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10 Cards in this Set

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respiratory diseases in calves < 1 month old (key point)
Unlike diarrhea, respiratory diseases are not common in calves < 1 month old.
< 1 month old: respiratory signs with severe neonatal calf diarrhea
+frequently tachypnoeic & hyperpnoeic
+usually result of respiratory compensation for metabolic acidosis from diarrhea
+occasionally from acute exudative pneumonia (infectious)
+recumbent animal can develop hypostatic pneumonia
< 1 month old: neonatal acute respiratory distress syndrome
+calf born prematurely before surfactant producing type II pneumocytes are mature
+usually unable to stand
+severe dyspnoea with mouth breathing
+tachycardia with no murmur or cyanosis
+no effective treatment but betamethasone, doxapram, clenbuterol & millophylline can be given
< 1 month old: acute exudative pneumonia
+primary bacterial infection
+Arcanobacterium pyogenes is most frequent
+also Mannheimia and Pasteurella
+severe neonatal diarrhea predisposes
+sudden onset dullness +/- anorexia, pyrexia, tachypnoea & hyperpnoea with infrequent coughing
+auscultation: soft crackles (cranio-ventrally)
+histo: congestion & oedema with neutrophils & macrophages in alveoli & bronchioles
+Tx: broad spectrum ABs usually give marked improvement if prompt
+occasionally incomplete recovery with relapse - can progress to chronic suppurative pneumonia (evident later in life)
< 1 month old: aspiration pneumonia
+usually calves forced to drink milk from a bucket
+also careless drenching
+sudden onset of marked dullness, anorexia, pyrexia, tachypnoea & variable thoracic pain
+auscultation: soft crackles cranio-ventrally
+attributable to toxaemia resulting from extensive necrotizing pneumonia affecting cranioventral area of both lungs
+either coagulative necrosis or suppurative necrosis depending on organism involved
+Tx: prompt ABs give recovery if small amount of fluid inhaled
+if large amount of fluid and does not die, likely to remain unthrifty b/c development of chronic pulmonary abcesses
+prevent by patiently coaxing calves to drink from a bucket rather than forcing
< 1 month old: pulmonary abscess
+can arise as part of septicaemia following omphalophlebitis
+usually multiple and in several lung lobes
+may occur following incomplete recovery from 1 or more episodes of an acute exudative pneumonia
< 1 month old: respiratory signs due to congenital cardiac disease
+VSD most common: acute left
heart failure & pulmonary oedema may develop if defect is large
+tetralogy of fallot
+tachypnoea, hyperpnoea, reduced appetite, pyrexia +/- cyanosis
+auscultation: loud systolic murmur at ICS 3 & 4 on both sides
+may be smaller than normal
+Tx: no possible
respiratory disease in housed calves > 1 month old (key points)
+many aetiological agents, often act in combination
+environmental factors play important role
+major economic importance
+acute episodes may develop into a chronic condition
respiratory disease in housed calves > 1 month old (aetiology/pathogenesis)
1. primary:
+mycoplasmas: M. bovis, M. dispar, Ureaplasma spp.
+viruses: parainfluenza 3 (PI3), respiratory syncytial (RS) virus
2. secondary
+commonly isolated bacteria: Arcanobacterium pyogenes, Mannheimia haemolytica, Pasteurella multocida, Staph aureus, Strep pneumoniae
+probably only exert a significant clinical effect following bronchopulmonary damage by other agents
+may be isolated from healthy animals
+modified by stress of other diseases, physical factors that affect respiratory tract defense mechanisms (eg. chilling, wide temp fluctuations, overcrowding) or mixing of calves from various sources
respiratory disease in housed calves > 1 month old (clinical signs - acute group problem)
+enzootic pneumonia can be primary or secondary complication to chronic
+within a couple weeks of stress (eg. mixed with different groups in a new house, sale/transport)
+dull, anorexic, tachypnoea, hyperpnoea, pyrexia (39.5-41C; 103-106F)
+nasal discharge common sign - initially mucoid but later mucopurulent
+coughing frequency increases markedly
+auscultation: fluid sounds (soft crackles) in cranial-ventral areas
histo: pulmonary congestion, oedema, hyaline membranes, alveolar epithelial hyperplasia, interstitial emphysema