90 – Pneumonias of horses Glanders (farcy, malleus)

90 – Pneumonias of horses
Glanders (farcy, malleus)
2010.
(Broncho)interstitial pneumonia
• Equine influenza
– Type A virus, two subtypes
• A/equi/2 – H3N8; A/equi/1 – H7N7
– Clinical signs
• Coughing, serous to purulent oculonasal discharge,
fever, weakness
• Rarely sytemic involvement and death
– Lesions
• Hyperemia, focal erosions in the upper respiratory tract
• Bronchointerstitial pneumonia
– edema
– necrosis of bronchiolar epithelium
– secondary bacterial pneumonia
(Broncho)interstitial pneumonia
• Equine herpesviruses (EHV-4, EHV-1)
– Mild upper respiratory signs
– Secondary bacterial bronchopneumonia
– Systemic lesions in neonates!
• Rhinovirus, reovirus, equine arteritis virus, adenovirus
– similar clinical signs and lesions
– predisposing factors for heaves (COPD)?
• African horse sickness
– severe edema, vascular damage (Reoviridae, Orbivirus)
• Hendra virus
– syntitial giant cells (Paramyxoviridae, Morbillivirus)
• Clamydophila psittaci
• Idiopathic proliferative interstitial pneumonia
– sequel: pulmonary fibrosis, toxicosis / viral infection?
Topics – morphological categorization
• (Broncho)interstitial pneumonia
– equine influenza, EHV-1, EHV-4 infection
• Bronchopneumonia
– catarrhal-purulent bronchopneumonia
– fibrinous bronchopneumonia, pleuropneumonia
• Streptococcus equi ssp. equi, ~ zooepidemicus; Bordetella
bronchiseptica, Klebsiella pneumoniae, Staphylococcus sp.
– necrotic/gangraneous bronchopneumonia
• aspiration pneumonia
• Focal/multifocal pneumonia
– septic thromboembolism related pneumonia
• (Pyo)granulomatous pneumonia
– Rhodococcus equi infection
– glanders (Burkholderia mallei infection)
– fungal pneumonias
• aspergillosis, pneumocystosis
Interstitial pneumonia
EIV infection, donkey
Pulmonary fibrosis, horse
1

Bronchopneumonia
• Catarrhal-purulent pneumonia
• Fibrinous (pleuro)pneumonia
– cranioventral consolidation
– predisposing factors
• stress, viral infections etc.
– secondary bacterial infection
• Streptococcus equi ssp. equi, ~ zooepidemicus;
Bordetella bronchiseptica, Klebsiella pneumoniae,
Staphylococcus sp.
Bronchopneumonia
• Necrotic/gangrenous pneumonia
– aspiration pneumonia
• anatomical predisposition
– „tracheal puddle”
• iatrogenic
– nasogastric tubing
• CNS involvement!!!!!!!!
– rabies, WNV or other viral encephalitides, lead
poisoning, fumonisin toxicosis etc.
– usually unilateral, foul smell, rapid autolysis,
necrosis predominates, mixed bacterial flora
Aspiration pneumonia, horse
Chronic purulent bronchopneumonia, horse
Aspiration pneumonia
Pyogranulomatous pneumonia
• Rhodococcus equi infection
– Rhodococcus equi
• Facultatively intracellular bacterium, complex lipids
in its cell wall
• Normal inhabitant of soil and intestinal tract of
different species
• Disease in foals of 1-6 months of age
• Pathogenesis is incompletely understood
– Clinical signs
• Fever, cough, nasal discharge, increased
respiratory rate
• High mortality
2

Pyogranulomatous pneumonia
• Rhodococcus equi infection
– Lesions
• Lungs and tracheobroncial lymphonodes
– Multiple large, firm nodules of various size
– Caseation necrosis without fibrous capsule formation
(not a proper abscess!)
– Predominantly pyogranulomatous inflammation
• Intestinal tract
– Ulcerative enterocolitis, involvement of mesentarial
lymphonodes
• Arthritis, dermatitis, hepatitis, vertebral
osteomyelitis, ulcerative lymphangitis
Rhodococcus equi pneumonia, horse
Rhodococcus equi pneumonia, horse Rhodococcus equi pneumonia, horse
Granulomatous pneumonia
• Mycobacteriosis
–Mycobacterium avium complex
–Mycobacterium tuberculosis
–Mycobacterium bovis
• Predominantly proliferative
tuberculosis
Granulomatous pneumonia
• Fungal pneumonias
–Pulmonary aspergillosis
• secondary to mucosal damage
–intestines! ulcerative fungal colitis
• systemic lesions
–brain, lungs, skin
• severe disseminated fibrinonecrotic to
granulomatous pneumonia
3

