Diabetic ketoacidosis in dogs and cats

Diabetic ketoacidosis is a medical emergency secondary to a state of diabetes mellitus. This condition can be the initial manifestation of diabetes, or may occur, as a result of an absolute or relative deficiency of insulin, at any time in a patient already being treated.

DEFINITION

Diabetic ketoacidosis is defined as a state of hyperglycaemia, glycosuria and ketonuria (ketonaemia)  associated with metabolic acidosis (pH <7.35, bicarbonates <15 mmol/l).

EPIDEMIOLOGY

The subjects affected are usually cats or dogs with previously undiagnosed diabetes mellitus. Less frequently diabetic ketoacidosis may occur in diabetic animals already being treated, but in which the insulin dose is inadequate because of a concomitant infection, inflammatory process or metabolic alterations.

The signalment of cats and dogs with diabetic ketoacidosis is the same as that for subjects with diabetes mellitus, given the strong relationship between the two conditions. Although diabetic ketoacidosis can be diagnosed at any age, it is seen more frequently in middle-aged or elderly animals (4-14 years). The condition is more common among female dogs than among male dogs; in contrast, in cats it is more common among males.

PATHOGENESIS

Diabetic ketoacidosis is the consequence of a relative or absolute deficiency of insulin, associated with increases in the concentrations of the counter-regulatory hormones of glycaemia such as glucagon, cortisol, catecholamines and growth hormone. Insulin is normally produced and secreted by pancreatic β cells in response to an increase in blood glucose levels. This hormone enables glucose to enter most cells and, in particular, supplies energy to muscle, liver and adipose tissue.

In a condition of insulin deficiency, hyperglycaemia develops through four mechanisms: (i) an increase of gluconeogenesis, (ii) accelerated glycogenolysis, (iii) increases in the concentrations of glucagon and other counter-regulatory hormones (catecholamines, cortisol and growth hormone), and (iv) the inability of tissues to use circulating glucose.

Since glucose is the main energy substrate, in the case of a marked deficit of insulin availability there is a shift from metabolism based on glucose oxidation to one based on lipid oxidation. In fact, most cells are able use free fatty acids (FFA) as an alternative source of energy: nerve cells, however, cannot do so.

Large amounts of FFA are released through hydrolysis of triglycerides in adipose tissue; these FFA are transported to the liver, where they are converted within hepatocytes into ketone bodies (β-hydroxybutyrate, aceto-acetate, acetone). In detail, oxidation of FFA leads to the formation of  aceto-acetate which, in the presence of NADH, is reduced to β-hydroxybutyrate. Acetone, in contrast, is the result of spontaneous decarboxylation of aceto-acetate.

The accumulation of these ketone bodies leads to a state of metabolic acidosis and their continuous elimination through the kidneys worsens the existing osmotic diuresis, dehydration and loss of electrolytes.

Insulin deficiency can be caused by an absolute lack of insulin (inadequate function of the pancreatic β cells, interruption or insufficient dose of exogenous insulin therapy) and/or a concomitant relative lack of insulin due to peripheral insulin resistance. This can occur during inflammatory states or infections, in particular pancreatitis and infections of the genito-urinary system, hormonal imbalances (dioestrus, Cushing’s syndrome) or organ failure during which there is release of counter-regulatory hormones with a hyperglycaemic effect.

CLINICAL SIGNS

The clinical manifestations of diabetic ketoacidosis are varied, depending on its severity and the possible presence of other concomitant disorders. The clinical signs generally include polyuria/polydipsia, vomiting, dehydration, anorexia, lethargy, asthenia, loss of weight, poorly looked after coat and, sometimes, abdominal pain.

Polyuria/polydipsia:as the blood levels of glucose increase, the capacity of the proximal convoluted tubules of the kidney to reabsorb the glucose is lost and there is a consequent osmotic diuresis. The same happens for ketone bodies: increased levels of these metabolic products in the blood, and consequently also in the urine, worsen osmotic diuresis, thereby increasing the excretion of solutes such as sodium, potassium and magnesium and increasing the patient’s state of dehydration. 

