Introduction
Sugar diabetes, more correctly
know as diabetes mellitus, is a complex disease that is difficult to
control, particularly in cats. Proper treatment requires a
significant commitment on your part, usually for the life of your
pet. This page describing diabetes disease is very thorough and will
require some time in reading if you want to understand it fully. We
have a summary
page on this problem if
that better suits your needs.
A glossary of medical terms will be used in
this page:
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euglycemia- normal
blood glucose level
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polyphagia- excess
appetite
|
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hypoglycemia- low
blood glucose level
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polyuria- excess
urinating
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hyperglycemia-
high blood glucose level
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polydypsia- excess
drinking
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glycosuria- high
glucose in the urine
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PU/PD- polyuria
and polydypsia
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ketonuria- ketones
in the urine
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DKa- diabetic
ketoacidosis
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Normal
Physiology
In response to a decreasing blood glucose level the appetite
center in the brain is stimulated and hunger ensues. A
meal is then eaten, which consists of fats, carbohydrates, and proteins in different
percentages. When these fats, carbohydrates, and proteins are broken down by
the digestive system and absorbed into the bloodstream they are used by the
body for differing functions. The main function of the carbohydrates is eventual
conversion to an energy source in the form of glucose, the primary energy source
for all cells in the body. Some of this glucose is stored in the liver in the
form of glycogen, which is released and converted back to glucose when cells
need energy in-between meals.
Once in the bloodstream the glucose that
circulates throughout the body is available for use by all cells as
their primary energy source. These individual cells cannot absorb
this glucose that passes by in the bloodstream unless the hormone
insulin is circulating in the bloodstream at the same time. Insulin
causes a chemical reaction in the cell wall that allows the glucose
to enter the cell. The only cells in the body that do not need
insulin to absorb glucose are specific brain cells.
This is a picture of
the pancreas from a cat. It is adjacentt to the beginning part
of the small intestine called the duodenum. The pancreas is the
pinkish tissue directly underneath the cylindrical duodenum.
For such a small organ it has an important job.
Pathophysiology
The relative lack of insulin
causes the blood glucose to go abnormally high. Normal blood glucose
in a cat varies from 80 to 150, but can temporarily go much higher
(300-400 or more) in stressful situations. When the blood glucose is
consistently high, as seen in diabetes mellitus, several negative
effects occur.
Inadequate insulin levels force the cell to
perform its functions with alternative sources of energy besides
glucose. This causes problems for the organ that is made up of these
cells and eventually will lead to significant disease and the
complications that occur in untreated diabetes mellitus.
The cells of the body (except most
brain cells) are deprived of their primary source of energy. This
means they do not function at optimum efficiency. Since they are
starved of glucose they need to rely on other sources of energy,
namely fat and amino acids. These are not as good an energy source as
glucose in the long run.
Why the pancreas stops secreting
adequate levels of insulin is a mystery. There is a strong
correlation for diabetes mellitus to occur in cats that previously
had an episode of pancreatitis. This makes sense because the pancreas
is the source of insulin. Yet, many cats that have diabetes mellitus
had no apparent pancreatitis in the past. In some cats the immune
system attacks the beta cells in the islets and deposits a compound
called amyloid which makes the beta cells unable to secrete insulin.
This amyloid, which contains a protein called amylin, is thought to
play a significant role in non-insulin-dependent diabetes (your will
learn about this soon).
Classification
Most people are familiar with the
classification scheme used in human medicine. Even though the disease
is similar in people and cats, the human classification scheme does
not always correlate with diabetes mellitus in cats. Differentiating
between Type I and Type II in cats can be difficult.
Type I
Has similarities to insulin
dependent or juvenile onset diabetes mellitus. Most commonly
occurs in middle aged cats. Insulin is needed to treat the
problem. This is also known as insulin dependent diabetes mellitus
(IDDM).
Type II
Similar to adult onset or
non-insulin-dependent in humans. Obesity is a significant risk
factor. Insulin is not needed in all cases. Type II cats can
become Type I cats when exposed to significant stress.
Fortunately, when the stress is resolved they can revert back to
Type I. This is also known as non-insulin dependent diabetes
mellitus (NIDDM).
Diabetes can occur secondary to other problems.
