This month’s survey question

Thank you for responding to our Fluid Therapy survey! Here are the results:

The Benefit of Bicarbonate

The results of our survey indicate that more than a third of our respondents place a greater emphasis on bicarbonate than on phosphorus, magnesium, calcium and glucose levels when making fluid therapy decisions. Sodium, potassium, chloride and bicarbonate are the four most important electrolytes used in an initial assessment of a patient’s health status and for monitoring the effectiveness of ongoing treatment.

Bicarbonate is the primary buffer system of extracellular fluid, helping to keep the blood from becoming overly acidic—thus maintaining a neutral pH. Abnormal bicarbonate levels may be an indicator of such as pulmonary or renal disease, lactic acidosis, diabetic ketoacidosis, dehydration and ethylene glycol toxicity.

Both the Fluid Therapy/Acid-Base and the Respiratory/Blood Gases cassettes of the IDEXX VetStat® Electrolyte and Blood Gas Analyzer report bicarbonate information in-house in minutes. The VetStat Analyzer allows you to quickly make the most appropriate fluid therapy choice and begin treatment immediately.

Featured case study:
Ten-year-old spayed female domestic shorthair cat, Missy
by John Christian, DVM, PhD, Associate Professor of Veterinary Clinical Pathology, Purdue University School of Veterinary Medicine, and Dennis B. DeNicola, DVM, PhD, DACVP, Adjunct Professor of Veterinary Clinical Pathology, Purdue University School of Veterinary Medicine and Chief Veterinary Educator, IDEXX Laboratories, Inc.

Detailed history
Missy presented to the primary veterinarian because of recent vomiting. She had lost a lot of weight over the last few weeks and was eating less and less until she became completely anorectic. Missy stopped eating soon after a recent change in diet. There is a dog and another cat in the household and the two cats compete for food. Missy is several years overdue on immunizations.

Physical exam
Missy was thin but bright, alert and responsive.
Weight = 8.5 lb (12 lb three months previously)
T = 101.3°F
P = 180
R = 40
Conjunctiva = icteric

Referring veterinarian laboratory data
Laboratory data from a commercial reference laboratory submitted for evaluation on the day of presentation revealed a markedly increased alkaline phosphatase, a moderate increase in alanine aminotransferases as well as increased total and direct bilirubin.

Differential diagnoses
With the clinical presentation and laboratory data collected at initial presentation, the referring veterinarian suspected hepatic disease with hepatic lipidosis highest in the differential list. Potential biliary involvement was of concern also. Both primary and secondary hepatic disease, including metabolic, inflammatory (infectious and noninfectious) and neoplastic disease, would all have to be considered.

Plan
Because the clinical picture was relatively severe and no additional laboratory data was generated since the initial presentation at the referring veterinary hospital, re-evaluation of a complete blood count (CBC), clinical chemistry profile and urinalysis was deemed essential to characterize the severity of the disease as well as to investigate if any other organ system was involved beyond the liver.

Laboratory data

Morphology comments: Adequate platelets, polychromasia noted, Heinz bodies 1+, microcytes noted, few keratocytes, pincer cells and schistocytes, moderate icterus noted.

Figure 1: 100x oil objective field of view of the monolayer of the blood film, Wright’s stain. Note the mildly decreased erythrocyte density supporting the finding of mild anemia, the presence of easily identified polychromasia supporting a regenerative anemia, the single Howell-Jolly body (center left), the microcytes and the increased amount of central pallor compared to normal feline erythrocytes. Several poorly defined Heinz bodies and one pincer cell (top left) are present also.

Figure 2: 100x oil objective field of view of the monolayer of the blood film, Wright’s stain. Note the multiple Heinz bodies (black arrowheads), the tiny microcyte (black arrow) and the keratocyte (red arrow).

Figure 3: 100x oil objective field of view of the monolayer of the blood film, new methylene blue stain. Note the multiple Heinz bodies (black arrows), the aggregate reticulocytes (black arrowheads) and the punctuated reticulocyte (red arrowhead).

Erythron—There is a mild normocytic, normochromic anemia with polychromasia, Heinz bodies and microcytes noted. Besides Heinz bodies, the presence of pincer cells and keratocytes also support oxidant injury. TThe decreased hematocrit in the face of the findings of within reference values for hemoglobin and RBC is explained by the low normal MCV and observation of microcytes. The latter findings are in contradiction to the polychromasia noted and the mild reticulocytosis supporting a regenerative anemia. One typically anticipates the MCV to be in the upper reference interval or increased, and a decreasing MCHC in a classic regenerative profile; however, the microcytes in this case are bringing the MCV down. Although normal numbers of RBC are present, their tendency towards small size results in a low RBC mass (HCT). The absolute reticulocyte count proves essential in objectively characterizing this as a regenerative anemia. The morphologic changes suggest that the oxidant injury is directly related to the anemia in this case.

