22-24. neonatal calf diarrhea 1-3

risk factors for neonatal diarrhea

• poor dry cow management

• contaminated colostrum

• failure of passive transfer

• poor nutrition

• lack of water & comfort

• dirty environment

• exposure to adults

• group housing

• stressful management: dehorning, castration, vaccination

• change in: food, housing, weather, commingling

• inappropriate vaccination / treatment

where / how does exposure to diarrheal pathogens occur?

• in the maternity / calving area

  • dirty bedding / udders, stocking density

• contaminated colostrum

• contaminated tube feeders / feeding equipment

• warming box

• calf housing & bedding

• contaminated people

when does peak ETEC shedding generally occur?

first few days of age unless co-infection with rotavirus, which can extend ETEC infection up to 10 days of age

when does peak crypto (c. parvum), rota, and coronavirus shedding occur?

peak prevalence is typically 5-10 days of age (but can occur later; 12-18 days of age for some herds)

when does peak salmonella & clostridium shedding occur?

can occur at any time

when does peak coccidia & giardia shedding occur?

after 21 days of age (due to life cycle & pre-patent period)

what is the main diagnostic test used for diarrheal pathogens?

PCR appropriate for age of animals affected

rotavirus pathology

• infects enterocytes → villus atrophy & malabsorption

• test early in course of disease

  • infected cells shed rapidly (within 24-72h) after onset of diarrhea

coronavirus pathology

infects enterocytes & colonocytes

• villous blunting → malabsorption

• blood if colon involved

salmonella pathology

• S. typhimuria, newport, Dublin

  • diarrhea (and sepsis, interstitial pneumonia for Dublin)

• fibrinonecrotic enteritis

  • distal small intestine & proximal large intestine

  • inflammation, hypersecretion → secretory, malabsorptive diarrhea

  • can result in sloughing of intestinal mucosa (“intestinal casts”)

clostridium perfringens type C & A pathology

• necrotic enteritis (type C); hemorrhagic abomasitis (type A)

  • associated with large intake of soluble carbs/protein

  • inconsistent feeding

• exotoxins damage intestinal & abomasal mucosa

  • severe enterotoxemia, rapid death without treatment

  • inflammation, necrosis → malabsorptive diarrhea

ETEC pathology

• must demonstrate virulence attributes as e. coli is a normal inhabitant of gut

• adheres to enterocytes through fimbriae (F4 / F5)

  • ↓ affinity after 3-4 days (unless concurrent rotavirus infection)

• little to no inflammation (no blood in manure)

• secretory diarrhea due to enterotoxins

  • induce H₂O, Na⁺, Cl^- secretion

why might it be important to know the etiology?

• specific diagnostic & preventive strategies

  • bacterial vs. viral vs. nutritional

  • vaccination protocols

• zoonosis potential

  • crypto, salmonella spp., giardia

how are samples for herd level testing collected? when should results be considered problematic?

• collect fresh feces from 6 untreated calves representative of affected age group

• do NOT pool samples → goal is to assess how many samples are positive

• for rota, corona, crypto: > 2 positive tests out of 6 suggest problem with that pathogen

• for salmonella: zero tolerance policy — any positives are problematic

what are the general components of colostrum?

• nutrients

• antibodies

• non-specific antimicrobials

• maternal leukocytes

• growth factors / cytokines

what tests can be used to measure passive transfer?

• direct measurement of IgG1

  • radial immune diffusion assay (RID) = gold standard

  • individual animal test

• indirect estimation of IgG1

  • herd level test

    • serum total protein concentration

    • serum brix concentration

describe the quantity and timing of feeding after birth

• 4L in 1-2 hrs — esophageal feeder or nipple bottle

  • may feed 3L if colostrum is very high quality

• 2L at 12 hrs — nipple bottle only; do not force feed

colostrum management

• collect ASAP

• clean equipment

• refrigerate

  • small volumes (1 gallon)

  • 2-3d; 7 if pasteurized

  • 1 yr frozen

• measure quality

• warm slowly

  • hot water bath

• tube feed (1st meal)

how are samples collected for assessing passive transfer?

collect blood from 12 calves 1-7 days of age

• use tubes without additive (red top or serum separator tubes)

what percentage of calves tested should have an STP of 5.8-6.1 g/dL?

≥ 70%

what percentage of calves tested should have an STP of ≥ 6.2 g/dL?

≥ 40%

what volume of milk or milk replacer should average sized holstein calves drink per day?

2-3 gallons

how does a higher plane of nutrition impact calves infected with c. parvum (crypto)?

• minimize effect of c. parvum on neonatal calf

• minimize early life weight loss

what are 3 measures of disease (NND)?