Gastrointestinal symptoms: vomiting and diarrhoea can be the outcome of a concomitant disorder such as inflammation of the pancreas, peritoneum, uterus or other abdominal organs. In detail, vomiting is caused by stimulation of the chemoreceptor trigger zone: the blood-brain barrier is less efficient in this area which is, therefore, more sensitive to acid-base imbalances, electrolyte changes and alterations in osmolarity.

Loss of weight and anorexia:an animal with compensated diabetes mellitus usually has polyphagia associated with weight loss because the insulin deficiency causes both lack of inhibition of the hunger centre and an incapacity of the peripheral tissue to use glucose as an energy source. In contrast, anorexia prevails in diabetic ketoacidosis.

Dehydration/hypovolaemia:animals often lose up to 10-12% of their body weight as a result of the excessive renal loss of water and electrolytes, secondary to glycosuria and ketonuria. Furthermore, repeated episodes of vomiting and diarrhoea, together with a lack of water intake, lead to a state of tissue under-perfusion and, therefore, pre-renal hyperuraemia and lactic acidosis.

Depression of the sensorium:sensorial depression, which can reach the level of coma, is due to dehydration, shock, severe acidosis and hyperglycaemia/hyperosmolarity.

Kussmaul’s breathing:this fast, deep breathing is secondary to severe metabolic acidosis. It is a form of compensatory hyperventilation in which the increase in respiratory rate has the purpose of increasing the elimination of carbon dioxide in the presence of a decrease in the pH of the blood. Sometimes the animal’s breath can smell of acetone.

Clinical examination:abdominal palpation may be painful in some cases. Enlargement of the liver may also be found and cats may be jaundiced as the result of severe fatty liver, pancreatitis or pancreatic malignancy causing cholestasis.

DIAGNOSIS

The four diagnostic laboratory signs of diabetic ketoacidosis are hyperglycaemia (usually >250 mg/dl), glycosuria, ketonuria and metabolic acidosis (pH <7.5, HCO₃ <15 mEq/l).

LABORATORY INVESTIGATIONS

Blood-gas analysis

The typical findings are a state of metabolic acidosis, more or less compensated, together with an increase in the anion gap. In conditions of metabolic acidosis there is a decrease in blood pH and/or a reduction in the levels of serum bicarbonates (HCO₃^-), with or without a compensatory decrease in the partial pressure of carbon dioxide (pCO₂).

The mechanisms responsible for the development of metabolic acidosis are: (i) production of ketone bodies, (ii) production of lactate acid by tissues, (iii) retention of phosphates by the kidneys, and (iv) loss of electrolytes and bicarbonates with the urine.

The anion gap is the calculated difference between the measured levels of cations (Na⁺, K⁺) and anions (Cl^-, HCO₃^-) and, therefore, represents the amount of anions not measured, such as lactates, phosphates, proteins, metabolites of ethylene glycol and ketone bodies.

Full blood count

The haematocrit is often increased secondary to the state of dehydration. In cats, in particular, anaemia and leucocytosis are common, whereas in dogs, a non-regenerative anaemia, associated with an increase in immature neutrophils and thrombocytosis, is found frequently.

Biochemical profile

A biochemistry screen often shows, besides hyperglycaemia, an increase in liver enzymes (aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase), which can be secondary to the state of hypovolaemia that leads to a decrease in liver perfusion or, in particular in cats, to a concomitant state of hepatic lipidosis. The hypovolaemia can cause pre-renal hyperuraemia with increases in the levels of urea and creatinine.

The electrolyte disturbances include low levels of sodium, chloride, calcium and magnesium. The concentrations of potassium and phosphorus can be increased, decreased or normal. Hypophosphataemia (plasma concentrations of phosphorus < 0.5 mmol/l) is particularly important in cats as it can cause an acute haemolytic crisis.

High levels of blood glucose can also produce an increase in plasma osmolarity, which can be measured directly or calculated using the following formula:

Osmolarity (mOsm/kg) = 2(Na⁺ ) + Glucose (mg/dl)/18 + Urea (mg/dl)/2.8

In fact, sodium and glucose are the two main electrolytes that contribute to plasma osmolarity, since urea is osmotically inactive given that it can diffuse across the cell membrane. Ketone bodies and other substances (toxic substances, alcohol and glycols) can also cause an increase in osmolarity.

