Food Animal Respiratory Disease, Pt. 3 Flashcards
In what 2 ways is Mycoplasma transmitted?
- oronasal secretions
- ingestion of milk from cows with mycoplasmal mastitis
What is the pathogenesis of Mycoplasma like? How do infected cattle present?
- infection of bronchoalveolar epithelium leads to hematogenous spread to synovial surfaces
- systemic immunosuppression aids in hematogenous spread
same as other cases of BRDC, but with poor response to antibiotic therapy + arthritis and tenosynovitis
What are 4 other syndromes associated with Mycoplasma infection?
- mastitis
- otitis media
- genital infection
- keratoconjunctivitis
How is Mycoplasma infection best diagnosed? What things are seen? What is another option for diagnosis?
joint fluid cytology - cloudy, decreased viscosity, contains fibrin, high PMNs and protein, rarely see organisms
culture of joint fluid, tissues, tendon sheaths, or lung - must request 48 hours for isolation and culture on special media (fried egg appearance)
What is the most effective treatment for Mycoplasma infection? When is response particularly poor?
Enrofloxacin (Baytril) - extra-label use is illegal, only used for pneumonia
+/- OTC, Tylosin, Lincomycin, Spectinomycin, Florfenicol
joint or tendon sheath involvement
How is Mycoplasma infection controlled/
- clean pens, feed bunks, and water tanks between groups of cattle
- isolate clinically affected cattle
- vaccination - reduce clinical disease, protection provided after 3 doses at 10-14 day intervals
What lungworm infects cattle? What may act as hosts?
Dictyocaulus viviparus - host-specific, unlikely to infect small ruminants, L1 larvae in fresh feces act as diagnostic stage
- young cows
- buffalo calves
- deer, reindeer
- camels
What treatment is recommended for bovine lungworm? How is infection controlled?
Levamisole
avoid first year’s grazing
How do adult Dictyocaulua viviparius look?
- mouth surrounded by 4 lips
- mouth opening leads into a small buccal capsule
- males have a prominent copulatory bursa
What helps disseminate lungworm larvae?
Pilobolus fungal spores explode and cast larvae long distances from the fecal pat
Dictyocaulus viviparum lifecycle:
What is the major factor that affects susceptibility to lungworm infection?
age –> most common in calves in first grazing season
- calves in zero-grazing farms were infected at lower levels
Where and when are lungworm infections most common?
temperate areas
spring > summer > fall > winter
What are the 4 sources of lungworm infection? How is it transmitted?
- clinically infested animals
- contaminated environment
- carriers - low infective doses, strong immune system
- overwintered larvae
ingestion of L3
What 3 things does the pathogenic effect of lungworms rely on?
- location of worm
- number of infective larvae ingested
- animal’s immune status
What are the 4 phases of lungworm infection? What happens at each point? What clinical signs are seen at each point?
- penetration (1-7 days) - L3 penetrate bowl and migrate to local LNs and molt into L4; no clinical signs
- prepatent (8-25 days) - L4 migrate to alveoli and bronchioles and molt into L5; alveolitis, bronchiolitis
- patent (26-60 days) - immature adults mature in the bronchi and trachea; bronchitis, pnuemonia
- post-patent (61-90 days) - mature worm is expelled; recovery
What happens during the prepatent phase of lungworm infection? What causes differences in clinical signs? What history is commonyl associated?
(8-25 days) - blockage of bronchioles by eosinophilic infiltrate –> obstruction of the airways and collapsed alveoli
- FEW LARVAE = moderate coughing, tachypnea (60 bpm), crackles
- LARGE NUMBER OF LARVAE = death due to interstitial emphysema
moving to new pasture 7-12 days previously