Top 10 Pig Conditions Part 1

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Only 6% of NAVLE® test questions cover pigs.

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Guess which NAVLE® topic stresses vet students out the most? "PIGS"

5 of Zuku's Top Pig Conditions To Know For Boards Success:

  1. Erysipelas

    Rhomboid skin lesions of erysipelas

    Cellular and colonial morphology of Erysipelothrix rhusiopathiae

    Synovitis and arthritis in chronic erysipelas

    • Classic case: Sporadic, occasional outbreaks
      • Acute:
        • Excessive squealing when handled
        • Sudden/unexpected death (esp. growers and finishers)
        • Fever
        • Joint pain
        • Skin lesions vary - generalized cyanosis (purple ears!) to classic diamond skin (rhomboid urticaria) lesions
      • Chronic:
        • Enlarged joints and lameness
        • Vegetative valvular endocarditis
    • Dx:
      • Etiology: Erysipelothrix rhusiopathiae, a gram-positive, aerobic bacillus bacterium with at least 28 serotypes
      • Outbreak: Skin lesions and lameness are strongly suggestive
      • Single acute or chronic cases:
        • Culture E. rhusiopathiae from blood
        • PCR on blood or tissue samples
        • Rapid response to penicillin
        • Tissue immunohistochemistry
      • Serology: Helps distinguish previous exposure or evaluate success of vaccines
    • Rx:
      • Acute cases:
        • Penicillin: q12h for ≥ 3 d
        • Tetracyclines in water if large number affected
        • +/- NSAIDs for fever
      • Chronic cases: Treatment rarely successful and not cost effective
      • Vaccination:
        • Very effective!
        • Give around time of weaning because it's stressful
        • Booster pigs kept for breeding herd
    • Pearls:
      • Excreted in feces and oronasal secretions
      • Pigs become infected by ingestion or skin abrasions
      • Half the pigs in intensive swine operations have colonized tonsils and are silent shedders (healthy carriers)
      • Can occur in turkeys, wild birds, and lambs
      • Resistant to many environmental effects

  2. Hog cholera (a.k.a. classical swine fever)

    Blue ears typical of hog cholera

    Turkey egg kidneys in necropsy of pig with hog cholera

    • Classic case: Clinical signs vary with strain and host factors
      • Can affect all age groups
      • High fever, lethargy
      • Yellowish diarrhea, vomiting
      • Internal HEMORRHAGE, many organs-larynx, body wall, bladder, kidneys
      • Vasculitis: Purple discoloration or erythema of ears, lower abdomen, and extremities
      • Ataxia
      • Poor reproductive performance in sows
      • Can be acute, subacute, or chronic causing death within 10, 20-30, or unlimited days, respectively
    • Dx:
      • Etiology: Highly contagious RNA Pestivirus (family Flaviviridae)
      • Virus isolation or antigen detection (fluorescent antibody) on tonsils, lymph nodes, spleen, kidney, nasal swabs, ileum, or whole blood
      • Viral RNA detection via RT-PCR on nasal swab or tonsil scraping
      • Serology via virus neutralization
      • CBC: Leukopenia
      • Necropsy: Turkey egg kidneys
    • Rx: None!
      • If hog cholera-free country: Cull and quarantine
      • Endemic countries: +/- Vaccination
    • Pearls: REPORTABLE!
      • Prognosis:
        • Poor
        • Morbidity and mortality can reach 100%
      • Eradicated in US in 1976
      • Use vaccines for prevention in endemic countries only
      • Economically important and seen worldwide
      • "Evil Twin": African swine fever is clinically indistinguishable

  3. Mycoplasmal pneumonia (enzootic pneumonia)

    Lung consolidation secondary to enzootic pneumonia.
    Image used with permission, courtesy of The Pig Site