Hyperosmolarity in cats and dogs is defined as a value greater than 330 mOsm/Kg; this state results in a shift of water into the extracellular spaces, causing cellular dehydration; in neurones this leads to the onset of neurological signs such as disorientation, lethargy, depression, convulsions and coma.

Physico-chemical examination of the urine

Analysis of the urine shows glycosuria; initially, ketonuria may not be present.

The dip sticks (Fig. 1) commonly used to determine the presence of ketones in the urine evaluate the concentration of aceto-acetate and a small part of the acetone, while the ketoacid predominantly present during diabetic ketoacidosis is actually β-hydroxybutyrate. β-hydroxybutyrate is formed from aceto-acetate in the presence of hydrogen ions; therefore, the greater the acidosis of the patient, the higher the concentration of β-hydroxybutyrate. This limitation of the urine dipsticks led to the development of methods to evaluate the concentration of β-hydroxybutyrate in the blood. There are now some commercially available portable instruments, validated for use in both cats and dogs, which give a quick and immediate evaluation of blood concentrations of β-hydroxybutyrate (Fig. 2).

Furthermore, it is important to carry out a bacteriological screen of the urine, with an antibiogram if necessary. In fact, bacteria can be found in the urine of 20% of dogs with diabetic ketoacidosis even in the absence of white blood cells in the urine.

TREATMENT

Diabetic ketoacidosis is one of the most complex metabolic disorders: it is difficult to manage and requires intensive treatment. Close monitoring with frequent and constant evaluations of the clinical and laboratory profiles is necessary, particularly in the first few hours, in order to make the appropriate adjustments to the therapeutic protocol.

The aims of treatment are to: (i) restore the circulating fluid volume, (ii) correct the dehydration and electrolyte disturbances, (iii) correct the acidosis, (iv) gradually lower the level of glucose in the blood, (v) supply sufficient amounts of insulin in order to normalise glucose metabolism, and (vi) identify and treat concomitant/triggering disorders.

Appropriate therapy should not be focused on a return to normality within the shortest time possible; in fact, interventions that are too hasty can be harmful, creating osmotic and biochemical imbalances, and rapid changes in vital parameters can be more dangerous than a lack of treatment. The probability of therapeutic success is higher if the haematological and biochemical parameters are normalised gradually (36-48 hours).

The treatment includes fluid therapy, electrolyte supplements, insulin and close monitoring.

Fluid therapy

The first step in the treatment of diabetic ketoacidosis is always adequate fluid therapy, which is aimed at restoring circulatory volume, correcting a state of shock, if present, and increasing the blood pressure, thereby promoting reperfusion of tissues, correcting electrolyte imbalances and reducing blood glucose levels. Consequently, it is important to place a venous catheter (preferably a central venous catheter, but alternatively a peripheral wide bore catheter) in order to start the administration of fluids by the intravenous route. The amount of fluid necessary to correct 80% of the deficit in 10 hours can be calculated using the following formula:

percentage of dehydration x body weight (Kg) x 10 = deficit in ml

and then adding the maintenance volume, which is about 2.2 ml/kg/h, and another volume to replace any additional losses (vomiting, diarrhoea and polyuria).

Further changes can be made following careful assessment of the state of hydration, the urine production, uraemia and persistence of vomiting. Unless evaluation of the electrolyte levels dictates otherwise, the initial intravenous fluid of choice is physiological saline (0.9% sodium chloride), given that subjects with diabetic ketoacidosis are often hyponatraemic. Subsequently, the type of solution is modified depending on the plasma concentrations of sodium and other electrolytes. Other suitable crystalloid solutions are isotonic fluids such as Ringer’s lactate solution or Ringer’s acetate solution.

Hypotonic fluids, such as a 0.45% saline solution, should normally be avoided since, even in the case of severe hyperosmolarity, there is the risk that they could lower plasma osmolarity too quickly, with potential severe repercussions on the central nervous system.

