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July/August Newsletter
  August/September 2013
Focus: GI Diagnostics
 
  Why Consider PCR First (Not Last) for Diarrheic Patients?
Interview with Marilyn Mikiciuk, DVM, DACVIM
 
  Campylobacter infection sickens DVM and his dog
A cautionary tale regarding zoonotic risk
 
  Clinical Approach to Diagnosis for Vomiting
Suggested testing workflows for acute and chronic cases
 
  In Brief: Promising Treatment for Dry Form FIP Emerges  
  Practical Tip: Best Samples for Fungal/Bacterial Skin Cultures  
 
 

Why Consider PCR First (Not Last) for Diarrheic Patients?

 

Interview with Marilyn Mikiciuk, DVM, DACVIM
ANTECH Gastrointestinal Medicine Consultant

Q: Since real-time PCR panels for GI pathogens became readily available, you have increasingly recommended that the profiles should be run on diarrheic patients prior to starting them on therapy. Why is that?

A: First and foremost, because the PCR panel is broad spectrum, encompassing an array of etiologies for diarrhea (see below) including viral and bacterial causes, coccidia and Giardia. If a diarrheic puppy is presented to you from a pet store or puppy mill, that patient could be harboring Giardia, coronavirus, parvovirus, Campylobacter, Cryptosporidium or Salmonella – a long list of rule-outs. Rather than saying first I’m going to culture the stool and then I’ll do a SNAP test for parvo, etc., you can test for all the etiologies upfront and get more bang for your buck. You’ll also detect co-infections that could complicate treatment. The clinicians I speak with are often surprised by the positive results they get back because the causative agent wasn’t even on their rule-out list.

  FastPanel® PCR Canine GI Profile (Test Code: T950)
Tests For:
Campylobacter coli
, Campylobacter jejuni, canine enteric coronavirus, canine parvovirus, Clostridium difficile toxins A/B, Clostridium perfringens enterotoxin, Cryptosporidium spp., Giardia spp., Salmonella spp.
PLUS: Follow-up cultures are immediately performed on samples found to be PCR-positive for Salmonella. Additionally, samples found to be PCR-positive for DNA of C. perfringens enterotoxin or C. difficile toxins are immediately tested for these toxins by ELISA.
Specimen Req.
Feces (0.5 to 1 gram) and 1 Copan fecal swab. Please submit prior to antibiotic administration.

Testing prior to treatment is best because if you treat first, you’ll have to wait an additional five to seven days without meds before you can order the test, in order to avoid false negatives from antibiotics or anthelminthics. And the animal is still diarrheic during that delay; so don’t view PCR as a test of last resort.

A more effective approach that can save time and client frustration, particularly in the case of very ill or chronic cases, is to order the PCR panel first. You’ll have an excellent chance of nailing the disease etiology the first time and getting your patient on the right therapy ASAP – a big improvement over the “trial and error” approach in my opinion. You have the option, of course, of starting your patient on meds while you wait one to three days for the PCR panel results.

Q: Isn’t it a lot cheaper to try therapy first?

A: It is cheaper in the short run, but for the significant percentage of patients that don’t respond to therapy or have recurrences, you are looking at much greater expense in terms of repeat office visits, additional testing and meds compared to the cost of the PCR panel. And of course for very ill patients, you can’t afford to try shortcuts.

  FastPanel® PCR Feline GI Profile (Test Code: T955)
Tests For:
Campylobacter coli
, Campylobacter jejuni, Clostridium difficile toxins A/B, Clostridium perfringens enterotoxin, Cryptosporidium spp. and C. felis, feline parvovirus, Giardia spp., Salmonella spp., Tritrichomonas foetus
PLUS: Follow-up cultures are immediately performed on samples found to be PCR-positive for Salmonella. Additionally, samples found to be PCR-positive for DNA of C. perfringens enterotoxin or C. difficile toxins are immediately tested for these toxins by ELISA.
Specimen Req.
Feces (0.5 to 1 gram) and 1 Copan fecal swab. Please submit prior to antibiotic administration.
If you are nervous about test price sticker shock, I suggest presenting both the traditional and more comprehensive PCR testing options to your client and let them choose, rather than choosing for them. One reference I give our clients: the cost of our Feline GI profile, which includes Tritrichomonas foetus and nine other pathogens, is similar to what our clients used to pay for a single send-out Tritrich PCR test! And you’re getting 1-3 day turnaround instead of a week or longer.

