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10 Cards in this Set
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respiratory diseases in calves < 1 month old (key point)
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Unlike diarrhea, respiratory diseases are not common in calves < 1 month old.
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< 1 month old: respiratory signs with severe neonatal calf diarrhea
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+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 |
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< 1 month old: neonatal acute respiratory distress syndrome
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+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 |
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< 1 month old: acute exudative pneumonia
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+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) |
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< 1 month old: aspiration pneumonia
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+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 |
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< 1 month old: pulmonary abscess
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+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 |
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< 1 month old: respiratory signs due to congenital cardiac disease
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+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 |
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respiratory disease in housed calves > 1 month old (key points)
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+many aetiological agents, often act in combination
+environmental factors play important role +major economic importance +acute episodes may develop into a chronic condition |
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respiratory disease in housed calves > 1 month old (aetiology/pathogenesis)
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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 |
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respiratory disease in housed calves > 1 month old (clinical signs - acute group problem)
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+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 |