Pulmonary aspergillosis, horse
Pneumocystosis, GMS stain →
Pulmonary aspergillosis, horse Pulmonary aspergillosis, horse
← Pneumocystosis, H-E stain
Granulomatous pneumonia
• Fungal pneumonias
–Pneumocystosis
• Pneumocystis carinii fungus
• Secondary to immunosuppressive agents /
immunodeficiencies
– SCID
– Viral infections, Rhodococcus equi inf.
• Histological diagnosis
– foamy structure within alveoli
– Gömöri’s Methenamine Silver stain (GMS)
– minimal inflammatory changes
Pyogranulomatous pneumonia
• Glanders (malleus, farcy)
• Burkholderia mallei
– Gram-negative, obligate aerobic, nonmotile,
obligate pathogen
– Zoonotic agent, bioterrorism!
• Occurrence
– Asia, North-Africa, (far-far) East-Europe (?),
South-and Central America
• Susceptible species
– Equidae (solipeds), carnivores, guinea-pig,
hamster, goat, man
4

Glanders - history
• 3 rd Century BC
–Described by Aristotle
• 1664: Contagious nature recognized
• 1830: Zoonotic nature suspected
• 1891: Mallein test developed
• 1900: Control programs implemented
Glanders - history
• World War II
– Japanese infected horses, civilians and POW’s
– U.S. and Russia investigated use as biological
weapon
Glanders
• Pathogenesis
– the disease develops through several
successive stages, each is characterised
by distinctive clinical signs and lesions
– outcome depends on the immunological
status of the host
– p. os uptake: primary complex in the
alimentary tract
• early generalisation: lungs, spleen, liver etc.
• late generalisation: septicaemia, nasal mucosa,
skin
Glanders - history
• World War I
– Suspected use as biological agent to infect
Russian horses and mules
• Affected troops and supply convoys
– Large number of human cases in Russia
during and after WWI
Glanders
• Way of infection
–per os
• contaminated feed, water, carcasses of
infected dead animals
–percutaneous or conjunctival, aerogenical
–asymptomatic carriers
Glanders
• Incubation time
– Few days to several months
• Clinical forms and signs
– Acute form
• donkeys, mules, certain horses, carnivores, (man)
• coughing, fever, nasal discharge
• septicaemia, (pyemia), bronchopneumonia, death in
days
– Chronic form
• certain horses, mules, (man)
• granulomatous changes in the lungs, in the nasal
mucosa, in the skin
• subclinical infection does occur (mallein-test)
5

Draining fistulous tracts
in the skin
Glanders
Glanders,
intradermo-palpebral test
• Lesions
– Different lesions might be present in the
same animal
• Lungs
• Nasal mucosa, paranasal sinuses, lips
• Skin (lymphatics)
• Lymphonodes
• Testicles, liver, spleen
• Basic forms of lesions
– Malleotic nodule (granuloma)
– Predominantly exsudative form
– Predominantly proliferative form
Glanders, nasal and dermal lesions
Malleotic nodule
Glanders,
Strauss reaction,
male guinea-pig
• Exsudative development
– pathogen in the centre, surrounded by PMNs,
exsudation and hyperemic ring around
– later histiocytes and giant cells appear
– the center becomes necrotized, fibroblasts
appear on the perimeter
• Proliferative development
– pathogen in the centre, surrounded by
epitheloid cells and giant cells
– more epitheloid cells accumulate
– the center becomes necrotized, fibroblasts
appear on the perimeter...
6

Malleotic nodule
• Developed malleotic nodule
–pyogranuloma with narrow demarcation
zone
• colliquated or caseous centre with
occassional calcium salt deposition,
surrounded by epitheloid cells, giant cells
and granulation tissue
• poppy seed to pea sized nodules with
greyish-yellow dry or liquid centre
Malleotic nodules, nasal septum, horse
„Farcy”,
ulcerative lymphangitis
Malleotic nodule, lung
Malleotic ulcer
• Malleotic ulcer
– nodules close to the surface
• mucous membranes, skin
– nasal cavity, trachea, larynx
– necrosis, shedding of the necrotized part
– shallow to deep erosions – ulcers
• uneven margin
• undermined edge
• covered with egg-white like material
– healing with scar formation
Different stages of malleotic nodules and ulcers, nasal septum, horse
7

Malleotic ulcer on the lip,
donkey
Malleotic nodules and ulcers, nasal septum, horse
Chronic malleotic ulcers, nasal septum, horse Chronic malleotic ulcers, nasal septum, horse
Predominantly exsudative glanders
• Lungs, other tissues
–serofibrinous inflammation around the
pathogen
• bronchopneumonia
–necrosis with caryorhexis, colliquation
–healing with proliferation of malleotic
granulation tissue
• may contain dry areas with calcium
deposits
Disseminated pyogranulomas, bronchopneumonia
8

Thrombosis, necrotizing rhinitis
(„Zahn-lines” in the thrombus)
Predominantly proliferative glanders
• Mucous membranes
–proliferation of malleotic granulation
tissue
• fibroblasts
• histiocytes, giant cells
–barley seed sized greyish-white firm
nodules on mucous membranes
Glanders
• Differential diagnosis
– Strangles
• Streptococcus equi ssp. equi
– Epizootic lymphangiitis
• Histoplasma sp.
– Ulcerative lymphangiitis
• Corynebacterium pseudotuberculosis
– Melioidosis
• Burkholderia pseudomallei
– Blastomycosis, cryptococcosis
• Blastomyces sp., Cryptococcus sp.
Fibrinous vasculitis
Proliferative malleotic nodules, trachea, horse
9