    • Classic case:
      • If endemic: Morbidity high
      • Cough, pneumonia
      • Slow growth, feed inefficiency
      • Stress leads to outbreak
      • More severe in naïve herds
      • Carrier pigs spread to naïve pigs
    • Dx:
      • Etiology: Mycoplasma hyopneumoniae, a fastidious, small, pleomorphic organism
      • Identification of M. hyopnuemoniae on impression smear of cut lung
      • Fluorescent antibody
      • PCR on nasal/bronchial swabs: Very sensitive and specific
      • Culture: Tricky because fastidious organism
      • Herd serology: Difficult to interpret
    • Rx:
      • Acute disease in naïve herds or single pigs: Antibiotics!
      • Prevention/control
        • Vaccinate sows before farrowing
        • Management: Improve ventilation, avoid overcrowding, all-in-all-out, biosecurity
        • Rapidly inactivated by most disinfectants
    • Pearls:
      • COMMON! 30-80% of pigs at slaughter have signs in lungs
      • Frequently complicated by other infectious agents (e.g., Pasteurella multocida, porcine respiratory disease complex, influenza)
      • Can travel windborne more than a mile!
      • M. hyosynoviae causes epidemic synovitis in growers
      • M. hyorhinis causes fibrinous polyserositis in young pigs

  4. Atrophic rhinitis

    Atrophic rhinitis causes epistaxis

    Snout deviation in chronic atrophic rhinitis

    Atrophic rhinitis causes damage to the nasal turbinates.
    Images used with permission, courtesy of The Pig Site

    • Classic case: Low levels in herds are common
      • Acute: 3-6 wks age
        • Sneezing, coughing
        • Epistaxis
        • Blocked tear ducts with tear staining
        • Impaired growth rate and feed conversion
      • Chronic: Snout laterally deviated or shortened
    • Dx:
      • Etiology is combination of:
        • Bordatella bronchiseptica
        • Toxigenic Pasteurella multocida
        • Management factors: Ventilation, sanitation, overstocking
      • Clinical signs almost pathognomonic
      • Bacterial cultures/PCR from nasal swabs of affected pigs
      • Herd monitoring: "Atrophy score"
        • Measure turbinate atrophy at level of 2nd premolar at 7-9 mos of age
    • Rx: None, prevent or control
      • If levels of disease rise:
        • Chemoprophylaxis: To sows before farrowing, to newborns, and to newly weaned pigs
        • Vaccination: Sows (4 and 2 wks before farrowing) and piglets (at age 1 and 4 wks)
        • Temporarily close herd to new pigs
        • Management changes
          • Improve ventilation and hygiene
          • Decrease dust in feed
      • Pearls:
        • Nonprogressive atrophic rhinitis:
          • B. bronchiseptica
          • Mild, transient
          • Minimal long-term effects
        • Progressive atrophic rhinitis:
          • Toxigenic P. multocida
          • Severe
          • Permanent, stunted growth
        • No longer a major health risk in US
        • Severity in herd depends on if toxigenic P. multocida involved and herd immune status
        • Introduced into herd by new pigs (esp. inapparent carriers!)

  5. Zearalenone toxicosis

    Sow with enlarged mammary glands as seen with zearalenone toxicosis

    Wheat is commonly infected with Fusarium graminearum

    • Classic case:
      • Weaned and prepubertal gilts:
        • Hyperemic and enlarged vulva (i.e., "vulvovaginitis")
        • Enlarged uterus and mammary glands
        • Severe: Prolapsed uterus
      • Mature sows:
        • Pseudopregnancy if fed at d 12-14 of estrous cycle
        • Early embryonic death if fed early in gestation
      • Boars: Infertility
    • Dx:
      • Etiology: Fusarium graminearum, a mold that commonly infects corn, wheat, barley, oats, and sorghum, produces the mycotoxin
      • History of diet-related occurrence
      • Classic clinical signs
      • Rule out differential reproductive infections or diethylstilbestrol in feed
      • Suspected feed: Chemical analysis or mice bioassay
    • Rx:
      • Signs resolve 1-4 wks after stopping feed
        • Except multiparous sows may be anestrus for 8-10 wks
      • Can give prostaglandin F to mature sow to lyse corpora lutea and resolve anestrus
    • Pearls:
      • Zearalenone (nonsteroidal estrogen) is a mycotoxin that causes hyperestrogenism
      • Zearalenone inhibits secretion of follicle-stimulating hormone


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Images courtesy of Alvesgaspar (pot-bellied pigs), R.L. Wood (erysipelas lesions, Erysipelothrix colonies, synovitis), Dingar (pig with blue ears), USDA (turkey egg kidneys), Glen Bowman (pig snout), Jacqueline Macou (sow with mammary development), Naeemakram319 (wheat), woodleywonderworks (suckling piglets), Evelyn Simak (Kune Kune pig), and CDC (C. perfringens).