march 2011, issue 29 - aspen meadow...diabetic ketoacidosis (dka) by dr. laura higgins, emergency...

Dr. Wendy Yaphe

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March 2011, Issue 29

What's New at AMVSThis month, our beloved clinic cat, Studley, finally earned his keep by donating blood to a very ill cat. His life-saving efforts are fully appreciated by all. In other news, Aspen Meadow VeterinarySpecialists' (AMVS') Internal MedicineSpecialist, Dr. Wendy Yaphe, has visited localclinics for our continuing "Lunch and Learn" lectures. Most recently she visited a clinic in Longmont andspoke about urinalysis testing and its importanceas a diagnostic procedure. If your clinic would like to host a "Lunch and Learn" lecture, please contact Kelly Walker at303-678-8844. Additionally, AMVS and Canine Rehabilitation andConditioning Group (CRCG) are hosting a special event for owners and their dogs. The event will include lectures by staff at CRCG and AMVS as well as a one-hour "Open Swim" session for canines and a complimentary consultation with one of the presenters. Topics will include Rehabilitation and Prevention of

In This Issue

What's New at AMVS

Diabetic Emergencies and

Complications

Archives of our past newsletters

containing timely and useful medical information are on

our website.

In addition to our regular ER hours,

AMVS is providing emergency and

critical care services

to your patients:

of 6News from Aspen Meadow Veterinary Specialists

3/25/2011https://ui.constantcontact.com/visualeditor/visual_editor_preview.jsp?agent.uid=11048726...

Neurologic Issues and Common Neurologic Conditions in Sporting Breeds. The event will be held at the Broomfield CRCG location(8855 W. 116th Circle, Broomfield, CO 80021) onWednesday, March 30 from 6-9 p.m. Please R.S.V.P. by Tuesday, March 29 to 303-762-7946 or [email protected].

Diabetic Emergencies and Complications -Diabetic Ketoacidosis (DKA)By Dr. Laura Higgins, Emergency Veterinarian

Practice points for your next case:

1. Documenting metabolic acidosis is a key distinction for the diagnosis of DKA.

2. It is critical to work-up and evaluate a possible DKA patient for coexisting disease as approximately 70% of dogs and 90% of cats have concurrent disease at the time DKA is diagnosed.

3. Urinalysis alone cannot rule-out a bacterial UTI in DKA patients due to dilution and immune suppression resultingin false negatives.

4. Ketones can be falsely negative on urinalysis given thatdipsticks do not detect beta-hydroxybutyrate, thedominant ketone body produced in DKA.

5. Fluid therapy is the foundation of treatment of DKA and 0.9% NaCl is the fluid of choice.

Last spring we began a discussion of three complications seen in diabetic cats and dogs - Hypoglycemic crisis, Non-Ketotic Hyperglycemic Hyperosmolar Syndrome, and Diabetic Ketoacidosis. Previous issues of Veterinary Voice have addressed Hypoglycemic Crisis and Non-Ketotic Hyperglycemic Hyperosmolar Syndrome - this month we are going to focus on Diabetic Ketoacidosis (DKA).

DKA is characterized by metabolic acidosis due to the overproduction of ketones, following a lack of availableintracellular glucose. Intra-cellular glucose may not be available either due to low insulin levels, or insulin resistance. Concurrent disease is almost always a factor of DKA because stress hormones such as cortisol,

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303-678-8844

AMVS is:

PACE certified,LEED certified,

anda zero-waste

facility.



epinephrine, and growthhormone are counter-regulatory, contributing toinsulin resistance. In addition, stress hormonesworsen hyperglycemia and ketosis by stimulatinglipolysis and gluconeogenesis. In a DKA patient, the resultant glucosuria will cause osmotic diuresis, leading to fluid and electrolyte lossthrough the loop of Henle. Consequently prerenalazotemia and dehydration lead to hypoperfusion oftissues including the kidneys (decreased GFR), often made worse by vomiting and/or diarrhea. Decreased GFR will worsen acidosis due to inadequate excretion of H+ ions by the kidneys.

Hyperglycemia, glucosuria, ketonuria, and acidemia are the four hallmarks of DKA. Diabetic patients can have an excess of ketones in their system (ketosis), without thepresence of acidosis and are not clinically ill. This syndrome is referred to as "healthy" diabetic ketosis and does require evaluation by a veterinarian as it indicates unregulated DM, however it is not responsible for the illness described in this article. Documenting acidemia is a key distinction for the diagnosis of DKA. A blood gas analysis to assess blood pH is most accurate on an arterial sample. However, a venous sample is also valuable, especially for determining trends during treatment. If a blood gas analyzer is unavailable, treating for DKA isrecommended based on the presence of consistentphysical exam findings and history, in the presence of hyperglycemia, glucosuria, and ketonuria. Ketones are infrequently negative on urinalysis given that dipsticks do not detect beta-hydroxybutyrate, the dominant ketone body produced in DKA.

