Bovine Respiratory Disease (BRD) - PDF

Bovine respiratory disease LAMS 5333 Clare Ryan, DVM, PhD, DACVIM Learning Objectives: Describe and contrast the classifications of Bovine Respiratory Disease Recognize the infectious agents (viral and bacterial) associated with Bovine Respiratory Disease Describe risk factors, clinical...

Bovine respiratory disease LAMS 5333 Clare Ryan, DVM, PhD, DACVIM Learning Objectives: Describe and contrast the classifications of Bovine Respiratory Disease Recognize the infectious agents (viral and bacterial) associated with Bovine Respiratory Disease Describe risk factors, clinical signs, treatment of of bronchopneumonia in: Nursing dairy calves Stockers and feedlots Describe the causes, pathogenesis, clinical findings, and treatment of: Metastatic Pneumonia Interstitial pneumonia Necrotic Laryngitis Bronchopneumonia (BP) Invasion of pathogenic organisms into lung through bronchial tree Characterized by fever, depression, signs of sepsis Bronchointerstitial pneumonia (BIP) Bronchopneumonia complicated by interstitial lung disease Metastatic pneumonia Septic embolization of lungs from other foci in body Sequelae to rumen acidosis and liver abscessation Interstitial pneumonia (AIP) Interstitial reaction to ingestion or inhalation of toxins or allergens; Viral respiratory tract infection  Bovine respiratory disease: Bronchopneumonia Opportunistic disease Viral infection of URT precedes bacterial colonization of lung Increased bacterial numbers Longer duration of shedding Increased disease severity  Bovine respiratory disease: Viral-Bacterial Synergy Viral infection affects: 1. Mucous 2. Mucocilliary apparatus 3. Immune cell function: Reduced macrophage fxn Tissue damage 2°to neutrophils  Bovine respiratory disease complex: Bronchopneumonia Viruses Bovine Herpes Virus-1 (BHV-1), Bovine Respiratory Syncitial Virus (BRSV) Bovine Viral Diarrhea Virus (BVDV), Parainfluenza 3 Virus (PI3) Coronavirus Influenza D Bacteria Mannheimia haemolytica, Pasturella multocida, Histophillus somni, Mycoplasma bovis  BRDC Bronchopneumonia Clinical Signs: Little variation b/t pathogens Fever Cough Anorexia Depression Increasedrespiratory rate/effort Reduced milk production  BRDC: primarily in calves Dairy: 4L of milk per day in calves < 21 days of age Administration of vaccines to dry cows prior to calving Stocker/Feedlot Cattle https://doi.org/10.1186/s13567-022-01086-1  Stocker/feedlot Common causes of morbidity  Stocker/feedlot Multifactorial disease syndrome  Stocker/feedlot: Risk Factors Arrival weight of cohort Lower weight = greater risk 20-35% increase in mortality risk for each hundred weight decrease in cattle weight Gender Bulls = greater risk 140% increase in morbidity 142% increase in mortality Month of arrival September - November  Feedlot Cattle: Preconditioning Castrate Vaccinate/deworm Wean at least 45 days prior to shipping Train to eat from a feed bunk and drink from a water trough  Stocker/feedlot: Importance of Preconditioning  Mannheimia haemolytica highlight Gram (-) facultative anaerobic rod 12 serotypes Some pathogenic, others nonpathogenic commensals: Serotypes A1 and A6 = most common isolates from BRD cases Serotype A2 = most common serotype in normal cattle DOI: 10.1177/0300985810377182  Mannheimia haemolytica: Lipopolysaccharide Systemic inflammatory response syndrome (SIRS) Tachycardia Tachypnea Cool extremities Dark mucous membranes  Mannheimia haemolytica: Leukotoxin Essential virulence factor Binds to cells via CD18 Causes the death of bovine leukocytes Neutrophil lysis and release of digestive enzymes Mannheimia haemolytica  Bronchopneumonia treatment Gold Standard = Antimicrobials Parenteral 16 compounds registered for use in cattle with BRD Little evidence to support use of other therapeutic modalities  Vaccination Numerous multivalent vaccines Modified live or killed Parenteral or intranasal Differences in efficacy: Dairy vs Beef Weaned vs Pre-weaning  Metastatic pneumonia Cattle feed rations high in rapidly fermentable carbohydrates Rumen acidosis Rumenitis Liver abscessation Thrombosis of vena cava Spread of emboli from septic thrombi in caudal vena cava DO - 10.1590/1678-5150-pvb-7226  Metastatic pneumonia: Two Presentations 1. Chronic weight loss and coughing Intermittent fever 2. Hemoptysis and epistaxis Tachycardia, tachypnea, coughing Heart murmurs  Metastatic pneumonia Clinical Findings  Metastatic pneumonia: Ultrasound Dilatation of caudal vena cava Normal Abnormal  Metastatic pneumonia: Treatment Prognosis poor- therapeutics generally unrewarding Antimicrobials and other supportive care T. pyogenes F. necrophorum E. coli Control conditions that precipitate disease Nutritional management to reduce occurrence of acidosis  Necrotic laryngitis Infection of laryngeal mucosa and cartilage Acute or chronic Laryngeal contact ulcers essential to development of disease Invasion of tissue by respiratory commensals Fusobacterium necrophorum  Necrotic laryngitis: Clinical Signs Calves: 3-18 months of age Feedlots or overcrowded conditions Moist, painful cough Inspiratory dyspnea with stertor Head and neck extended Ptyalism  Necrotic laryngitis: Diagnosis Clinical signs usually sufficient Endoscopy or radiographs Ultrasound  Necrotic laryngitis: Treatment Antimicrobials Florfenicol (20 mg/kg IM q 48 or 40 mg/kg SQ once) Corticosteroids Dexamethasone (0.1 mg/kg IV/IM for 2-3 days) Tracheostomy Rest airway Necrotic laryngitis Necrotic laryngitis  Interstitial pneumonias Idiopathic form of acute lung injury characterized by: Bilateral lung infiltrates Diffuse alveolar damage Pathologic definition confirmed by microscopic analysis of lung tissue from animal with characteristic history and clinical signs  Interstitial pneumonia Acute respiratory distress syndrome (ARDS) Acute onset of progressive dyspnea, tachypnea, and hypoxemia Pulmonary/extrapulmonary insult →→ release of inflammatory mediators Neutrophil accumulation Pulmonary edema, hyaline membrane formation, decreased lung compliance  Interstitial pneumonias: Known causes Viral infection BRSV (naïve or immunocompromised animals) Feedborne pneumotoxins 3-Methyl Indole “Fog fever” Perilla mint ketone 4-ipomeanol (Moldy sweet potato)  Interstitial pneumonia: Fog Fever Adult cattle > 2 years of age Association: ration changes Dry, sparse winter forage to lush green pastures in spring Conversion of L-tryptophan to 3-methylindole (3MI) by rumen microbes  Interstitial pneumonia: Fog Fever Within 2 weeks of pasture change to lush pasture Acute onset of dyspnea with loud expiratory grunt Frothing at mouth Mouth breathing Tachypnea Interstitial pneumonias Interstitial pneumonia: Fog Fever Pathogenesis  Interstitial pneumonia: Treatment No specific treatment Handling can precipitate deaths Careful removal from offending pastures If attempted: Diuretics Corticosteroids