Enzootic Bovine LeukosisEnzootic Bovine Leukosis(Bovine Lymphosarcoma)(Bovine Lymphosarcoma)

Robyn ElgieRobyn Elgie

OVC 2010OVC 2010

OutlineOutline

•• EtiologyEtiology

•• Case reportCase report

–– HistoryHistory

–– Diagnostic resultsDiagnostic results

–– Treatment/ControlTreatment/Control

–– PlanPlan

•• ImplicationsImplications

EtiologyEtiology

•• Primary mode of transmission is HorizontalPrimary mode of transmission is Horizontal

–– Infected lymphocytes in blood, milk, tumor tissueInfected lymphocytes in blood, milk, tumor tissue

•• Vectors and Fomites can disemminate virusVectors and Fomites can disemminate virus

–– Insects, Needles, Gouge Dehorners, Rectal sleevesInsects, Needles, Gouge Dehorners, Rectal sleeves

•• Vertical transmission transplacentallyVertical transmission transplacentally

–– 44--8% of calves born to BLV8% of calves born to BLV--positives cowspositives cows

–– Colostrum (Rare)Colostrum (Rare)

EtiologyEtiology•• Exposure to BLV:Exposure to BLV:

1.1. Resist InfectionResist Infection

2.2. Seroconvert: No lymphocytosis, No tumorSeroconvert: No lymphocytosis, No tumor

3.3. Seroconvert: Lymphocytosis, Benign HyperplasiaSeroconvert: Lymphocytosis, Benign Hyperplasia

4.4. Seroconvert:Seroconvert: ±±Lymphocytosis, Tumor/MalignantLymphocytosis, Tumor/Malignant

•• Expression of disease dependent on:Expression of disease dependent on:

1.1. GeneticsGenetics

2.2. Viral LoadViral Load

3.3. Immune StatusImmune Status

EtiologyEtiology

•• Subclinical infection is commonSubclinical infection is common

–– 40% prevalence in Canadian herds, 640% prevalence in Canadian herds, 6--11% of cow population11% of cow population

•• Clinical expression of lymphosarcoma is rareClinical expression of lymphosarcoma is rare

–– 1% of BLV positive1% of BLV positive

–– Mortality rate can reach up to 5% due lymphosarcomaMortality rate can reach up to 5% due lymphosarcoma

•• Common Predilection sites:Common Predilection sites:

–– Peripheral Lymph Nodes, Heart, Abomasum, UterusPeripheral Lymph Nodes, Heart, Abomasum, Uterus

Bovine Leukosis VirusBovine Leukosis Virus

•• Entry: New additions to the herdEntry: New additions to the herd

–– Most common point of entryMost common point of entry

•• Closed Herd?Closed Herd?

–– Insect vectors, IatrogenicInsect vectors, Iatrogenic

LymphosarcomaLymphosarcoma -- Clinical SignsClinical Signs

•• Most common:Most common:

•• Decreased milkDecreased milkproductionproduction

•• Reduced weight gain orReduced weight gain orweight lossweight loss

•• InappetenceInappetence

•• Enlarged lymph nodesEnlarged lymph nodes

•• Less common:Less common:

•• PallorPallor

•• WeaknessWeakness

•• Bilateral exophthalmosBilateral exophthalmos

•• Diarrhea orDiarrhea orconstipationconstipation

•• Ataxia, LamenessAtaxia, Lameness

CaseCase -- PresentationPresentation

•• Signalment (Farm):Signalment (Farm):–– Closed herdClosed herd

•• Heifers, Feed mixer from other farmHeifers, Feed mixer from other farm

–– Milking 133 head, Average DIM 209Milking 133 head, Average DIM 209

–– Average 33 kg Milk/Cow/DayAverage 33 kg Milk/Cow/Day

–– Average butter fat of 3.9% and protein of 3.3%Average butter fat of 3.9% and protein of 3.3%

