Message Number: YG1603 | New FHL Archives Search
From: Bruce Williams, DVM
Date: 2001-03-22 23:25:00 UTC
Subject: Re: Digest Number 79Kidney disease and proper foods

--- In Ferret-Health-list@y..., twpfi@a... wrote:
> Katharine from surcool has a good questions regarding the proper
level of
> protein for ferrets with kidney disease.
> We began a limited study looking at lowered levels of protein for
> damaged ferrets a few years ago. We had problems because there was
mixed and
> limited data and information regarding what was considered the
> definition of kidney disease or the diagnoses for kidney disease in
> We did have one situation, which was not in a controlled
environment, where
> several 8 or 9 week old kits were given an improper antibiotic and
> subsequently destroyed a great deal of the kidney function if not
the tissue
> itself in all of the ferrets. This was defined as a BUN of 100+.
(I received
> this information directly from the owner as the vet who recommended
> antibiotic in the first place would not call me.) Three had died
by the time
> I received the call. The vet had prescribed the Hills k/d canned
diet as the
> recovery diet for the remaining kits. The owner said after three
days the
> remaining kits were not doing well and the BUN's still over 100 +.
> suggested that she feed Totally Ferret which had 37% protein and
24% fat plus
> much higher levels of vitamins and minerals than the cat k/d. I
knew that in
> order for the kits to recover they had to build new tissue plus
their immune
> system. It would take all nutrients not just protein or vitamins.
> two weeks the BUN's were below 40 and after four weeks below 30.
The normal
> range is about 20 to 40. I realize that this is purely anecdotal
but the
> principle is that any time an animal has damaged tissue, kidney or
other wise
> it needs proteins of high biological value (BV) and a complete
> profile of over 60 nutrients in the proper proportion to rebuild
the damaged
> tissue.
> This subject has been studied in both dogs and cats extensively in
the past
> several years at the U of GA vet school with similar conclusions.
So my
> response to the question as to what is the proper level of protein
> ferrets suffering from kidney damage is I have no data to support
> recommending lowering it when feeding a diet such as Totally Ferret
or any
> other that has protein from quality animal sources of 90% or
> Hopefully there will be veterinarians or owners who may have input
to this.

Well, I'll weigh in on this a bit, and I have learned a bit myself by
spending some time with the recent literature on restricted protein
diets in animals with chronic renal failure. There is a large body
of evidence recently that is showing that the effects of protein
restriction does little to preclude the development of renal
disease. What it does do, however, is delay the onset of uremia in
animals with failing kidneys, and keep BUN levels lower for a longer

We need to realize that this information is gained in other species,
and under other than natural conditions, in the laboratory with
surgically manipulated animals. But it is likely that the general
principles are applicable in other mammals as well.

Tom - regarding your situation with the ferret kits and the
inappropriate antibiotic (I'll be a dollar to a doughnut this was
gentamicin - a drug that ferrets are extremely susceptible to) - this
represents a case of acute renal failure rather than chronic renal
failure. The levels of protein probably had little or nothing to do
with the survival of these animals - in drug-related acute renal
failure, survival is based on regeneration of the injured epithelium
(which, if the basement membrane of the tubule is preserved, will
usually occur as long as there is sufficient uninjured renal tissue
to keep the animal alive) rather than the prevention of injury to the
remaining nephrons, which is our current rationale for protein
restriction in CRF. You are correct however, in that a high quality
food may help animals in this state to regenerate lost tissue more
efficiently and quickly.

The bottom line is that for aging animals, our long-standing belief
that a protein restricted diet will prolong renal health is probably
inaccurate. (In fact, phosphorus content may be more important in
the diet than the level of protein.) Additionally, as protein
restricted diets are generally less palatable, older animals on low
protein diets may actually take in less calories as well, and may
achieve poor nutritional levels overall. But for animals like Champ,
who is already in documented renal failure, a protein-restricted diet
very well may stave off the signs and symptoms of uremia for a while

With kindest regards,

Bruce H. Williams, DVM, DACVP
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