Equine Respiratory Disease Flashcards
What is the pathogenesis of equine Strangles? What are common clinical signs?
Streptococcus equi subsp. equi shed in respiratory secretions of infected horses are inhaled or ingested
- fever, lethargy, anorexia
- mucopurulent nasal discharge originating from guttural pouch empyema
- enlarged head and neck LNs, most commonly submandibular –> can progress to abscessation
What are 3 sequela of equine Strangles?
- bastard strangles - dissemination of abscesses to internal organs
- purpura hemorrhagica - aseptic vasculitis (severe edema, petechiae, septicemia) due to an immune reaction from repeated exposures to natural infection or vaccination
- chondroids - solidified caseous material in guttural pouches, can persist for years and be a source of bacterial shed
How are acute and chronic cases of equine Strangles diagnosed?
ACUTE - PCR from nasal swab, nasopharyngeal lavage fluid, or guttural pouch lavage fluid + bacterial culture
CHRONIC - serology for SeM-specific antibody –> high titers suggest purpura hemorrhagica or bastard strangles + guttural pouch endoscopy
What treatments can be used for equine strangles? What is most commonly done? What is contraindicated?
- lavaging guttural pouch and instilling Penicillin to speed clearance
- anti-inflammatories
- supportive care
- emergency tracheostomy if LN abscesses become large enough to block off the airway
natural clearance of infection
systemic antibiotics - can prolong clearance and recovery, only used in complicated or severe cases
When will a horse no longer be considered a carrier for equine Strangles?
negative guttural pouch fluid PCR or 3 negative nasal PCRs
How can equine Strangles be prevented?
- isolate new or infected horses with strict biosecurity
- modified-live IN vaccine or killed IM vaccine
What method of prevention of equine Strangles is contraindicated in outbreaks?
vaccination –> increases risk of purpura hemorrhagica
What is the major risk factor for horses becoming infected with equine herpesvirus 1 and 4 (equine rhinopneumonitis)? What is the pathogenesis?
young horses that show or travel with frequent exposure to other horses
- EHV1 and 4 are endemic in the equine population and remain latent in individuals until times of stress
- then it can cause clinical or subclinical disease and allow for spread via respiratory secretions
What is a possible sequelae to equine herpesvirus 1 infection?
mutation into an EHV-1 wildtype or neurogenic strain to cause equine herpes myeloencephalopathy (EHM)
What are some possible clinical signs associated with equine herpesvirus 1 infection?
- fever, lethargy, anorexia
- cough
- mucopurulent nasal discharge
- secondary pneumonia
- abortion in pregnant mares - EHV1 can rarely infect the endometrium and fetal tissues
(worse in naive young horses <5 y/o, vaccinated horses will have less severe signs and can act as a source of subclinical spread)
How is equine herpesvirus 1/4 infection diagnosed? Treated?
PCR of nasal discharge
- anti-inflammatories
- supportive care
- antiviral drugs
- antibiotics for secondary pneumonia
How can equine herpesvirus 1/4 infection be prevented?
- isolate new horses or infected horses with strict biosecurity
- MLV IN or killed IM vaccine - biannual in high-risk horses and mares during pregnancy to prevent abortion
What is a major risk factor for horses to become infected with equine influenza A? What is the pathogenesis?
endemic in the equine population - outbreaks commonly from horses that show or travel with frequent exposure to other horses, especially young horses and racehorses
inhalation of aerosolized virus from respiratory secretions
What clinical signs are associated with equine influenza A infection?
- fever, lethargy, anorexia
- dry cough
- mucoid nasal discharge
- secondary pneumonia
How is equine influenza A infection diagnosed? Treated?
PCR of nasal discharge
- anti-inflammatories
- supportive care
- antibiotics for secondary pneumonia