Potassium supplementation 

Animals with diabetic ketoacidosis usually have normal or low concentrations of serum potassium. It is important to remember that blood levels of potassium decrease rapidly because of: (i) fluid therapy, i.e., by dilution, (ii) movement from the extracellular space to the intracellular space as the metabolic acidosis is corrected, and (iii)  co-transport of potassium and glucose into cells under the effect of insulin.

Supplementation is, therefore, necessary to replace the deficit and to prevent severe hypokalaemia prior to starting insulin therapy. An exception should be made for subjects with hyperkalaemia associated with oliguric renal failure in which recovery of adequate glomerular filtration and increased urine output are necessary before starting potassium supplementation. Hypokalaemia causes muscles weakness, ventroflexion of the neck (in cats), cardiac arrhythmias and, in the most severe cases, respiratory failure as a result of impaired function of the respiratory muscles.

Ideally the amount of potassium to administer should be based on the serum concentration of potassium at admission; the concentration of electrolytes should then be monitored after 2 hours and the supplementation given according to the protocol in Table 1. The amount of potassium supplementation should never exceed 0.5 mmol/Kg/h, in order to avoid cardiac arrhythmias.

Table 1: Guidelines for potassium supplementation in fluid therapy in normal conditions and during diabetic ketoacidosis.

Phosphate supplementation

Most cats and dogs with diabetic ketoacidosis have normal or decreased levels of phosphorus at diagnosis. Severe hypophosphataemia can develop after fluid therapy as the result of a dilution effect, intracellular movement of phosphorus after starting insulin therapy and continued gastrointestinal and renal losses. Hypophosphataemia has predominantly haematological and neuromuscular repercussions, leading to haemolytic crises which, if not promptly treated, can be potentially fatal. Hypophosphataemia can be clinically silent or cause weakness or even convulsions. 

Phosphate supplementation is indicated when there are clinical signs or in the presence of haemolysis, or when serum levels are below 0.5 mmol/l in the dog and 0.8 mmol/l in the cat. Potassium phosphate (KPO₄) must be administered by continuous infusion in fluids at a dose of 0.03 up to 0.12 mmol/kg/h, monitoring the serum phosphorus concentration every 8-12 hours and modifying the infusion accordingly; the supplementation should be suspended if hypocalcaemia develops. Supplementation is not indicated in subjects with hypercalcaemia, hyperphosphataemia or renal function impairment.

Magnesium supplementation

Low levels of magnesium are common in subjects with diabetic ketoacidosis and often worsen after starting treatment, although they can improve without requiring therapy as the diabetic ketoacidosis is resolved. Clinical manifestations occur when the serum concentrations of total and ionised magnesium fall below 1 and 0.5 mg/dl, respectively. This condition is not treated unless signs occur, such as persistent lethargy, anorexia, asthenia or refractory hypocalcaemia or hypokalaemia after 24-48 hours of fluid therapy. In these cases supplementation with magnesium sulphate (4 mEq/ml) is indicated and should be administered as a continuous infusion at the dose of 0.5-1 mEq/Kg/day.

Treatment with bicarbonate

In most cases, correction of the hypovolaemia restores the acid-base equilibrium. Administration of bicarbonate in order to correct the metabolic acidosis is often unnecessary and even potentially dangerous. Indeed there are descriptions of various adverse effects of bicarbonate treatment: (i) increased risk of hypokalaemia, (ii) increased affinity of haemoglobin for oxygen with consequent decreased release of oxygen to the tissues, (iii) risk of alkalosis, (iv) paradoxical acidosis, and (v) delayed reduction in lactates and ketone bodies.  

Bicarbonate therapy must, therefore, only be considered in extreme cases and when it is possible to monitor blood-gases during the treatment. Administration of bicarbonate solution may be considered if the pH is <7.1, if iHCO₃^-  is <11 mEq/l and if the animal does not have renal failure.

The bicarbonate deficit (in mmol) can be calculated  using the following formula:

mEq HCO₃^- = body weight (kg) x 0.3 x (12-bicarbonates of the subject) x 0.5

This amount should be administered over 6-12 hours with close monitoring of blood-gas values.

