Large Animal Medicine Exam 1

mastitis

inflammation of mammary gland

mastitis is often associated with…

bacterial infection

what is the purpose of the keratin in the teat canal?

it is sticky so it prevents bacteria from traveling up the canal

the blood milk barrier makes it difficult for…

immune cells and antibodies to function

mastitis leads to increased/decreased vascular permeability

increased

what proteins/ions are increased in mastitis milk?

• albumin

• lactoferrin

• sodium

• chloride

lactoferrin

acute phase antibacterial for iron sequestration

what cells are more common in mastitis milk?

neutrophils

teat stays open for _____ minutes after milking

20-30

2 categories of mastitis:

clinical and subclinical

clinical mastitis

visibly abnormal milk (mild, moderate, or severe)

subclinical mastitis

visibly normal milk but measurable infection or inflammation

contagious mastitis reservoir is the _______

cow

environmental mastitis reservoir is the _______

environment

what are the major contagious mastitis pathogens?

• Staph aureus

• Strep agalactiae

• mycoplasma spp (mainly M. bovis)

what are the major environmental mastitis pathogens?

• coliforms

  • escherichia coli

  • klebsiella

• strep uberis

what are the minor mastitis pathogens?

coagulase negative staph

mild clinical mastitis appearance:

• abnormal milk

moderate clinical mastitis appearance:

• abnormal milk

• abnormal quarter

severe clinical mastitis appearance:

• abnormal milk

• abnormal quarter

• abnormal cow

clinical mastitis severity is correlated with…

appearance

biggest cost of clinical mastitis is…

milk discard

milk loss vs milk discard

• milk loss is milk not produced by cow due to infection

• milk discard is milk that has been produced but is dumped out due to infection

farm goals for clinical mastitis case rate is…

<2%

in ontario clinical mastitis is most common during…

fall

incidence of clinical mastitis is highest during ______ days in milk

first 20

subclinical mastitis is detected by…

somatic cell count (SCC)

linear score

a numerical value that describes the linear relationship of SCC with milk loss

typical SCC cut point for mastitis infection:

200,000

regulatory SCC limit mastitis infection:

400,000

california mastitis test

detergent in solution reacts with DNA in neutrophils to form gel

• thicker the gel, the more nucleated cells in milk

the california mastitis test is not sensitive/specific

sensitive (only tests positive when SCC is at least 400,000)

milk conductivity increases/decreases with mastitis

increases (more electrolytes in milk)

clinical cure for mastitis is based on…

appearance of milk

bacteriologic cure for mastitis is based on…

culture before and >1 week after treatment

cow factors that affect whether or not mastitis is cured:

• parity

• SCC

• duration of infection

• colony count

• number or previous cases of clinical mastitis

• number of quarters affected

what is the treatment success factor for mastitis?

duration of treatment

most antibiotics used in vet med are time/concentration dependent

time

which pathogens that cause mastitis are easiest to kill?

• strep agalactiae

• strep spp

• staph spp (exception staph aureus)

what is the ideal way to treat mastitis?

targeted therapy based on bacterial cause

intramammary mastitis treatment in a lactating cow:

• cetiofur

• cephapirin

intramammary mastitis treatment in a dry cow:

• cetiofur

• cephapirin

• cloxacillin

dry period is during…

the last 2 weeks of pregnancy

new infections occur in teats that fail to _______ during the dry period

close

strep agalactiae is very/not susceptible to IMM antibiotic

very

staph aureus tends to establish acute/chronic infections

chronic

what is the dry cow cure rate for staph aureus mastitis?

40-60%

what is the lactating IMM cure rate for staph aureus mastitis?

10-40%

staph aureus mastitis diagnosis:

culture is most sensitive

mycoplasma mastitis clinical signs:

• clinical mastitis that is unresponsive to treatment

• shifting quarters

• mastitis followed by respiratory disease and/or otitis or septic arthritis in cows or calves

T/F there is/isn’t a cure for mycoplasma mastitis

isn’t

environmental mastitis caused by coliforms is usually self-…

resolving

environmental streptococci has a ______ cure rate from IMM antibiotics

40-65%

coliform mastitis peak bacterial growth precedes…

clinical signs

what is the temperature of a cow udder?

