Page 321 - Problem-Based Feline Medicine

17 – THE CAT WITH WEIGHT LOSS AND A GOOD APPETITE 313

● Most cats with uncomplicated diabetes respond during a 12–24 h period. The level of the
well to once- or twice-daily subcutaneous admin- blood glucose at its nadir (lowest point) deter-
istration of lente, protamine zinc insulin (PZI) or mines whether or not the dose of insulin needs
glargine. to be changed, while the duration of insulin
● The source of the insulin does not appear to be action determines how frequently it needs to
important in cats, as anti-insulin antibodies do not be given.
cause many problems.
Water drunk measured at home on at least two con-
● The duration of action of the different preparations
secutive days is better correlated with mean blood
varies between cats (lente – peak 2–10 h, duration
glucose than is fructosamine concentration. If water
of action 6–16 h; PZI – peak effect at 3–12 h, dura-
intake is < 20 ml/kg on wet food or < 70 ml/kg on
tion of action 6–24 h; glargine peak effect at 16 h,
dry food, it indicates good glycemic control.
duration of action > 24 h). In general, PZI and
glargine are preferred because of their longer dura- At all times, but especially after altering the insulin
tion of action, improved glycemic control and dosage, the owners should be warned to look for signs
increased remission rates. of hypoglycemia (weakness, lethargy, shaking, ataxia,
● Start at ~0.25–0.5 IU insulin/kg/per injection, then collapse and coma). If these signs occur, the cat’s gums
adjust as necessary, usually by 0.5–1.0 IU per dose. should be rubbed with sugar water, jam or honey, and
See page 239, Diabetes mellitus in The Cat With immediate veterinary attention sort.
Polyuria or Polydipsia, for detailed criteria for ● Reasons for apparent insulin resistance include
adjusting the insulin dose. ineffective insulin (out of date, poor storage,
● The aim of therapy is to prevent the clinical signs of incomplete mixing), poor injection technique,
diabetes and, if possible, maintain blood glucose out-of-date urine test strips and insulin overdose
concentration between 5.5–14 mmol/l (100–250 leading to insulin-induced hyperglycemia. The
md/dl). Somogyi over-swing occurs when hypoglycemia
● It takes 2–3 days for glucose homeostasis to adjust induces counter-regulatory hormones such as epi-
after starting or altering insulin doses. Any changes nephrine and glucagon to induce hyperglycemia.
in dose should therefore be based on recurring True insulin resistance can result from recent
effects, not a single urine (or blood) glucose deter- weight gain, infection, acromegaly, hyperadreno-
mination. Owners can monitor water intake, urine corticism, hyperthyroidism, the administration of
glucose and ketone levels at home. Ideally glucose diabetogenic drugs, renal or hepatic insufficiency,
will be negative or trace, and ketones will be nega- anti-insulin antibodies or presence of certain
tive. Glucose curves can also be performed at home types of tumor.
by obtaining a drop of blood for glucose testing via
ear vein pricking.
– It is generally recommended that glucose curves Prognosis
be performed every 1–2 weeks until the diabetes
The prognosis is very variable. It depends on the
is stable. After this time they need be performed
owner’s commitment, the presence of concurrent and
less frequently, and the dosage can be adjusted
interacting disease and the ease of glycemic control. If
in response to changed clinical signs, ± serum
diabetes arises secondary to chronic pancreatitis it can
fructosamine concentrations.
be particularly difficult to control.
– The usefulness of glucose curves can be very
limited in easily stressed cats that become hyper-
glycemic whenever they are hospitalized.
Prevention
Anorexic cats may have a lower blood glucose
concentration in the hospital than at home when The risk of developing diabetes can be reduced by not
eating. allowing cats to become obese or physically inactive
– A glucose curve is performed by giving the cat and not giving long courses of diabetogenic drugs. A
its usual breakfast and dose of insulin, then low-carbohydrate, high-protein diet may also help to
determining blood glucose level every 1–2 h reduce the demand on beta cells to produce insulin.