Some of these problems include hormone imbalances and reactions to medications.
A medication called Ovaban, a hormone used to treat numerous cat ailments, can
cause diabetes.
Symptoms
The classic signs of a cat with diabetes mellitus
are PU/PD. These signs are subtle at the beginning stages of the
disease and are easily missed. This is especially true in outdoor
cats who do most of their urinating outside.
Other symptoms include weakness, an increase in
appetite, occasionally a decrease in appetite, weight loss, lethargy
and rarely, vision problems due to cataracts (this problem is more
common in dogs). Cats with a severe liver
problem associated with this disease might
have icterus (jaundice).
These are also the symptoms of other diseases
commonly seen in cats, and can only be differentiated by diagnostic
tests. These other diseases include, but are not limited to,
hyperthyroidism,
kidney
disease, cancer,
liver
disease, Cushing's
disease and adverse reaction to medications.
The yellow
discoloration to these gums is icterus. It is commonly, but not
always, caused by liver disease.
Diagnosis
By the time a diagnosis of diabetes mellitus
is made the disease process has been present for a significant period of time.
When the disease process first started the cat did not show any symptoms because
of compensatory mechanisms in the body. As diabetes progresses these compensatory
mechanisms lose their ability to maintain euglycemia. Eventually, symptoms of
PU/PD and weight loss occur and the cat is brought in to be examined. This emphasizes
the point that middle aged and older cats should have a routine blood panel
and urinalysis every year once they reach 8.
This is a complex disease, and no
specific set of symptoms tells us your pet has diabetes mellitus. It
is important to follow the tenets of the diagnostic
process closely when
making a diagnosis of diabetes mellitus, especially since
kidney
disease and
hyperthyroidism
have similar symptoms. We will use the diagnostic process as an
example of how we make this diagnosis:
Signalment
Typically this disease is seen
in obese cats that are middle aged or older, and more commonly in
males (the opposite of dogs). There is no specific breed
predilection in cats.
History
The classic signs of PU/PD,
polyphagia, and weight loss occur in many cases, but not all.
These signs depend on how well entrenched the disease process is
before the cat is brought in for an examination. Sometimes the
only thing an owner notices is accidents around the house in a
previously housebroken cat.
Since this disease occurs in
middle aged and older pets there can be other diseases occurring
simultaneously. Some cats have a history of vomiting in the recent
past, an indication that they might have had an episode of
pancreatitis. Some cats are borderline diabetics that have had a
recent illness, stress, or adverse reaction to medication. There
might also be blood in the urine or straining to urinate, an
indication of a urinary tract infection.
Cats presented in DKa might
have a history of abdominal pain and distention, vomiting,
inappetance, and lethargy.
Physical
Examination
The findings of the physical
exam depend on how severe the diabetes is, how long it has been
present, what caused it, and if there are any other disease
processes occurring simultaneously.
Many cats will have lost
weight, yet they still could be obese. There might be dehydration,
weakness, lethargy, an enlarged liver on abdominal palpation, and
an acetone (juicy fruit) smell to the breath. Hypothermia and
shock could be present in advanced cases and those with
DKa.
Diagnostic Tests
The primary method of diagnosis
is with a blood panel and a urinalysis. The blood panel will
reveal hyperglycemia (at least > 200 mg/dl) while the urine
sample will reveal glycosuria. Not every case of hyperglycemia
means a cat has diabetes mellitus. Cats that recently ate, or
those that eat canned foods that are rich in sugar, might have
blood glucose levels higher than the normal range. Cats that are
on cortisone, are in heat, on phenobarbital medication or hormone
medications might also have hyperglycemia.
Cats are unique in that their stress response
can cause a tremendous rise (up to 4x normal) in the blood
glucose. This is a common occurrence when we take a blood sample
in a cat and needs to taken into consideration when we analyze a
blood report. This stress
induced response is a normal reaction to the release of
epinephrine (adrenaline). It is a transitory response and will not
persist like the hyperglycemia of diabetes mellitus. These cats
sometimes need to adjust to a hospital environment before we are
able to determine their true blood glucose level.
Here is a blood glucose
report from our lab for a cat that does not have diabetes
mellitus. The blood glucose is 317.
