VM 536 Exam 2: Learning Objectives | Complete Solutions (Verified Answers)

VM 536 Exam 2: Learning Objectives | Complete Solutions (Verified Answers) What does BRDC stand for? Bovine Respiratory Disease Complex. What is the common name for BRDC? Shipping fever. What 3 factors contribute to BRDC? Stressors, viral agents, bacterial agents Examples of stressors in BRDC weaning, shipping, overcrowding Examples of viral agents in BRDC IBR, BVDV, BRSV, PI-3 Examples of bacterial agents in BRDC M. haemolytica, M. bovis, P. multocida, H. somni Why is BRDC economically important? Causes high morbidity/mortality, reduced feed efficiency, poor weight gain, and increased treatment costs. Gram stain and shape of M. haemolytica? Gram-negative pleomorphic cocobacillus. Oxygen requirements of M. haemolytica? Facultative anaerobe, CO₂ required for culture. β-hemolytic or α-hemolytic of M. haemolytica? β-hemolytic. Extracellular or intracellular; M. haemolytica? Extracellular Main hosts of M. haemolytica? Cattle, sheep. Where is M. haemolytica carried commensally? In the tonsils, often in biofilms. How does stress influence infection? Stress allows bacteria to spread from tonsils into lungs. 2 transmission routes for M. haemolytica? Endogenous spread + exogenous via aerosols/direct contact. What toxin is unique to M. haemolytica? Leukotoxin (LKT, an RTX toxin). What receptor does LKT target? CD18 on bovine/ovine leukocytes. Effect of LKT on neutrophils? Kills them → release granules → tissue necrosis. What is the role of capsular polysaccharide? Inhibits phagocytosis & complement. In respiratory infections caused by Mannheimia haemolytica, what would you expect to see if you collect lung tissue at necropsy and examine the histopathology of the tissue sample? Alveoli filled with bacteria, edema fluid, fibrin, neutrophilic exudate and blood and loss of architecture of alveolar septae Mycoplasma bovis attaches to: Ciliated respiratory epithelial cells Mycoplasma bovis is innately resistant to inhibitors of cell wall synthesis such as β-lactam antibiotics because: they do not make the target for these antibiotics T or F: BRDC is an interaction of host, environment, and pathogenic agents. True According to the information provided, in 2003/2004 approximately _______ % of feedlot deaths in Michigan were due to pneumonia. 75% Which of the following antibiotics can be lethal if injected into a human. a) Enrofloxacin (Baytril) b) Tilmicosin (Micotil) c) Ceftiofur (Naxcel, Exede) d) Tulathromycin (Draxxin) e) Ampicillin (Polyflex) What is the primary role of Bovine Viral Diarrhea Virus (BVDV) in the Bovine Respiratory Disease Complex? Causes subcutaneous emphysema What does LPS cause? Strong inflammatory response. Why are pili important? Mediate adhesion to respiratory epithelial cells. How does M. haemolytica obtain iron? Iron-binding proteins specific to bovine transferrin. M. haemolytica sequence of events in pathogenesis? Stress → colonization via pili → LPS → neutrophil recruitment → LKT kills neutrophils → necrosis. What necropsy lesion is typical of M. haemolytica? Fibrinous, necrotizing, hemorrhagic pneumonia with pleuritis. Max fever in severe cases of M. haemolytica? Up to 107°F. Classic posture in dyspnea? Head/neck extended, elbows abducted. Morbidity and mortality rates of M. haemolytica? ~35% morbidity; 5-10% mortality. Why must treatment of M. haemolytica be early? To prevent irreversible necrosis from neutrophil destruction. Why continue antibiotics in M. haemolytica after recovery? To ensure clearance of bacteria. What vaccine type is effective in M. haemolytica? Bacterin + LKT toxoid. When should vaccines be given in M. haemolytica? ~3 weeks before shipment + booster at arrival. What is metaphylaxis? Mass antibiotic treatment on arrival to prevent outbreak. Key management prevention strategies in M. haemolytica? Reduce stress, isolate sick animals, improve ventilation, reduce overcrowding. Mycoplasma bovis: Peptidoglycan present? No Why can't β-lactams treat M. bovis? No peptidoglycan target. What provides structural stability instead of a cell wall in M. bovis? Sterols and membrane proteins. How does M. bovis stain? Poorly on Gram stain; requires special stains. Environmental survival of M. bovis? Very poor; host-adapted. What adhesins are used for attachment in M. bovis? Variable Surface Proteins (VSPs). How do VSPs help evade immunity? Antigenic & phase variation. How does M. bovis damage cilia? Produces hydrogen peroxide. What are modulins? Bacterial proteins/lipoproteins that alter immune response (stimulate cytokines or suppress phagocytes). Is M. bovis mainly extracellular or intracellular? Extracellular (tight adherence to host cells). Typical respiratory presentation of M. bovis? Chronic hacking cough, mild pneumonia, nasal/ocular discharge. 