Reference Tables

Laboratory Requests and Specimen Collection/Types

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General Suggestions

The most useful culture specimens are from sites that are normally sterile (e.g. joint fluid, peritoneal fluid, blood) because any bacteria isolated from the site are likely to be causative. Culture of sites that are normally colonized by bacteria (e.g. nasopharynx, oral mucosa) are less likely to yield significant results. Normal flora can act as opportunistic pathogens, but their isolation by culture is not necessarily indicative of a true infection. An exception to this rule is if the clinician is trying to detect a pathogen not normally present in the non-sterile sites of normal animals (e.g. detection of Streptococcus equi subsp. equi from a nasal swab).

Tissues and fluids are the best samples to collect for culture. Larger samples tend to increase the likelihood of culturing a significant organism, particularly for anaerobic culture. Samples should be collected as aseptically as possible and quickly transported to the lab in a sterile and appropriate container or transport medium. Swabs are often a poor choice for sample collection because their small surface area will collect a very limited amount of material. If swabs are used for anaerobic culture, they must be placed within a transport medium (e.g. Port-a-Cul, BD Diagnostic Systems, Franklin Lakes, NJ) to minimize sample exposure to the air and loss of sample integrity.

Sample Collection and Submission for a Suspected Infectious Disease

The process of obtaining a culture and sensitivity does not start in the lab; it starts with you, the clinician, collecting the sample. A properly collected and transported specimen sample is essential to identifying and classifying the causative agent in an infectious disease. Here you will find some guidelines to optimize these procedures so that an accurate and reliable test result is obtained. If at any time questions may arise, call the laboratory for assistance.

Sample Collection and Submission
  1. Use an aseptic technique. This will prevent possible contamination and improve the chances of detecting the causative pathogen.
  2. Label all samples. Labeling will help the laboratory technicians know what tests are best for certain tissues.
  3. Properly obtain necropsy samples. Collect non-GI tissue samples BEFORE opening the gastrointestinal tract. Tissue samples (lung, liver, spleen, kidney, etc.) should be 5 g or larger (no smaller than a golf ball). Place each tissue in a separate container or bag to prevent cross-contamination. If the intestine is to be cultured, tie off both ends of a segment and place in a separate container. Freezing tissues may be a good alternative if samples will not be delivered to the lab within 72 hours of collection. Contact the lab if there are concerns or if there is a need to discuss alternatives.
  4. Communicate with the laboratory. If submitting a large number of samples (i.e. > 10, feces, milk, swabs), please call the laboratory for scheduling purposes.
Form Completion
  1. Be sure to specify the species of animal, tests requested and suspected diseases on the form. This will help the laboratory personnel in inoculating the proper media. If the lab does not know what you are looking for, you may not get a diagnosis.
  2. Provide the laboratory with as much of the case history as possible. If you are uncertain as to what could be causing a disease process, a detailed clinical history will help the specially-trained veterinarian assigned to the case create a list of differential diagnoses in addition to determining if additional testing is warranted. This will lead you closer to a possible causative agent.
  3. Specify the collection method and antibiotic use status when submitting urine samples for culture. This will help the diagnostic laboratory correctly interpret culture results.
Sample Transport
  1. Most samples should be kept cold (but not frozen) from the time they are collected until they reach the diagnostic laboratory. This reduces the chance of bacterial overgrowth and contamination, which could compromise testing. Exceptions to this rule, which should be kept at ROOM TEMPERATURE, include:
    1. Blood cultures (Blood culture bottles/Isolator tubes)
    2. Cerebrospinal fluid
    3. Joint fluids
    4. Trichomonas specimens (Preputial scrapings from bulls, vaginal scrapings or fluids from cows, fecal samples from cats)
    5. Dermatophytosis cultures (plucked hairs, scab material or scurf)
  2. Sample collection requires the correct transport media. The following chart will help you select the best transport media for your sample. Contact the lab if any questions arise.

