When should we do blood tests?

There are many times where the testing of blood is required.

• The most obvious is where we have a sick animal whose clinical signs could be consistent with a number of diseases. There are many different diseases whose clinical signs are similar yet the treatment can be completely different .

• Where we are monitoring the progress of a treatment eg. diabetes, to ensure that drug levels etc. are adequate.

• Where the animal has the potential to develop problems (such as senior pets) and we want a baseline measurement of body function to compare with later. One of the problems faced is that normal levels for the tests we do can be quite varied. A single test may be a high normal which may not be significant if they always were a high normal but it would be significant if it represented a marked change from a previous measurement. It would be pretty unusual for us these days to go to the doctor and not have some blood drawn to check cholesterol amongst other things. Early identification of problems and practicing preventative medicine has probably been one of the biggest factor in us living longer and better.

• Where an animal is going to have an anaesthetic, pre-anaesthetic testing can be important. Most of the drugs we use are metabolised and excreted by the liver and/or kidney. If an animal has early problems with these organs they may not have any clinical signs yet the anaesthetic may be prolonged or there could be post-anaethetic problems. Evidence of underlying problems doesn't mean that the anaesthetic should be given. It will just mean that perhaps a different anaesthetic regime be used or intra-operative fluid be given to keep promoting kidney function.

• Where an animal is having surgery we need to know if it has evidence of any possible bleeding problems or is possibly anaemic.

• Many drugs we use can have negative effects on various organs though there positive effects easily outweigh the negative ones. We still, however, need to know what is happening so we can anticipate any problems and know what we need to monitor and how often.

What blood tests should be done?

This is very much dependent on the veterinarian in charge of the particular case. Some are very specific, such as testing for heartworm prior to putting a mature animal on heartworm prevention. Others will be very dependent on the clinical signs or what is to be done. But there are a few rules that can apply in certain cases as to what needs to be done at a minimum

• Animals under going any surgery and/or anaesthesia should at a minimum have a pre-anaesthetic profile which checks their blood count, liver and kidney function and their electrolytes levels. Sick or very old animals should probably have a full screen as they have a far greater likelihood of having problems.

• Any animal going onto long term anti-inflammatory treatment for arthritis should have their kidney function monitored

• Animals being treated for most chronic diseases such as diabetes, Cushings syndrome, kidney disease, heart disease, hyperthyroidism and epilepsy to name a few should be routinely tested to monitor organ function and/or drug levels.

• Animals on long term corticosteroid therapy should be monitored for liver function along with routine physical exams looking for evidence of side effects.

• Senior animals (animals over 7 years old) should have the equivalent of a pre-anaesthetic blood screen to establish certain baselines and pick up early problems. In an ideal world this should be done once a year.

• Sick animals, particularly with a fever of unknown origin, severe vomiting, weight loss or non response to therapy should have a full blood profile done along with urine analysis.