decreasing pneumonia in pre-weaned heifers would lead to better health and welfare of these animals and reduced antimicrobials usage. NaI is safe, economical and easy to administer. Scientific evidence of decreased respiratory disease in dairy calves would have positive effects on animal health, economy and food safety.HYPOTHESES1. Oral administration of NaI increases levels of iodide in respiratory fluids of pre-weaned dairy calves.2. Oral administration of NaI results in decreased treatments for respiratory disease in pre- weaned dairy calves.SPECIFIC OBJECTIVES1. To determine the kinetics of iodine in airway fluid following oral administration of two different doses of NaI, based on a small population of dairy calves.2. To determine whether calves receiving oral NaI receive significantly fewer treatments for respiratory disease as compared to control calves, and to determine if NaI causes a change in airway pathogen profile.