Both undiagnosed diabetics and those currently being treated for DM are at risk of developing DKA, however this syndrome is most often seen in undiagnosed diabetics and may be the pet's first manifestation of DM. Typicalcomplaints for patients experiencing DKA are nonspecific and include pu/pd, lethargy, anorexia, vomiting. Although any age, sex, or breed can develop DKA, it is most commonly a disease of middle-aged to older dogs and cats. Female dogs and male cats appear to be more commonly affected than their counterparts.



It is critical to work-up and

evaluate a possible DKA patient for coexisting disease as approximately 70% of dogs and 90% of cats have concurrent disease at the time DKA is diagnosed. The mostcommon culprits in dogs are pancreatitis, bacterial urinary tract infections, and Cushing's disease. In cats, hepatic lipidosis, chronic renal failure, pancreatitis, bacterial and viral infections including FIV/FeLV, and neoplasia areimplicated. For these reasons, complete bloodwork,urinalysis, urine culture, endocrine testing, and, ideally, imaging studies such as ultrasound should be considered in a patient's work-up.

Urinalysis alone cannot rule-out a bacterial UTI in DKA patients due to dilution and immune suppression resulting in a falsely negative urinalysis. In one study, 20% of dogs with DKA had a negative urinalysis, but a positive aerobicbacterial urine culture. Azotemia is a common finding in DKA patients, therefore a USG is important to distinguish between renal and prerenal causes. A USG less than 1.020 in the presence of dehydration indicates primary orconcurrent renal disease that should be further evaluated by imaging and a urine culture. Keep in mind glucosuria will increase the USG measured by refractometers.

Common lab abnormalities include hyperglycemia (BG typically around 500 mg/dl), hyponatremia, hypokalemia, azotemia, elevated liver enzymes and/or total bilirubin(either due to hypovolemia or a symptom of concurrent disease), and elevated cholesterol and triglycerides. Nonregenerative anemia is reported in approximately 50% of dogs. Stress leukograms are also frequent. Concurrent illness such as inflammatory, infectious, or neoplastic processes should be considered in patients with a WBC count of greater than 30,000 and evidence of toxic ordegenerative neutrophils.

Both phosphorus and potassium may be normal on initial evaluation, however shifts in the intra and extra cellularfluid can result in profound hypophosphatemia andhypokalemia during treatment. Therefore it is important to monitor these values carefully and supplement as necessary. Magnesium levels are not often measured,



however cats with DKA are at risk of hypomagnesemia and dogs are at risk of hypermagnesemia. It is unclear how these patients are affected clinically, and treatment should only be considered only if it's thought a low ionized Mg is resulting in cardiac arrhythmias, muscle tremors, or refractory hypokalemia.

Fluid therapy is the foundation for treatment of DKA. It is important that IV fluid therapy be given over time, with careful monitoring as rapid changes in blood glucose and electrolytes can result in worsening clinical outcome. The fluid of choice for stabilization of DKA patients is 0.9% NaCl. Once hyponatremia is corrected, switching to LRS or Normosol-R should be considered. It is recommended to monitor hydration, BG, and electrolyte status frequently in order to tailor therapy. Bicarbonate therapy for treatment of acidosis is controversial and often not necessary as fluid therapy alone will normally correct acidosis. If there is evidence of CNS depression secondary to severe metabolic acidosis (bicarbonate values of less than approximately 10mEq/L), ¼ to ½ of the calculated bicarbonate deficit may be given over a six-hour period.

While treatment ofunderlying disease and fluid therapy alone may correct hyperglycemia, insulin therapy based on BG monitoring is important. Two methods of insulintherapy are the IM technique and the CRI technique, which is the preferred method for treatment of DKA at AMVS. For both techniques, BG

is measured every one to two hours and an adjusted dose of regular insulin is given IM, or the regular insulin CRI titrated accordingly. While these patients are being regulated and monitored carefully in hospital, the BG will shift rapidly, requiring dextrose supplementation as needed. We use an insulin CRI and fluid therapyadministration chart to allow the technicians to adjust the insulin and dextrose supplementation as needed. We would be happy to discuss this charting system with you should you wish to use something similar in your own clinic. Guidelines for administration of an insulin CRI, as well aspotassium supplementation, are readily available in most books with chapters covering DKA.

With fairly aggressive treatment, it is reported that 70% of dogs and cats with DKA survived to discharge. However, one study showed the concurrent diagnosis of Cushings,



and the degree of acidosis both to be associated with apoor outcome. Owners should also be warned this disease may recur, most often in cats (40%) and less so in dogs (7%). Though the pathophysiology of DKA is complicated and results in severe metabolic derangements, treatment and monitoring is relatively simple and often results in a good outcome.

Thank you for your continued support. -Aspen Meadow Veterinary Specialists

104 S. Main StreetLongmont, CO 80501303-678-8844 (p)303-678-8855 (f)

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march 2011, issue 29 - aspen meadow...diabetic ketoacidosis (dka) by dr. laura higgins, emergency...

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