Infectious Disease

Question 1

Reasons for Vaccinations

Answer 1

Administered to prevent and reduce the severity of disease by stimulating immune system to produce a protective response.
Limitations include incomplete protection due to variability in the horse’s antibody response, strain specificity, and the duration of immunity provided.
Vaccines are often required for participation in events, boarding, and other activities, making them essential for compliance with regulations and maintaining herd health.

Question 2

Core Vaccines for Horses

Answer 2

Core vaccines protect against diseases that are widespread, have a high fatality rate, or are zoonotic (transmissible to humans), including Tetanus, Rabies, West Nile Virus, and Eastern and Western Equine Encephalomyelitis.
These diseases are preventable with routine and timely vaccination programs.

Question 3

Tetanus: Overview

Answer 3

Tetanus is caused by the bacterium Clostridium tetani, which thrives in anaerobic environments such as deep wounds or contaminated surgical sites.
The bacterium produces a potent neurotoxin that interferes with the horse’s nervous system, leading to muscle rigidity, spams, face changes, sawhorse, sensitivity

Question 4

Tetanus; Mechanism and Signs

Answer 4

The tetanus toxin prevents the release of inhibitory neurotransmitters (GABA and Glycine), resulting in uncontrolled muscle contractions and stiffness.
Early signs include a stiff gait and muscle tremors, which progress to severe symptoms like lockjaw, difficulty swallowing, and respiratory distress.

Question 5

Tetanus; Treat,m

Answer 5

Treatment is often unsuccessful in advanced cases due to respiratory or cardiac failure. Early intervention with antitoxins and supportive care may improve prognosis.
Prevention is achieved through a primary series of two doses of tetanus toxoid followed by annual boosters and timely administration of antitoxin at injury.

Question 6

West Nile Encephalitis

Answer 6

Birds serve as the primary reservoirs for West Nile Virus, and mosquitoes act as vectors, transmitting the disease to horses and humans.
Clinical signs include hind limb ataxia, muscle tremors, and hypersensitivity to touch, with some horses recovering fully while others succumb to severe neurological damage.
Prevention involves annual vaccination and effective mosquito control measures.

Question 7

Eastern, Western Equine Encephalomyelitis

Answer 7

EEE and WEE are mosquito-borne diseases caused by alphaviruses, with birds as the main reservoirs.
EEE has the highest mortality rate (75–95%), WEE ranges from 20–50%, and VEE varies but is highly contagious in outbreaks.
Vaccination before mosquito season and reducing mosquito habitats are critical preventive steps.

Question 8

Rabies

Answer 8

is a fatal zoonotic disease caused by a virus that affects the nervous system.
Transmitted by bites foxes and skunks
Symptoms in horses include ataxia, colic, dysphagia, and behavioral changes such as aggression or self-mutilation, progressing to death within days.
Vaccination is crucial and must be administered yearly after the horse is three months old.

Question 9

Botulism

Answer 9

caused by Clostridium botulinum (types B and C), is a potentially fatal condition resulting from ingestion of preformed toxins, wound contamination, or ingestion of spores in forage.
Symptoms include generalized weakness, difficulty swallowing, and flaccid paralysis.
Vaccination for type B botulism is recommended in endemic areas, alongside proper forage storage.

Question 10

Pigeon Fever

Answer 10

caused by Corynebacterium pseudotuberculosis, leads to abscess formation, particularly along the horse’s chest, abdomen, and groin.
Symptoms include fever, weight loss, and reluctance to move, with treatment often involving abscess lancing and NSAIDs.
The disease is highly contagious, spreading through fomites and flies, emphasizing the need for biosecurity measures.

Question 11

Equine Protozoal Myeloencephalitis

Answer 11

is caused by protozoal parasites (Sarcocystis neurona or Neospora hughesi) transmitted via opossum feces contaminating feed or water.
Horses exhibit signs such as ataxia, limb weakness, and muscle atrophy, which vary in severity based on the parasite load and the areas of the CNS affected.
Treatment includes antiprotozoal medications (e.g., ponazuril), anti-inflammatory drugs, and Vitamin E supplementation.

Question 12

Equine Infectious anemia

Answer 12

also known as “Swamp Fever,” is caused by a retrovirus and transmitted by biting flies, contaminated equipment, or vertically from mare to foal.
Acute cases involve fever, anemia, and edema, while chronic cases show recurrent signs or unapparent carrier status.
Diagnosis is via the Coggins test, and control requires strict isolation of positive horses or euthanasia.

Question 13

Veicular Stomatitis

Answer 13

affects horses, cattle, and occasionally other livestock, causing painful sores and vesicles on the mouth, coronary bands, and teats.
The disease spreads through insect vectors or direct contact and can result in significant economic losses due to quarantine restrictions.
Quarantine and supportive care are essential for disease management.

Question 14

Equine Herpevirus Myeloencephalopathy

Answer 14

caused by EHV-1, leads to devastating neurological signs such as ataxia, urine retention, and recumbency.
Economic impacts include quarantine, veterinary costs, and lost performance potential in affected horses.
Vaccination reduces respiratory and abortion risks but does not prevent neurological forms of the disease.

Question 15

EHV

Answer 15

EHV-1 and EHV-4 primarily cause respiratory symptoms, including fever, nasal discharge, and coughing.
Vaccination reduces the severity of respiratory disease but requires boosters every 3–4 months for high-risk horses.

Question 16

Influenza

Answer 16

is a highly contagious respiratory disease, spreading rapidly through aerosolized droplets or contaminated equipment.
Clinical signs include high fever, nasal discharge, and a dry, persistent cough, which may lead to complications such as bacterial pneumonia.
Prevention includes vaccination every six months and isolating infected horses.

Question 17

Strangles

Answer 17

is a bacterial infection caused by Streptococcus equi, leading to fever, nasal discharge, and abscessed lymph nodes.
Highly contagious, it spreads through direct contact or contaminated objects and can persist in asymptomatic carriers.
Prevention includes vaccination and biosecurity, while treatment may require draining abscesses and antibiotics for complications.

Question 18

Vaccine Limitation

Answer 18

may not fully prevent infection but significantly reduce disease severity, shedding, and transmission risk.
Protection is strain-specific, making regular updates and adherence to vaccination schedules essential.

Question 19

Mosquito Borne Disease Prevention

Answer 19

Vector control measures, such as eliminating standing water and applying insect repellents, are critical in reducing mosquito populations.
Timely vaccination before mosquito season is vital for diseases like WNV, EEE, and WEE.

Question 20

EIA Testing Protocol

Answer 20

Horses must undergo annual Coggins testing for movement and event participation.
Positive cases must be strictly isolated or humanely euthanized to prevent further transmission.

Question 21

EPM Pathogensis

Answer 21

progression of EPM depends on the parasite load, duration of infection, and the specific areas of the CNS affected.
Prevention includes reducing opossum exposure and maintaining clean feeding areas.

Question 22

Pigeon Fever Prevention

Answer 22

Takes a lot of effort due to its contagious nature and involves maintaining clean, dry environments, reducing fly populations, and promptly treating wounds to limit bacterial entry.
Early intervention and proper sanitation significantly reduce outbreaks.