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May 2007 Issue
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This month's survey question:
In response to the pet food recall, how are you screening for renal disease?
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April survey results! What you told us about the occurence of tick-borne diseases in your practice. Also find a resource to help with your parasitic testing needs.
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Featured Case Study:
10-month-old spayed female Labrador retriever, Terra: Terra has been progressively lethargic and has had soft, dark stools over the past week. By Dr. Dennis B. DeNicola
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Pet Food Recall—Monitoring guidelines, answers to frequently asked questions and more.
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NEW! Practice Developer® calculator—Now there's a convenient way to tally your Practice Developer points. |
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Training and Events—Webinars, seminars and online training, including Feline Health Champion Course Two and VetTest® Certificate Course
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From Our Readers
He swallowed WHAT? What’s the strangest thing you’ve ever found in one of your patients? Send us an X ray and we’ll share it with your colleagues!
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Research Corner
Long-Term Drug Study—Uncovers 35% Abnormal Test Results by Ernest E. Ward, Jr., DVM—Monitoring patients on long-term drug therapy is not only important, it may also be critical in some cases.
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Interactive Challenge: Now earn FREE continuing education credit in Australia and parts of Canada! Test your knowledge by identifying nucleated cells and a common condition in a peripheral blood film from a cat with respiratory difficulty.
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Thank you for responding to our April survey! Here are the results:
 Tick Talk
Our survey indicates that tick prevalence is growing—and a growing concern!
Of 307 respondents, 57% of you are expecting to see an increase in the incidences of tick-borne diseases in the coming year. How will your practice prepare for an increase in testing symptomatic and screening nonclinical cases of Lyme disease, ehrlichiosis and anaplasmosis?
IDEXX offers the SNAP® 4Dx® Test, a simple, quick and accurate method for determining the presence of all three of these tick-borne diseases plus mosquito-borne heartworm.
Visit our site to see an interactive incidence map of your area, more information on these four parasitic diseases and more about the SNAP® 4Dx® test.
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Featured case study:
10-month-old spayed female Labrador retriever, Terra
by Dennis B. DeNicola, DVM, PhD, DACVP, Chief Veterinary Educator, IDEXX Laboratories, Inc.
Physical exam
Quiet, alert, responsive. Mucous membranes pale pink and moist, CRT 2 seconds, normal hydration. Temperature and RR WNL, HR 150, lungs auscult normally. Tenses slightly with abdominal palpitation; fecal staining around anus. Rectal examination revealed black, tarry feces with specks of fresh blood.
Diagnostic plan
Comprehensive CBC, chemistry panel, UA, fecal floatation, abdominal radiographs
Hematology
Hemogram—Severe macrocytic, normochromic anemia with marked polychromasia and moderate anisocytosis. Reticulocyte panel revealed moderate to marked regeneration. Marked polychromasia, moderate anisocytosis and macrocytosis are consistent with regeneration.
Leukogram—Mature neutrophilia, eosinophilia and basophilia. Neutrophilia typically seen with infectious or inflammatory processes. Eosinophilia and basophilia may be due to hypersensitivity reactions, parasitic diseases or mast cell disease, among other causes.
Platelet Evaluation—Normal
Chemistry
Panhypoproteinemia secondary to loss of globulins and albumin through gastrointestinal tract can result from a protein-losing enteropathy (e.g., inflammatory bowel disease, neoplasia), or from gastrointestinal hemorrhage. Markedly elevated BUN with concurrent normal creatinine (resulting in significantly elevated
B/C ratio), especially with well-concentrated urine, suggested gastrointestinal bleeding.
Urinalysis
Concentrated urine (specific gravity 1.042), no abnormalities noted on chemistry strip or microscopic examination of urine sediment.
Additional diagnostics
Fecal flotation by centrifugation—hookworm ova present
Abdnominal radiographs—Fecal material noted in intestinal tract and colon; no abnormal gas patterns. Other abdominal structures WNL.
Assessment
The two main causes of regenerative anemia are blood loss and hemolysis. Terra’s black, tarry stools and clinicopathologic abnormalities were consistent with gastrointestinal bleeding. Hookworm infection can be severe enough to cause anemia, even in medium- to large-size dogs.
