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
What clinical signs are associated with the patent period of lungworm infection? What are 3 complications?
- chronic, nonsuppurative, eosinophilic granulomatous pneumonia
- FEW ADULTS - coughing, tachypnea, crackles
- LARGE NUMBER OF ADULTS - frequent deep coughing, tachypnea (>80 bpm), crackles, standing with head stretched forward and mouth open
- interstitial emphysema
- pulmonary edema
- secondary bacterial infection
What are the 2 most common clinical findings in cases of lungworm in adult dairy cattle? What commonly happens in the fall?
- milk yield drops severely
- weight loss
reinfection phenomenon - less severe than initial infections, widespread coughing, tachypnea, dropped milk yield
What happens during the post-patent period of lungworm infection? What clinical signs may be seen?
animal survivial past patent period (2-3 months) allows expulsion of adults and resolution of cellular exudate over 4 weeks –> most recover unless there is a secondary bacterial infection
RARE - diffuse, proliferative alveolitis characterized by hyperplasia of Type II alveolar epithelial cells
Bovine lungworm:
Dictyocaulus viviparum
What are 3 options for diagnosing bovine lungworm infection? What is considered a lethal infection?
- fecal examination - Baermann to find L1 in fresh feces
- pasture examination
- ELISA and immunoblot - best serologic tests
3 larvae per 500 gm
What is considered the diagnostic stage of lungworms?
L1 found in fresh feces
When are larvae not found in cattle infected with lungworm? What does absence of L1 in feces of animals with severe clinical signs?
those in the pre-patent or post-patent phases and not in the reinfection phenomenon
strong immunity, but undergoing a severe challenge infection
What nematicides are recommended for lungworm infection?
- Levamisole (Ucimisole, Vermisole)*
- Panacur (oral)
- Rintal
- Citarin*
- Cidarin
- Ivomec*
- Dectomax
What are 7 oral preparations that work for lungworm infection?
- Banminth*
- Levamisole
- Systamex
- Curafluke*
- Albendazole
- Anthel-All*
- Panacur
How is lungworm infection controlled?
- treat clinically infected animals
- quarantine all new arrivals, paying close attention to age
- control animal density and rotation of pasture
- graze by age group with proper grazing height
- rest the land
- plant nematicide plants
- improve drainage, manure management, and fertilizers
What are the characteristic clinical and pathologic sign of acute respiratory disease syndrome (ARDS)?
sudden onset of severe dyspnea
- pulmonary congestion and edema
- hyaline membranes
- alveolar epithelial hyperplasia
- interstitial edema
- emphysema
What is the most common cause of ARDS? What is the main exception?
non-infectious agents - pneumotoxins
BRSV
What is fog fever? What causes it? In what cattle is it most commonly seen?
acute bovine pulmonary edema and emphysema due to the ingestion of high amounts of the second growth of grass (foggage)
L-tryptophan ain the grass is metabolized into indole acetic acid by rumen microflora and 3-methylindole, which is converted into a highly reactive intermediate by Clara cells and type 1 pneumocytes
adult cattle moving from dry, poor pasture onto lush pastures (grasses, alfalfa, rape, kale, turnip)
What symptoms are associated with fog fever?
- dyspnea, coughing
- frothing at the mouth
- anxiety, separation from group
- collapse, death
How can fog fever be avoided?
- limit time grazing in the first 10 days when cattle arem loved to a new pasture
- allow cattle to graze a couple hours a day and build this time up gradually
no specific treatment, mild cases typically recover without treatment
What is 4-ipomeanol? What does it cause?
pre-toxin from Fusarium solani fungus, commonly found on moldy sweet potatoes
ARDS - metabolized in the lung similar to 3-methylindole
What volatile oil found in plants can also cause ARDS?
perilla ketone (similar ot 4-ipomeanol) produced in perilla mint and purple mint (Perilla frutescans) during the late growing season (August-October)
What are 4 additional causes of ARDS?
- poison gases - nitrogen dioxide, zinc oxide, chlorine
- milk allergy - auto-allergy to alpha-casein, more common in adult dairy cows –> urticarial
- paraquat and diquat
- BRSV
What are the most common signs associated with ARDS?
acute onset
- severe dyspnea with an expiratory grunt
- obvious distress - head and neck extended, mouth open
- crackles due to edema in the airways
- acute death
no age, sex, or breed predilection
What are 6 necropsy lesions associated with ARDS?
- lungs fail to collapse when the thorax is opened
- rib imprints on lungs
- pulmonary congestion and edema
- hyaline membrane
- alveolar epithelial hyperplasia
- interstitial edema and emphysema
How is ARDS treated?
- remove source of intoxication
- avoid handling to decrease stress
- corticosteroids +/- NSAIDs
- diuretics - Furosemide
- antihistamines - epinephrine, atropine
How is ARDS controlled?
- don’t create hungry cattle
- caugtion when grazing hay pasture with rapid growth (can add ionophores into feed to reduce conversion to toxic compounds)
- avoid feeding sweet potatoes
- vaccinate for BRSV
- avoid situations that cause gas buildup (silos, manure pits)
What are the 3 most common causes of aspiration pneumonia? What clinical sign is commonly seen?
- iatrogenic
- impaired swallowing
- regurgitation
foul breath
How is aspiration pneumonia treated?
long-term antibiotics + corticosteroids or NSAIDs
What is the prognosis for aspiration pneumonia?
a. fair
b. good
c. guarded
d. hopeless
C
Fog fever has to do with…
a. 4-ipomeanol
b. L-tryptophan
c. paraquat
B
To eliminate ARDS due to 4-ipomeanol, you must remove access to…
a. moldy sweet potatoes
b. recently mown lush hayfields
c. weeds
A