This cat has diabetes
mellitus, its blood glucose is 390.
How do we differentiate them when both are well
above the normal range?
Diabetes mellitus is
diagnosed when there is a persistent fasting hyperglycemia along
with glycosuria, that is consistent with a history of PU/PD and
polyphagia.
Other blood tests are sometimes
used in this disease. The two more common ones are serum
fructosamine and glycosylated hemoglobin. They are used to to
distinguish stress induced hyperglycemia from diabetes mellitus,
and to also monitor insulin
therapy. They give us an indication of
what the blood glucose level has been for the preceeding
weeks.
In addition to glucose in the
urine and ketones, the urinalysis might indicate that a urinary
tract infection is present. This is detected by a change in the pH
of the urine, excess white or red blood cells, and
bacteria.
This is a
urinalysis from a cat that has diabetes mellitus. Its
glucose is 4+, fortunately,it is negative for ketones, there
are no white or red blood cells present, and there are no
bacteria visible either. This cat does not have ketonuria or
an infection.
Treatment
Some cases of diabetes mellitus are not straightforward. An
obese cat can have NIDDM in its normal, unstressed home environment. These cats
are secreting insulin but in low levels. As
long as they are in a stress free environment they are able to maintain euglycemia.
If they encounter a stressful situation, get sick, or are put on certain medications,
their blood glucose will increase. If it goes beyond the renal threshold for
glucose, PU/PD will ensue.
These cats are then brought to a veterinarian
because of the PU/PD and diagnosed as having diabetes mellitus. They
are put on insulin therapy and the problem improves. The problem
occurs when these cats are returned to their normal environment and
the problem that started the increased blood glucose in the first
place (stress, illness, drugs) is now gone. In some of these cases
these cats will now become hypoglycemic because they are being given
insulin injections when they do not need them. Identifying these cats
that have converted from insulin-requiring to non-insuin requiring
NIDDM is difficult. This is one of the numerous reasons why diabetic
cats should be brought to our hospital every 1- 3 months for a
urinalysis and blood glucose curve.
Diet
Increasing the complex carbohydrates and fiber in the diet
will minimize the rise in blood glucose level as the body digests this food.
The food we recommend for this is called Hills W/D. This allows for less fluctuation
in blood glucose and easier treatment with insulin. In addition, since many
of these cats are obese, the higher fiber will help minimize this problem.
Dietary therapy might be all that is needed for the obese cat with NIDDM.
A cat that is
underweight from diabetes mellitus should not be put on a high fiber diet.
Since this disease is prevalent in older cats this change in diet might be
met with resistance. In these cases mix the higher fiber food with its regular
diet to get some advantage of the higher diet. Do not feed foods that contain
excess sugar like semi-moist canned foods.
Oral
Hypoglycemics
The goal of oral hypoglycemic medication is to
minimize glucose absorption by the intestines and to also minimize
the conversion of glycogen to glucose by the liver. They also help
increase insulin secretion from the pancreas.
They are used in cats that are not underweight,
have negligible ketones in the urine, no indication of
pancreatitis or no history of being on medication that could cause
hyperglycemia. In conjunction with diet, oral hypoglycemics can
sometimes help us differentiate NIDDM form IDDM. Cats with NIDDM
will have significantly lower blood glucose levels when checked
several days after initiating this protocol.
Some cats will vomit and might even develop
hepatitis from oral hypoglycemics. Giving the medication with food
helps minimize vomiting.
New oral hypoglycemics are being used in cats
with some success, sometimes in conjunction with insulin
injections.
Insulin
For many years the insulin used to treat cats
was derived from a beef-pork combination (90% beef and 10% pork)
that was used in human diabetes mellitus. The pharmaceutical
companies are now relying more on human recombinant (genetically
engineered) insulin. This is the insulin source we currently use
to treat cats.
The goal of insulin therapy in the cat is to
mimic naturally secreted insulin from the pancreas as closely as
possible. This can be quite difficult in any species, let alone
the cat. The dose of insulin and the type of insulin that is
effective will vary from cat to cat. Once a proper dose is
initially determined at some point in time in the future this dose
will probably change.
Initially, insulin is dosed conservatively in
order to see an individual cat's response and to minimize any
chance of hypoglycemia. There are many different types of insulin
used.