Diagnosis
Hookworm infection resulting in severe gastrointestinal blood loss.
Treatment
Fenbendazole (Panacur®) 50 mg/kg po SID for five days.
Clinic case outcome
Terra was placed on a highly digestible diet and treated for hookworm infection. After receiving Fenbendazole, the first bowel movement she passed was teeming with hookworms. Terra regained normal activity level, and the color and consistency of her stools returned to normal within three to four days. Her owner was educated about the risks of potential infection (particularly with parasitic and protozoal organisms) from visiting dog parks and environmental decontamination of their yard was discussed. A fecal sample for a recheck examination was to be dropped off in one month. In compliance with Companion Animal Parasite Council guidelines, it was also recommended that Terra be placed on a year-round heartworm/anthelmintic preventive and routine fecal analysis by an ultracentrifugation flotation technique be performed once to twice yearly.
Case comments
Terra’s veterinarian could quickly identify hookworm infection as the cause of the melena and regenerative anemia, allowing safe, effective and immediate treatment. Zinc sulfate centrifugation analysis of feces results in significantly greater numbers of Ancylostoma caninum (hookworm) eggs being identified
as compared to simple flotation techniques.
Fecal flotation by centrifugation diagnosed Terra’s serious and potentially life-threatening parasitic infection and prevented her veterinarian from performing additional expensive and potentially invasive diagnostics. Diagnosis of her hookworm infection also had human health implications as A. caninum can be zoonotic, causing cutaneous larval migrans.
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.
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Resources to help manage pet food recall cases
The massive pet food recall is affecting animals and practices across the United States and Canada. IDEXX is offering practical suggestions and information to help veterinary practices deal with an unprecedented number of clinically ill patients and concerned pet owners. This section contains some of the information provided in our new Pet Food Recall Web site, which includes monitoring guidelines, a list of recommended tests, additional resources and answers to frequently asked questions. Check back often as we will keep this site updated.
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Pet Food Recall Q & A
Question: What should I test in an exposed nonclinical dog or cat?
Answer: A complete urinalysis with detailed microscopic examination of the urine is critical. Melamine appears to be associated with the formation of distinctive crystals that may serve as a marker of potential renal tubular injury. With significant loss of renal function, increases in creatinine, urea and phosphorus may be seen as well as electrolyte (Na, K, Cl, and tCO) disturbances with possible acid-base changes; therefore, these parameters should be evaluated.
Collection of a baseline data set of a complete blood count, a general clinical chemistry health profile and a complete urinalysis are recommended to enable following both clinically ill and healthy animals. This data can be used to monitor disease progression or as objective data points for early detection of future disease. Serial data evaluation provides a more sensitive indicator of disease status. This is especially important with renal disease, where enzyme changes are elevated outside of the reference range only with considerable loss of renal function. See the IDEXX letter to our veterinary customers.
 Question: What are your recommendations for testing clinical vs. nonclinical dogs and cats exposed to recalled food?
Answer: We are recommending the same testing regardless of clinical presentation. Since the clinical signs associated with renal disease are often subtle and usually seen only after significant renal function loss, testing is critical in all exposed pets. In the clinically ill pet we need to monitor disease progression (or regression) and in the clinically healthy patient we want to screen for any underlying or developing problem. Moreover, a complete data base allows you to screen for many disease states, not just renal disease—as well as establish a useful baseline for future testing. Until we know more about this problem, we cannot be sure that renal disease is the only disease state associated with the contaminated foods. See the IDEXX letter to our veterinary customers.
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Monitoring Guidelines
Help monitor your patients that may be affected by the recalled pet foods.
