SDL: Respiratory Disease in Adult Cattle Flashcards
What is fog fever and what toxin causes it?
- Atypical form of interstitial pneumonia.
- Ingestion of large quantities of L-tryptophan
What types/ages of cattle is fog fever generally seen in?
- Cattle over two years old
- More common in suckler herds
- Common in cattle that have previously been on little nutrition and are then put on more lush pasture in autumn (September to November)
- Normally seen within two weeks of entry to new pasture
- Hereford and Hereford crosses seem particularly susceptible
How does ingestion of large quantities of L-tryptophan cause disease?
- L-tryptophan in grass is metabolised in the rumen to indole acetic acid (IAA)
- IAA decarboxylated by Lactobacillus spp. to produce 3-methyl indole (3MI)
- 3MI causes destruction of the pulmonary cells e.g. type I pneumonocytes and monociliated bronchiolar secretory cells resulting in pathological changes
What clinical signs do cattle with fog fever show if severely affected?
- Sudden onset dyspnoea
- Loud respiratory grunt
- Mouth breathing
- Frothing at the mouth
- Auscultation often reveals little, soft, moist sounds, occasionally crackles
What clinical signs do cattle with fog fever show if not severely affected?
- Tachypnoea (50-80 per minute)
- Hypernoea
- No dyspnoea
- Auscultation less severely effected: harsh sounds
- Normal rectal temperature
How would you diagnose fog fever?
- Necropsy findings (haemorrage, pulmonary oedema, erythema of the lungs etc.)
- Histological examination (Severe congestion and oedema of pulmonary tissue)
- History
- Clinical signs
What other differentials would you have alongside fog fever?
- Husk
- Pneumonic pasteurellosis
- Nitrate poisoning
- IBR
- Thrombosis of caudal vena cava
- Brassica poisoning
How would you treat fog fever?
- Remove cattle from incriminated pasture
- Treatment tends to be empirical (supportive)
- Atropine 1g per 450kg BW IV acts as a bronchodilator
- Corticosteroids can be beneficial
- Flunixin meglumine can be beneficial in acute pulmonary emphysema
- Reduce stress
- Movement and unnecessary stressing of affected individuals at this point can cause animals to drop dead
How would you prevent fog fever?
- Restrict grazing for short periods during the first two weeks
- 2 hours on the first day then increasing by an hour a day
- Strip graze/graze with sheep prior to putting cattle on pasture
- Monesin sodium 200mg/head/day before and after entering the pasture
When does infectious bovine rhinotracheitis tend to occur?
- Condition can occur in animals at grass but is much more severe when a group of housed animals are affected.
- Introduction of infection to a group of cattle is usually via a carrier or animal incubating the disease.
- Can occur after purchase of animals, or if off the farm on agricultural shows etc.
What are the clinical signs of IBR?
- Dullness
- Reduced appetite
- Pyrexia
- Profuse nasal and ocular discharges
- Frequent coughing.
- In severe cases, finding necrotic plaques on nasal mucosa.
- Auscultation of the chest may reveal loud lung noises, but often difficult to interpret.
- Reduced milk yield and abortion may also occur.
What is atopic rhinitis?
- Upper respiratory tract disorder of grazing cattle.
- Can be confused with IBR.
- Highly seasonal – seen at start of grazing period. Caused by allergy to inhaled antigens such as pollens
What are the clinical signs of atopic rhinitis?
- Ocular and nasal serous discharge
- Nasal pruritis
- Sneezing.
- This progresses over several weeks to:
- Mucopurulent discharge
- Swelling of nasal mucosa
- Ulceration of nasal mucosa with bleeding and white nodules up the nostrils.
- Does not spread to other cattle like IBR does – helps to differentiate the two diseases.
What is Farmers lung?
- Extrinsic allergic alveolitis
- Inhalation of spores and metabolic products of Micropolyspora faenia produce a type III hypersensitivity at the level of the alveoli
When is farmers lung generally seen?
- Seen in cattle who have been fed hay that has been baled at too high moisture content
- Metabolism of saprophytic microflora causes overheating and consequently M. faeni proliferates
- More common in West of UK
- Commonly occurs during winter when feeding conserved fodder
What are the clinical signs of acute farmers lung cases?
- Respiratory signs
- Hyperpnoea
- Occasionally dyspnoea with mouth breathing
- Crackles on auscultation in cranioventral lung fields in some cases
- Other clinical signs
- Complete agalactica
- Occasionally pyrexia
- Bright demeanour
What are the clinical signs of chronic farmers lung cases?