Leukon—There is a normal leukocyte count characterized by a mild neutrophilia with a lymphopenia. This is most consistent with a stress (glucocorticoid response) leukogram.

Thrombon—Normal.

Hepatobiliary profile—There is evidence for moderate hepatocellular injury (ALT) and cholestasis (ALP, GGT, conjugated bilirubin and urine bilirubin). The mixed bilirubin profile with a predominance of conjugated bilirubin, although subject to numerous explanations, is most consistent with intrahepatic cholestasis or a long-standing posthepatic cholestasis. The bilirubin profile reported separates the conjugated form of bilirubin into protein-free (conjugated bilirubin) and protein-bound (delta bilirubin); the presence of detectable protein-free bilirubin in the serum/plasma is highly supportive of current cholestasis. Importantly, the possibility of hepatic lipidosis should be considered strongly given the characteristic large elevation in ALP relative to GGT [Figure 4]. No significant evidence for decreased hepatic functional mass is present.

Kidney panel—The BUN, creatinine and urine SG are within normal limits. The 1.022 SG in a cat is relatively low and could suggest diuresis. The urinalysis reveals a neutral pH (see acid-base profile), 2+ proteinuria associated with the presence of 1+ occult blood, mild pyuria, bacteruria and granular casts. These changes support a urinary tract infection with associated mild hematuria, proteinuria and renal tubular degeneration. The concurrent presence of glucosuria and ketonuria indicates diabetes mellitus (see pancreas profile). Bilirubinuria in cats is consistent with cholestasis (see hepatobiliary profile).

Pancreas (exocrine/endocrine) profile—The concurrent presence of hyperglycemia, glucosuria and ketonuria, barring iatrogenic hyperglycemia, is diagnostic for diabetes mellitus (i.e., lipids are being metabolized for energy in the face of hyperglycemia). The approximately threefold increase in lipase indicates concurrent pancreatitis. Lipase in the cat is reported to be poorly sensitive (many cases of pancreatitis in the cat with no increase in lipase activity); however, when increased, lipase proves to be highly specific for active pancreatitis.

Electrolyte profile—The decreases in serum sodium, chloride and potassium are best explained in this case by osmotic diuresis. The decreases in sodium and chloride are proportional to one another suggesting loss with total water loss. The presence of hypokalemia in an unregulated diabetic cat is a potentially critical finding since insulin administration will drive potassium intracellularly and may exacerbate the hypokalemia into a life-threatening crisis [Figures 1 and 2]. Similarly, phosphorus in the low reference range is of concern since it is also driven intracellularly with insulin administration, potentially leading to a hemolytic crisis [Figure 3].

Acid-base profile—No specific abnormal patterns are observed even in the presence of ketonuria. Since small molecular weight ketone bodies are freely filtered by the kidney, ketonuria generally precedes significant ketonemia or acid-base abnormalities (e.g., titrational metabolic alkalosis).

Interpretations

1. Diabetes mellitus with probable pancreatitis.
2. Hepatocellular injury and cholestasis. Hepatic lipidosis should be considered strongly.
3. Generalized electrolyte depletion, probably secondary to osmotic diuresis. Special attention should be given to the hypokalemia and low normal phosphorus in light of impending insulin therapy [Figure 2].
4. Urinary tract infection (with associated pyuria, hematuria and proteinuria) with tubular degeneration.
5. Stress leukogram.
6. Mild regenerative anemia most likely associated with oxidant injury.

Additional tests to be considered

1. Imaging and fPLI to help confirm pancreatitis.
2. Aspiration cytology/biopsy of liver to confirm lipidosis.
3. Electrolyte therapy should be monitored serially in conjunction with insulin therapy.
4. Urine culture and imaging (to aid localizing and characterizing renal involvement).
5. Serial CBC to monitor anemia.