Category
of Disease |
Clinical Signs and Laboratory Results |
Recheck Guidelines |
| Apparently unaffected |
No clinical signs, initial screening labwork normal, urine is concentrated without crystals or casts |
Recheck bloodwork* and urinalysis 3–4 weeks after last possible exposure to recalled pet food |
| Possible subclinical disease |
No clinical signs, normal renal values, but unconcentrated urine (Specific gravity ≤ 1.030 in dogs,
≤ 1.035 in cats) |
Recheck bloodwork* and urinalysis in one week or sooner if clinical signs develop |
| Mild disease |
Mild azotemia, isosthenuria, casts, and/or crystalluria |
Treat and recheck bloodwork* and urinalysis in 2–3 days |
| Severe disease |
Moderate to severe azotemia and isosthenuria |
Treat aggressively and recheck bloodwork* and urinalysis in 2–3 days or sooner based on clinical progression |
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| Long-term follow-up for all patients |
All affected animals should have long-term monitoring of renal parameters, even if initial azotemia and signs resolve with therapy. This may include re-evaluation of bloodwork* and urine 2–4 weeks following initial hospitalization and then every 3–6 months; or more frequently depending on severity of initial disease and persistence of azotemia. |
Please note: These monitoring recommendations are meant as a guideline only. Clinical discretion should be used with each patient based upon complete evaluation of the patient, including history, physical examination and laboratory data.
Upcoming issues of the Diagnostic Edge® newsletter will include additional information on management and monitoring of dogs and cats exposed to a recalled food.
Analyte trending is an effective indicator of disease
 Monitoring analyte values over time is extremely under-utilized in veterinary medicine. Serially following changes in various chemistry profiles and hematologic measurements can prove to be extremely helpful to identify early developing disease, whether it be naturally occurring disease or potential disease induced by long-term medications. The reference intervals are quite broad for most analytes; however, individual animal analyte values typically are maintained within relatively tight ranges during periods of good health. Therefore, when slight changes are noted in an increasing or decreasing trend, this should prove effective in early detection of developing problems.
Yearly serial monitoring of creatinine values in a healthy animal is an excellent example of where trending can prove helpful. This parameter is a relatively constant predictor of renal glomerular filtration. Its concentration is based on both total muscle mass, which is relatively constant in most animals during health, and renal excretion capabilities, assuming that hydration status is relatively constant. Detecting slowly increasing creatinine concentrations year after year in a clinically healthy and normally hydrated animal is a great predictor of developing disease. Because creatinine values may not increase above the reference interval until there is loss of three-quarters of renal function, an isolated creatinine measurement is a relatively insensitive measure of renal function.
The attached graph of serial changes in creatinine concentration in a clinically normal cat demonstrates this point extremely well. The majority of the creatinine values are within the reference interval and individually would be of no concern, especially if there was evidence of concentrating ability based upon evaluation of urine specific gravity during the complete urinalysis each year. Even the last value that is only slightly out of the reference range would likely be interpreted as being “insignificant” in a clinically normal cat. Potential explanation for this increase would be that this animal is within that “third standard deviation” from the clinically normal group of cats and that this value is “normal” for this cat or that there might be slight clinically undetectable dehydration. However, in following the serial changes over time, a clear decreased glomerular filtration rate and renal function can be observed.
Trending is not only useful in predicting early developing disease in various organ systems. It is also extremely helpful in monitoring the progression or regression of disease. Trending analyte changes with time proves to be an extremely objective measure of progression or regression of disease. For example, a continually decreasing ALT value over time following the identification of clinically significant hepatocellular injury indicates a probable resolution to the injury. Maintained high values or increasing values indicate ongoing hepatocellular injury or increased hepatocellular injury, respectively.
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 IDEXX Practice Developer®
Practice what's possible. The rewards will follow.
Are you an IDEXX Practice Developer member?
IDEXX Practice Developer is a valuable points-based program designed to thank you for doing business with us.
As a member, your privileges include:
- Opportunities to earn points redeemable toward any IDEXX product or service
(1 point = $1)
- Member-only savings on popular and new offerings
- Invitation-only educational events
All of these membership privileges can help you deliver patient-focused care while managing a more profitable practice.
 Now there’s an easy tool to help you tally your points! Try out our new Practice Developer points calculator and see how your points can grow!
Simply enter your quarterly IDEXX purchases where applicable in the Quarterly Spending fields and click the Calculate button to determine your potential or estimated Practice Developer® points. Each quarter, the practice Developer calculator shows you the easiest way to earn more points.
Visit our site to see how you can use your points anytime!
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IDEXX Learning Center
Visit the IDEXX Learning Center to see a full listing of available webinars, seminars, teleconferences and online training courses from IDEXX about emerging trends and best practices in veterinary diagnostics in a forum designed to involve, educate and motivate you and your staff. Click the date to view the details, fill out and submit the form to register.
