Equine Respiratory Diseases Flashcards
What are causes of Bronchopneumonia associated with foals
aspiration of contaminated amniotic fluid (mares with placentitis) or meconium aspiration.
Hematogenous spread via sepsis: E.coli, Klebsiella, Pasteruella, Actinobacillus
What are causes of bronchopneumonia associated with adults
Aspiration of upper respiratory or GI flora
Long distance transport, stress, recent viral infection: Strep equi ss zooepidemicus, Pasteurella, actinobacillus
Frequently progresses to pleuropneumonia: Anaerobic bacteria: Bacteroides, Peptostreptococcus, Fusobacterium
Bronchopneumonia Clinical Signs
Anorexia, fever, cough, depression, tachypnea, dyspnea, abnormal lung sounds, nasal discharge, weight loss, pleural pain
CBC- leukocytosis, neutrophilia, hyperfibrinogenemia
How is Bronchopneumonia diagnosed?
Radiographs, US
Culture: Transtracheal wash and pleural fluid (ideal)
Treatment methods for Bronchopneumonia
Antibiotics- broad spectrum (gram positive, gram negative, anaerobic), NSAIDs
Pleuropneumonia- pleural drainage, thoracotomy
What are the causes of Rhinopneumonitis
EHV 1 and 4
How is rhinopneumonitis transmitted
via inhalation (droplet/aerosol) Transmitted in utero to foals -> severe fatal disease in neonates
Herpesvirus= latent carriers, recrudescence, shedding following stress w
What are clincial signs associated with EHV 1 and 4
Primary respiratory syndrome: usually subclinical to mild, mild fever, serous nasal discharge, depression.
Can have severe disease when secondary infection with bacteria occurs or when foals are infected at birth
Also causes abortions and neurologic disease
How is EHV 1 and 4 diagnosed?
PCR: nasal swabs, blood and tissues
Paired sera confirms infection has occurred
How is EHV 1 and 4 treated?
No specific treatment, respiratory disease typically self-limiting
Monitor for secondary bacterial infections
What are recommended prevention methods for EHV 1 and 4
Prevent introduction of new virus strains: quarantine or separate housing for horses that go to shows, races, fairs, trail rides, etc.
Vaccination using the “Rhino/flu” vaccine: Recommended in all horses. Routinely used in young horses and those with frequent exposure to other horses
What causes Equine multinodular pulmonary fibrosis?
Equine herpesvirus 5
What age horse is commonly affected by EMPF?
Middle to older age horses
What clinical signs are associated with EMPF
Chronic progressive respiratory signs
Tachypnea, increased respiratory effort, dyspnea, intermittent fever and cough, weight loss
How is EMPF diagnosed?
Failure to respond to bronchodilators, antimicrobial therapy
Ultrasound- nodular interstitial pattern
PCR- BAL or lung biopsy
How is EMPF treated
Generally there is a poor response to treatment: Corticosteroids, Valcyclovir/Acyclovir, Doxycycline
How is Rhinitis (ERAV/ERBV) transmitted?
Respiratory secretions. Infection results in viremia with long-term fecal and urinary shedding.
What is the difference between ERAV and ERBV?
ERAV: systemic disease: fever, nasal discharge, coughing, pharyngitis and swelling of th elymph nodes in the head and neck.
ERBV: Usually a mild infection: pharyngitis, respiratory signs and depressed appetite.
How is Equine Rhinitis diagnosed?
PCR: nasal swabs, TTW, urine. Frequently part of respiratory disease panels.
Virus isolation: nasal swabs
Treatments associated with Equine Rhinitis
No specific treatment, respiratory disease typically self-limiting
Monitor for secondary bacterial infections
How can Rhinitis be controlled and prevented?
Prevent introduction of new virus strains: quarantine or separate housing for horses that go to shows, races, fairs, trail rides etc.
Vaccination: Single conditionally licensed vaccine used for ERAV only. Not included as an AAEP recommended vaccine
In what situations are influenza outbreaks common
in Naive populations: (racetracks, shows, barns)
what are clinical signs associated with Influenza?
Typically present as an outbreak of respiratory diseas in young>older animals
FEver (103-107), anorexia, depression, harsh dry cough, serous nasal discharge and lymphadenopathy, conjunctivitis, corneal clouding
Can have severe disease when secondary infeciton with bacteria occurs or in naive neonatal foals
Diagnosis of Influenza in horses
PCR of nasal swabs or TTW. frequently part of respiratory disease panels
Virus isolation and Hemagglutinaiton inhbition
what treatment is associated with Influenza?
No specific treatment, respiratory disease typically self-limitng with recovery in 2-3 weeks
How do you prevent/control Influenza?
quarantine clinical cases
What are vaccination recommendations associated with Influenza?