Q: What about an alternative approach of reserving a diarrhea sample for PCR testing, and submitting it only if the patient doesn’t respond to therapy or the cause isn’t identified by other means?

A: That is a viable alternative. You can refrigerate a diarrhea sample for 24 to 48 hours and then send it out for PCR testing if the dog or cat isn’t responding to treatment, but don’t store it any longer than 48 hours because further delay can impact the sample’s viability for reliable PCR testing.

GI Pathogen Frequency in FastPanel PCR Results (cases assumed diarrheic)
Canine GI Results (n=771) Positive
C. perfringens enterotoxin 23.1%
C. difficile toxins A/B 8.8%
Giardia spp. 7.5%
Canine parvovirus 4.7%
Canine ent. coronavirus 4.3%
Cryptosporidium spp. 4.2%
Campylobacter jejuni/coli 2.2%
Salmonella spp. 2.1%
   
Feline GI Results (n=496) Positive
C. perfringens enterotoxin 11.5%
Cryptosporidium spp. 7.3%
Tritrichomonas foetus 5.4%
Giardia spp. 5.4%
C. felis (incl. in spp. total) 4.8%
Feline parvovirus 3.6%
C. difficile toxins A/B 2.8%
Campylobacter jejuni/coli 2.2%
Salmonella spp. 1.0%
   
All samples found to be positive for the Clostridium perfringens enterotoxin were also tested by a CPE immunoassay; 42% of these samples were also positive for CPE by ELISA. Similarly, all samples found to be PCR-positive for the DNA of C. difficile toxins A/B were tested by a toxin ELISA; 18% of these samples were also positive for the C. difficile toxins by ELISA.

Q: When does it make sense to stick to the more traditional protocol of running a routine fecal, Giardia ELISA and starting a diarrheic patient on metronidazole first? And what about fecal cultures?

A: Testing and treatment protocols should always be based upon history and physical exam findings. A dog presenting with an Addisonian crisis, a dog with acute pancreatitis, or an older dog with suspected GI neoplasia, for example, would require alternate testing to the GI PCR panel.

Fecal cultures can be unrewarding because, most often, normal bacterial flora is grown. PCR testing is as sensitive, if not more sensitive, for detecting Salmonella or Campylobacter.

Q: Finally, are you seeing any particular trends in the organisms detected on GI PCR panels?

A: I have been surprised, as have many ANTECH clients, at the frequency of Campylobacter and Cryptosporidium. But we can’t say that is a function of increasing prevalence; rather, it is more likely that we simply weren’t detecting these agents previously.

Salmonella is increasingly important given the growing popularity of raw food diets and the various pet food recalls we’ve seen over the past two years, so we’re glad it’s included in the two GI profiles.

Questions? Please contact the ANTECH Consult Line and request Dr. Mikiciuk if you have a question about GI diagnostics or a particular gastroenteritis case.

Note: Pet food recall announced June 18 due to potential Salmonella contamination. Natura Pet Products recently announced that it is voluntarily recalling specific lots of dry pet food because of potential contamination with Salmonella. In addition to affecting pets eating the products, there is risk to humans from handling contaminated pet products. For additional details on the specific brands recalled, click here. For suspected cases of Salmonella poisoning, the FastPanel® PCR GI canine or feline profiles can assist in identification.