2 extra-respiratory manifestations of M. bovis? Arthritis (swollen joints, lameness) & otitis media/interna (ear droop, head tilt, exudate). What dairy disease can M. bovis also cause? Mastitis. Why is treatment often unsatisfactory in M. bovis? Chronic infection + immune evasion. Which antibiotics are effective in M. bovis? Macrolides, tetracyclines, florfenicol. Which antibiotics are ineffective in M. bovis? β-lactams, vancomycin. What is the current vaccine status of M. bovis? New modified live vaccine exists, but efficacy is uncertain. Key management prevention strategies of M. bovis? Reduce stress, improve ventilation, preconditioning (weaning, bunk training, castration, vaccination). Major economic effect of M. bovis? ↓ feed efficiency, slower growth, chronic treatment costs. Why must Banamine (flunixin) be given IV in cattle? To avoid tissue residues & injection site damage. Why is aspirin controversial in cattle? Not FDA-approved, dose not well established. What is the main role of pen riders? Daily observation & early identification of sick cattle. Why are subcutaneous neck injections preferred? Protect prime carcass cuts (BQA guidelines). What is preconditioning? Management before shipment: weaning 30-45 days, bunk training, castration, dehorning, vaccination. What does CIRD stand for? Canine Infectious Respiratory Disease Complex. Why is "kennel cough" a misleading term? Because CIRD occurs in any situation with dog co-mingling (parks, shows, daycares, grooming, shelters), not just kennels. What is the principal risk factor for CIRD? Exposure to other dogs. What is the primary transmission route of CIRD pathogens? Direct dog-to-dog transmission via droplets/aerosols from breathing, barking, coughing, or sneezing. What is the function of the mucociliary apparatus? Traps and clears inhaled pathogens via mucus and ciliary motion. Where is Nasal Associated Lymphoid Tissue (NALT) located? Just below the nasal epithelium in the lamina propria. Which two immunoglobulins provide protection in CIRD? IgA and IgG. What is the function of IgA in CIRD? Provides immune exclusion by binding pathogens in mucus, preventing attachment to cilia/epithelial surfaces. Why does IgA provide only short-term protection? It has a short half-life and titers wane quickly. How does IgG reach mucosal surfaces? It leaks into mucosa after inflammation and vasodilation. What are the main functions of IgG? Opsonization, complement activation, and recruitment of phagocytes. Name the three primary bacterial pathogens in CIRD. Bordetella bronchiseptica, Mycoplasma cynos, Streptococcus equi subsp. zooepidemicus. Which viral pathogen is considered "wimpy" but predisposes to co-infection by damaging cilia? Canine parainfluenza virus (CPiV). Which pathogens primarily affect puppies? Canine herpesvirus (CHV-1), Canine adenovirus-2 (CAV-2). Which influenza subtypes cause CIRD? H3N8 and H3N2. Which CIRD pathogens currently have vaccines? Bordetella bronchiseptica, CPiV, CAV-2, CDV, CIV (H3N2 & H3N8). Which pathogens have no vaccines? Mycoplasma cynos, CRCoV, pneumovirus, CHV. What are the major adhesins of Bordetella bronchiseptica? Filamentous hemagglutinin, fimbriae, and pertactin. What role does the capsule play in Bordetella infection? Prevents phagocytosis and blocks complement activation. What does the tracheal cytotoxin do? Kills ciliated epithelial cells, impairing mucociliary clearance. What is unusual about the tracheal cytotoxin? It's a peptidoglycan fragment released during bacterial growth. What is the function of the adenylate cyclase toxin? Increases cAMP → hypersecretion of mucus, inhibits phagocyte function. What is the net effect of Bordetella's toxins? Loss of cilia + excess mucus → impaired clearance + persistent cough. Which dogs are most at risk for CIRD complications? Puppies, immunocompromised dogs, and dogs with chronic respiratory disease. How many air exchanges per hour should kennels target for ventilation? 12-20. How far can droplets travel in still air during barking or coughing? 4-6 feet. Describe the cough in uncomplicated CIRD. Sudden onset, dry, hacking, honking, paroxysmal, often with retching. How do dogs with uncomplicated CIRD typically appear systemically? Bright, alert, eating and drinking normally, afebrile. How long does uncomplicated CIRD usually last? 1-3 weeks. What are signs of complicated CIRD? Productive cough, fever, lethargy, anorexia, dehydration. What radiographic pattern is typical of bronchopneumonia from CIRD? Cranio-ventral alveolar pattern ± caudo-dorsal interstitial infiltrates. In uncomplicated CIRD, what three elements are often enough for diagnosis? Signalment, history, and physical exam. What is the incubation period between exposure and symptom onset? 