Insulin treatment

Insulin treatment should only be given 4-8 hours after starting fluid therapy and potassium supplementation; this allows the intervention in a better hydrated patient with fewer electrolyte imbalances.

Regular crystalline insulin can be administered intermittently by the intramuscular route or by continuous infusion (the better option). In both cases the aims are to reduce the blood glucose levels, to interrupt the production of ketones in a gradual and controlled manner, to decrease the osmotic diuresis and to improve the acid-base status.

The blood glucose concentration must be monitored frequently, measuring the level of glycaemia with a portable glucometer every hour in the first 24 hours and subsequently every 2 hours. It is important to use instruments validated for dogs and cats; in fact, most glucometers tend to underestimate the real level of glycaemia. Furthermore, it appears to be very useful to measure blood concentrations of β-hydroxybutyrate, again with hand-held instruments. Measuring blood ketone levels using a portable instrument enables frequent evaluations, which can demonstrate the interruption of the ketogenic process efficiently, and is easier than measuring ketones in the urine. This method is now commonly used in human medicine and the American Diabetes Association advises the use of hand-held instruments for the evaluation of β-hydroxybutyrate in capillary blood.

In humans the cut-off concentration of β-hydroxybutyrate is 3.0 mmol/l; concentrations above this cut-off are strongly indicative of diabetic ketoacidosis. Recent studies in veterinary medicine have established that, in dogs, β-hydroxybutyrate values ≥ 3.8 mmol/l (Duarte et al., 2002) or ≥ 3.5 mmol/l (Di Tommasoet al., 2009) are strongly indicative of clinically manifested diabetic ketoacidosis.

Blood-gas analyses supply information on the acid-base status and electrolyte balance, enabling appropriate therapy; these analyses should be performed every 8 hours in the first 24 hours and subsequently every 12 hours.

Continuous intravenous infusion of insulin

• Initially administer regular insulin through a new peripheral venous access.
• The amount of insulin to administer is 0.09 U/Kg/h (2.2 U/Kg in 24 hours) in the dog and 0.04 U/kg/h in the cat (1.1 U/Kg in 24 hours).
• Add 50 ml of physiological saline 0.9% to the insulin (2.2 U/Kg in the dog or 1.1 U/Kg in the cat). Particular care must be taken since insulin tends to adhere to the synthetic material from which the infusion set is made; for this reason, before starting a continuous infusion of insulin, it is essential to flush the entire infusion set with at least 50 ml of a solution of insulin and NaCl 0.9%. A new solution is then used to start the continuous infusion.
• Start the infusion with an infusion pump or, even better, a syringe pump set at a rate of 2 ml/h (Table 2). When the blood glucose level is below 250 mg/dl the infusion rate should be reduced by 25-50%, as shown in Table 2 and fluid therapy with a solution of glucose 2.5% with added potassium should be introduced.
• Continue the continuous infusion of insulin until ketones are no longer present in the blood and/or urine and the pH is >7.3. If the animal is not vomiting, try introducing food already after 12-24 hours. Then start giving rapid-acting insulin by the subcutaneous route at a dose of 0.1-0.4 IU/Kg every 6-8 hours.
• When the clinical condition of the patient has been stabilised and is tending to improve, convert to slow- or ultraslow-acting insulin at a dose of 0.25-0.5 U/Kg subcutaneously every 12 hours together with meals.

Table 2: Rate of infusion of solutions consisting of regular “R” crystalline insulin, at a dose of 2.2 U/Kg (dog) or 1.1 U/Kg (cat), in 50 ml di NaCl 0.9% or NaCl and glucose, and the type of fluid to use depending on the level of glucose in the blood.

