Thursday, September 22, 2016

 

    

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This 4-part series on the top 20 bovine conditions will set you up for NAVLE® success.


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Missed parts 1 and 2? Find them here…
(Part 1) (Part 2)



5 more of Zuku's top 20 bovine conditions to know for NAVLE® success:

  1. Selenium (Se) and magnesium (Mg) deficiencies

                   Stiff and ataxic heifer with selenium deficiency

    • Classic case: Stiffness, tetany
      • Se deficiency: 2 types
        • Cows < 1 year old: acute recumbency, stiff gait, heart failure
        • Adult cows: retained placenta, anestrus, cystic ovaries
      • Mg deficiency: adult, recently fresh, multiparous cow
        • Recumbency, hyperesthesia
        • Stiffness, hypertonicity, sudden death
    • Dx:
      • Se deficiency: blood Se < 0.05 ppm; increased serum CK/AST/LDH
      • Mg deficiency: serum Mg < 1.5 mg/dl
    • Rx:
      • Se deficiency: give Se; supportive care - sling, vitamin E, oxygen, diuretics if heart failure
      • Mg deficiency: give Mg & calcium after sedation with diazepam (otherwise Rx may cause fatal seizure!)
    • Pearls
      • Prognosis: fair to good for Se deficiency and guarded to poor for Mg deficiency
      • Mg deficiency is more common in lactating cows on lush/potassium-rich pastures with recent environmental changes
      • Rx with Se does NOT make necrotic muscles recover, only prevents further damage

  2. Mastitis

                    Milk from a cow with mastitis

    • Classic case: Divided into acute (high mortality) vs. chronic (low mortality), contagious vs. environmental, & by different types:
      • Acute: serous to serosanguineous milk, diarrhea, obtunded, tachycardic, febrile
      • Chronic: swollen, firm, hot udder; discolored, flakey, or watery milk; few systemic signs
    • Dx:
      • Etiology: Almost any bacteria, most common are:
        • Streptococcus spp.
        • Staphylococcus spp.
        • Coliform bacteria
      • Individual animal:
        • Udder palpates abnormally: hard, abscessed
        • California mastitis test (CMT): high somatic cell count (SCC)
        • Culture milk
      • Herd-level:
        • SCC > 750,000/ml
        • Various methods to measure amount of bacteria in milk
    • Rx: Different Rx for dry cow vs. lactating cow
      • Intramammary antibiotic choices differ for lactating vs. dry cows (and have different colored tips to make sure no mistake)
      • Observe withdrawal times!
    • Pearls:
      • Prognosis: excellent for Streptococci, variable for Staphylococci
      • Practice good udder hygiene and monitor milking machine function
      • Environmental pathogens infect udders between milkings
      • Infectious pathogens infect udders during milking

  3. Milk fever

                    Typical S-curve to neck, cow with milk fever looking at her flank

    • Classic case: Down cow
      • Acute to peracute, afebrile, flaccid paralysis
      • Multiparous mature dairy or beef cow
      • Early cases (stage I): hyperexcitability, ataxia, aggression
      • Advanced cases (stage II): listless, down, hypothermic
    • Dx:
      • Down, weak cow that recently calved or is about to calve is usually diagnostic
      • Total blood calcium < 8.0 mg/dL
      • Ionized blood calcium < 4.5 mg/dL
    • Rx:
      • For stage I: oral calcium salts
      • For stage II: IV calcium in water
        • STOP infusion if: pulse gets weak or cow begins to pant
        • Signs of positive response to Rx: muscle fasciculations, belching, restlessness, and urination, heart slows, improved pulse strength
      • Float cow in a water tank if refractory
    • Pearls:
      • Prognosis good to excellent if no concurrent disorders
      • Diets that are high in potassium and low in anionic ions predispose cows to milk fever
      • Pre-partum dry cow ration influences the incidence of milk fever

