HYPOGLYCEMIA

MISSY HORNACC# 165211

Missy Horn• Acc#164629

• 6 year old FS Labrador Retriever

• Presented for progressive generalized weakness and muscle atrophy for 1 year

• BW done in January by rDVM: WNL

Physical Exam Frequently sits/lays down during exam

Mild palmigrade/plantigrade stance

Mild weakness/decreased control and precision when placing paws with each limb advancement

Generalized muscle atrophy; most pronounced over epaxials and pelvic limbs

Neurolocalization: neuromuscular

Bloodwork Performed prior to performing EMG Big 4:

PCV 50% TS 8.0 BUN normal Blood glucose: 38 Insulin levels: Pending

CBC normal

EMG Spontaneous activity noted on multiple

muscles with greatest severity in distal limbs

Slow/abnormal NCV ~41m/s

Consistent with a peripheral neuropathy

Causes of Hypoglycemia Excess insulin secretion or insulin-like factors

Insulinoma, extrapancreatic tumors and islet cell hyperplasia

Dec glucose production Addisons, hypopituitarism, GH deficiency, liver dz,

glycogen storage dzs, neonates, and toy breeds Excess glucose consumption

Sepsis, extreme exercise Drugs

Insulin, oral hypoglycemics, salicylates, acetaminophen, beta blockers, TCAs, ACE -, tetracycline

Spurious

Paraneoplasitc tumors Several tumors can cause a paraneoplastic

syndrome with the production of insulin like growth factor type II Causes hypoglycemia Mesenchymal tumors more common than epithelial Leiomyosarcoma and leiomyoma of the GI tract are

the most frequent mesenchymal tumor Splenic hemangiosarcoma has also been described

Epithelial tumors most commonly from hepatocellular carcinoma

Sporadic cases of oral melanoma and salivary adenocarcinoma have been reported

Insulinoma Diagnosis:

Repeated hypoglycemia: BG < 60 Insulin > 20 Histopathology of a pancreatic mass/nodule

Clinical Signs: Mean age: 9 years Seizures, collapse, weakness, ataxia, disorientation, mental

dullness, and visual disturbances Imaging:

Ultrasonography sensitivity of 56% in dogs and abdominal metastasis identified in 20%

CT: Sensitivity of 71% using conventional pre- and postcontrast CT. sensitivity not determined for dual phase CT angiography but is used for humans

Pathophysiology Insulin secreting tumor of the pancreatic

beta cells Carcinomas account of 60%, with the

remainder being adenomas Are rare but insulinoma is the most

common pancreatic endocrine tumor (insulinoma, gastrinoma, and glucagonoma)

Large breed dogs most affected(Irish Setters, Boxers, and GSDs) but any breed can be affected

Islets of Langerhans: island of endocrine tissue in the otherwise exocrine pancreas

1. Alpha cells: produce glucagon

Acts to inc BG

2. Beta cells: produce insulinActs to dec BG and allows for uptake of glucose into cells

3. Delta cells: produce somatostatinInhibits insulin and glucagon

4. Pancreatic polypeptideInhibits both endocrine and exocrine pancreatic secretions

Treatment Planning Determine if mass is present and/or

resectable If surgically excisable increases life

span Large percentage of animals has

metastasis at time of diagnosis Removal or mass will still increase prognosis

Median survival time of 12-14 months with partial pancreactomy

Young dogs have a worse prognosis

CT characteristics Precontrast: typically iso to hypoattenuating

to adjacent parenchyma Arterial phase: contrast enhancing(peak

enhancement) Venous: less contrast enhancing but still

hyperattenuating compared to adjacent parenchyma

Delay phase: iso to hypoattenuating Insulinomas are highly vascular making

sense why they have peak enhancement during the arterial phase

CT characteristics CT angiography is not 100% sensitive in

detecting insulinomas, likely depending on the vascular supply and size of the tumor

CT angiography is more sensitive than other imaging modalities and is also more sensitive in detecting metastatic disease

If hypoglycemic and elevated insulin levels, surgical exporatory with histopathology is still needed for diagnosis

Hepatic LN

Hepatic Lymph Node

Right Lobe of Pancreas

Pancreatic Mass

Contrast enhancing mass in the left lobe of the pancreas

Acc#15110110yr MC Boxer

Missy If insulin levels are elevated owners will

likely go ahead with abdominal exploratory

In the mean time are feeding small meals frequently and giving prednisone

Prednisone antagonizes the effect of insulin by causing insulin resistance at the level of the insulin receptors

References1. Robben JH, Pollak YW, Kirpensteijn J, et al. Comparison of ultrasonography,computed tomography, and single-photon emission computed tomography for the detection and localization of canine insulinoma. J Vet Intern Med 2005;19:15–22.

2. Mai W, Caceres A. Dual-Phase Computed Tomographic Angiography in Three Dogs With Pancreatic Insulinoma. VRUS(2008) 49; 2: p141-148

3. Ettinger S and Feldman, E. Textbook of Veterinary Internal Medicine: Sixth Edition. 2005 Elsevier Saunders: p1560-1563

4. Zini E, Glaus TM, Minuto F, Arvigo M, Hauser B, Reusch CE. Paraneoplastic hypoglycemia due to an insulin-like growth factor type-II secreting hepatocellular carcinoma in a dog. J Vet Intern Med 2007. Jane-Feb; 21(1): 193-5