 
   
 

Campylobacter infection sickens California DVM and his dog
A cautionary tale regarding zoonotic risk

A noteworthy case that recently came to our attention is that of a veterinarian in California who was hospitalized for dehydration following several days of severe diarrhea. The etiological agent identified was Campylobacter jejuni, which can cause diarrhea, abdominal pain and cramping, fever, nausea and vomiting in people.  The veterinarian was given fluids, treated with Cipro (ciprofloxacin) and released after overnight hospitalization.

The DVM soon discovered that his 7-year old border collie, who had diarrhea as well, was positive for Campylobacter jejuni on the FastPanel® PCR Canine GI profile. While campylobacteriosis is more often a problem in puppies, the bacteria can sicken mature dogs.  In this particular case, the DVM suspects his sheep-herding dog became infected by eating sheep feces, a peculiar habit she sometimes exhibits when nervous.

Zoonotic transfer: how it happened.  Most cases of campylobacteriosis occur through ingesting raw or undercooked poultry or foods contaminated by raw chicken, having contact with farm animals, or drinking contaminated water or raw milk.  But Campylobacter is a zoonotic agent and infection can also be passed from an infected dog or cat to an owner or family member.  In this case, the diarrheic dog was kept in a crate on a covered porch.  Cleaning the crate thoroughly was difficult; the DVM used paper towels and cleaned his hands with soap & water afterwards.  This precaution proved to be insufficient, however, as the DVM became ill very soon after cleaning the crate.

Both the DVM and his dog recovered within a few days. Following treatment, both patients had repeat testing that found them negative for Campylobacter.

Concluding note:
Take appropriate precautions in handling diarrheic patients and when
cleaning surfaces in sickened animal confinements, including wearing
and carefully disposing of gloves.

Additional campylobacteriosis prevention tips from the CDC*:

  • Cook all poultry products thoroughly - no longer pink with juices running clear (minimum internal temperature of 165°F).
  • If you are served undercooked poultry in a restaurant, send it back for further cooking.
  • Wash hands with soap before preparing food and immediately after handling raw foods of animal origin.
  • Prevent cross-contamination in the kitchen by using separate cutting boards for foods of animal origin and other foods and by thoroughly cleaning all cutting boards, countertops, and utensils with soap and hot water after preparing raw food of animal origin.
  • Do not drink unpasteurized milk or untreated surface water.
  • Make sure that persons with diarrhea, especially children, wash their hands carefully and frequently with soap to reduce the risk of spreading the infection.

*Source: Centers for Disease Control and Prevention web site www.cdc.gov. Downloaded July 1, 2013.

 
     
 

Clinical Approach to Diagnosis for Vomiting
Suggested testing workflows for acute and chronic cases

While diagnosis of vomiting – with or without diarrhea -- is often straightforward, choosing the right laboratory tests will increase your diagnostic accuracy and allow for the most prompt and effective treatment. The following overview presents two checklists of suggested tests for vomiting patients: the first for acutely vomiting patients, and the second for chronic/recurring cases.

The Acutely Vomiting Patient
For the pet with acute vomiting, getting baseline diagnostics is often adequate, although signalment, history and physical examination will best guide the choice of tests run. For example, for the younger pet in whom an infectious or ingested (toxin or foreign body) cause is more likely, additional testing such as abdominal radiography or ultrasonography may be indicated, especially if the pet is overtly ill, shows abdominal pain, or has protracted and repeated vomiting. Additionally, because diarrhea is often present with vomiting, additional testing on the feces may be indicated and can be helpful with the diagnosis and treatment. 