- Respiratory signs
- Chronic coughing over several housing periods with remission when turned out on grass
- Coughing, produces copious amounts of green discharge
- Hyperpnoea
- Tachypnoea
- Crackles and squeaks over anteroventral lung fields
- Other clinical signs
- Insidious weight loss
- Weight loss
- Reduced milk yield
What history do cases of acute bacterial pneumonia generally present with?
- Individual animal affected
- Animals may have history of transport which has caused chronic suppurative pulmonary disease which has been exacerbated to present as acute disease.
- History of bad drenching technique or regurgitation in a weak cow can result in inhalation pneumonia which will present the same.
What are the clinical signs of acute bacterial pneumonia?
- Sudden onset pyrexia
- Dullness
- Tachypnoea
- Coughing
- Anorexia
- Reduced milk production will occur
- Harsh auscultatory sounds due to tachypnoea
- Occasionally squeaks may also be heard
How is acute bacterial pneumonia diagnosed and treated?
- Diagnosis: Often diagnosed under umbrella terms of pneumonic pasteurellosis or bacterial pneumonia
- Treatment: Rapid response to antibiotics will be seen
How does a milk allergy develop in cattle?
- Hypersensitivity reaction – cow develops allergy to the alpha casein in her own milk
- Associated with interruption of normal milking routine such as drying off or showing animal
- More often seen in Channel Island breeds – probably inherited component
What are the clinical signs of a milk allergy in cattle?
- Tachypnoea, hyperpnoea (increased effort) in in severe cases dyspnoea.
- Usually no cough.
- Auscultation may reveal adventitious sounds, particularly crackles in ventral lung fields
- Sometimes urticarial skin lesions are seen
- Clinical signs alleviated by prompt milking
What is chronic suppurative pneumonia and when does it usually present?
- Most common chronic pulmonary disorder of individual adult animal
- More commonly present during housing but may present when at grass
- Clinical course of disease is normally long.
What are the clinical signs of chronic suppurative pneumonia?
- Dullness
- Weight loss
- Tachypnoea
- Coughing
- Thoracic pain may be seen upon percussion of chest and often causes bout of pained coughing
- Adventitious lung sounds may or may not be heard. If present are usually restricted to cranioventral lung lobes and tend to be squeaks.
- Occasionally animals develop nectrotising bronchopneumonia with pleurisy and become markedly duller, pyrexic, exhibit halitosis, severe thoracic pain and die within a few days
Posterior vena cava thrombosis with pulmonary embolism occurs sporadically in adult cattle. What are the clinical signs?
- Haemoptysis
- Thoracic pain (associated with the pulmonary embolism)
- Pallor of mucus membraes
- Melaena
- Audible squeaks on auscultation of the lung fields
- Hepatomegaly
- Occasionally ascites if hepatic veins have been blocked by the thrombus
What is the usual history of posterior vena cava thrombosis with pulmonary embolism?
- Protracted weight loss
- Coughing but duration and severity can vary
- Some have chronic cough
- Others initial signs if coughing up blood
What is diffuse fibrosing alveolitis?
- Chronic condition
- Older animals
- Aetiology unclear
- May be due to an endstage of repeated annual bouts of fog fever or farmers lung
What are the clinical signs of diffuse fibrosing alveolitis?
- Prolonged history of:
- Coughing
- Weight loss
- Bright
- Hyperpnoeic
- Widespread adventitis sounds over both lung fields
- May develop clinical signs of congestive heart failure due to cor pulmonale (abnormal enlargement of the right side of heart as a result of disease of the lungs or the pulmonary blood vessels)
List differentials for: a group of adult suckler cows at grass which have developed respiratory signs over the last 48 hours.
- Fog fever
- Reinfection husk
- Atopic rhinitis
- IBR
List differentials for: a single adult dairy cow which has developed respiratory signs over the last month.
- Acute bacterial pneumonia
- Milk allergy
- Posterior vena cava thrombosis with pulmonary embolism
- Chronic supprative pneumonia
- Diffuse fibrosis alveolitits
List differentials for: a straw yard full of 3-10 month old barley beef bulls which have developed respiratory signs over the last 48 hours.
- Farmers lung
- Fog fever
- IBR
- Aspiration pneumonia
- Diffuse fibrosis alveolitis
- Dusty feed rhinotracheitis
- Other viral respiratory diseases
- Parainfluenza 3
- Bovine synccitial virus