Further diagnostics

Diagnostic cytology—Fine-needle aspirates of the diffusely enlarged liver were collected for microscopic evaluation. The samples were highly cellular and primarily contained blood and many hepatocytes present individually and in cohesive clusters of varying size. Cytoplasm was abundant and contained variably sized clear vacuoles consistent with lipid accumulation. Dark brown-black pigment material consistent with bile pigment is found between hepatocytes (within bile cannaliculi) and intracytoplasmically within occasionally seen hepatocytes. Increased numbers of mature nondegenerate neutrophils and low numbers of normal-appearing small lymphocytes were present also; no associated infectious agents were seen or suggested.

Liver—Moderate vacuolar hepatopathy consistent with lipid accumulation. Changes are consistent with hepatic lipidosis. Mild neutrophilic inflammation is suggested also.

Figure 4: 50x oil objective field of view of fine-needle aspirate of liver, Wright’s stain. Note the multiple discrete clear cytoplasmic vacuoles within the cluster of hepatocytes (top left), cell-free lipid material and moderate numbers of neutrophils and erythrocytes.

Figure 5: 50x oil objective field of view of fine-needle aspirate of liver, Wright’s stain. Note the many vacuolated hepatocytes and the dark brown-black bile pigment material trapped between individual hepatocytes.

Clinical case outcome
The owners of Missy were informed of the severity of the disease process and were advised to pursue aggressive treatment immediately. Due to financial concerns and the projected length of hospitalization, the owners elected euthanasia.

References

1. Bruskiewicz KA, Nelson RW, Feldman EC, Griffey SM. Diabetic ketosis and ketoacidosis in cats: 42 cases (1980–1995). J Am Vet Med Assoc. 1997;211:188.
2. Greco D. Endocrine emergencies. Part 1. Endocrine pancreatic disorders. Compend Contin Educ Pract Vet. 1997;19:15.
3. Adams LG, Hardy RM, Weiss DJ, Bartges JW. Hypophosphatemia and hemolytic anemia associated with diabetes mellitus and hepatic lipidosis in cats. Journal of Veterinary Internal Medicine. 1993;7:266.
4. Center SA, Baldwin BH, Dillingham S, Erb HN, Tennant BC. Diagnostic value of serum glutamyl transferase and alkaline phosphatase activities in hepatobiliary disease in the cat. J Am Vet Med Assoc. 1986;188:507.

The recommendations contained in Diagnostic Edge educational materials are intended to provide general guidance only. As with any diagnosis or treatment, you should use clinical discretion with each patient based on a complete evaluation of the patient, including history, physical presentation and complete laboratory data. With respect to any drug therapy or monitoring program, you should refer to product inserts for a complete description of dosages, indications, interactions and cautions.

Tell us what you think of this case, or let us know if you have a case that you would like to submit. E-mail us at diagnosticedge@idexx.com to get the process started.

IDEXX Learning Center

The IDEXX Learning Center provides knowledge you can put into practice. Take part in the evolution of animal diagnostics through an ongoing educational partnership with leading veterinarians from across the globe and take advantage of a wide range of education resources, reference materials and events. Visit the IDEXX Learning Center to see a full listing of available Webinars, seminars and online training courses from IDEXX.

Here are some of the opportunities available this month:

New course! Canine Pancreatitis: Diagnosis and Management With this free online course, veterinarians and technicians will: Identify and understand the presenting signs and risk factors associated with canine pancreatitis. Understand the differences between acute and chronic pancreatitis. Explore the benefits and limitations of the current diagnostic options. Participate in a discussion on common treatment options. Take the course!

Webinar Safe Start: The Value and Importance of Preanesthetic Testing Ernie Ward, DVM

	Seminars Canine Pancreatitis: Diagnosis and Management Robert M. DuFort, DVM, DACVIM The Most Commonly Misdiagnosed Diseases in Veterinary Medicine Fred Metzger, DVM, DABVP
The North American Veterinary Conference (NAVC) Orlando, Florida, January 19–23, 2008
Real-Time PCR: Solutions for Routine Diagnostic Challenges Christian Leutenegger, DrVetMed, PhD, FVH Jane Robertson, DVM, DACVIM A Clinical Approach to Fluid Therapy Stephen P. DiBartola, DVM, DACVIM Three Steps to a Healthy and Profitable Practice Ernie Ward, DVM The Most Commonly Misdiagnosed Diseases Fred Metzger, DVM, DABVP Move Over, Rover—Heartworm Is No Longer Just a Dog Disease Tom Nelson, DVM Changing our Ideas in the Diagnosis and Treatment of Pancreatitis David Twedt, DVM, DACVIM A Case-Based Approach to Emerging Tick-Borne Diseases Michael Dryden, DVM, PhD; Matt Eberts, DVM To register, and for times and locations, please visit: www.idexxlearningcenter.com
Come see IDEXX at Booth 2207 and check out IDEXX’s newest innovations. See firsthand our newest analyzers, including the Catalyst Dx™ Chemistry Analyzer and the SNAPshot Dx™ Analyzer, and learn about the latest enhancements to the VetTest® Chemistry Analyzer. See other IDEXX innovations in this newsletter.

