Lecture 22-23 4/23/24 Flashcards
What are the characteristics of equine papillomavirus/equine sarcoids?
-skin warts of horses
-not as common as those in cattle
-typically seen on nose and around lips of young horses
-small, elevated, papillary masses
-most common equine skin tumor
-often self-limiting
What are the characteristics of equine influenza virus?
-type A influenza
-highly contagious
-accounts for majority of upper resp. infections in horses
-able to undergo antigenic drift and shift
-spread via aerosol
-infects and replicates in both upper and lower resp. tracts
What are the clinical signs of equine influenza?
-inflammation and serous discharge
-febrile for 4-5 days
-cough
-depression and/or inappetence
Why is it important that equine influenza severely damages resp. epithelium and destroys the mucociliary apparatus?
predisposes horses to secondary bacterial infection, esp. with gram-neg aerobic bact.
How is equine influenza virus diagnosed?
RT-PCR on nasal swab
-serological testing
Which options are available for equine influenza prevention?
-inactivated vaccines
-modified live intranasal vaccines
What are the characteristics of EHV-1?
-herpesvirus
-causes equine rhinopneumonitis
-once present in a population, it will stay
What are the common clinical signs of EHV-1?
-cough
-mucopurulent nasal discharge
-fever
-depression
-abnormal lung sounds
How does EHV-1 cause fetal death/abortion?
-after infection the upper resp. tract, EHV-1 infects the WBCs
-WBC infection causes viremia and dissemination of virus to repro. tract
What are the consequences of EHV-1 spreading to the CNS?
-thrombosis
-ischemic neural damage
-myeloencephalopathy (EHM)
-hindlimb paralysis
-cranial nerve abnormalities
-tail and anus paralysis
What are the risk factors for EHV?
-positive and susceptible horses in herd
-fall, winter, or spring season
-EHM in horses older than 3 years
-resp. disease in horses younger than 2 years
-abortion in mares at any age/gestation length
How is EHV-1 diagnosed?
-qPCR
–nasopharyngeal swabs if showing resp. signs
–whole blood if animal is viremic
What are the characteristics of using serum testing for EHV-1?
-does not indicate whether virus is actively present
-need paired titers to potentially identify infection
-can only be used to rule out infection in adult horses
What are the characteristics of doing CSF analysis when suspecting EHV-1?
-EHV-1 causes a yellow discoloration of CSF due to breakdown of RBCs
-not specific to EHV-1, but can rule it in or out
What are the treatment options for EHV-1?
-supportive care
-steroids to decrease CNS inflammation
-acyclovir and valacyclovir
What are the characteristics of EHV-1 prevention/control?
-inactivated and modified live vx available
-vx do not claim to protect against EHM and are contraindicated in neurologic animals
-viral shedding can occur 2 weeks after infection
-aborted materials are major source of virus
What are the characteristics of rabies in equine?
-invariably lethal and of public health significance
-five licensed rabies vx in the US
-“dumb” form leads to lots of drooling; can look like other diseases
What are the characteristics of eastern and western equine encephalitis?
-caused by alphaviruses
-maintained in environment by birds and mosquitos
-most common in mid-summer and fall
-present with fever, depression, blindness, ataxia, convulsions
-EEE is nearly always fatal; WEE has 30-40% mortality
What are the characteristics of Venezuelan equine encephalitis?
-reportable foreign animal disease
-caused by an alphavirus
-transmitted by mosquitos
-rodent reservoir
-very deadly in humans; zoonotic
How are the equine encephalitis viruses prevented?
-EEE and WEE vx are considered core vx
-VEE is a risk-based vx
What must a practitioner weigh when deciding whether or not to vaccinate for VEE?
vaccination may confound testing in the event of an outbreak
What are the characteristics of west nile virus?
-most significant insect-borne encephalitis virus in US
-flavivirus
-affects birds, humans, and horses
-causes ataxia and motor deficits
-fever is not consistently present
How is west nile virus diagnosed?
serum immunoglobulin M ELISA
How is west nile virus prevented?
-vaccination is considered core
-vx is currently licensed for horses and foals but not pregnant mares
-chimeric vx exists
What are the characteristics of rotaviruses?
-nonenveloped RNA viruses
-causes foal diarrhea
-morbidity is often high; mortality is low
-inactivated vaccine is licensed for use in pregnant mares to induce colostral antibodies
How is rotavirus diagnosed?
-ELISA
-rapid antigen detection kits
What are the characteristics of equine coronavirus?
-common but highly contagious
-causes colitis and diarrhea
-additional clinical signs include anorexia, lethargy, fever
-generally resolves with minimal supportive care
How is equine coronavirus diagnosed?
molecular detection/RT-qPCR on feces (antemortem) or intestinal tissue (postmortem)
How is equine coronavirus prevented?
-any horse with clinical signs should be strictly isolated
-strict isolation procedures and secondary quarantine of source stable after virus is confirmed
-cleaning and disinfection
What are the characteristics of equine infectious anemia?
-caused by a lentivirus (a retrovirus)
-closely related to HIV-1
-reportable
-once infected, a horse remains so for life
How is EIA transmitted?
-blood feeding flies
-unclean/reused medical supplies
-in utero from mare to foal
What happens when an animal survives the acute phase of EIA?
they become a chronic, in-apparent carrier
How is EIA diagnosed?
serologic detection at an EIA approved lab
-agar gel immunodiffusion
-ELISA
Which proteins from EIA are detected on serologic testing?
-p26 capsid protein (AGID and ELISA)
-gp45 glycoprotein (ELISA only)
How is EIA prevented?
-reducing exposure to biting flies
-never reusing needles/syringes/IV sets
-blood transfusions performed by licensed individuals with tested blood
-surveillance and testing
-NO VX
How far away should a suspected EIA horse be moved from other horses, and why?
200 yards; the biting flies that spread the virus cannot travel this far
What are the characteristics of equine viral arteritis?
-caused by an arterivirus
-typically causes minimal clinical signs and recovery occurs without incident; can go undetected
-can cause abortion in pregnant mares
-breeding stallions can be long term carriers
What are the possible clinical signs for equine viral arteritis?
-fever
-depression
-anorexia
-edema
-hives
-conjunctivitis
-abortions/stillbirths
-decreased fertility
How is equine viral arteritis transmitted?
resp. secretions in close contact settings
How is equine viral arteritis diagnosed?
RT-qPCR on nasopharyngeal swabs and whole blood
How is equine viral arteritis prevented?
-modified live vx
-determining known carriers
-biosecurity
What are the characteristics of vesicular stomatitis?
-arbovirus
-spread by biting flies and midges
-reportable
-zoonotic
-causes vesicular lesions
-differential is FMD, which horses do not get
How is VSV diagnosed and treated?
-clinical signs
-serologic or antigen detection
-supportive care
How is VSV controlled?
-biosecurity
-vector control
-involvement of state vet
Which vaccines are considered core?
-EEE and WEE
-rabies
-west nile virus
-tetanus
