Recipient Organization
NORTH CAROLINA STATE UNIV
(N/A)
RALEIGH,NC 27695
Performing Department
College of Vet Medicine
Non Technical Summary
Mortality in dairy calves exceeds 10% (1), and historical losses are worse in warmer climates such asthe Southeast (2). A South Carolina study showed dairy calf mortality from birth to 3 months or birthto 1 year ranged from 6.5 to 22.0% (3). Heifer health, including sickness and death, was reported as thetop challenge rated very important by 92.5% of dairy calf-raisers in a recent study, yet only half ofdairy calf-raising operations reported testing heifers for any disease during 2010 (4). Producers needlow-cost, on-farm tests that give near immediate results that can be used to dictate treatment (personalinterviews). Such tests do not currently exist. The testing used is typically specific to a disease andrequires submission to central labs that take days to weeks to report results.The blood leukocyte differential (BLD) could meet producer needs for testing. Blood leukocytes, orwhite blood cells, play a crucial role in defense against infection (5). The total number and percentagesof leukocyte types change at the onset of and throughout stages of disease (6). Thus, the leukocytedifferential has become widely accepted in human hematology and is commonly used for screening,diagnosis, and monitoring of hematologic and nonhematologic disorders (6). The number and type ofcells not only indicate the presence of infection or disease but also differentiate between bacterial, viraland parasitic infections. Similarly, in companion animals the differential is a useful triage tool thatimproves the rapid diagnosis and care of pets (7). Such a tool would be useful in calf management toreduce mortality and morbidity, improve overall animal health and producer profitability and minimizethe opportunity for antibiotic resistance resulting from non-judicious or incorrect use of antibiotics.Technology from Advanced Animal Diagnostics (AAD) is well-suited to provide a rapid BLD test thatcan identify the presence of a disease or infection and classify the causative agent (bacteria, virus orparasite) in less than one minute from a single drop of blood. Given the limited number of therapeuticsavailable, accurate treatment decisions can be made by confirming the presence of disease andidentifying the causative agent. AAD has been successful developing similar technology to perform aleukocyte differential in milk for diagnosis of infection in the mammary gland of dairy cattle. Thecompany is preparing for commercial sales of a reader instrument that acts as an automated cytologist.With different software customized for blood, the system could be used to produce a BLD.
Animal Health Component
25%
Research Effort Categories
Basic
75%
Applied
25%
Developmental
0%
Goals / Objectives
This proposal evaluates a blood leukocytedifferential (BLD) test that could provide rapid insights into calf health and effectivemanagement. Once blood leukocyte ranges for normal, healthy calves and for those affected by keydiseases are developed, producers would have an economical, easy-to-use test that could tell them inless than a minute if a calf is healthy or not. If not, test results would indicate whether the disease isbacterial or viral. Given the limited number of therapies available, that information would be sufficientto make treatment decisions, so dairy producers could take correct and immediate action.
Project Methods
TASK 1: AAD System ModificationsThe AAD system is currently configured to perform a milk leukocyte differential. To develop theBLD, the following modifications must be made:A. Optimize stain formulation for calf blood. AAD staff have already completed significantresearch with various stain formulations in human and cow blood.1) To finalize selection of a stain, calf blood will be collected from 10 animals determinedto be healthy by physical examination and tested at AAD in combination with a varietyof stain formulations.2) AAD cytologists and software engineers will evaluate images collected from eachsample to select the stain best suited to work for blood in the reader instrumentmarketed by AAD.B. Modify reader software to confirm the five-part differential on calf blood reported by the AADreader correlates well with manual differentials.1) Calf blood will be collected from 30 animals determined to be healthy by physicalexamination and of varying ages. Images will be captured using the AAD reader andstain identified in A2 above.2) Cells will be manually identified by type, and the resulting images will be used todeveloping a cell recognition and identification algorithm for the five cell types inblood.3) To test the accuracy of the software vs. manual differentials, calf blood will be collectedfrom an additional 30 animals of varying ages. Each sample will be processed throughthe AAD reader, which will provide a five-part differential count. In addition, a manualwet stain smear will be made in duplicate from each sample. Manual cytology will beperformed in duplicate by two independent cytologists on the smears and results will becompared to the AAD differential.TASK 2: Establish normal ranges of leukocyte differential patterns for different ages of calvesfrom newborn to six months.TASK 3: Determine the specific leukocyte differential patterns associated with septicemia.TASK 4: Determine the ability of leukocyte differential patterns to differentiate betweenbacterial and viral pneumoniaTASK 5: Determine the ability of leukocyte differential patterns to identify the organismassociated with diarrhea (scours).