Page 871 - Small Animal Internal Medicine, 6th Edition

CHAPTER 49 Disorders of the Endocrine Pancreas 843

BOX 49.12 hours while supplying maintenance fluid needs and match-
ing ongoing losses. Rapid replacement of fluids is rarely indi-
VetBooks.ir Common Clinicopathologic Abnormalities Identified in cated unless the dog or cat is in shock. Once the animal is
out of this critical phase, fluid replacement should be
Dogs and Cats With Diabetic Ketoacidosis
Neutrophilic leukocytosis, signs of toxicity if septic decreased in an effort to correct the fluid imbalance in a slow
but steady manner. As a general rule of thumb, a fluid rate
Hemoconcentration of 1.5 to 2 times maintenance (i.e., 60-100 mL/kg q24h) is
Hyperglycemia typically chosen initially, with subsequent adjustments based
Hypercholesterolemia, lipemia
Increased alkaline phosphatase activity on frequent assessment of hydration status, urine output,
Increased alanine aminotransferase activity severity of azotemia, and persistence of vomiting and
Increased blood urea nitrogen and serum creatinine diarrhea.
concentrations
Hyponatremia Potassium Supplementation
Hypochloremia Most dogs and cats with DKA initially have normal or
Hypokalemia decreased serum potassium concentrations. During therapy
Metabolic acidosis (decreased total carbon dioxide for DKA the serum potassium concentration decreases
concentration) because of rehydration (dilution), insulin-mediated cellular
Hyperosmolality uptake of potassium (with glucose), continued urinary
Glycosuria losses, and correction of acidemia (translocation of potas-
Ketonuria
Urinary tract infection sium into the intracellular fluid compartment; Fig. 49.18).
Severe hypokalemia is the most common complication that
develops during the initial 24 hours of treatment of DKA.
Dogs and cats with hypokalemia require aggressive potas-
deficiencies in total body sodium and potassium, dampen sium replacement therapy to replace deficits and to prevent
the potassium-lowering effect of insulin treatment, and worsening, life-threatening hypokalemia after initiation of
lower the blood glucose concentration in diabetic individu- insulin therapy. The exception to potassium supplementa-
als, even in the absence of insulin administration. Unfortu- tion of fluids is hyperkalemia associated with oliguric kidney
nately, fluid therapy alone does not suppress ketogenesis. For failure. Potassium supplementation should initially be with-
this reason, insulin is always required. held in these dogs and cats until glomerular filtration is
The type of parenteral fluid used initially will depend on restored, urine production increases, and hyperkalemia is
the animal’s electrolyte status, blood glucose concentration, resolving.
and osmolality. Most sick dogs and cats with DKA have Ideally, the amount of potassium required should be
severe deficits in total body sodium, regardless of the mea- based on actual measurement of the serum potassium con-
sured serum concentration. Ringer’s solution or Plasma-Lyte centration. If an accurate measurement of serum potassium
148 (Baxter Healthcare Corp.) can be used for mild hypona- is not available, potassium should be added to the liter of
tremia (serum sodium concentration of more than fluids to bring the potassium concentration to 40 mEq/L. For
130 mEq/L) and 0.9% (physiologic) saline for more severe example, 0.9% saline solution does not contain potassium,
hyponatremia (serum sodium concentration of less than and Ringer’s solution contains 4 mEq of potassium per liter,
130 mEq/L) with appropriate potassium supplementation. thus these fluids should be supplemented with 40 mEq and
Alternative isotonic crystalloid solutions that could be used 36 mEq of potassium, respectively. Subsequent adjustments
include Ringer’s lactated solution and Normosol-R® (Abbott in potassium supplementation should be based on measure-
Laboratories). Each of these solutions has a slightly different ment of serum potassium, preferably every 4 to 8 hours until
electrolyte composition; none contain as much sodium as the dog or cat is stable and serum electrolytes are in the refer-
0.9% saline (see Tables 53.1 and 53.2). Most dogs and cats ence range.
with severe DKA are sodium depleted and therefore not suf-
fering from dramatic hyperosmolality. Hypotonic fluids (e.g., Phosphate Supplementation
0.45% saline) are rarely indicated in dogs and cats with DKA, Most dogs and cats with DKA have normal or decreased
even when severe hyperosmolality is present. Hypotonic serum phosphorus concentrations on pretreatment testing.
fluids do not provide adequate amounts of sodium to correct Within 24 hours of initiation of treatment for DKA, serum
the sodium deficiency, restore normal fluid balance, or sta- phosphorus concentration can decline to severe levels (i.e.,
bilize blood pressure. Rapid administration of hypotonic <1 mg/dL) as a result of the dilutional effects of fluid therapy,
fluids can cause a rapid decrease in the osmolality of extra- the intracellular shift of phosphorus following the initiation
cellular fluid (ECF), which may result in cerebral edema, of insulin therapy, and continuing renal and gastrointestinal
deterioration in mentation, and eventually coma. Hyperos- loss (see Fig. 49.18). Hypophosphatemia primarily affects the
molality is best treated with isotonic fluids and the judicious hematologic and neuromuscular systems in dogs and cats.
administration of insulin. Fluid administration should be Hemolytic anemia is the most common problem and can be
directed at gradually replacing hydration deficits over 24 life-threatening if not recognized and treated. Weakness,