Regulation in the Hospital
Most diabetic cats need to be regulated (the
correct dose of insulin determined) in the hospital. Starting this
can take 5 days and sometimes longer. Most cats have well
entrenched pathology that is not conducive to rapid change. The
dose has to be given in small amounts initially to prevent
hypoglycemia. It takes several days for a cat to respond to a
change in dose. This initial regulation only gives us a starting
point for your cat's insulin dose since there will be numerous
mitigating factors that will affect insulin levels when your cat
returns home.
During its hospital stay your cat's blood
glucose level will be checked frequently. This is called a blood
glucose curve, and it is a critical part of determining the proper
insulin dose for your cat. It is such an important part of
monitoring that we use a special blood glucose instrument called
an accucheck.
Since it takes several days for a cat to show
decrease in blood glucose due to insulin we might not start this
curve immediately. The blood glucose curve will give us an idea of
how it is reacting to the type and amount of insulin we are using.
Every cat is different, so this trending is needed to understand
specifically how your cat will react.
Our goal is to get the blood sugar level down
to somewhere between 100-250 mg/dl. Some cats are regulated fine
even if the blood glucose peaks at greater than 250 mg/dl. It is
much better to have a cat that has a slightly high blood glucose
level than to try and refine the dose so closely that hypoglycemia
is risked.
The first step in the process of running a
blood glucose test in our hospital involves taking blood from your
pet and putting it on a special strip.
The blood has to spend 60 seconds on the tip of
the strip before it can be inserted in the blood glucose machine.
Here we are at the halfway point (30 seconds have elapsed) in the
process.
After 60 seconds we wipe away the excess
blood on the strip.
Now the strip is inserted in
the machine for 2 minutes
This cat's blood glucose
reading is 63 mg/dl. It is hypoglycemic at this point.
In addition to starting insulin therapy we will
feed your cat a higher protein, lower carbohydrate food. as was
previously described, this will help minimize the fluctuations in
blood sugar level. also, pets that exercise need less insulin. In
cats this is not as much of a factor as in dogs.
The typical cat needs anywhere from 2-10 units
given from once to twice daily. Of course this dose depends on the
weight of your cat, the type of insulin used, its diet, its
exercise level, and its individual response.
After we have an idea
of how your cat is responding to insulin in the hospital we will send him/her
home for you to refine the dosage. It may take up to a month to find the optimum
dose for your cat. The ultimate goal of long term insulin administration is
to achieve a blood glucose level as close to euglycemia as possible. Doing
so will minimize the symptoms of diabetes mellitus and minimize the chance
of long term complications due to the disease.
We recommend you return for a blood glucose
check in 7 days to assess your home therapy. Feed your pet and
give it its insulin just prior to dropping your pet off to us in
the morning. We will perform a blood glucose curve during the day.
Insulin
Injections
It is imperative that you administer the
precise amount of insulin required since small changes can have
dramatic effects in the cat. Be consistent and give the insulin
the same time and at the same location every day. If your cat is
on twice daily insulin injections give each morning and evening
dose at the same time every day. always feed your cat in the
morning prior to giving the insulin.
If it does not eat its
food skip the morning dose of insulin.
If it eats only half of
its food, give it only half of its insulin dose. Giving a normal
dose of insulin to a cat that is not eating greatly increases the
risk of hypoglycemia. You must always err on the side of
hyperglycemia instead of hypoglycemia.
The actual administration of insulin is very straightforward.
As a matter
of fact, it is easier to give insulin injections at home than it is to give
SQ (subcutaneous) fluids to cats that have chronic
renal failure, a common finding in our hospital.
This is because an insulin injection takes 1 second to give, whereas fluids
take 5 minutes. The technique used to give insulin injections or SQ fluids
is the same- click here
to view an actual demonstration of the administration of SQ fluids. When you
are finished learning the proper technique return here to finish.
You will never be forced into doing something
that makes you feel uncomfortable. While your cat is in the
hospital with us you can observe how we give the insulin
injections. One of our nurses
will demonstrate its proper administration when we release your
pet from the hospital. You can return to our hospital for
assistance in giving the insulin at any time.
