Infectious and Misc Respiratory Diseases 1 Flashcards
How can equine respiratory viruses be spread?
-Horse to horse transmission
-contact with excretions
-Recrudescence of latent infections
What is the pathology of viral respiratory infections?
Virus attaches to respiratory epithelium, enters epithelial cells and uses the cell to replicate, its released from epithelial cells, killing cells, its shed in 48 hours, damages the epithelium and mucociliary clearance mechanism, spread systemically, epithelium take month or more to recover
What immune response is created to viral infections?
Innate - secrete soluble factors into mucus(complement and cytokines)
Humoral Response - upper IgA and lower IgG
Cell Mediated - viral antigens presented locally by dendritic cells, replication inhibited by NK and cytotoxic T cell
Who is commonly effected by equine respiratory viruses and what are the signs?
Young horses
Acute signs: high fever, malaise, cough, nasal discharge, lymph node swelling and tenderness, limb and ventral edema
Chronics: Decreased performance, chronic discharge, chronic pharyngitis, cough
What are some syndromes that are secondary to viral infection?
Bacterial infection, lower airway hyper-reactivity and inflammation, pericarditis, vasculitis, purpura
On clinical pathology what is suggestive of viral respiratory infection?
CBC: mild, normocytic, normochromic anemia, leukopenia with mild lymphopenia, mild to modearte neutrophilia, monocytosis, fibrinogne
Chem: elevated CK, AST and LDH
How do you treat equine viral infections?
Treat the symptoms
-Fever and malaise - NSAID (flunixin or phenylbutazone)
-Cough - Bronchodilator or nebulizer (Clenbuterol, saline)
-Nasal Discharge - Clean
-Dehydration (oral or IV Fluids)
-Neurologic Signs - Antiviral - acyclovir or Oseltamivir or corticosteroids - dexamethasone, prednisolone inhaled
-Laminitis prevention - ice boot, NSAID
-Concurrent bacterial infection/pleuritis - broad spectrum
How do you monitor viral infecitons?
Temp, resp rate, pleural pain, monitor fluid intake, fecal consistency, soak feed, feed softer, clean environment, rest 3-week past resolution fever and other signs
What are some good biosecurity measures to prevent the spread on farm?
Isolate, dedicated clothing, footwear and tolls, monitor, remove and isolate more horses, submit samples PCR for diagnosis, no off-farm movement
How can you prevent equine viral respiratory disease?
Vaccination - stimulate cell mediated and antibody response
MLV, Killed, Antiviral
What are some diagnostic tests that can be used to detect viruses?
Equine Respiratory Panel - swab, lavage, TTW BAL
Viral Isolation - swab (best)
Viral Titers - serum
What are some common causes of equine respiratory disease?
Equine Influenzas (RNA)
Equine Herpes Virus 1 and 4 (DNA)
Equine Arteritis (RNA)
What are some less common causes of infectious ERD?
Equine Rhinovirus (foal >3-4wk)
Equine Adenovirus (foals)
Equine Herpes Virus 2 (weanling)
Equine Herpes 5 (Multinodular pulmonary fibrosis
What are some rare causes of ERD?
African Horse Sickness
Hendra Virus
What are some viral characteristics of Equine Influenza?
Most common URT virus horse
RNA and Fragile
Orthomyxoviridae
Type A - classified on hemagglutinin and Neuroaminidase
-Can experience Antigenic drift or shift
What are the 2 types of Equine Influenza?
H7N7 and H3N8 (more common and worse disease)
How do you prevent equine influenza?
Vaccination - ML, Inactivated, canary pox vectored
-Intranasal is option that’s effective
- Foals: 9-11 months
-Young Performance - e2-4m
-Adult pleasure - e6-12m
-Pregnant Mare - 8 wk. prior to foaling
-Isolate new horses 3 weeks
-Sick animals need to isolate and change and do last
-Recuperating horses in clean environment
What are some characteristics of Equine Herpes 1 and 4?
DNA
Herpesviridae, alphaerpesvirinae
-most infected by 2yr
Vertical transmission
Incubate 2-10 days
-Latent n resp lymphoreticular system and trigeminal ganglia
-Steroid make it shed
-Can become a carrier
What are the 5 syndromes that Herpes causes?
-Upper respiratory tract infection - most common presentation
-Late Term Abortion - 5 month in, minimal autolysis, high viral load in placenta and fetus, several mares (storm)
-Pulmonary Vasculotropic Infection - herpes1, acute and severe fever, resp, fatal, pulmonary edema second to vasculitis
-Neonatal Foal Death - cant nurse, interstitial pneumonia, poor prognosis
-Myeloencephalopathy - cauda equina syndrome, xanthochronic, point mutation
-Neuropathic = mutation EHV1 - no vaccine for this part
What does treatment and monitoring look like for EHV?
Same as Equine influenzas
Prevent with vaccine (Inactivated, ML, mono or bivalent)
-Vaccine 1 at 6 months, 2 doses 3-4 week intervals and third 8-12 weeks
-Then every 4-6 months
- Broodmare: 5,7-,9- and 11-month gestation (Prevent abortion)
What are some characteristics of Equine Viral Arteritis?
RNA
Arteriviridae
Abortion and Respiratory
Worldwide
Standardbred and Warmblood
Pathogenesis: aerosolized, contact infected horse, veneral
-Cells affected: viremia, replication, macrophage, endothelium, mesothelium
What are the clinical signs of EVA?
Respiratory infection mild or subclinical
-Conjunctivitis, edema periorbital region, edema mid-ventrum, limbs, prepuce, scrotum and mammary gland
-Young foals fatal interstitial pneumonia
-Abortion 3-10months, mare has resp sign, fetus autolyzed
-Persistent Infection - testosterone can affect (stallion has in accessory sex gland)
What is treatment and prevention for EVA?
Like other virus
Vaccination:
MLV, under certain circumstance
-Breeding colt 6-12m
-Seronegative mare - before breeding to carrier stallion, isolate 21-day post breed still shed
Once vaccinated =seropositive
What are some additional viruses?
Equine Rhinitis - young, older shed, incubate 3-8 d, wide host
Adenovirus - foals
Equine Herpes 2 - B - URT, Ocular disease, pneumonia, 2-3m old
Equine Herpes 5- multinodular interstitial disease
Exotic Virus: African Horse Sickness and Hendra Virus