Here are some of the opportunities available this month:
 Online Training Courses
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Webinar
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Seminars
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He swallowed WHAT?
 Pets chew on—and swallow—the strangest things. What's the most unusual item your practice has found in one of your patients? Share it with your colleagues in a future issue of the Diagnostic Edge!
E-mail us a copy* of your X-ray or a photograph of the item or the pet, or mail it to:
Diagnostic Edge
c/o Erica Archer
IDEXX Laboratories, Inc.
One IDEXX Drive
Westbrook, ME 04092
Please include your practice name, address, telephone number and a contact number in case we need to get in touch with you.
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Long-Term Drug Study Uncovers 35% Abnormal Test Results
by Ernest E. Ward, Jr., DVM
 In a recent IDEXX study of 2,943 pets receiving at least one long-term medication, 34.6% were found to have at least one abnormal laboratory test result. This finding underscores the importance of performing routine monitoring blood tests on patients receiving long-term medications. The most commonly prescribed medications included in this study were carprofen, etodolac, methimazole, phenobarbital, enalapril, furosemide and levothyroxine sodium. The study found no single drug elicited an unusually high number of abnormal test results. Rather, the even distribution of abnormal findings among all drugs tested suggested that pets undergoing long-term medical treatments often had secondary or emerging diseases that were only identified when blood tests were performed.
The majority of pets that had abnormal laboratory findings were seven years of age and older. This corroborates other scientific data indicating that older patients receiving long-term drug treatments must be closely monitored to ensure normal organ function. Older pets have a higher likelihood of decreased liver or kidney function, increasing their risk of drug-related adverse events. Further, this study suggests that organ function may potentially decline over time and any changes must be recognized as early as possible to prevent any drug-related issues. Routine follow-up blood and urine tests every three to six months is generally accepted as adequate to recognize any developing organ system compromise.
One of the interesting highlights of the study indicated that older, mixed-breed dogs were as likely to have an abnormal laboratory test finding as older pure-breed dogs. This reinforces the long-standing belief that most drug-related issues are as much age related as breed predisposed. The benefits of testing all pets receiving long-term drugs, regardless of breed, were well substantiated in this study. If a doctor chooses to test only breeds reported to be at risk for certain medications, they may place their mixed-breed patients at risk.
 As more and more medical treatments for chronic diseases become available for pets, veterinarians must ensure they are performing due diligence to protect the health and welfare of their patients. This study proved that over one-third of the pets receiving at least one long-term medication had an abnormal laboratory test result. Through early recognition of a change in organ system function, the veterinarian can alter the treatment course to avoid potential adverse drug events. Failure to recognize a drug-related problem can result in irreversible organ damage and even death. Further, the veterinarians can often improve the quality of life of their patients by diagnosing secondary emerging diseases early in their course, improving the chances of successful treatment.
Accompanying each new medical advance is the revelation that new monitoring protocols must be created. We are now well into the age of long-term medical treatments in veterinary medicine. This new era in treatment has brought about the need to perform routine followup blood and urine testing to help prevent any inadvertent harm. Today’s pets are living longer, healthier and more comfortable lives than ever before thanks to medical breakthroughs. We owe it to them to follow the Hippocratic Oath and “do no harm.” Long-term drug monitoring can help us fulfill that promise.
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With FREE Continuing Education Credit!*
NOW Approved in Australia and parts of Canada!†
Have you taken advantage of every qualifying Interactive Challenge for FREE CE credits?
Every Interactive Challenge from June 2006 on has been worth 0.5 continuing education credits—that's three credits so far this year—and you get the credits 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!
Question:
Can you identify the nucleated cell types and the condition present in this peripheral blood film from a cat with respiratory difficulty, monolayer region?
- Identify the nucleated cell indicated with an arrow (A).
- Identify the nucleated cell indicated with an arrow (B).
- Which of the following conditions is commonly associated with increased numbers of cells A and B in the peripheral blood?
- Bacterial infections
- Chronic inflammatory disease
- Hypersensitivity/allergic phenomena
- Neoplastic disease (leukemia and nonleukemic conditions)
Figure 1: Peripheral blood film from a cat with respiratory difficulty, monolayer region of blood film, Wright’s stain, 100x objective field of view.
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