Blood tests are used to learn more about your dog’s health. Blood is a mixture of cells, fluid, protein and biochemicals. Many of these can be measured and variations often indicate problems with your dog’s health so a vet will often recommend a blood test if your pet is unwell. It can help obtain information that cannot be gained from a physical examination.
As well as helping with diagnosis, blood tests can be used to assess the effectiveness of treatments or any side effects of drugs as well as checking the health of your dog prior to an operation.
Blood samples are usually taken from the jugular vein in the neck, although the cephalic vein in the foreleg and the saphenous vein in the hindleg can also be used. The hair over the vein is clipped to allow the vet to visualise the vessel, a needle is inserted, and the blood withdrawn into a syringe. Most dogs tolerate this very well without sedation.
Some bloods will be able to be analysed onsite at your vet’s surgery whereas others may need to be sent away for analysis. Many in-house blood results will be available the same day but others can take a lot longer. A complete blood count or CBC looks at the amounts of red and white blood cell and platelets. If red blood cells are low, then your dog is anaemic. White blood cells are helpful in learning about your dog’s immune system, they are often raised if your dog is fighting an infection.
Routine tests on the blood look at the health of the major body organs. Glucose is measured to check for diabetes. Urea, creatinine, and phosphorus help check the health of the kidneys. An increase can mean a problem with the kidney filter system. ALT, ALKP and GGT are liver enzymes - these are raised if the liver is inflamed or damaged. Protein levels can be low if the liver or kidneys are not working well or high if there is an infection. Bilirubin is associated with the bile ducts, and this is the chemical that causes jaundice. Amylase and lipase are pancreatic enzymes - these are raised if there is a tummy upset. Pancreatic enzymes are raised if there is a tummy upset due to pancreatitis. Electrolytes can be increased and decreased with severe tummy upsets or hormonal problems.
There are a multitude of additional blood tests that can be performed to check for more specific problems such as hormonal levels or checking antibody levels to a specific infection. Blood tests are an invaluable diagnostic tool that are used on a daily basis.