SDL: Respiratory Disease in Adult Cattle Flashcards
1
Q
What is fog fever and what toxin causes it?
A
- Atypical form of interstitial pneumonia.
- Ingestion of large quantities of L-tryptophan
2
Q
What types/ages of cattle is fog fever generally seen in?
A
- 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
3
Q
How does ingestion of large quantities of L-tryptophan cause disease?
A
- 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
4
Q
What clinical signs do cattle with fog fever show if severely affected?
A
- Sudden onset dyspnoea
- Loud respiratory grunt
- Mouth breathing
- Frothing at the mouth
- Auscultation often reveals little, soft, moist sounds, occasionally crackles
5
Q
What clinical signs do cattle with fog fever show if not severely affected?
A
- Tachypnoea (50-80 per minute)
- Hypernoea
- No dyspnoea
- Auscultation less severely effected: harsh sounds
- Normal rectal temperature
6
Q
How would you diagnose fog fever?
A
- Necropsy findings (haemorrage, pulmonary oedema, erythema of the lungs etc.)
- Histological examination (Severe congestion and oedema of pulmonary tissue)
- History
- Clinical signs
7
Q
What other differentials would you have alongside fog fever?
A
- Husk
- Pneumonic pasteurellosis
- Nitrate poisoning
- IBR
- Thrombosis of caudal vena cava
- Brassica poisoning
8
Q
How would you treat fog fever?
A
- 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
9
Q
How would you prevent fog fever?
A
- 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
10
Q
When does infectious bovine rhinotracheitis tend to occur?
A
- 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.
11
Q
What are the clinical signs of IBR?
A
- 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.
12
Q
What is atopic rhinitis?
A
- 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
13
Q
What are the clinical signs of atopic rhinitis?
A
- 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.
14
Q
What is Farmers lung?
A
- Extrinsic allergic alveolitis
- Inhalation of spores and metabolic products of Micropolyspora faenia produce a type III hypersensitivity at the level of the alveoli
15
Q
When is farmers lung generally seen?
A
- 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
