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Equine Health Resource

Complete Blood Count, CBC



A CBC is a diagnostic test that counts the numbers of red and white blood cells and platelets in blood collected from a vein. The CBC is commonly used in veterinary and human medicine. It is also a routine screening test that is used before surgery to assess general health.

Since this diagnostic is a study of the cells and not the liquid constituent of blood, a blood sample is collected and placed into a tube with an anticoagulant in it. The anticoagulant prevents the blood from clotting and preserves the cells for analysis. Red cell and white cell numbers are counted either manually from a blood smear on a slide, or automatically in a cell counter.

Red blood cell numbers change in various disease states including dehydration and anemia, among many others. White blood cell counts are commonly analyzed to assess inflammation or infection.

Reasons to UseRelated Observations

Appears Dehydrated
Depressed, Dull, Sick or Lethargic
Fever, Rectal Temperature Greater than 101.5 (in Adult)
Not Eating, Loss of Appetite, Not Hungry
Manure is Watery, Diarrhea (in Adult)
Shock, Ears & Limbs Seem Cold, Pulse is Weak & Rapid
Weight Loss, Thin, Losing Weight
Membranes of Mouth, Gums appear Pale
Foal or Newborn, Under 1 Week Old has Diarrhea
Foal Over 1 Week Old has Diarrhea
Foal or Newborn, Navel or Umbilicus Seems Swollen & Firm
Capillary Refill Time (CRT) Prolonged
Discharge from Both Nostrils (White, Yellow or Green)
Mangy Looking, Widespread Hair Loss & Poor Coat
Membranes of Mouth, Gums appear Blue or Purple
Rapid Breathing, Flaring Nostrils at Rest (Not after Exercise)
Manure is Soft But Not Liquid, "Cow Pie" or Watery (in Adult)
Membranes of Mouth, Gums appear Red
Recurrent Colic Episodes without a Diagnosis
Foal or Newborn, Coughing
Foal or Newborn, Abdominal Pain (Colic)
Bleeding from Anywhere on Body, Severe
Generalized Swelling of Throat Behind Jaw
Flanks Sunken, Drawn Up
Foal or Newborn, Swollen Limb or Leg
Gums have Dark Red Line above Teeth
Foal Lameness, 1-6 Months Old
Foal Lameness, Under 1 Month Old
Heart Rate, Pulse Rapid, Greater than 48 BPM at Rest (in Adult)
Noticeably Wobbly or Weak
Membranes of Mouth, Gums appear Brown
Swelling around Both Eyes or Eyelids
Winded, Fatigues Easily with Work
Abdominal Pain, Colic Signs
Membranes of Mouth, Gums appear Yellow, Jaundice
Starving or Very Thin Horse
Membranes of Mouth, Gums appear Dark
Skin Pinch or Tent at Shoulder Prolonged
Swelling Under Belly or Lower Abdomen
Dull or Poor Haircoat
Purple, Red or Dark Spots on Gums or inside Nostril
Swelling of Jaw or Under Jaw
Swelling of Multiple Lower Limbs or Legs
Bloated Belly, Distended Abdomen
Reduced Racing Performance
Newborn Foal, Fails to Stand or Nurse
Wound to Belly or Ribcage
Depressed & Not Eating Right after Intense Exercise
Drinking Excessively
Bute, Banamine®, NSAID Overdose, Excessive Amount Given
Urine appears Red, Bloody or Blood Clots in Urine
Blister Beetle in Hay, Horse May have Eaten Some
Newborn Foal, Seems Small or Underdeveloped
Grunting or Groaning when Moving
Grunting or Groaning when Breathing
Newborn Foal, Gums (Mucous Membranes) Abnormal Color
Rat, Mouse or Rodent Bait Ingested, Known to Have Occurred
Rapid Breathing Persists Longer Than Normal after Exercise
Head in Corner or Against Wall, Head Pressing
Sheath Swelling or Enlargement
Eye appears To Have Blood Inside Clear Front Chamber


The CBC is a cornerstone diagnostic that is used initially to help determine overall health, and may be repeated throughout a treatment course to determine the efficacy of treatment or the progression of a disease. It is usually performed in-clinic. Results are determined within minutes in most cases.


If this test cannot be performed in-house, there will be a time delay of days due to offsite processing. This can make the test result of less value.

Some of the detailed results that are helpful in small animal practice are not helpful in assessing the health of horses. Red blood cell counts and packed cell volume can be complicated by dehydration.

Helpful Terms & Topics in HSVGWritten, Reviewed or Shared by Experts in Equine Health


  • Will the CBC change the course of treatment?
  • Will the results aid in reaching a diagnosis?
  • Will I get a result now or does the blood have to go out to a lab?
  • Author: Doug Thal DVM Dipl. ABVP


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