Insulinoma

Signalment

• More common in dogs than cats
• Middle-aged to older dogs
• No sex predilection
• Breed predisposition, more common in medium to large-breed dogs:
  • Irish Setter
  • German Shepherd
  • Labrador Retriever
  • Standard Poodle
  • Boxer

Description

Insulinomas are well slow growing, encapsulated, functional tumours of the beta cells of the pancreatic islet cells, They secrete inaappropriately high amount of insulin irrespective of the serum glucose level. They are predominantly malignant (90% of canine isulinomas), with a high metastatic rate to regional lymph nodes, liver and omentum.

Diagnosis

Clinical Signs

The following signs are attributal to hypoglycaemia:

• collapse
• muscle tremor
• muscle weakness
• ataxia
• mentally dull and disorientated

• These sigs may be intermittent at the beginning of the disease, but this becomes progressively more often. In between hypoglycaemic episodes, the animals are normal.

Laboratory Tests

Biochemistry

• Hypoglycemia

Diagnostic Imaging

Radiography

A thoracic radiograph may be used to identify any pulmonary metastases, but this is uncommon.

Ultrasonography

Occasionally, it may be possible to visualise the location of the tumour on the pancreas. However, this may not be possible if the tumous is too small. Metastases to lymph nodes and liver can sometimes be revealed.

References

• Ettinger, S.J. and Feldman, E. C. (2000) Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2 (Fifth Edition) W.B. Saunders Company.
• Fossum, T. W. et. al. (2007) Small Animal Surgery (Third Edition) Mosby Elsevier
• Nelson, R.W. and Couto, C.G. (2009) Small Animal Internal Medicine (Fourth Edition) Mosby Elsevier.