This document summarizes bacterial diseases that affect equines. It discusses key diseases such as glanders, strangles, tetanus, Rhodococcus equi, salmonellosis, anthrax, and others. For each disease, it describes the causative agent, transmission, clinical signs, lesions, diagnosis and treatment. It emphasizes the importance of understanding disease pathogenesis and implementing preventive control measures like biosecurity and surveillance to avoid production losses in equine farms.

1. Study Circle Programme
Equine Diseases
Topic
Bacterial Diseases of Equine
Presentedto :
Dr. Aarti Bhatele
[Instructor]
College of Veterinary & Animal Sciences
SVP University of Agriculture & Technology,
Meerut - 250110
Presentedby :
Surya Kant
[V-3098/14]

2. BACTERIAL DISEASES IN EQUINE
• Glanders
• Strangles
• Tetanus
• Rhodococcus equi
• Leptospirosis
• Botryomycosis
• Salmonellosis
• Clostridial disease
• Tuberculosis
• Guttural pouch empyema
• Purpura hemorrhagica
• Botulism
• Actinobacillus equuli
• Anthrax
• Ulcerative lymphangitis
• Staph dermatitis
• Dermatophilosis
• Chest abscess
• Necrobacillosis
• Mastitis

3. Glanders
i. Fatal, contagious and zoonotic
disease
ii. Caused by Burkholderia mallei , Gram
-Ve, non-motile, non- sporulating
obligate aerobic organism
iii. Acute or chronic form
iv. Characterized by nodular lesions in
the lungs and nodular or ulcerative
lesions in the respiratory tract,
mucosa and skin
v. Occupational disease of
veterinarians, farriers and animal
workers
vi. Last report on glanders outbreak in
India - June, 1985, recently from july,
2006 from Maharashtra (26 cases)
Purulent mucous nasal discharge in donkey

4. Transmission
 Excretions and discharges of affected animals skin and
nasal mucosa
I. Oral - chronic respiratory disease
II. Intranasal - acute disease
 Virulence and immuno-evading factors -
I. Intracellular status
II. High level of genomic alterations in the host
III. such rapid genomic variation upregulate virulence
gene expression in B. mallei
IV. Genomic unstability has had impact on vaccine
development

6. Clinical signs and lesions
I. Acute - cough and nasal discharge, ulcers on
nasal mucosa and nodules on the skin of
lower limbs or abdomen
II. Chronic - chronic cough, epistaxis . Nasal
and skin form occur togather
III. Cutaneous lesions - medial hock
IV. Lymphadenopathy and cording of
lymphatics
V. Milliary nodules in lung
Microscopically - pyogranulomatous lesions

7. Mucopurulent nasal discharge

9. Strangles
I. Acute infectious disease of horses
- Equine distemper
II. Caused by the bacterium
Streptococcus equi sub-species
equi (S. equi)
III. Characterized by abscess in
pharyngeal and maxillary LN,
pericarditis, pleuritis, suppurative
pneumonia, presence of abscesses
on liver, kidney and spleen

10. Nasal shedding
usually begins 4-7
days after infection

11. Clinical signs
i. High fever of 103˚F to 106˚F
ii. Loss of appetite
iii. Moist cough
iv. Clear nasal discharge that becomes yellow
v. Difficulty in breathing and swallowing (as if strangling,
hence the name)
vi. Swelling of sub-mandibular lymph nodes that rupture
The most severe form of strangles involves –
“inflammation of all lymph nodes”

12. Guttural pouch empyema
I. Most common disease of the guttural pouches
II. LN swelling, abscess and rupture either externally through
the horse’s skin
III. In retropharyngeal LN, usually internally into the guttural
pouch
IV. This air-filled sack is an enlargement of the Eustachian tube
that drains into the nasal cavity
V. Drainage of abscess material into the nasal cavity from the
guttural pouch contributes to the mucopurulent nasal
discharges commonly observed during strangles
VI. Residual pus becomes inspissated to form chondroids (pus
hardens into round balls)

13. Swelling behind the ramus of the
mandible

16. Tetanus
I. Tetanus - lockjaw caused by exotoxins
produced by Clostridium tetani, motile,
anaerobic, G+ve bacilli
II. Soil/intestinal inhabitant
III. Horse – most sensitive animal to toxin
IV. Associated with deep puncture wound,
naval stump infection in foals
V. Reduced oxygen tension promote the
growth
Drum stick shaped organism

