by Jennifer Prince, DVM
Drs. Foster & Smith
Veterinary Services Department
here for the link to this article found at PetEducation.com
Insulin is used in the treatment of diabetes mellitus. It comes in
various forms and strengths, with corresponding syringes for each strength.
The proper dose of insulin must be determined through monitoring blood
glucose. The amount and time of insulin administration, the type of food,
feeding time, and exercise must be consistent every day. An overdose of
insulin can cause hypoglycemia (low blood sugar), with symptoms of weakness,
trembling, unresponsiveness, seizures, coma, and death. If your pet experiences
hypoglycemia, contact your veterinarian and feed the pet a normal meal,
a sugary food, or place a small amount of sugar water or maple/karosyrup
on the gums.
Humulin, Iletin, Lente Iletin, NPH, and PZI
Type of Drug
Form and Storage
Store in the refrigerator.
Indication for Use
Treatment of diabetes mellitus.
For more information on diabetes mellitus and the use of insulin in
see Diabetes Mellitus in Cats: Causes and Characteristics.
Not FDA approved for use in dogs and cats but it is a common and accepted
practice to use insulin in dogs and cats. Available over the counter but
have your veterinarian call in a prescription the first time so the proper
type of insulin and appropriate syringes are received. Diabetes mellitus
results when the pancreas quits producing insulin or the body becomes resistant
to the insulin and needs it in a higher quantity. Insulin is needed by
the body to drive the glucose (blood sugar) into the cells where it is
used for energy. When the glucose stays in the blood rather than go into
the cells, the cells keep telling the body it needs more glucose so the
body keeps producing it which causes the levels in the blood to rise. When
it reaches a certain point, the glucose is passed out of the body through
the urine. The glucose takes water with it producing more urine and causing
the pet to drink more. If the diabetes is not controlled, it results in
dehydration, weight loss, ketoacidosis (too much acid in the blood), coma,
and death. Treatment consists of replacing the insulin from the pancreas
with insulin that is injected under the skin which the body then absorbs.
It may take multiple trips to the veterinarian and multiple blood tests
to get the pet regulated, but pets may live for years if treated. Dogs
and most cats need insulin injections for life while some cats are more
difficult to treat as they may alternate between a diabetic state requiring
insulin injections and a normal state not requiring insulin injections.
They require more time and commitment by the owner.
The only way to know how the body is responding to the insulin is by
taking blood glucose levels over the course of the day. Fructosamine levels
can be taken every several weeks to determine long term response especially
in cats that have high glucose readings due to the stress of drawing blood.
Urine glucose levels can be used to monitor glucose levels at home if needed.
Contact your veterinarian for specifics on monitoring.
Human insulin is the most commonly available insulin because that is
what humans use. Most dogs do well on human forms of insulin. Cats do better
on beef and/or pork insulin but PZI which is beef/pork insulin has been
removed from the market. It is available on an investigational basis. Cats
typically need a larger amount of the human based insulin than the beef/pork
Insulin is available as regular (short-acting), NPH and Lente (intermediate-acting),
and Ultralente and PZI (long-acting). Regular insulin is usually used in
a veterinary hospital to get the pet's glucose level down before starting
on an intermediate- or long-acting insulin that will be sent home with
Usual Dose and Administration
Doses vary considerably between patients. Usually start at 0.25-1.0
unit per pound daily in dogs and 1-3 units per cat daily. Insulin is given
by a subcutaneous (SQ/under the skin) injection. Doses may need to be given
twice a day. Doses may need to be much higher to get the diabetes under
control and then decreased. Doses may need to be increased over time. Alter
the injection site to decrease irritation to the tissue.
Roll the bottle or turn it end over end to mix the insulin as it settles
out in the bottom of the bottle between treatments. Do not shake the bottle
as that will cause air bubbles to form, and it will be more difficult to
get an accurate measurement. The insulin should be uniformly cloudy in
the bottle when you draw it into the syringe. Draw the insulin into the
syringe once and inject it back into the bottle. Redraw it into the syringe.
This is helpful in accurately dosing as insulin may stick to the inside
of the plastic syringe or an air bubble may be present in the syringe.
May see hypoglycemia (low blood sugar level) with symptoms such as
weakness, lethargy, shaking, seizures, or coma. Cats may just sit and do
nothing. May also see an insulin-induced hyperglycemia (too much sugar
in the blood) where the body increases the blood sugar level because it
had dropped too low.
Do not change the pet's food, feeding schedule, or exercise schedule
once regulated for that food and schedule.
Avoid semi-moist food due to the high sugar content.
Females should be spayed as estrus will change insulin requirements.
Know which formula of insulin is being given and which syringes need
to be used. The syringes come in U-100 and U-40 size that corresponds to
the amount of insulin per milliliter (100 units per ml or 40 units per
ml). (A milliliter (ml) and a cubic centimeter (cc) are the same.) Take
a syringe and the bottle of insulin to the pharmacy when a refill is needed
to make sure you have the correct supplies. Let the pharmacist know the
amount you give and he can help you determine the size (such as 3/10cc
or 5/10cc) of the syringe to get.
Dogs that are poorly regulated have a greater risk of developing cataracts.
Drug or Food Interactions
Increased risk of hypoglycemia if used with anabolic steroids, beta-blockers,
monoamine oxidase inhibitors, phenylbutazone, sulfinpyrasone, tetracycline,
or salicylates like aspirin.
Increased risk of hyperglycemia if used with glucocorticoids, thyroid
medications, dobutamine, epinephrine, estrogen/progesterone combinations,
Hypoglycemic agents such as glipizide may help lower insulin requirements
as may chromium picolate.
Use care when starting treatment for thyroid disorders in a diabetic
animal as insulin needs may change.
Changes in potassium levels may occur when using insulin, heart medications,
In general, if the pet is on 1 injection a day, it should receive at
least 2 meals: one at the time the insulin is administered and again at
the time of day when the blood glucose is at its lowest level. If a pet
receives 2 injections a day, generally feed at the time of each injection.
If your pet does not eat, contact your veterinarian before giving the insulin.
Hypoglycemia. Signs include weakness, trembling, unresponsiveness,
seizures, coma, and death. In case the pet is given a double dose of insulin
or is showing signs of low blood sugar, contact your veterinarian and feed
the pet a normal meal, a sugary food, or place a small amount of sugar
water or maple/karosyrup on the gums. Do not put anything in the mouth
of an unresponsive patient. Do not get bit treating the pet. Contact your
veterinarian or the Animal Poison Control Center if you think your pet
may have accidentally received or been given an overdose of the medication.
© 2000 Drs. Foster & Smith, Inc.
Reprinted as a courtesy and with permission from PetEducation.com
On-line store at http://www.DrsFosterSmith.com
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