This is a “risk based” vaccine recommendation
Killed parenteral product: 2 or 3 dose starting at 4-6 months
MLV intranasal products: administer a single dose intranasal 11 months of age or older
Revaccinate at 6-12 month intervals based on risk.
Foals <6 months of age likely have maternal antibody that may interferewith immunization
How are vaccinations affected by different influenza strains?
Vaccine virus should be a field isolate within the last 5 years.
Vaccines should contain both clade 1 and clade 2 viruses of the Florida sublineage.
Kentuky lineage is optional
do all equine influenza virus vaccinations follow the recommendations in regards to the vaccine strains?
No.
How si Equine Viral Arteritis transmitted?
Transmission is either via respiratory secretions or venereal.
establishment of viremia -> Persistently infected stallions –> abortion in females
What cells do Rhodococcus equi infect?
These infect equine macrophages.
vapA gene virulence plasmid is key to disease
How is Rhodococcus equi transmitted?
Via inhalation of contaminated dust thought to be key to transmission very early in life.
cLincial Signs associated with Rhodococcus equi
Respiratory disease predominates, slowly progressive. Cough, low grade fever intiially
+/- mucopurulent nasal discharge.
Remain BAR until severe lung compromise: anorexia, lethargy, tachypnea, dyspnea, weight loss
Subclinical disease is common
Extrapulmonary disease (GI, abdominal abscesses, polysynovitis, uveitis) are common Increased mortality with GI disease
How is Rhodococcus equi definitively diagnosed?
TTW- PCR targeted at the vap A gene
treatment of Rhodococcus equi
Most subclinical cases will spontaneously resolve.
Antibiotics: Macrolides (azithromycin or clarithromycin), Long acting macrolides, Doxycycline + rifampin
caution-severe enterocolitis reported in mares whose foals are treated with erythromycin
How do you prevent Rhodococcus equi?
Close monitoring via ultrasound- early treatment of foals with >10cm ultrasonographic lesions + clinical signs
Vaccination: There is a modified live vaccine licensed in Europe, but not currently available in US
Hyperimmune plasma
Chemoprophylaxis is not recommended (blanket treatments)
What is the causative agent associated with Strangles
Streptococcus equi ss equi
How is Strangles transmitted?
ingestion or inhalation of bacteria from lymph node discharge or respiratory secretions or contact with contaminated fomites
What are clinical signs associated with Strangles?
sudden onset of fever followed by mucopurulent nasal discharge, inappetence. Acute swelling of the submandibular and retropharyngeal lymph nodes. Abscess formation in the lymph nodes- may or may not rupture and drain.
What is “bastard” strangles
Metestatic abscessation
What is purpura hemorrhagica
aseptic necrotizing vasculitis
How is strangles diagnosed
in acute cases- presumptive diagnosis based on CS
Culture or PCR nasopharyngeal washes, nasal swabs or aspirate of lymph nodes for definitive diagnosis.
Chronic carrier animals: culture or PCR of guttural pouch wash
Where is Strep. equi ss equi harbored in chronic carrier animals
guttural pouch
How is Strangles treated?
Isolate to prevent spread
Acute cases- uncomplicated- supportive care only
Antibiotic therapy- not routinely recommended (penicillin). In horses with early clinical signs may prevent abscessation and shedding but no immunity will develop.
Antibiotic therapy indicated in bastard strangles
Purpura hemorrhagica- steroids.
How should you treat animals that are chronic carriers of Strangles
Flushing of the guttural pouches and topical and systemic antimicrobials are used to resolve the carrier status
How do you prevent Strangles
Quarantine all new arrivals for 3 weeks. Detection via guttural pouch endoscopy and PCR and aggressive treatment of carrier horses has been of some venefit in controlling disease in larger groups of animals.
How do you control Strangles in an outbreak situation
quarantine the premise for 3 weeks past last clinical case. Fever precedes contagious phase- monitor twice daily and isolate all animals that develop fever
Separate feed and equipment for suspect cases and non clinicals
How are vaccinations associated with Strangles
Risk based vaccine
Killed parenteral, MLV intranasal options
Annual to emiannual revaccination recommended unless recent exposure- immunity following natural infection is fairly long-lived (5 years) in most.
What are the most common bacterial agents in Guttural pouch infections
Strep. equi ss. equi or S. zooepidemicus
What clinical signs are associated with guttural pouch infections?
Persistent mucopurulent drainage
Epistaxis due to damaged blood vessels
Damage to cranial nerves- dysphagia, facial nerve paralysis
How do you diagnose guttural pouch infections?
Endoscopy, and Culture +/-PCR
How are bacterial Guttural Pouch infections treated
Flushing and antibiotics
Parenteral treatment alone is unrewarding
Topical antibiotics directly into guttural pouch
How are fungal Guttural Pouch infections treated?
Flushing
Topical and systemic antifungal agents
May need to occlude the carotid artery proximal and distal to any lesion