17. Pathogenesis
• Two toxins – tetanolysin, tetanospasmin

18. Clinical signs
i. I.P – 7-10 days
ii. Rigidity of muscles around head and
neck
iii. Tenesmus
iv. Prolapse of nictitating membrane
v. Rigidity extend to limbs, elevated tail
vi. Saw horse
vii. Death due to asphyxia
Lesions
i. Intramuscular hemorrhages,
tendon avulsion, fracture of long
bones, aspiration pneumonia

19. Rhodococcus equi
I. Causes disease in young foals
II. Pyogranulomatous pneumonia
III. Pleomorphic, aerobic, non-motile, G+ve,
intracellular pathogen

22. Salmonellosis
 Mostly S. typhimurium
 One of the most commonly diagnosed infectious causes
of diarrhea in adult horses
 2200 serotypes
 Causes typhoid fever, food poisoning, gastroenteritis,
enteric fever and other illnesses
 Clinical Signs :
 Fever, weakness, Lethargy, Increased heart rate at rest,
Diarrhea, abscesses, septicemia and other ailments
 Subclinical carrier = Acute
 Stress plays important role
 Symptoms develop 12 to 72 hours after infection

23.  Transmission -
 Contact with contaminated animals that are actively
shedding the bacteria
 Ingestion of contaminated water, hay, grass, feeds, or insects
 Contact with contaminated environment or objects,
including water buckets, tack, grooming tools, equipment,
stalls, bedding, boots, or handlers
 Contamination through an open wound
 Aerosol contamination through eyes and nose
 Foal infection through the umbilical stump
Oral ingestion of the Salmonella
bacteria
Bacteria is shed in the feces of
contaminated horses, which is usually
transmitted through contaminated
environments or objects
 Causes of Salmonella in Horses -
Intestine: Salmonellosis

24.  Diagnosis of Salmonella-
 based on clinical signs, a history
of salmonella in other horses in
the population, a history of
transportation, and the results
of testing
 Other tests can include blood
counts and cultures, electrolyte
analysis, and joint,
cerebrospinal or tracheal fluid
testing in foals
 Treatment = antibiotics, rehydration
 Very resistant
 Control = isolation, disinfectant
 Live in soil and manure
Equine cecum ulcers
Large Colon - multi-focal ulceration

25. Anthrax Zoonotic Disease!
Rods shaped bacteria
 The Organism -
i. Bacillus anthracis
ii. Large, gram-positive, non
motile rods
iii. Two forms -
 Vegetative and spore
iv. Over 1,200 strains
v. Nearly world wide
distribution
 Transmission –
Bacteria present in hemorrhagic exudate from mouth, nose, anus
Oxygen exposure
- Spores form
- Soil contamination

26.  Sporulation does not occur in a closed carcass
 Ingestion
-Most common
 Inhalation
 Mechanical (insects)
 By direct contact or, on rare
occasion by the air
• Acute disease
• Disease onset within 96 hours
in horses
 RAPID ONSET:
• High fever, severe colic,
swelling on underside of neck
and chest,
difficulty breathing, rapidly
followed by death(1-3 days)

27.  Diagnosis –
 Do not open carcass !
 Necropsy not advised !
 Samples of peripheral blood needed
-Cover collection site with disinfectant soaked bandage to
prevent leakage
 Treatment –
I. Penicillin, Tetracyclines if started early
II. Supportive care ( Antibiotics, Anti- inflammatory
drugs)
III. Reportable disease
 Control – quarantine area, destruction of carcasses
(burning/ deep burrial)
• Disinfection – formaldehyde, bleach etc.

28. Other Bacterial Diseases
S.N. DISEASE CAUSATIVE AGENT
A - Nocardiosis Nocardia asteroides
B - Tuberculosis (TB) Mycobacterium tuberculosis
C - Botryomycosis Staphylococcus aureus
D - Contagious Equine Metritis Taylorella equigenitalium
E - Botulism Clostridium botulinum
(and rarely by C. butyricum and C. baratii)
F - Caseous Lymphadenitis Corynebacterium pseudotuberculosis
G - Enterotoxaemia Clostridium perfringens
H - Dermatophilosis Dermatophilus congolensis

29. Conclusion
I. Many diseases are emerging and re-emerging in these days
II. Understanding the pathogenesis, molecular characterization
of the organism and epidemiology of these diseases are very
important for the implementation of preventive and control
measure
III. Spreading of diseases in the farm can be effectively prevented
by good biosecurity measures
IV.Surveillance and monitoring of important equine diseases
including emerging and existing diseases is needed to avoid
production losses
V. Development of effective, affordable diagnostics and immuno-
prophylactics against important diseases threatening equines
in India