Intramuscular administration

• Only administer regular “R” crystalline insulin intramuscularly.
• The initial dose is 0.2 U/Kg intramuscularly, then 0.1 U/Kg intramuscularly every hour until the blood glucose is <250 mg/dl; subsequently, administer 0.1-0.4 U/Kg subcutaneously every 4-6 hours and start the administration of glucose solution 2.5%. Ideally, the concentration of glucose in the blood should be reduced by 54 mg/dl/h, in order to avoid large changes in osmolarity which could have deleterious effects.
• Try to feed the animal after 12-24 hours of treatment. Continue the administration of insulin until there are no ketone bodies in the urine and the patient has started to feed spontaneously. At this point start subcutaneous administration of a rapid-acting insulin at a dose of 0.1-0.4 U/Kg every 6-8 hours.
• When the animal’s clinical condition is stable, it is not vomiting and it has been feeding spontaneously for at least 2 days, start treatment with subcutaneous slow- or ultraslow-acting insulin at a dose of 0.25-0.5 U/Kg every 12 hours together with meals.

Monitoring in the first 24 hours of treatment

Close monitoring of the animal’s clinical, haematological and biochemical conditions is essential in order to be able to promptly correct any electrolyte and acid-base imbalances or hypoglycaemia. It is, therefore, useful to:

• Evaluate glycaemia every hour, possibly using an glucometer validated for the species in which it is being used;
• Monitor blood β-hydroxybutyrate levels, if possible, with a portable instrument, every 4-8 hours;
• Carry out blood-gas analyses and urinalysis every 8 hours;
• Measure the haematocrit, total proteins and concentration of phosphorus every 12 hours;
• Monitor clinical parameters every 4-6 hours, in particular: temperature, pulse, breathing and capillary filling time;.
• Measure the animal’s body weight every 24 hours.

Monitoring in the subsequent 24-48 hours of treatment

• Measure glycaemia with a portable blood glucose monitor every 2 hours and subsequently every 3 hours, possibly using portable instruments validated for the type of animal being tested.
• Evaluate the blood concentrations of β-hydroxybutyrate, with a portable instrument, every 4-12 hours.
• Carry out blood-gas analyses and a physico-chemical examination of the urine every 12 hours.
• Measure the haematocrit, total proteins and concentration of phosphorus every 24 hours.
• Monitor clinical parameters every 24 hours, in particular: temperature, pulse, breathing and capillary filling time.

PROGNOSIS

The prognosis of animals with diabetic ketoacidosis is profoundly influenced by concomitant disorders, complications developing during treatment and the severity of the acidosis. Despite prompt application of suitable protocols, the reported mortality rate among animals ranges from 26% to 30%, including animals that die naturally and those that are euthanized.

In humans there has been a decrease in mortality due to a better understanding of the physiopathology of diabetic ketoacidosis and the use of new therapeutic protocols. Nowadays the mortality rate is 3.4% – 4.6% and deaths are often associated with underlying morbid conditions.

