Swine 11 Flashcards
most common cause of diarrhea in swine???
Salmonellosis
types of salmonellosis in swine and what causes them? hosts?
-Enteric form caused by S.Typhimurium
> Can infect other livestock, poultry, mice, and people
> Pigs are considered most likely source of S. Typhimurium DT104 in people
-Systemic form caused by S. Cholerasuis
> Host-adapted** i.e., considered restricted to swine
> Rare reports in humans out of Asia (**zoonotic potential)
> Can live in mice
salmonella seotype diversity? general characteristics? toxins? how to inactivate?
n >2000 Salmonella serotypes
n Salmonella are notoriously diverse
n Hardy, small, ubiquitous, gram-negative bacilli
n Contain ENDOTOXIN
n Inactivated by iodine and phenol-based disinfectants
where in the host in salmonella generally found? how does it spread? are there always clinical signs? when do we usually see a clinical outbreak?
- Salmonella in gastrointestinal tracts (of many hosts)
- Spreads via fecal-oral route
- New infections in pig herds
> Usually, fecal contaminated feed or water
> Pigs may act as asymptomatic carriers = source of infection especially if comingling pigs or new introductions into herd - Farm may be positive with no clinical signs of disease
- Clinical outbreak typically follows a stressful event
> Shipping, mixing, overcrowding, concurrent disease
S. Typhimurium causes:
enterocolitis
Enterocolitis form of salmonella:
how it spreads? who it affects? prevalence?
- Fecal-oral route
- Typically pigs in nursery to mid-grower
> ~50% herd prevalence in Ontario
> ~2% recognize as a problem
S. Typhimurium: pathogenesis
- Endotoxin results in mucosal GIT damage and endothelial necrosis
> Vasculitis, microvascular thrombosis - Diarrhea attributed to tissue fluids leaking from damaged mucosa. Malabsorption diarrhea
S. Typhimurium – Clinical signs? sequelae?
Enterocolitis form of salmonella:
- Moderate pyrexia, anorexia and dehydration
- Typically, a yellow-coloured diarrhea due to fluids leaking through the damaged mucosa
> As progresses more mucus, fibrin, and blood in feces. But blood is not a primary feature
- Morbidity high (over time) and mortality low
- May cause emaciation and slow growth
- Sequelae: rectal stricture …….rectal prolapse
S. Typhimurium – public health concerns
Public heath issue:
- Concern due to pigs shedding in abattoir DT104
- Multi-drug resistant strains
S. Typhimurium - lesions
- Lower small intestine and large intestine are heavy, edematous and thickened
- Enlarged, congested mesenteric lymph nodes
- Focal necrosis on intestinal mucosa
- Chronic cases may have raised circular lesions in the colon (button ulcers)
- Excess peritoneal fluid and strands of fibrin – peritonitis
> pigs have small amount of abdominal fibrin which is normal. Look for “excess fibrin”
S. Typhimurium – laboratory Diagnosis
Culture & Sensitivity
- Untreated animal and demonstrating typical signs
- Culture multiple organs
- PCR
- Serotype
> Special test for DT 104 by Public health Agency of Canada - zoonotic
Histopathology
- Rule-out other enteric and septicemic diseases
S. Cholerasuis causes what form of salmonellosis?
Septicemic form
Pathogenesis and transmission
Septicemic form of salmonellosis
- Fecal-oral route or inhalation of organism
- Invades tonsil (Mr. Tonsil!) and mucosa of small intestine
- Spreads to regional lymph nodes and can survive in macrophages
- Results in a septicemia and localizes in tissues where cause lesions:
> Releases endotoxin, vasculitis (present in all forms of salmonellosis)
> Liver, lung, brain, meninges, joints, lymph nodes
S. Cholerasuis - what age affected, what immunity usually protects?
All ages of pigs but usually nursery to mid-grower
- Lactogenic immunity is usually protective
S. Cholerasuis - Clinical Signs? common in ontario?
- Clinical signs mediated by endotoxin - variable
- Inappetance, depression, high fever, acute death
- Discolored skin (red to purple), cyanosis
- Diarrhea may develop later (if pig lives) but not a typical clinical sign
- Respiratory signs - dyspnea and cough
- High mortality, low morbidity
- VERY VERY rare in Ontario (last reported in 2015)
S. Cholerasuis - lesions
- Cyanotic extremities
- Enlarged spleen, lymph nodes and liver
- Liver may have white/ grey necrotic foci
- Petechial hemorrhage of the kidneys
- Interstitial pneumonia – congestion, interlobular edema, fibrinous pleuritis
- Congestion, fibrinous inflammation, of the intestinal mucosa
- Necrotic entero-colitis if the pig lives long enough
S. Cholerasuis - lab and histo Diagnosis
Laboratory
- Culture from multiple organs of septicemic pigs
- Differentiate from other septicemic diseases and causes of interstitial pneumonia
Histopathology:
- Unique paratyphoid nodules in liver
Salmonellosis - Control
Prevention preferred! Good production practices
- Introductions from single source, quarantine
- AI/AO management
- Minimize stress
- Control rodents, birds, wildlife
But when outbreaks occur
- Provide clean, warm environment
- +/- antibiotics
Vaccine – oral/intranasal
- Avirulent live culture
- Increase ADG in enteric disease
- Limited value economically
> Remember ~2% Ontario herds perceive a
problem with S. typhimurium
FYI: 2015 Salmonella cholerasuis in Ontario linked to vaccine use
rectal prolapse in common in what age group
Common in grower finisher age group
- seldom seen in nursery pigs
rectal prolapse risk factors
- Diarrhea – irritation, tenesmus, prolapse
- Increased abdominal pressure
> Straining, piling (cold environment) - Zearalenone (mycotoxin, estrogen-like compound)
- Antibiotics- lincomycin, tylosin may result in rectal prolapse
what is Porcine hemorrhagic bowel syndrome
Excessive gas production in intestines leading to extreme distension (bloat) causing venous blockage, rapid necrosis, shock and sudden death
- Etiology unknown
- Usually in grower-finisher (4-6 months of age)
- Found dead, pale, distended carcass
- Lesion similar to mesenteric torsion but there is no torsion
GI torsions that can occur in swine
- Gastric torsion or volvulus
-Torsion of the bowel
rectal prolapse diagnosis
n Clinical signs
n Other pigs with blood on their nose/face
Rectal Prolapse treatment
- Move pig to hospital pen
- +/- Surgical correction - reinsert and purse string or surgical removal
- Address underlying infectious disease, management
- May develop rectal stricture as sequelae
