Page 319 - Problem-Based Feline Medicine

17 – THE CAT WITH WEIGHT LOSS AND A GOOD APPETITE 311

IAPP is co-secreted and accumulates as amyloid in It can occur in any age, sex or breed of cat, but is seen
normal cats as they age, it accumulates more exten- most frequently in older obese neutered male cats.
sively in cats with diabetes. The accumulation of
In Australia, New Zealand and Great Britain, Burmese
islet amyloid eventually leads to loss of beta cells.
cats appear to be predisposed, with ~1 in 50 affected.
● Obesity is a significant risk factor for diabetes
because it results in peripheral insulin resistance. The most consistent signs are polyuria, polydipsia
Other specific types of diabetes, previously called type 3 and polyphagia. In the early stages these signs may go
or secondary diabetes, results from diseases which destroy unnoticed by the owners, possibly because of free
beta cells or cause marked insulin resistance, such as: choice feeding and outdoor toileting habits.
● Beta cell destruction due to pancreatitis or neopla-
Possible initial weight gain is followed by weight
sia. Pancreatitis may be more common than previ- loss.
ously thought, as >50% of diabetic cats have
evidence of past or current pancreatitis at necropsy Urinary tract infections are common, and cats may
(see below under pancreatitis/exocrine pancreatic present with signs of cystitis and/or renal failure.
insufficiency). The coat may be ill kept and a pot-bellied appearance
● Insulin resistance resulting from unrelated
may result from hepatomegaly.
endocrinopathies, e.g. acromegaly or hypera-
drenocortisim (see below under Acromegaly and Hindlimb weakness and a plantigrade stance due to dia-
Hyperadrenocorticism). betic neuropathy are seen quite frequently, but cataracts
● Insulin resistance from drug administration, e.g. occur rarely.
corticosteroids, megestrol acetate. Cats are frequently presented only when they become sys-

60–70% of cats with diabetes require exogenous temically ill with signs of anorexia, vomiting and/or diar-
insulin, at least temporarily. rhea, jaundiced and depression (see page 261, The Cat
With Depression, Anorexia or Dehydration).
10–80% of cats with diabetes may lose the need for
exogenous insulin. This may result from: Cases of diabetes that result from chronic pancreatitis
● Correction of ‘glucose toxicity’. Prolonged hyper- may have a history that includes episodes of depres-
glycemia causes impaired insulin and increased sion, anorexia, vomiting, diarrhea and/or abdominal
peripheral insulin resistance, termed glucose toxic- pain. Since diabetes is most likely to occur when most
ity. Exogenous insulin administration and reduction of the pancreatic mass has been destroyed, it may be
of hyperglycemia can result in resolution of this accompanied by signs of exocrine pancreatic insuffi-
toxicity and return of sufficient insulin secretion to ciency, evidenced by large quantities of voluminous
maintain normoglycemia. Long-acting insulin fatty feces and a voracious appetite (see below under
administered twice daily and a low-carbohydrate, pancreatitis/exocrine pancreatic insufficiency).
high-protein diet appear to facilitate this.
● Reduction of obesity which deceases insulin resist- Diagnosis
ance.
● Resolution of pancreatitis. Diagnosis of diabetes mellitus is based on docu-
● Treatment of underlying disease, e.g. acromegaly or menting persistent fasting hyperglycemia (> 11
hyperadrenocortisim. mmol/l [200 mg/dl]) and glucosuria in a cat with
● Removal of diabetogenic drugs, e.g. progestogens appropriate clinical signs (polyuria, polydipsia and
(megestrol acetate) or exogenous corticosteroids. polyphagia).
Stress-induced hyperglycemia can result in glucose lev-
Clinical signs els above the renal threshold and hence glucosuria, so a
single documentation of these findings is not diagnos-
Diabetes is the second most common endocrinopathy
tic of diabetes.
in cats following hyperthyroidism. However, while it
used to affect ~1 in 400 pet cats, in Great Britain this has Allowing the cat to settle down then re-testing it after a
risen to ~1 in 200. few hours may help to determine whether or not the