Blood samples from small mammals need to be of high quality and of sufficient volume to be useful. We've got lots of helpful hints
Posted: 11 July 2017
We’re all used to running diagnostic blood samples from our dog, cat and rabbit patients, but when it comes to working with smaller mammals, the challenge is greater. The blood samples still need to be of high quality and of sufficient volume to be useful.
With very small animals such as mice, hamsters and gerbils, we are limited to how much we can safely collect. A common guideline is to collect no more than 10% of blood volume. The total blood volume is assumed to be no more than 8% of body weight, so we shouldn’t be taking any more than 0.8mls of blood per 100gms body weight. This is assuming the animal is well – for dehydrated or anaemic patients, this volume should be reassessed and reduced.
The choice of sample site is based on clinical experience and your own personal preference.
With most of the small rodents, manual restraint is very difficult and blood collection can be extremely difficult. Light chemical restrain is often required to immobilise the patient.
Common sites used include the lateral saphenous vein, the tarsal vein and lateral tail vein.
Venipuncture usually carries some degree of risk, including injury or death caused by restraint and handling.
Risks of blood collection itself include;
A combination of careful assessment, restraint and good clinical technique will all help reduce the risks.
The method of restraint we use will depend on the species and collection site.
Rabbits are prone to hind limb and spinal injury if restrained inappropriately. Wrapping the animal in a towel or blanket will help minimise these risks.
Guinea pigs and larger rodents can often be restrained by simply grasping them securely around the shoulders and thorax. Alternatively you can use the towel wrap as you would with rabbits.
Manual restraint of species smaller than guinea pigs for blood collection is extremely difficult – chemical restraint is preferred.
For animals where manual restraint is difficult, sedation or anaesthesia should be considered. The risk of using chemicals is carefully balanced against the risk of not performing a blood test.