Cats: Diagnosis and treatment of diabetes mellitus

Related diseases

Other diseases that may contribute to the development of feline diabetes include:

  • Acromegaly
  • Exocrine pancreatic insufficiency
  • Hyperthyroidism
  • Pancreatitis

Acromegaly overview

Acromegaly is a rare endocrine disease caused by excessive secretion of growth hormone by the pituitary gland. In cats, acromegaly results from a pituitary tumor that secretes the excess growth hormone.

Acromegaly is characterized by chronic overgrowth of connective tissue, bone, and viscera. Clinical signs of acromegaly in cats include:

  • Insulin-resistant diabetes
  • Enlargement of soft tissue organs
  • Proliferation of gum tissue

Radiation therapy appears to be the most effective treatment for feline pituitary tumors.

Exocrine pancreatic insufficiency (EPI)

Exocrine pancreatic insufficiency (EPI) is a congenital or acquired condition that can affect both dogs and cats, although it is more common in dogs. In cats, EPI typically manifests as the final stage of pancreatitis. EPI may occur concurrently with diabetes mellitus if both the exocrine and endocrine pancreas are damaged.

EPI pathophysiology

  • Digestive enzymes are not secreted normally by the pancreas.
  • Food is not sufficiently digested and processed.
  • Diarrhea and weight loss occur despite normal or increased appetite.

EPI diagnosis and treatment

EPI is diagnosed based on blood tests and is treated with pancreatic enzyme replacements and dietary management, which usually improve clinical signs. However, if EPI results from chronic pancreatitis accompanied by diabetes mellitus, it can be more difficult to treat.

Feline hyperthyroidism overview

Hyperthyroidism is the most common endocrine (hormone) disorder affecting cats. It creates a wide range of clinical signs resulting from the overproduction of thyroid hormone made by the thyroid gland. This condition often presents concurrently with diabetes mellitus.

Common clinical signs of hyperthyroidism include:

  • Weight loss
  • Polyphagia
  • Polyuria
  • Polydipsia
  • Vomiting
  • Diarrhea
  • Hyperactivity
  • Matted or greasy haircoat

Over time excessive thyroid hormones can cause heart disease and cats may exhibit:

  • Heart murmur
  • Difficulty breathing
  • Tachycardia
  • Arrythmias

Diagnosis of feline hyperthyroidism
In most cats, laboratory measurement of thyroid hormone T4 will confirm the presence of hyperthyroidism. A small percentage of cats with hyperthyroidism will show normal T4 levels. In these cases, if you still suspect a cat has hyperthyroidism, conduct:

  • Follow-up total T4 measurement 3 or more weeks later
  • Free T4 measurement (by equilibrium dialysis)
  • T3 suppression test

Treatment of feline hyperthyroidism
After you have confirmed a hyperthyroidism diagnosis, three treatment options exist including:

  • Surgical thyroidectomy
  • Radioactive-iodine therapy
  • Anti-thyroid medications

Pancreatitis overview

Pancreatitis or inflammation of the pancreas causes digestive enzymes to leak into and damage the surrounding pancreatic tissues. In most cases, the cause of pancreatitis is idiopathic, however risk factors include:

  • High-fat, low-protein diet
  • Breed—Siamese cats are at higher risk
  • Cholangiohepatitis
  • Toxoplasmosis
  • Feline leukemia virus
  • Feline herpesvirus
  • Obesity
  • Diabetes mellitus
  • Cushing's disease
  • Chronic renal failure
  • Neoplasia

Acute pancreatitis or pancreatic neoplasia may produce temporary diabetes mellitus. If extensive pancreatic necrosis occurs, diabetes may become a permanent condition.