In order to simplify the process we will give you an insulin
syringe that has been designed to be used with the specific type of insulin
your pet requires. You will be giving insulin in a measurement called "units",
and not in ml (milliliters) or cc (cubic centimeters) as is commonly used
in most syringes. A
typical insulin syringe is called U-100. If you look back at the 3 insulin
bottles above you will notice that they have 100 units per ml, which is why
we use the U-100 syringe with them. Another
type of insulin syringe is called U-40. A
U-40 syringe is used if the insulin bottle contains 40 units per ml.
This is what a
U-100 syringe looks like. The needle is very small and sharp
so your cat will not feel it during its
injection.
Insulin should be kept refrigerated
at all times to preserve its freshness, although this is not
mandatory. Prior to use it should be gently warmed in your
hands. Gently roll it (never shake it vigorously because
excess bubbles will form) between your hands for 1-2 minutes
to bring it to the proper temperature for administration.
Storing the insulin bottle on its side in the refrigerator
will help in mixing.
Make sure you are in a
relatively calm location when you give the injection. Hold
the insulin bottle upside down and draw out slightly more
than the number of units your cat requires. Tap the syringe
a few times to remove any air bubbles-this aids in accuracy
(a few tiny bubbles are OK). Push the plunger in the syringe
slightly forward until you have the exact number of units
you need to administer is in the syringe. Put the cap back
on the syringe and put the insulin bottle back in the
refrigerator. Do not reuse the syringe.
Give the injection in the scruff of the neck just as you
would when giving SQ fluids described above. Your pet should not feel anything
because the needle is so tiny and sharp. The whole process, from warming the
insulin to giving the injections, should only take a couple of minutes. As
you get confidence it is recommended to rotate your injection sites. We can
shave a section of hair to make this whole process easier.
Improper administration of
insulin is one of the most common causes for improper regulation.
Please do not hesitate to contact us at any time for assistance in
this vital procedure.
Home
Monitoring
Determining the daily dose of insulin required
at home is not an easy task. The best way to monitor your pets
blood glucose at home is to perform the blood glucose yourself.
Ears and pads are areas in which a small prick will give
sufficient amount of blood to run an in home blood glucose. In
some cats this method of obtaining a blood glucose level is
preferable to running a glucose curve in the hospital. This is
because the stress of the car ride and the obtaining of blood
several times while in the hospital can mislead us as to your cats
actual blood glucose level.
Most people prefer to monitor the glucose in
their cat's urine because it is simpler. Monitoring of the glucose
in your cats urine will give you at best a rough idea of its blood
glucose level.There are significant
limitations to home monitoring using urine glucose as a
criteria.
Urine glucose measurements do not necessarily correlate with
blood glucose measurements, the more important of the two. Also,
if the blood glucose level is below the renal threshold a negative glucose
in the urine can not differentiate between euglycemia and hypoglycemia. If
you note a significant amount of glycosuria consistently for several days
your cat needs a blood glucose curve.
To help in the urine monitoring process your
cat's normal litter can be replaced with special litter that will
not absorb urine. You can also use regular paper, newspaper, or
even plastic wrap in the bottom of the cage. There is even a
special litter that reacts with the glucose in the
urine.
One
of the more common urine dipstick kits is the
Keto-Diastix. In addition to monitoring glucose it
also monitors for ketones.
This is the chart on the
Keto-Diastix bottle. The box to the far left is negative,
which is the goal. The next box to the right is 100 mg/dl.
Its OK to have this urine glucose value on
occasion.
On the same bottle
there is a chart to monitor for ketones in the urine. Your
goal is to have negative with an occasional
trace.
What is just as important as urine glucose is
your subjective interpretation of how your cat is doing. If the
original symptoms are greatly reduced then you are probably giving
an accurate dose.
One of the ways the urine dipstick can be
particularly helpful is in monitoring ketones. Occasional trace
ketones is no cause for alarm. Consistent ketonuria in a cat that
is not feeling well requires immediate veterinary care.
Another good method
to monitor your pet at home is the amount of water it is drinking. A
typical cat will drink water from its bowl 3 times per day.
Do not make any changes in insulin dose unless
you talk with one of our doctors. Do not make daily changes in
insulin doses either, wait 3 days to determine if the new dose is
having any effect.
