Diseases Related to Feline Diabetes Mellitus
Certain diseases may contribute to the development of feline diabetes:
Hyperthyroidism
Hyperthyroidism is a common endocrine disorder of middle-aged and older cats.Diabetes mellitus and hyperthyroidism may present concurrently.
Pathophysiology
and clinical signs
A thyroid adenoma causes secretion of increased amounts of thyroid
hormones (tri-iodothyronine (T3) and thyroxine (T4).
Hyperthyroidism is a multi-system disorder. Clinical signs include:
- weight loss
- polyphagia
- polydipsia
- polyuria
- hyperactivity
- diarrhoea
The high levels of thyroid hormones can cause the development of heart disease, and these patients may have:
- a heart murmur
- difficulty breathing
- tachycardia
- arrhythmias.
Diagnosis
Hyperthyroidism must be differentiated from diabetes mellitus. This
is usually done using laboratory measurement of T4 concentration.
In a few cats the diagnosis may need to be confirmed by:
- A follow-up total T4 measurement 3 or more weeks later or
- Free T4 measurement (by equilibrium dialysis) or
- A T3 suppression test.
Treatment
Once hyperthyroidism has been confirmed, there are several treatment
options, including:
- surgical removal of the gland
- radioactive iodine
- anti-thyroid medications
The initial choice of treatment is often guided by concern about the cat's kidney function, since treatment may precipitate renal failure. For hyperthyroid cats that are assessed with normal kidney function, surgery or radioactive iodine treatment are most frequently recommended.
Acromegaly
Acromegaly is a rare endocrine disease caused by growth hormone excess. It is characterized by chronic overgrowth of connective tissue, bone and viscera.
In cats, acromegaly is due to a growth hormone-secreting pituitary tumour.
Clinical signs
- insulin resistant diabetes
- enlargement of soft tissue organs
- proliferation of gum tissue
Treatment
Currently the best treatment for a cat with a pituitary tumour appears
to be radiation therapy.
Exocrine pancreatic insufficiency (EPI)
Exocrine pancreatic insufficiency is a congenital or acquired condition that can affect both dogs and cats, although it is more common in dogs.
In cats EPI is usually the end-stage of pancreatitis. It may be seen together with diabetes mellitus if there is damage to both the exocrine and endocrine pancreas.
For more information see EPI in dogs
Hyperadrenocorticism (Cushing’s disease)
Hyperadrenocorticism
is rare in cats.
Formore
information see Hyperadrenocorticism
in dogs.
Pancreatitis
Pancreatitis is an inflammation of the pancreas. Digestive enzymes leak into and damage the surrounding pancreatic tissues.
Aetiology
In most cases the cause of pancreatitis is idiopathic. Other predisposing
factors may be:
- high fat, low protein diet
- other diseases (Cushing's disease, diabetes mellitus)
- in cats - toxoplasmosis, feline leukaemia virus, feline herpesvirus
Risk Factors for pancreatitis include:
- breed - Siamese cats are at higher risk
- diabetes mellitus
- Cushing's disease
- chronic renal failure
Acute pancreatitis may produce temporary diabetes mellitus, if there is extensive pancreatic necrosis this may become permanent. A similar situation can arise if there is pancreatic neoplasia.