–– Pregnancy rate is 16%, ranges from 15Pregnancy rate is 16%, ranges from 15--18%18%

–– Cosynch for heat detection and breedingCosynch for heat detection and breeding

–– Resynch with regular biResynch with regular bi--weekly herd healthweekly herd health

CaseCase -- PresentationPresentation

•• Vaccination:Vaccination:Calves:Calves:

–– at 3at 3--4 months and 104 months and 10--12 months with Pyramid FP5 + Presponse®12 months with Pyramid FP5 + Presponse®(Wyeth™) for BRSV, PI3, IBR and(Wyeth™) for BRSV, PI3, IBR and M. haemolyticaM. haemolytica

Cows and Heifers:Cows and Heifers:–– PostPost--calving: Bovishield Gold FP5® (Pfizer™) for BRSV, BVD, IBR andcalving: Bovishield Gold FP5® (Pfizer™) for BRSV, BVD, IBR and

PI3PI3

–– Dry off: JDry off: J--VAC® (Merial™) for E. coli mastitis and Jencine® (IntervetVAC® (Merial™) for E. coli mastitis and Jencine® (IntervetScheringSchering--Plough™) for E. coli, rotavirus, coronavirus and C.Plough™) for E. coli, rotavirus, coronavirus and C.perfringens, each boostered 3 weeks prior to calvingperfringens, each boostered 3 weeks prior to calving

CaseCase -- PresentationPresentation

•• Signalment (Animal):Signalment (Animal):

–– 4 year old second lactation Holstein, six months4 year old second lactation Holstein, six monthsinto gestationinto gestation

•• History:History:

–– Decreased milk production prior evening milkingDecreased milk production prior evening milking

–– Moved to hospital penMoved to hospital pen

–– Not treated with any medicationNot treated with any medication

–– Vaccinated according to farm protocolVaccinated according to farm protocol

CaseCase –– Physical ExamPhysical Exam

•• General Inspection:General Inspection:–– BCS 2.5, InappetantBCS 2.5, Inappetant

–– Enlarged prefemoral lymph nodes (20cm x 10cm)Enlarged prefemoral lymph nodes (20cm x 10cm)

–– Right hind limb lamenessRight hind limb lameness

•• Physical Exam:Physical Exam:–– TPR normal, moderate rumen motilityTPR normal, moderate rumen motility

–– Rectally:Rectally:•• fremitus, cotyledons, calffremitus, cotyledons, calf

•• Large inguinal lymph nodes (10cm x 5cm)Large inguinal lymph nodes (10cm x 5cm)

Enlarged lymph nodeEnlarged lymph node

CaseCase -- HypothesesHypotheses

•• Enzootic bovine leukosis (lymphosarcoma)Enzootic bovine leukosis (lymphosarcoma)

–– Primary/WorkingPrimary/Working

•• Generalized lymphadenopathyGeneralized lymphadenopathy

•• AbscessationAbscessation

•• Recommendation:Recommendation:

–– CullCull

–– Donated to OVCDonated to OVC

CaseCase -- DiagnosticsDiagnostics

CaseCase -- DiagnosticsDiagnostics

•• NecropsyNecropsy–– Left exopthalamusLeft exopthalamus–– Lymph Nodes:Lymph Nodes: Cervical, Thoracic and Abdominal nodesCervical, Thoracic and Abdominal nodes

markedly enlarged (up to 20cm by 15 cm by 15cm)markedly enlarged (up to 20cm by 15 cm by 15cm)•• Finely mottled red and tan on cut surface and all nodesFinely mottled red and tan on cut surface and all nodes

lacked normal architecturelacked normal architecture–– Heart and Kidney:Heart and Kidney: multiple small (1multiple small (1--3cm) randomly3cm) randomly

distributed, focal and coalescing nodulesdistributed, focal and coalescing nodules–– Bone Marrow:Bone Marrow: multiple red foci of 1 cm diameter within amultiple red foci of 1 cm diameter within a

largely tan surfacelargely tan surface–– Pathologist’s tentative diagnosis:Pathologist’s tentative diagnosis: Multicentric lymphomaMulticentric lymphoma

involving cervical, thoracic and abdominal lymph nodes,involving cervical, thoracic and abdominal lymph nodes,heart and kidneysheart and kidneys

