Questions About VETSCAN IMAGYST™?

Counting Chamber⁴

• Modified McMaster Technique
• Moredun Method
• FECPAK^G2
• FLOTAC
• Mini-FLOTAC

Test Tube and Coverslip⁴

• Stoll Technique
• Wisconsin Method
• Cornell-Wisconsin Method

There are numerous factors that can influence the accuracy of parasitic detection and use of fecal flotation, including how much fecal material is examined, whether or not a centrifuge is used, type of flotation solution and length of the flotation process. In addition, there is “the personal factor,” which considers varying levels of individual technical proficiency even when staff follow the same set of directions.⁵

Flotation solutions are used to concentrate and separate internal parasite eggs, cysts and oocysts from fecal debris. There is no perfect flotation solution for detecting all the different parasitic elements—each has advantages and disadvantages. Some things to consider when selecting a solution are the specific gravity (SG) of the solution, the viscosity of the solution and the rate of plasmolysis caused by the solution (which can cause degradation of parasitic elements).^6,7

If the flotation solution is too low in SG, many of the parasitic elements will not float and will settle at the bottom of the solution. Alternately, if a flotation solution is too high in SG, it can lead to increased debris floating along with the parasitic elements, resulting in decreased efficiency of the test. In addition, a high SG can lead to plasmolysis and potentially rupture the parasite eggs, cysts or oocysts of interest.⁷

• If the SG is too low⁷:
  • No or fewer parasite eggs/cysts/oocysts float

• If the SG is too high⁷:
  • More fecal debris floats
  • Hyperosmotic solution may damage eggs
  • Solution on slide dries up rapidly

Again, there is no solution that is perfect for detection of all parasites and parasitic elements. The benefits and drawbacks of each should be considered when selecting a solution.⁶ This is summarized in the table below, which was adapted from Veterinary Clinical Parasitology (8th ed).⁶

Studies have shown that sugar solutions are often more efficient than other types for recovery of equine parasites. Specific findings include the following:

• Sugar solutions were found to recover a higher EPG for strongyles and ascarids and have a lower coefficient of variation (CV%) than using salt solutions via the Mini-FLOTAC and modified McMaster techniques⁸
• Sugar solutions were found to recover a higher EPG for ascarids and have a lower CV% than salt solutions utilizing the modified McMaster technique^8,9

VETSCAN IMAGYST can identify strongyles and Parascaris spp. in horses.¹

The VETSCAN IMAGYST AI FEC analysis application can identify hookworm (Ancylostoma spp.), roundworm (Toxocara spp.), and tapeworm (Taeniidae) eggs in dogs and cats; whipworm (Trichuris vulpis) in dogs; coccidia (Cystoisospora spp.) oocysts in dogs and cats; and Giardia spp. cysts in dogs and cats.^10,11

Currently, the VETSCAN IMAGYST AI equine FEC analysis is only verified for equine fecal samples.

The following supplies, not provided by Zoetis, are required to process an equine FEC analysis:

1. Disposable cups
2. Food scale (with gram measurements)
3. Graduated cylinder or syringe
4. Tongue depressors (act as collection and stir sticks)
5. 2-ply cheesecloth (or 2-ply, 4”x 4” gauze)
6. Flotation solution (Sheather’s sugar solution is recommended [SG 1.26])

   In addition to these supplies, the VETSCAN IMAGYST AI Equine Fecal Kit, which can be ordered from Zoetis, contains the following supplies:

7. Glass slides
8. VETSCAN IMAGYST fecal coverslips
9. Transfer loops
10. Slide template

    The Grundium Ocus^® 40 scanner is required for the scanning and processing of the prepared fecal slide.

The steps for sample collection are as follows:

1. Using a gram scale, measure out 4.0 g of manure into a clean, labeled disposable cup.
2. Add 26 mL of flotation solution to the cup containing 4.0 g of manure.
3. Using tongue depressor, mix the manure and solution well for 30 seconds.
4. Filter the mixture through 2-ply cheesecloth or gauze into a clean disposable cup.
5. Once strained, discard the manure and cheesecloth/gauze. Allow the mixture to sit for at least 5 minutes to allow eggs to float on the surface of the solution; do not stir or disturb the solution.
6. Place the glass slide into the IMAGYST slide template. Make sure that the name or barcode on the slide is positioned toward the top.
7. Obtain sample from the top surface of the disposable cup using the IMAGYST transfer loop. Make sure to skim the entire top layer of the sample.
8. Place 1 loop of the collected fluid onto the glass slide, distributing sample around the edge of target circle.
9. Place coverslip, with IMAGYST readable in the lower left-hand corner, onto the slide over the targeted area of the slide template.
10. Place the slide on the IMAGYST scanner. Make sure to position the coverslip on the left-hand side of the scanner.
11. Choose the correct Test Type and select SCAN.
12. Select a scanner, and make sure the tray is open.
13. Unlock the slide holder and place the slide (with coverslip) on the slide tray.
14. Place any label or writing toward the right side of the slide tray and lock the slide holder.
15. Select SCAN SLIDE.
16. Open the sample results, review any captured images and select examples for inclusion in the report.
17. Add any comments and select FINALIZE.
18. Select VIEW REPORT to view a shareable PDF or review results in a FUSE-connected software system.

There are many flotation solutions that can be utilized to concentrate and separate internal parasite eggs, cysts and oocysts from fecal debris. There is no fecal solution that is perfect for detection of all parasites and parasitic elements, and the advantages and disadvantages of each should be considered when selecting one.⁶

Three flotation solutions were tested for their recovery sensitivity using the VETSCAN IMAGYST AI equine FEC analysis application: Apafix sugar solution, sodium nitrate NaNO3 (SG 1.22), and Sheather’s sugar solution (SG 1.26). All 3 solutions can be utilized with the FEC analysis application; however, the recommended flotation solution is Sheather’s sugar solution (SG 1.26). Sheather’s sugar solution is easy to produce in clinic, commercially available for purchase, had fewer complications when used, and showed an excellent recovery sensitivity for strongyles and Parascaris spp.^1,12

The table below shows the recovery sensitivity results from 3 verification studies for the VETSCAN IMAGYST AI equine FEC analysis application. All samples were read by an expert clinical parasitologist. In this data, the sensitivity is the key performance indicator, as it measures the proportion (%) of actual infected samples (positives), which are correctly identified as infected. This data will be discussed in further detail later; however, the Sheather’s sugar solution (SG 1.26) had the highest recovery sensitivity for both target parasites.¹

95% Jeffreys confidence interval.

Samples read by an expert clinical pathologist.

*Compared to modified McMaster technique.

^†Compared to Mini-FLOTAC Method.

^‡Excludes Mini-FLOTAC <15 EPG.

The analysis by the convolutional neural network is done in the cloud. The time for scanning and analysis is mostly influenced by internet speed. At an upload speed of 10 Mbps, the equine FEC analysis will be completed in about 6.5 minutes. This is faster than the expected 9 minutes for canine and feline samples at the same upload speed, as the equine FEC algorithm is only scanning 1 layer of fecal matter compared to 2 layers for canine and feline.

Assuming a 10 Mbps upload speed, total time from sample preparation to result is about 14 minutes. This includes the 7.5 minutes for sample preparation and about 6.5 minutes for scan time. The hands-on time is minimal after sample collection and preparation, because the scanner is performing the analysis, freeing the veterinary professional to focus on other tasks.

Note that the analysis time and total time to results are dependent on internet speed for upload of the slide image.