As always, IDEXX will be sponsoring educational events as well. Watch the mail for a schedule of IDEXX events and sign up early!

Spotlight on Dr. Katie Thompson of the Veterinary Center at Fishhawk in Lithia, Florida

Yes, she was our Suite Stories grand prize winner, and she couldn’t be happier about her new next-generation IDEXX VetLab® Suite! We talked with Dr. Katie Thompson again recently to learn more of her thoughts on in-house diagnostics.

Dr. Thompson has been practicing veterinary medicine since 1998 and in March 2007 she opened her own clinic in Lithia, a small community near Tampa, Florida. In just nine months, the clinic has exceeded 1,000 clients with almost 2,000 active patients. This community response has allowed the addition of an associate veterinarian to the staff, which also includes a full- and a part-time receptionist, an office manager and four (soon to be five!) full-time technicians.

When thinking about the role of veterinarians today, Dr. Thompson says, “Veterinarians are being forced to look hard at what services we’re providing. We need to offer more than the Internet and feed stores do. We need to start offering the diagnostics they can’t offer in order to be competitive. You can’t get a blood panel done on the Internet…that’s the kind of value veterinarians can offer.”

“I think what IDEXX has done is make diagnostics available to veterinarians that we didn’t really think about doing previously. If we did blood work, we sent it off and waited three days, and we didn’t even think about doing blood gas. I’m not a specialist, but there’s a lot I can do to lay the groundwork when referrals are necessary. You can really be part of a team.”

In-house diagnostics allow Dr. Thompson to provide her clients with quick answers. “They appreciate getting results back in a hurry. To be able to tell them in 15 minutes we’re going to have an answer, that’s huge. It’s so reassuring to them.” It’s also good business. “About 20 percent of our growth is in diagnostics. And it’s value added for the clients, too. I can feel better knowing I’ve done more for my patients.”

In perhaps her most compelling argument for in-house diagnostics, Dr. Thompson notes that when it comes to her clients and patients, “I want to make sure that whatever I do for them is what I’d do for my own dog. And I don’t want to sit around for two days waiting for my blood work to come back.”

Dr. Thompson admits that all the new technology can be intimidating. But she feels that putting years of experience together with these technologies creates “a great marriage. You’ve got your experience that tells you a lot and you can then confirm with in-house blood work…that’s a fabulous combination.”

Dr. Thompson summed it up this way: “In-house diagnostics have revolutionized the way I practice. I would never go back.”

See Dr. Katie Thompson’s winning Suite Story >
Find out more about the next-generation IDEXX VetLab Suite >

Chemistry • Hematology • Urinalysis • Electrolytes • Endocrinology • Coagulation • Blood Gas

IDEXX is dedicated to investing in research and development in order to offer veterinarians innovative tools and technologies that continue to improve your ability to provide patients with the highest level of care. Some of our most recent offerings from the past year include:

IDEXX VETLAB® INNOVATIONS

Catalyst Dx™ Chemistry Analyzer—Coming 2008

• Results in less time than it takes to prepare a sample to send out—Chem 22 in 8 minutes
• Run lab work immediately with preloaded CLIPs and onboard whole blood separation
• Multiple-patient load and go—4 Chem 10s in 18 minutes
• On board whole blood separation

SNAPshot Dx™ Analyzer—Coming 2008

• Immediate results to manage common diseases
• Run multiple patients at the same time
• Trusted SNAP® ELISA technology

Coag Dx™ Analyzer

• Immediate coagulation information
• Four veterinary-specific cartridges
• Fresh or citrated whole blood for PT and aPTT results

New for the VetStat® Electrolyte and Blood Gas Analyzer

• Multipack contains six each of the most used cassettes

New for the VetTest® Chemistry Analyzer

• New pipette tips for better sample flow
• Easy-open slides and no slide warm-up
• VetTest® Certificate Course at www.idexxlearningcenter.com at no cost!
• Avian profile, Diagnostic Health Profile and NSAID Panel