Warning signs that necessitate an exam and
blood glucose curve in the hospital:
- Lethargy or significant increase or
decrease in appetite
- Significant increase in drinking or
urinating
- (100 mg/dl) or more glycosuria for >
2 days
- Significant ketones in urine for > 2
days
Long Term Care
It must be understood that insulin administration
does not cure diabetes mellitus, it only controls it. as you learned
above in the physiology section, the body has very sophisticated and
refined mechanisms to keep the blood glucose at optimum levels. This
can not be replicated easily by giving insulin.
To minimize problems we should monitor your cat's blood glucose
level in the hospital and perform a urinalysis every 3 months. Since cats can
exhibit an exaggerated stress response causing a profound hyperglycemia a glucose
curve is necessary to ensure accuracy. Every 6 months we should also perform
a complete blood panel to look for changes in other organs caused by the diabetes.
A further reason
to run a complete blood panel every 6 months is to monitor routine age related
changes like hyperthyroidism
and kidney
disease. Diabetes can also predispose your pet to high
blood pressure (hypertension).
This long term monitoring is important for another
reason. In almost every diabetic cat insulin requirements change,
necessitating the need for close monitoring and communication with
us. If your cat goes into heat (another reason to spay
females and even neuter males) its insulin requirements might change.
In some diabetic cats the problem goes away and they no longer have a
need for insulin. Giving insulin to these cats can cause
hypoglycemia, which if it is severe enough, can lead to
seizures.
Complications
of Diabetes
Hypoglycemia
One of the more
alarming side effects to insulin administration is
hypoglycemia. You should be ever vigilant about its appearance
and always be ready to treat it at home.
Symptoms include shaking, a
starry eyed appearance, lethargy, shaking, greatly enlarged
pupils, muscle tremors and even seizures. If the problem is
serious and persists long enough coma and even death can occur
from depression of the respiratory system. Some pets don't show
any obvious symptoms except subtle behavior changes like
sleeping more than usual. Since cats sleep most of the time
anyway this can easily be missed.
In most cases the cause is an overdose
of insulin. A common scenario involves a cat that eats significantly less
than its normal amount for the day. Hypoglycemia can result if the dose
of insulin is not adjusted to take this into account. If your cat is not
eating well and you are unsure, either give less insulin that day or do
not give any at all. A blood glucose test in the hospital will let us know
for sure.
Close observation of your
cats appetite will go a long way towards preventing this
problem. Monitoring its urine for glucose will help since a
negative glucose in the urine should be noted. If the urine
test for glucose is negative you need to pay particular
attention to your insulin administration.
Liver
Disease
Cats with diabetes are forced into
using an energy source that will eventually cause a fatty infiltration of
liver
cells. As a result the liver will not function at optimum capacity, a potentially
serious problem since the liver is such a vital organ. The liver enzyme test
on the blood panel will alert us to this complication. When the diabetes is
treated this problem might resolve.
Radiography might
reveal an enlarged liver (hepatomegaly) due to the fatty
infiltration.This
liver is larger than normal-it is extending towards the
right far beyond the margin of the ribs. The 4 white
arrows on the bottom outline the lower edge of the wedge
shaped and enlarged liver.
Keeping the blood glucose level as close
to euglycemia as possible will help minimize this complication. Again, the
need for periodic blood glucose monitoring along with a routine blood panel
every 6 months become obvious.
Infections
Diabetic cats are
prone to infections, especially of the urinary tract. These
infections makes them more prone to DKa and insulin antagonism.
Good dental hygiene is critical also since many cats with
diabetes have dental
disease. Chronic
dental disease can make regulation almost impossible.
Summary
It is obvious that this is a complex disease that
requires diligence on your part for proper control. Since every cat
is different, your doctor will make a custom plan that will work for
you and your pet, and will not necessarily follow any pre-established
protocol. Be prepared for constantly changing insulin requirements
and potential complications. The more consistent you are with feeding
the same food, in the same amount, at the same time(s) every day,
will add to a successful outcome.
The majority of diabetic pets on insulin therapy
have a significantly increased quality of life. This usually makes
the time economic commitment necessary for proper regulation well
worth the effort.
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