Baseline tests for patients with recent onset of vomiting:
Fecal Analysis
(O&P / Giardia ELISA)
The first test to consider is a fecal analysis (in-house or by ANTECH) for common GI parasites. If positive, deworming is simple and usually curative. If the analysis is performed in-house and is negative, or if any unusual ova are detected, further analysis of the feces by an experienced technician or parasitologist is indicated. A fecal O&P plus Giardia ELISA can test for common parasites and provide results within 24 hours.
Case-dependent tests:
Fecal PCR If enteric toxins, bacteria such as Campylobacter or Salmonella, or enteric viruses such as parvovirus are suspected, a fecal PCR test is indicated with or without a fecal culture*. PCR testing allows identification of microbial DNA and provides comprehensive results within 1-3 days. If positive, additional confirmatory testing such as Clostridium toxin ELISA or fecal culture is performed at no charge.
Imaging Pets with suspected foreign body ingestion can be screened with conventional radiography and/or ultrasound.
CBC/Chem/UA Overtly ill pets require more extensive testing and treatment.  A thorough blood profile and urinalysis is indicated. Since Addison’s disease can manifest as vomiting, be sure the profile you select includes electrolytes. Thyroid testing (Total T4) should be included in middled aged and older cats. POC testing for pancreatic lipase may additionally be indicated.
Endoscopy If the pet is vomiting blood or demonstrates severe GI pain, endoscopy may also be indicated.

The Chronically Vomiting Patient
Pets with chronic vomiting typically require additional testing compared to pets with recent onset vomiting, including repeating some earlier testing to determine changes in baseline values. Patients with chronic vomiting may do so intermittently. A typical history is one of vomiting for one to several days with periods of normal GI activity before vomiting recurs (note: it is important to differentiate between regurgitation, which is a passive process and occurs uncommonly in pets, and vomiting which is an active process and much more common in pets).

The laboratory evaluation of these patients will vary depending upon what if any testing had been done previously, but in general these patients deserve a complete workup.

Baseline tests for the chronically vomiting patient:
CBC/Chem/UA A thorough blood profile and urinalysis is indicated.
Fecal Analysis
A fecal O&P plus Giardia ELISA can test for common parasites and provide results within 24 hours. Therapeutic deworming should be undertaken even if O&P testing is negative to exclude less common gastric parasites (Physaloptera, Ollulanus) as causes of vomiting.
Adrenal function evaluation Baseline cortisol measurement is an inexpensive way to exclude hypoadrenocorticism and should also be considered, as Addison’s disease is often overlooked (yet common) in patients with intermittent GI signs. An ACTH stimulation test can be performed initially if Addison's disease is highly suspected or can be done if the baseline cortisol is low-normal or low.
Imaging Abdominal radiography and ultrasonography. Note that ANTECH Imaging Services is available for STAT contrast radiography reads, with average turnaround of 40 minutes. (Visit antechimagingservices.com for more information.)
Additional tests (if baseline testing indicates further investigation necessary):
Endoscopy If laboratory testing fails to reveal an underlying cause, upper and/or lower GI endoscopy to look for inflammatory bowel disease (IBD), gastric foreign body, GI ulceration or neoplasia should be considered.
Fecal PCR Patients with vomiting and diarrhea and negative baseline fecal results should receive more extensive fecal testing to identify enteric toxins, bacteria such as Campylobacter or Salmonella, or enteric viruses such as parvovirus (or Tritrichomonas foetus for cats).
Special Blood Tests
  • Tests for pancreatic lipase may be helpful but have limited specifity for pancreatitis.
  • Blood lead concentrations should be considered to rule out lead toxicosis.
  • Other testing may be required to investigate abnormalities detected on laboratory screening (e.g., causes of liver disease or renal failure, hypercalcemia).

To help explain your selection of GI diagnostic tests to clients, download and customize the attached client handout.

Using appropriate testing early in the course of disease can save the pet owner time and money on additional visits, testing and treatment and allow the patient to recover as quickly as possible – earning your practice loyalty in the process. 

References
Clinical Veterinary Advisor, Dogs & Cats, 2nd ed, Cote E, Mosby/Elsevier, 2011:443-446.
The Feline Patient, Norsworthy G, Mitchell C, Brace S, Tilley L., 3rd ed, Blackwell, 2006:73-75.
Today's Veterinary Practice, May/June 2013, Vol 3 Issue 3, GI Intervention: Approach to Diagnosis and Therapy of the Patient with Acute Diarrhea, P Jane Armstrong.