35 degrees C

e coli mastitis is typically ______ duration while klebsiella mastitis is ______ duration

short; long

endotoxin from gram negative coliforms can lead to severe mastitis in _______

12-24 hrs

vaccine for endotoxin leads to a ______ drop in clinical cases

75%

when should cows be vaccinated for coliform mastitis?

just before dry period

treatment for severe coliform mastitis:

• anti-inflammatories

• fluids

• systemic antibiotics if targeting bacteremia

____ of severe mastitis cases are bacteremic

1/3

udder edema is associated with increased risk for…

clinical mastitis

udder cleft dermatitis

exudative, ulcerative dermatitis between right and left halves of udder, or between udder and inner thigh possibly caused by spirochetes

why is there a focus on swine farm biosecurity?

• disease

• international trade

• risk of foreign animal diseases and emerging diseases

what are some emerging diseases in swine farms?

• african swine fever

• PRRS

• circovirus

• PED

• Swine dysentary

what are some production limiting diseases in swine farms?

• PRRS

• Circovirus

disease entry on a swine farm:

• pig-to-pig

• other animals

• airborne spread, manure, deadstock management

• people

• fomites

how to prevent pig-to-pig transmission:

• one source of breeding stock

• test breeding stock herd

• purchased semen

• off site early weaning

• isolation and/or acclimation barn

CAZ (controlled access zone) includes:

• pig farm yard

• buildings and driveways

CAZ has what kind of access?

limited

RAZ (restricted access zone) includes:

where pigs are housed

RAZ has what kind of access?

defined entry protocol

multi-site production in swine

pigs from multiple sow barns move off-site into one nursery barn

how long is swine gestation?

115 days

when are pregnancy checks done on sows?

• 25-35 days

• 42-56 days

what are piglet weights when born?

1-1.5 kg

what are piglet weights when weaned?

5 kg

what is the goal weight of nursery pigs?

5 kg → 25-30 kg

when naturally breeding swine, how many sows per 1 boar?

20

majority of sows are bred through…

AI

what is the goal weight of grow-finisher pigs?

25-30 kg → 110-115 kg by 6 months old

what is the goal weight of gilt selection at 20-30 weeks?

74-140 kg

what is the goal weight for sows?

135-300 kg

what is the goal weight for boars?

360+ kg

what are common sow breeds?

• yorkshire

• landrace

what are common boar breeds?

• duroc

• hampshire

• synthetics

when are nursing piglets weaned?

16-28 days

what is goal preweaning mortality?

<8-10%

List the major pathogens that cause diarrhea in neonatal pigs and the timeline in which they occur:

• e. coli (colibacillosis): <12 hrs

• clostridium perfringens: <12 hrs

• swine enteric coronavirus diseases (PED and TGE viruses): 2 days

• cystoisospora suis (coccidiosis): 5 days

• rotavirus: 5 days

e coli are/aren’t part of normal flora of pigs

are

pathogenic e. coli strains of swine:

• ETEC (eneterotoxigenic)

• VTEC (verotoxigenic)

• SEPEC (septicemic)

ETEC signs:

• single, multiple, or all pigs of liiter affected

• alkaline diarrhea (watery in newborns, creamy in older nursing pigs)

• dehydration, lethargy, weakness, death

• peracute form: death before signs appear

ETEC pathogenesis:

• adhere to small intestine mucosa by fimbrial adhesins

• colonization of jejunal/ileal mucosa

• production of enterotoxins

• secretory diarrhea

kinds of ETEC fimbrial adhesins:

• F4 (K88)

• F5 (K99)

• F6 (987P)

• F41

kinds of ETEC enterotoxins:

• Sta (ST1), STb (ST11)

• LT

ETEC pathology:

• dehydration

• dilated, fluid filled small intestine

• congestion of small intestine vasculature

• dilated stomach

diagnosing ETEC:

• history and age of onset

• alkaline fecal pH

• culture from gut loop or rectal swabs

• histopathology with minimal villus atrophy

• PCR for fimbria and enterotoxin genes

what should be submitted for necropsy in neonatal swine diarrhea?

• 2-3 live piglets in acute stage (ill <24 hrs)

• not treated

• clinical signs present

ETEC control:

1. prevent chilling

2. hygiene

3. stop cross fostering between affected and unaffected litters

4. commercial killed bacterins that offer protection against adhesisn and enterotoxins

5. autogenous bacterins