1. detection of abnormal manure using fecal scores

   • no evidence-based recommendations or goals

2. dairy calf and heifer association gold standard

   • based on producer diagnosed & treated cases of diarrhea

   • goal: <25% preweaned calves treated for diarrhea

3. farm detection rate

   • # calves on treatment / # calves with FS ≥ 2

   • goal: ≥ 85%

   • helps identify when producers are missing cases of diarrhea that should be treated

clinical signs of mild NND

• FS = 2-3

• BAR or QAR

• standing

• good suckle and appetite

• fecal blood: minimal to none

clinical signs of severe NND

• FS = 1-3

  • severely dehydrated / peracute enterocolitis may have relatively normal fecal consistency

• depressed, slow to stand, recumbent, non-responsive

• minimal to no suckle

• temp: >103 or <100

• frank blood in feces

• dehydration

goals of oral fluid therapy for mild cases of diarrhea

• replace deficits

  • fluid, electrolytes, acid-base

• functional GI tract is a prerequisite for oral electrolyte solutions

  • do not administer to calves with abdominal distention or if not suckling

  • (suckling or chewing = signal that OES will be okay)

what are the 4 essential components of an OES?

1. sodium — needed to restore fluid deficits

2. glucose, citrate, acetate, propionate, OR glycine — needed to facilitate Na⁺ absorption

3. alkalinizing agent — to treat acidosis

   • acetate, propionate, bicarbonate

     • acetate does not interfere with clot formation in the abomasum like bicarbonate does

4. supplemental energy — treat neg. energy balance

what is an appropriate osmolality for an OES?

at least 250 mOsm/L, but no more than 450 mOsm/L

what are the cardiac effects of hyperkalemia? what does the ECG wave look like?

bradycardia, large T waves, bigeminy

what differentials should be added if neurological signs are noted?

• meningoencephalitis

• salt toxicity

• lasalocid toxicity

• d-lactic acidosis

• BVDV infection

• congenital defect

what change in body weight is estimated for mild, moderate, and severe dehydration?

• mild = 6-8%

• moderate = 8-10%

• severe = 10-12%

treating dehydration

correct half of hydration deficit (2-3 L IV) over 4-6 hrs then reassess clinical condition

• use isotonic IV fluids for rehydration

• should contain bicarbonate and dextrose to address acidosis and hypoglycemia

IV fluids for slow resuscitation & rehydration

isotonic bicarb solution (1.3%)

• 13g sodium bicarb to 1L distilled water

• 1-3 L slowly (>4h) depending on size and severity

what are 2 methods of rapid fluid resuscitation?

1. hypertonic saline: 4 mL/kg over 4 min (+2 L oral water & re-exam)

2. 8.4% hypertonic bicarb: 10 mL/kg over 8 mins (+2 L oral water & re-exam)

hypoglycemia treatment for severely affected calves

2.5-5% dextrose solution IV or administer single 10mL bolus of 50% dextrose IV over 1 minute

should milk be withdrawn as part of treatment?

only if not willing to eat

• force feeding has negative consequences

  • prolonged acidosis

  • clostridial overgrowth

• high energy (HE) electrolytes could be considered

  • poor body condition

  • off feed >36-48 hrs

  • 50% caloric needs provided if fed 2x/day

when should antibiotics be used? which antibiotic can / cannot be used?

if systemic signs (blood, depression, fever)

• Gram (-) coverage or according to sensitivities

• ceftiofur must be used at label dose, duration, frequency, route

  • restricted ELDU

• enrofloxacin CANNOT be legally used for diarrhea

  • prohibited ELDU

when are NSAIDs indicated?

if systemically ill

• flunixin meglumine

• meloxicam

  • both ELDU

• caution: GI ulcers, nephrotoxicity

cleaning & disinfecting protocol

• cool water rinse — removes protein without baking it on

• alkaline detergents emulsify fat — hot water (140-160°F)

• lukewarm acid rinses remove mineral buildup

• chlorine dioxide disinfectant — within 2 hrs of feeding

avoid high pressure hosing; low pressure foam instead

what luminometer measurements are appropriate for cleaned surfaces?

feeding equipment

• ATP meter <10 excellent, but <50 acceptable

housing

• ATP meter = 90% reduction pre and post C&D

how often should feeding equipment, waterers, and individual/group pens be cleaned & disinfected?

• feeding equipment

  • after each feeding

• waterers

  • weekly or if obviously soiled

  • more frequently during outbreak

• individual / group pens

  • before every new calf / every new group

• prioritize maternity area & newborn housing and feeding equipment

• scrub brushes: do not go waterer to waterer without C&D brush; have separate brushes