3-10 days. What is the best sample site for PCR testing? Deep nasal swab (past alar fold, against septum/turbinates). How can mucosal Bordetella vaccines affect PCR? They can cause false positives for up to ~28 days. When might culture and sensitivity be especially useful? In complicated CIRD or when antibiotic resistance is suspected. Why is cough suppression appropriate in uncomplicated CIRD? The cough is nonproductive and causes irritation without benefit. Which drug class is typically used for cough suppression? Opioids (hydrocodone, butorphanol). Should broad-spectrum antibiotics be used for uncomplicated CIRD? No, use narrow-spectrum if antibiotics are indicated (doxycycline, azithromycin, clindamycin). What is the quarantine period for infected dogs? 2 weeks beyond symptom resolution OR 4 weeks from onset. Which type of vaccine generates IgA at the mucosal surface? Mucosal (intranasal/oral) vaccines. Why are mucosal vaccines advantageous in puppies? They bypass maternal antibody interference. At what age can intranasal Bordetella vaccines be given? As early as 4 weeks. At what age are oral Bordetella vaccines typically given? As early as 8 weeks. What are key environmental control measures for preventing CIRD? Adequate ventilation, dog spacing, disinfection, and isolation of sick dogs. Which CIRD pathogen can infect immunocompromised humans? Bordetella bronchiseptica. What is the typical presentation in humans of Bordetella bronchiseptica.? Persistent cough, possible severe respiratory disease in immunocompromised patients. What does SOAP stand for in veterinary medicine? Subjective, Objective, Assessment, Plan. What medical record system is SOAP based on? The Problem-Oriented Medical Record (POMR). What belongs in the subjective section? All information collected before clinician's exam (owner complaint, HPI, previous records). How should the chief complaint be recorded? In the owner's own words. What does the History of Present Illness (HPI) include? Chronological timeline from last known normal to current illness. What are examples of pertinent past history to include? Chronic illnesses, preventive care, travel history, source of pet. Where do diagnostic results from another clinic belong: subjective or objective? Subjective (because you did not collect them). When does the objective section begin? With the clinician's first physical exam. What belongs in the objective section? PE findings, vitals, diagnostics ordered by you, specialist reports you request. Should normal findings be included in the objective section? Yes, because sometimes "normal" is diagnostically significant. What is the purpose of a problem list? To organize all abnormalities and guide SOAP development. How should problems be written? At your current level of understanding (“cough,” not “pneumonia” unless confirmed). What is a high-yield problem? localizing, life-threatening, tightly regulated (e.g., hypoglycemia, hypercalcemia). What is a low-yield problem? nonspecific (lethargy, fever). What is lumping problems? Prematurely combining separate problems into one diagnosis. What is co-localizing problems? Problems that clearly arise together (same onset, same resolution). What are the three components of an assessment? General pathophysiology of the problem. Differential diagnoses (rule-outs). Application to the patient (most likely differentials). Are "differentials" and "rule-outs" the same? Yes, they are interchangeable. Give an example of a low-yield problem you should not SOAP. Lethargy. What type of problems are most helpful in narrowing differentials? Problems with few differentials or tightly regulated values (hypoxemia, hypoglycemia, hyperkalemia). What types of plans can be included in SOAPs? Diagnostic, therapeutic, and palliative. How should emergency interventions be documented? Still as SOAP, but rapidly (can be done in 30 seconds). In emergencies, which comes first: diagnostics or stabilization? Stabilization (oxygen before testing cause of hypoxemia). What should plans always address? Pressing patient needs first, then refinement of diagnosis. What is clinical reasoning in SOAP writing? The process of applying pathophysiology and differentials to the specific patient to justify diagnosis and plan. Why is including normal results sometimes important? Because "normal" values can rule out differentials (normal creatinine with high BUN). Which two viruses account for 80-90% of feline viral upper respiratory disease (URD)? Feline herpesvirus-1 (FHV-1) and feline calicivirus (FCV). What are common secondary contributors to feline URD? Chlamydia felis, Bordetella bronchiseptica, Mycoplasma spp. What risk factors predispose cats to URD? Young age, stress (shelters/shows), overcrowding, poor ventilation, lack of vaccination. Why do some cats in an outbreak have only mild "sneezing" while others are severely ill? Disease severity depends on host immunity, pathogen strain, and environmental stress. What family and subfamily does FHV-1 belong to? Herpesviridae, Alphaherpesvirinae. Is FHV-1 DNA or RNA? Enveloped or non-enveloped? Double-stranded DNA, enveloped.