New for the IDEXX VetLab® Results Report with IDEXX VetLab® Station

• Fully integrated report shows results of all analyzers plus SNAP® test results
• Prior results column for easy comparison
• Reference ranges printed on report, including T₄
• Quicker identification of organ-specific abnormalities

IDEXX REFERENCE LABORATORY INNOVATIONS

• IDEXX RealPCR™ offers definitive answers through accurate, fast real–time PCR

IDEXX SNAP® INNOVATIONS

• SNAP® cPL™ (canine pancreas-specific lipase) Test provides immediate answers pet-side for canine pancreatitis
• SNAP® 4Dx Test supports pet owner education for heartworm and tick-borne disease prevention by screening for heartworm disease and three different tick-borne diseases

IDEXX DIGITAL INNOVATIONS

• IDEXX-PACS™ 3.0 software will increase your digital imaging diagnostic capabilities

IDEXX EQUINE INNOVATIONS

• IDEXX EquiView® All-Terrain Grade Digital Radiography System
• New equine specialty tests from IDEXX/EBI®
• Equine Herpesvirus I
• West Nile Virus
• Lyme disease and Anaplasma phagocytophilum

IDEXX CORNERSTONE® INNOVATIONS

• In-house/reference lab requests, results and trending data automatically downloaded to patient records
• Order, track and record patient treatments more efficiently with an integrated electronic whiteboard
• New inventory management capabilities with advanced bar-coding functionality
• LabREXX® test order forms ensure test orders are accurate

INTEGRATED PRACTICE

• Enabled by SmartLink™ technology, the IDEXX Integrated Practice links and automates equipment, services and data for exceptional levels of medical care, productivity and profitability
• Maximize patient care
• Capture missed charges
• Automate and simplify
• Empower staff

IDEXX LEARNING CENTER

• Online Courses—Individual, self-paced courses that you can take anytime, anywhere
• Webinars—Online group learning events that you join at a set time
• Local Seminars—Group learning events at a set time and place
• Conference Education—Breakout sessions at local and national veterinary conferences
   

Announcing the latest addition to the IDEXX VetLab® Suite!
The IDEXX Coag Dx™ Analyzer

The new IDEXX Coag Dx Analyzer provides fast and sensitive in-house diagnostic testing for coagulation disorders in animals. Abnormalities in intrinsic, extrinsic and common pathways can be detected in seconds by running the PT and aPTT tests on fresh or citrated whole blood.

Bleeding patients • Critical care management • Surgery cases

Screening at-risk animals for clotting problems before a surgical procedure helps avoid bleeding complications during or afterward, when corrective measures can be extremely difficult.

Visit our Web site for more information on the IDEXX Coag Dx Analyzer or the IDEXX VetLab Suite.

With FREE Continuing Education Credit!*

NOW Approved in the United States, Australia and parts of Canada!†

Have you taken advantage of every qualifying Interactive Challenge for FREE Continuing Education (CE) credits?

Every Interactive Challenge from June 2006 on has each been worth 0.5 continuing education credit in the United States—and you get the credit just for participating! Check out the Diagnostic Edge archive and take any qualifying challenges you may have missed. Don’t let these fun credits slip away!

Questions:

1. Which of the following is the BEST interpretation for the oval nuclei indicated with arrowheads in figures 1 and 2?

1. Cell-free nuclei from broken cells
2. Endothelial cells from capillaries in the sample
3. Connective tissue elements, such as fibrocytes
4. Discrete round cells distorted during slide preparation

2. Assuming these images are representative of the sample in question, which of the following is the BEST interpretation for this sample?

1. Nondiagnostic due to overall low cellularity
2. Benign mesenchymal tissue proliferation—fibrosis
3. Malignant mesenchymal tissue proliferation—sarcoma
4. Round cell neoplasia consistent with histiocytic neoplasia

Figure 1.	Aspirate of a skin mass on the leg of a dog, Wright’s stain, 50x objective field of view.
Figure 2.	Aspirate of a skin mass on the leg of a dog, Wright’s stain, 50x objective field of view.

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*Each interactive challenge meets the requirements for 0.5 hour of continuing education credit in jurisdictions that recognize AAVSB’s RACE approval, however, participants should be aware that some boards have limitations on the number of hours accepted in certain categories and/or restrictions on certain methods of delivery of continuing education.

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^†Interactive challenges are also approved in Australia for 0.5 AVA Vet Ed Point and from the following Canadian Veterinary Medical Associations: Alberta, Saskatchewan, New Brunswick and Prince Edward Island.

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