* Note: While fecal culture will show any live bacteria that are present that may be causing the pet’s GI issues, it will not show enterotoxins, parasites, or viruses, and will be negative if bacteria are not viable at the time of culture. Fecal PCR will allow diagnosis even if the microorganisms are not alive at the time of testing (unless antibiotics have been used recently) and also detects various parasites, viruses, and enterotoxins. If the practitioner is not sure if PCR testing should be done at the time of the initial visit and prefers to determine response to therapy, the feces can be refrigerated for 24-48 hours while awaiting treatment results and then the sample can be submitted for PCR testing.

 
     
 

In Brief: Promising Treatment for Dry Form FIP Emerges
Information on Current Research and How To Order Off-Label Drug

Multiple studies conducted by Dr. Al Legendre, Department of Small Animal Clinical Sciences, University of Tennessee College of Veterinary Medicine, and colleagues since 2006 have found that cats with the dry form of feline infectious peritonitis (FIP) have longer survival times and improved quality of life when treated with polyprenyl immunostimulant (PI), a plant based immunostimulant that upregulates innate immunity in animals.

Most recently, in a study funded by the Winn Feline Foundation (publication pending), 22% of 58 cats with the dry form of FIP survived at least 165 days on PI treatment; three cats lived longer than a year. Information about previous studies and an excellent FAQ document for pet owners are available on the University of Tennessee website (click here).

 
  Dr. Al Legendre with Hall of Fame kitty

How to Order PI: Veterinarians can now prescribe PI off-label as a treatment for cats with dry form FIP. In September 2012, the USDA issued a conditional license to Sass & Sass, Inc. to distribute PI. To order the drug, contact Sass & Sass via email at sales@sassandsass.com or by phone at 865-481-6000 to obtain their order form, pricing and product insert. Note that the states of LA, GA, MA and WA require that veterinarians obtain permission from their State Veterinaran to use PI; Sass & Sass will assist with this process.

Recommended Treatment Protocol: For cats weighing 5kg or less, the recommended dose of PI is 3mg/kg given orally every other day (drug concentration: 2 mg/ml). For cats above 5kg, Dr. Legendre administers a maximum dose of 7.5 ml, or 15 mg per dose.

 
     
 

Practical Tip: Best Samples for Fungal/Bacterial Skin Cultures

ANTECH clients often call our Consult Line to inquire about the best way to collect a sample for skin or mass/organ culture.

For skin culture samples, any of the following three options is recommended:
  1. If intact pustules are present, gently brush the surface using an alcohol swab to remove surface contaminants (being careful not to rupture intact pustules), puncture a pustule using a needle tip, and submit a swab of extruded pus for aerobic culture & sensitivity (Test Code: M020);
  2. Surface swabs are appropriate when there is superficial pyoderma and/or folliculitis. This includes circumstances when epidermal collarettes are noted or there is papular/pustular dermatitis (without intact pustules). In cases of epidermal collarettes, the swab should be vigorously rubbed for a minute from the center of the collarette to the periphery moving it under the exfoliating margin.
  3. Biopsies for macerated tissue culture should be taken when there is depth to the skin disease (e.g., cases of cellulitis, furunculosis, dermal to subcutaneous granulomatous to pyogranulomatous disease). A very lightly soaked alcohol swab should be used to gently brush the surface to remove surface contamination. A punch or wedge biopsy should be taken from the affected area and the tissue placed in a sterile red top tube. Try and biopsy an area that has not ruptured to the exterior. A swollen or purpuric area that looks like a newer lesion is preferred over an older open draining lesion. A tiny drop of saline is placed in the tube to keep the tissue moist (do not submerge the tissue in saline or have it floating in saline). Request aerobic culture (Test Code: M020).

For other sites, e.g., mass/organ culture samples:
  • Tissue is best;
  • Submit swabs or aspirates if a tissue sample is not feasible.

Comments and suggestions welcome! Please email us at insights@antechmail.com if you have any suggestions for future articles or focus areas for practical tips.

 
     
 
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