RVC | PET GAZETTE | 23
DIALYSIS
DEVELOPMENTS
FOR PETS
By Simon Cook, lecturer in emergency and
critical care at the Royal Veterinary College
T
he word dialysis will for many people conjure up images
of human patients with chronic kidney failure hooked up
to dialysis machines several times a week until they are
able to receive a kidney transplant.
At RVC Small Animal referrals
we have the technology and
expertise that allows us to help our
patients in a much broader variety
of circumstances. Our dialysis
programme, which started in 2011,
pushes the boundaries of veterinary
medicine to enable us to offer the
most effective treatment to our
patients.
Fundamentally, dialysis means
the removal of waste products and
fluids from the body, but the dialysis
machine we have can be used in
several different ways, including the
following:
Removal of waste products
(including potassium) and fluid that
accumulates when the kidneys
suddenly stop working, for any
reason. These are patients with
acute kidney injury (AKI). This process
would typically be performed two
or three times over the course of a
week, giving the injured kidneys time
to heal of their own accord. This is
called haemodialysis.
Removal of toxins or overdosed
drugs that are small molecules (e.g.
ethanol, phenobarbital). This is also a
form of haemodialysis but may only
need to be performed once.
Removal of part of the patient’s plasma. This can be beneficial in
patients with immune-mediated disease or in those with toxins or
overdosed drugs that are large molecules or highly protein bound
(e.g. non-steroidal anti-inflammatory drugs). This would be termed
therapeutic plasma exchange (or plasmapheresis). It involves removal
of larger molecules, proteins including immunoglobulins, cytokines
and fluid, while being replaced with donor plasma from our in-house
blood transfusion service.
Each of these three scenarios are slightly different to dialysis that
is typically offered to human patients with chronic kidney disease.
Dialysis for chronic kidney disease has been performed for dogs and
cats in other countries but is a life-long treatment which we are not
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currently able to offer at the RVC. The main indication for dialysis at the
RVC is therefore AKI.
There are a number of different toxins that we are able to remove
with dialysis. However, one of the common toxicities we see that
causes kidney failure is ethylene
glycol or antifreeze poisoning. To
be effective with dialysis to treat
ethylene glycol toxicity, we need to
start dialysis within a very narrow
time window (