Swine 5 Flashcards
Porcine Circovirus Associated Diseases
Includes:
- Post-weaning Multi-systemic Wasting Syndrome (PMWS)
- Porcine Dermatopathy and Nephropathy Syndrome
Porcine circovirus type 2 (PCV2)
PCVAD etiology; what circovirus types cause disease
- Porcine circovirus type II (PCV2)
– Isolates from 2a and 2b
– PCV1 is non-pathogenic
PCVAD pathogenesis
- Largely unknown – may occur after immune stimulation
-
Viremia (variable duration) replicates in lymphoid tissues
– Immuno-suppression – reduction in lymphocytes, macrophages
– Sets the pigs up for 2o diseases - Variation in lesions and clinical appearance
PCV2 - Epidemiology; what type of virus, environment, disease and clinical presentation considerations
- Non-enveloped ssDNA virus - Ubiquitous
- Potential rodent reservoirs
- Hardy in environment and organic substrates
– Stable, resistant to heat, cold & many disinfectants - PCV2 infection alone results in subclinical disease
- Overt disease expression requires PCV2 infection plus co-factors that enhance PCV2 replication
- PCV2 = necessary but insufficient agent in PCVAD
- PVC3 emerging
Factors influencing expression of PCV2:
- Known co-infections: – PRRS, MH, SIV, PPV
- Unknown co-infections: – Agent “X”
- Non-infective co-factors & inappropriate management
– Lack of Good Production Practices (GPP) – Immune stimulation (i.e. vaccinations??)
(PCV2- Clinical Signs) - PMWS; when do we see signs / what age? what do mortality and morbidity look like?
Post-weaning multisystemic wasting syndrome (PMWS)
Clinical signs vary: not all signs are noted in the same pig, but most are evident on an affected farm over time:
- Can begin at 6-8 weeks of age (nursery phase)
* Can affect pigs as old as into grower phase (~20 weeks of age)
* Rare in nursing pigs
-Elevated mortality
– Often morbidity rate is low BUT high case fatality rate
– Severely affected herds: 70% morbidity, 50% mortality
* Poor growth, weight loss, wasting, emaciation – gradual wasting
* Anemia, pallor
PMWS (PCV2)- Clinical Signs for individual pig
- Weight loss/emacitation*
-
Dyspnea, tachypnea
– coughing - Enlarged lymph nodes*
- Jaundice*
- May include diarrhea (grow/finish)
- +/- Enlarged spleen
- May include neurological signs
PCVAD wasting - what is it and when does it usually develop?
PCVAD Wasting:
Wasting is usually noted in the late nursery or early grower barns (top). Severe weight loss (emaciation) develops in chronic PCVAD cases if animals are not euthanized
PCVAD lymphadenopathy; what LN are affected?
PCVAD Lymphadenopathy:
Enlarged LN are a prominent feature of PCVAD. Generally, all LN are affected. Superficial inguinal (top) and mesenteric
LN (bottom) are easy to find.
PCVAD Skin abnormalities:
- Pallor is the most prominent skin lesion and is seen in many wasting pigs.
- Jaundice is less frequently noted but is remarkable and terminal.
- Cyanotic scabs initially seen over the rump and perineal area can be seen in PCVD affected herds (referred to as PDNS (usually from 8-18 weeks), but PDNS has not been experimentally reproduced by PCV2.
PMWS effect on internal organs
- severe liver atrophy (end-stage liver) possible
- enlarged kidney; chrnoic interstitial nephritis
- splenic infarcts, splenomegalu
- excessive fluid in gut resulting in profuse diarrhea
PDNS (PCV2) - Clinical Signs; when do they show up, what do we commonly expect
Porcine Dermatopathy & Nephropathy Syndrome
- Clinical Signs:
* 8- to 18-week old pigs
* Red to purple skin lesions on hind quarters, flank and perineum
PDNS (PCV2) - Clinical Signs; pathology
- Kidneys are large, with white spots and/or hemorrhage in the parenchyma
- Immune mediated vasculitis?
- Pigs usually die of 2o infections
PCV2 - PDNS; treatment
- Supportive * Euthanasia
PCV2 - PDNS; prevention
- None, unclear
- Review vaccine protocols
PCVAD - Diagnosis (IMPORTANT)
Clinical signs and gross pathology
* Emaciated, pale pigs
* +/- skin lesions
* large lymph nodes
* +/- enlarged and meaty spleen
* +/- icteric liver, +/-, mottled liver
* +/- spotted kidney, enlarged
* Cecum, colon: mottled, hyperemic, petechiated
PCR, RFLP, - typically positive – this virus is ubiquitous
**Must confirm through immuno-histochemistry (IHC)
- and histology showing large numbers of virus (PCV2) particles in the affected tissues
**Virus isolated in the affected organ
PMWS/PCVAD Control
Control
- Commercial Vaccines
* 1 and 2 dose piglet vaccines
* Sow vaccines
Management
* Control other diseases
– Control PRRS
* Reduce secondary pathogen challenge
* Prophylactic antibiotics and vaccination for secondary infections
Implement Good Production Practices
* Less mixing of pigs
* Strict all-in-all-out movement
* Proper stocking density
* Adequate air & environment quality
* Sanitation
Impact of PCV2 Vaccination? for piglets and sows:
Vaccination is extremely efficacious
- Many PCV2 vaccines available in Canada - all unique
- Piglet vaccination (1 or 2 dose products):
– Decreased mortality
– Decreased viral load in serum (do not prevent viremia)
– Increased ADG
– Decreased growth variation - Sow vaccination
– Same benefits as piglet vaccination, prolonged maternal antibodies
Post-weaning E. Coli Diarrhea; what causes it? what virulence factors does the organism have?
- Caused by Enterotoxigenic E. coli
– Possess adhesion factors
– Fimbrial type F4 (K88) is associated with most outbreaks
– Four main enterotoxins - STa, STb, LT, and VT
four main challenges for nursery pigs?
- Stress of weaning
- Declining immunity
- Change in GI flora
- Dietary change
how does digestive enzyme activity change as a function of age for piglets?
-start with mostly lactase, very little amyalse
- lactase amount declines, while amylase increases
-amylase surpases lactase around 4 wks old, and trends continue
clinical presentation of post-weaning E. coli
- May occur sporadically
- Sudden death (no previous signs)
- Distended abdomens, sunken eyes & discoloured skin
- Fluid-filled intestinal tract
Clinically affected pigs
* Pasty to watery diarrhea
* Depression
* Irritated perineum
Post-weaning E. coli; diagnosis
- History
– Recently weaned - Clinical signs
- Necropsy-fluid filled intestines & dehydration
- Culture and serotyping
- Histology-bacteriain intestines, vascular congestion & hemorrhage
Post-weaning E. coli; feed treatments
- Reduce quantity of substrates for E. coli proliferation
– Poorly digested or absorbed carbohydrates may provide substrate for E coli proliferation. Excess protein – can act as a substrate for E coli growth
> Hence, high quality ingredients used = $$$ - Acidify gastrointestinal pH
– Reduce excessive levels of calcium
– Add acidifiers to feed or water (COMMON) - Add fibre to the diet
– However, this reduces the growth rate - Medication
– Zinc oxide can control diarrhea (1500-3000 ppm)