Suggested readings

1. Abbas Kitabchi A.E., Umpierrez G.E., Fisher J.N., Murphy M.B., Stentz F.B. (2008):Thirty Years of Personal Experience in Hyperglycemic Crises: Diabetic Ketoacidosis and Hyperglycemic Hyperosmolar State. Journal of Clinical Endocrinology and Metabolism, 93(5): 1541–1552.
2. Bruskiwic K.A., Nelson R.W., Feldman E.C. Grieffey S.M. (1997): Diabetic ketosis and ketoacidosis in cats: 42 cases (1980-1995).Journal of the American Veterinary Association, 211(2): 188-192.
3. Bureau M.A.,Bureau M.A., Bégin R., Berthiaume Y., Shapcott D., Khoury K., Gagnon N. (1980):Cerebral hypoxia from bicarbonate infusion in diabetic acidosis. The Journal of Pediatrics, 96(6):968-73.
4. Casella M., Wess G., Hassig M., Reusch C.E. (2003): Home monitoring of blood glucose concentration by owners of diabetic dogs. Journal of Small Animal Practice,44(7): 298-305.
5. Casella M., Wess G., Reusch C.E. (2002): Measurement of capillary blood glucose concentrations by pet owners: a new tool in the management of diabetes mellitus. Journal of American Animal Hospital Association, 38(3): 239-245.
6. Di Tommaso M., Aste G., Rocconi F., Guglielmini C., Boari A. (2009):Evaluation of a portable meter to measure ketonemia and comparison with ketonuria for the diagnosis of canine diabetic ketoacidosis. Journal of Veterinary Internal Medicine, 23(3): 466-471.
7. Duarte R., Somones D.M., Franchini M.L., Merquezi M.L., Ikesaki J.H., Kogika M.M. (2002): Accuracy of serum beta-hydroxybutyrate measurements for the diagnosis of diagnosis of diabetic ketoacidosis in 116 dogs. Journal of Veterinary Internal Medicine,16(4): 411-417
8. Feldman E.C., Nelson R.W.(2004): Diabetic Ketoacidosis.In: Canine and Feline Endocrinology and Reproduction, 3^rd ed. Saunders, St Louis, Missouri, pp.580-615.
9. Feldman E.C., Nelson R.W. (2004b) :Canine Diabetes Mellitus. In: Canine and feline endocrinology and reproduction, 3^rd ed. Saunders, St.Louis, Missouri, pp. 486- 538.
10. Hess R.S. (2010): Insulin resistance in dogs. Veterinary Clinics of North America: Small Animal Practice, 40: 309-316.
11. Hess R.S., Saunders H.M., Van Winkle T.J., Ward R.C. (2000): Concurrent disorders in dogs with diabetes mellitus: 221 cases (1993-1998). Journal of American Veterinary Medical Association, 217(8): 1166-1173.
12. Hoenig M., Dorfman M., Koenig A. (2008): Use of a hand-held meter for the measurement of blood beta-hydroxybutyrate in dogs and cats. Journal of Veterinary Emergency and Critical Care, 18(1): 86-87.
13. Hume Z.D., Dobraz J.K., Hess S.R. (2006): Outcome in dogs with Diabetic Ketoacidosis: 127 Dogs (1993-2003). Journal of Veterinary Internal Medicine,20:547-555.
14. Kitabchi A.E., Umpierrez G.E., Murphy M.B., Barrett E.J., Kreisberg R.A., Malone J.I., Wall B.M. (2001): Management of hyperglicemic crises in patient with diabetes. Diabetes Care, 24(1): 131-153.
15. Macintire D.K. (1993): Treatment of diabetic Ketoacidosis in dogs by continuous low-dose intravenous infusion of insulin. Journal of American Veterinary Medical Association, 202(8): 1266-1272.
16. Nelson R.W. (2005) Diabetes Mellitus. In: Ettinger S.J., Feldman E.C. (Eds) Textbook of Veterinary Internal Medicine, Elsevier Saunders, St Louis, Missouri, pp. 1563-1591.
17. O’Brien M.A. (2010): Diabetic emergencies in small animals. Veterinary clinics of north America: Small Animal practice, 40(2):317-33.
18. Reusch C.E., Robben J.H., Kooistra H.S. (2010): Endocrine pancreas. In: Rijnberk A., Kooistra H.S. (Eds) Clinical Endocrinology of dogs and cats, Schlutersche, Hannover, pp. 159-172.
19. Steiner J.M. (2003): Diagnosis of pancreatitis. Veterinary Clinics of North America: Small Animal Practice, 33(5): 1181-95.
20. Weingart C., Arndt G., Kohn B. (2010): Measurement of beta-hydroxybutyrate in cats with nonketotic diabetes mellitus, diabetic ketosis and ketoacidosis using a portable ketone meter. Journal of Veterinary Internal Medicine .Research Abstract Program of the 2010 ACVIM Forum. Abstract numero 246, pp 746.
21. Wess G., Reusch C. (2000): Capillary blood sampling from the ear of dogs and cats and use of portable meters to measure glucose concentration.Journal of Small Animal Practice, 41: 60-66.
22. Zeugswetter F., Handl S., Iben C., Schwendenwein I. (2009): Efficacy of plasma beta- hydroxybityrate concentration as marker for diabetes mellitus in acutely sick cats. Journal of Feline Medicine and Surgery,  12(4): 300-5.
23. Zeugswetter F., Pagitz M. (2009): Ketone measurement using dipstick methodology in cats with diabetes mellitus. Journal of Small Animal Practice,50: 4-8.