MyocardiumMyocardium

PericardiumPericardium

Inguinal lymph nodeInguinal lymph node

AbomasumAbomasum

CaseCase -- DiagnosticsDiagnostics

•• HistologyHistology–– Compromised lymph node architecture withCompromised lymph node architecture with

infiltration of neoplastic lymphocytes throughinfiltration of neoplastic lymphocytes throughmedulla and cortexmedulla and cortex

–– Neoplastic lymphocytes also found kidneys,Neoplastic lymphocytes also found kidneys,spleen, omentum, bone marrow and the atrialspleen, omentum, bone marrow and the atrialmyocardiummyocardium

–– Consistent with multicentric enzootic bovineConsistent with multicentric enzootic bovineleukosisleukosis

–– Liver revealed vacuolated hepatocytes, consistentLiver revealed vacuolated hepatocytes, consistentwith hepatic lipidosiswith hepatic lipidosis

CaseCase –– Treatment & PrognosisTreatment & Prognosis

•• There isThere is nono treatmenttreatment

•• BLV infection is lifeBLV infection is life--longlong

–– Very few develop clinical disease (1%)Very few develop clinical disease (1%)

•• Prognosis for clinical lymphosarcoma is gravePrognosis for clinical lymphosarcoma is grave

•• Cull once clinical signs are apparentCull once clinical signs are apparent

CaseCase

•• How did this cow get infected?How did this cow get infected?

–– Most common source is new additionsMost common source is new additions

•• This is a CLOSED herd!This is a CLOSED herd!

–– Vectors and FomitesVectors and Fomites

•• Farm located in a dairy dense areaFarm located in a dairy dense area

–– Subclinical InfectionSubclinical Infection

•• Always present but clinical disease just identifiedAlways present but clinical disease just identified

CaseCase -- PlanPlan

•• Identify other positivesIdentify other positives

1.1. ELISA on bulk milkELISA on bulk milk

–– Detect presence of infection in other animalsDetect presence of infection in other animals

2.2. Pooled serum ELISAPooled serum ELISA

–– If positive found, test each individual in thatIf positive found, test each individual in thatgroupgroup

CaseCase -- PlanPlan

•• Identified PositivesIdentified Positives

–– Do not use colostrumDo not use colostrum

–– Clean pen after calvingClean pen after calving

–– Discontinue reuse of needlesDiscontinue reuse of needles

–– Rectal last/change glovesRectal last/change gloves

•• To EliminateTo Eliminate

–– Close (or maintain) the herdClose (or maintain) the herd

–– Do not rebreed positivesDo not rebreed positives

–– CULL at the end of lactationCULL at the end of lactation

ImplicationsImplications

•• LymphosarcomaLymphosarcoma

–– Lost milk production forLost milk production forcurrent and subsequentcurrent and subsequentlactationslactations

–– Value of the calf,Value of the calf,geneticsgenetics

–– Cost of raising anotherCost of raising anotherreplacementreplacement

–– TradeTrade--restrictionsrestrictions

•• SubclinicalSubclinical

–– Insidious economicInsidious economiclosseslosses

–– Decreased milkDecreased milkproductionproduction

•• Prevalence of infectionPrevalence of infectionwithin the herdwithin the herd

–– Longer calving intervalLonger calving interval

–– Premature cullingPremature culling

Thank You!Thank You!•• OABP and Pfizer™ Animal HealthOABP and Pfizer™ Animal Health

•• AHLAHL

•• Dr. Wayne Shewfelt and everyone atDr. Wayne Shewfelt and everyone atTavistock VeterinariansTavistock Veterinarians

QuestionsQuestions