  4. Bovine respiratory disease complex

                    Necropsy showing fibrinous pleuritis and bronchopneumonia

    • Classic case:
      • Enzootic calf pneumonia:
        • Thin, weaned calf with good appetite
        • Tachypnea, cough
        • Lung auscultation: crackles and wheezes, harsh sounds, no cranioventral sounds
      • Shipping fever:
        • Any age cow recently shipped or stressed
        • Tachypnea, soft cough, sepsis
        • Lung auscultation: crackles and wheezes, harsh sounds, no cranioventral sounds
    • Dx:
      • Etiology: Multifactorial - stress, +/- viral infection, and one or more of the following are commonly isolated...
        • Enzootic pneumonia: Often Pastuerella multocida type A, but may be Mannheimia haemolytica, or Mycoplasma bovis
        • Shipping fever: Most often M. haemolytica, but also may involve P. multocida, or Histophilus somni
      • Tracheal aspirate, pharyngeal swab: culture, cytology
      • Imaging: ultrasound & radiographs of thorax
      • Pleurocentesis
    • Rx:
      • Appropriate, legal use of antibiotics
      • Anti-inflammatories
    • Pearls:
      • Most calves recover but delayed time to maturity
      • Worse prognosis if concurrent bovine virus diarrhea (BVD) infection
      • Vaccinate against BVD, clostridial diseases, parainfluenza 3 virus, +/- P. multocida

  5. Clostridial diseases

                    Malignant edema: the skin of the brisket and ventral neck are discolored and exuding malodorous fluid

    • Classic case: Sudden death common; many varieties of Clostridial diseases in cattle:
      • Black disease: Icterus
      • Black leg: Swollen limb with crepitus and lameness
      • Bacillary hemoglobinuria ("red water"): Icterus, hemoglobinuria; concurrent liver flukes
      • Gas gangrene: Malodorous wound with crepitus
      • Enterotoxemia: Bloat, colic
      • Malignant edema: Necrotic fasciitis, lameness
      • Hemorrhagic bowel syndrome: Multiparous dairy cow in peak production with "blackberry jam feces," colic
      • Botulism: recumbency; weak tongue, tail, eyelids, jaw, anus
      • Tetanus: stiffness, bilateral prolapsed nictitans, recent metritis or wound
    • Dx:
      • Etiologies:
        • Black disease: C. novyi type B
        • Black leg: C. chauvoei
        • Bacillary hemoglobinuria: C. haemolyticum
        • Gas gangrene: Many Clostridial species, esp. C. perfringens
        • Enterotoxemia: C. perfringens type D
        • Malignant edema: C. septicum
        • Hemorrhagic bowel syndrome: C. perfringens type A with β-2 toxin
        • Botulism: C. botulinum
        • Tetanus: C. tetani
      • Aspiration or tissue collection for:
        • Anaerobic culture
        • Toxin analysis
        • PCR or fluorescent antibody testing
    • Rx: When applicable:
      • Wound debridement
      • Local antitoxin injection
      • Systemic antimicrobials
    • Pearls:
      • Prognosis poor to grave: rapidity of disease progression is inversely related to survival rate
      • Vaccinate using a 6-way clostridial bacterin/toxoid
      • Clostridia are common contaminants of ruminant digestive tracts and soil
      • Necrotic tissue is required for clostridial growth (anaerobes!)

owl    Zuku-certified bodacious websites on bovine diseases:




 Managing Clostridial Diseases in Ruminants

Courtesy of University of Wisconsin.

Comprehensive review of these disorders.

National Animal Disease Information Service

Courtesy of Merck Animal Health.

Good resource on a variety of bovine disorders, including those covered in this article as well as downer cows, the impact of mastitis and lameness on fertility, and lungworms.


Beef and dairy extension articles and links

Courtesy of Iowa State College of Veterinary Medicine.

Expansive compilation of informative articles and links.

Bovine Mastitis and Milking Management

Courtesy of North Dakota State University Extension.

Excellent compilation of info on this subject.

 

Example of NAVLE®-format bovine question:

A postpartum down cow is being treated for milk fever with a slow IV of calcium gluconate.
During treatment, the heart is ausculted and pulses in the facial artery are monitored.
What changes are expected as the treatment progresses?

   A. Tachycardia & weak pulse slowing to bradycardia & strong pulse

   B. Bradycardia & weak pulse speeding up to tachycardia & strong pulse

   C. Tachycardia slowing to bradycardia, pulse strength about the same

   D. Bradycardia & weak pulse, changing to tachycardia +/- arrhythmia

   E. Arrhythmia changing to steady rhythm

Click here for the answer and explanatory text…

 

zukureview

 

Images courtesy of L. Mahin (selenium-deficient heifer, cow with milk fever), Dr. Lisle George (mastitis milk, malignant edema, lung necropsy), and Keven Law (dairy cow, gray cow).

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