canis - Articles
Hypoglycemia
Introduction
- Plasma glucose less than 3.0 mmol/L (55 mg/dL) is significant.
- In animals which have chronically low blood glucose, concentrations may have to drop very low (less than 2.0 mmol/L (35 mg/dL) before clinical signs are exhibited.
- Signs: ataxia, weakness, disorientation, seizures.
- Diagnosis: blood or plasma glucose concentrations.
- Treatment: feeding and/or glucose (oral or intravenous) and correct underlying cause.
Presenting signs
- Weakness/collapse.
- Ataxia/incoordination.
- Lethargy/sleepiness.
- Trembling/muscle tremors.
- Anxiety/behavioral changes/bed wetting.
- Disorientation/confusion/apparent blindness.
- Collapse with or without loss of consciousness.
- Seizures.
- Other neurological signs.
- Polyphagia.
Acute presentation
- Often present following collapse or seizure.
- Signs may be acute or intermittent/episodic.
- Diabetic dogs receiving insulin treatment.
Age predisposition
- Older dogs (neoplastic causes).
- Neonate (malnourishment/hypothermia).
Breed/Species predisposition
- Toy and miniature breeds - prone to hypoglycemia if inadequate feeding and hypothermia when neonates.
- Large breeds overrepresented with insulinomas Pancreas: neoplasia: insulinoma.
- Working dogs during hard work.
Special risks
- General anesthesia/surgical procedures Anesthesia: in diabetic patient - hypoglycemia must be controlled, eg with continuous IV glucose infusion.
Pathogenesis
Etiology
- Functional islet cell tumor (insulinoma Pancreas: neoplasia: insulinoma ).
- Excessive insulin dosage in diabetics.
- Xylitol toxicity Xylitol toxicity due to consumption of sugar-free candies and other foods.
- Starvation/malnourishment of neonates.
- Liver disease, particularly large hepatomas Liver: neoplasia.
- Other intra-abdominal tumors, especially hepatocellular carcinoma Liver: hepatocellular carcinoma, splenic tumors Spleen: neoplasia and leiomyosarcomas Leiomyoma/leiomyosarcoma.
- Sepsis Shock: septic.
- Adrenocortical insufficiency Hypoadrenocorticism.
- Glycogen storage diseases Storage disease.
- Severe polycythemia Polycythemia: secondary.
Predisposing factors
- Neonatal/juvenile animals have immature mechanisms for regulating blood glucose.
- Over-activity, cold, other stresses tend to reduce blood glucose.
- Insulin treatment of diabetic dogs.
- Hard work - appears as functional disorder.
Pathophysiology
- Decrease of blood glucose towards the lower end of the physiological range stimulates secretion of counter-regulatory hormones (glucagon, adrenaline, noradrenaline, cortisol, and growth hormone), which increase glycogenolysis and gluconeogenesis and so increase blood glucose concentration.
- Hypoglycemia results from failure of these mechanisms due to excess insulin, deficiency of counter-regulatory hormones, and/or inadequate glucose production.
- Hypoglycemia also → and increased appetitie (might even result in pica Pica).
- If these protective counter-regulatory mechanisms are overwhelmed, hypoglycemia → reduced glucose availability to central and peripheral nervous system → lethargy, weakness, ataxia, disorientation, seizures.
- Prolonged, severe hypoglycemia → reversible or irreversible brain damage, and rarely → death.
Specific
- Neonatal hypoglycemia - gluconeogenesis limited in neonate and limited glycogen stores rapidly deplete - relies upon regular feeding - may develop hypoglycemia after only 12 hour fast.
- Starvaion - severe malnutrition → decreased hepatic glycogen, decreased fat stores → decreased gluconeogenesis → hypoglycemia.
- Glycogen storage diseases Storage disease - genetic abnormality → deficiency in enzymes/defective enzymes involved in glycogen degradation → hypoglycemia.
- Exogenous agents: direct drug action → hypoglycemia.
- Bacterial shock → depletion of glycogen stores, increased peripheral use of glucose, decreased gluconeogenesis + ?circulatory factors → hypoglycemia.
- Extra-pancreatic tumors:
- Secretion of insulin/insulin-like/insulin precursor.
- Accelerated glucose utilization.
- Inhibited glucose release from liver → hypoglycemia.
- Functional islet cell tumor → insulin secretion → hypoglycemia.
- Insulin overdose, inappetence/starvation, concurrent illness and/or sudden increase in exercise/stress levels during treatment with insulin may → hypoglycemia.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Behrend E, Holford A, Lathan P, Rudinsky R et al (2018) 2018 AAHA Diabetes Management Guidelines for Dogs and Cats. JAAHA 54 (1), 1-21 PubMed.
- Brooks E D, Yi H, Austin S L et al (2016) Natural progression of canine glycogen storage disease type IIIa. Comp Med 66 (1), 41-51 PubMed.
- Münnich A, Küchenmeister U (2014) Causes, diagnosis and therapy of common diseases in neonatal puppies in the first days of life: cornerstones of practical approach. Reprod Domest Anim 49 (Suppl 2), 64-74 PubMed.
- Northrup N C, Rasnick K M, Gieger T L, Kosarek C E et al (2013) Prospective evaluation of biweekly streptozotocin in 19 dogs with insulinoma. J Vet Intern Med 27 (3), 483-490 PubMed.
- Goutal C M, Brugmann B L, Ryan K A (2012) Insulinoma in dogs: a review. JAAHA 48 (3), 151-163 PubMed.
- Piscitelli C M, Dunayer E K, Aumann M (2010) Xytitol toxicity in dogs. Compen Contin Educ Vet 32 (2), E1-4 PubMed.
- Zini E, Glaus T M, Minuto F et al (2007) Paraneoplastic hypoglycemia due to an insulin-like growth factor type-II secreting hepatocellular carcinoma in a dog. J Vet Intern Med 21 (1), 193-195 PubMed.
- Syme H M & Scott-Moncrieff (1998) Chronic hypoglycaemia in a hunting dog due to secondary hypoadrenocorticism. JSAP 39 (7), 348-351 PubMed.
- Bagley R S, Levy J K & Malarkey D E (1996) Hypoglycaemia associated with intrabdominal leiomyoma and leiomyosarcoma in six dogs. JAVMA 208 (1), 69-71 PubMed.
- Leifer C E, Peterson M E & Matus R E (1986) Insulin secreting tumours - diagnosis and medical and surgical management in 55 dogs. JAVMA 188 (1), 60-64 PubMed.
- Leifer C E, Peterson M E, Matus R E & Patnaik A K (1985) Hypoglycaemia associated with nonislet cell tumours in 13 dogs. JAVMA 186 (1), 53-55 PubMed.