Suggested Samples and Tissues to Collect for Common Conditions and Diseases of Major Organ Systems

* Equine information adopted and modified from the Equine Infectious Diseases 2e, D.C. Sellon and M.T. Long, 2014.

* Information applies to all categories unless specified

Organ System/Condition Suggested Specimen Type(s)
  • Companion Animal: Swab
  • Feces (approximately 10-15 grams)
  • Loop of bowel close to site of lesion if collected from necropsy
  • Skin biopsy (punch biopsy)
  • Companion Animal: Aspirate from unruptured pustule or vesicle (under a crust or edge of a collarette if pustules unavailable)
  • Equine: Aspirate from intact pustule or vesicle
  • Farm Animal: Aspirate from unruptured pustule or vesicle
Lower Respiratory Tract
  • Tracheal secretions collected via transtracheal wash or bronchoalveolar lavage (BAL)
  • Joint fluid
  • Bone
  • Companion Animal: Affected muscle (after necrotic material is debrided)
  • Equine and Farm Animal: Affected muscle
Nervous System
  • Cerebrospinal fluid
  • Brain/spinal cord if collected from necropsy
  • Tracheal secretions collected via transtracheal wash or bronchoalveolar lavage
  • Thoracocentesis
  • Recommend cytology (advise microbiology lab if filamentous organisms are identified on in-clinic cytology so that the laboratory personnel can take appropriate personal protection precaution)
  • Send fluids, not swabs, to the laboratory
  • Blood culture
  • Companion Animal: Joint fluid
Urogenital – Abortion
  • Fetal stomach contents, liver, lung, heart, heart blood, and spleen
  • Placenta
  • Dam serum
Urogenital – Urine
  • Companion Animal: At least 1-2mL, ideally collected by cystocentesis in small animal species
Urogenital – Uterus
  • Guarded swab

Transport Media for Sample Submission to the Diagnostic Laboratory [COMPANION]

Transport Media Diagnostic Samples
Blood culture bottles
  • Blood
  • CFS and joint fluids
  • DO NOT refrigerate-store at room temperature
Specialized transport systems for aerobic/anaerobic (Port-A-Cul® tubes; ACTM II® tubes)


  • Tissues and swabs when aerobic, anaerobic, mycobacterial and/or fungal culture is required
  • Samples should be embedded in the agar
Port-A-Cul® vials; ACTM II ® tube
  • Sterile fluids
  • Fluids from which aerobic, anaerobic, mycoplasma and/or fungal culture is required
  • Fluid should be placed at the top of the media
Red top tubes, sterile containers
  • Urine
  • Fluids that only require aerobic culture
Screw top containers
  • Feces
  • Milk
Sterile plastic bags (e.g. Whirl-pak)
  • Tissues collected at necropsy (sample should be 5g or larger)
Sterile tube
  • Fetal fluids (thoracic fluids, peritoneal fluids or heart blood) to be examined for Leptospira spp. by fluorescent antibody testing; if possible, 10% buffered formalin should be added at a rate of 1.5 ml per 20 ml fluid
  • A swab should NEVER be submitted if biopsies/tissues, fluids, urine, feces or tissues are available. Therefore, submit fluids/tissues rather than swabs whenever possible.
  • If a swab is the only option, submit multiple swabs (i.e. one for aerobic, one for anaerobic, one for fungus). ESwabs are a good alternative
  • Swabs that contain Amies or Stuart media are good for conventional aerobic culture.
  • Swabs containing gel media or ESwabs are ideal for aerobic and anaerobic culture
  • Samples transported on swabs ALWAYS require a transport media. Dry swabs (without transport media) are a poor choice for culture
  • Swabs are recommended in the case of ear, eye and uterine infections
  • Dacron swabs are recommended because cotton swabs are toxic to Mycoplasma


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OSU VMC Antimicrobial Use Guidelines Copyright © 2018 by The Ohio State University College of Veterinary Medicine is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.