ANIMAL RESOURCE CENTER

Pinworm Treatment

Fenbendazole Feed

Fenbendazole is a broad spectrum anthelmenthic that is mixed with the animal feed at a concentration of 150 ppm. The feed is placed on the cages in alternating weeks to ensure that all animals being treated have adequate access to the feed.

Fenbendazole is a memeber of the Benzimidazole family of compounds. It is poorly absorbed from the GI tract. Absorbed fenbendazole is metabolized to oxfendazole in the liver.

Mode of action:

The mode of actio is not clearly delineated but the following effects on the parasite have been reported:

Degeneration of microtubules

Inhibition of glucose transport and uptake

Interference with energy production

Inhibition of fumarate reductase

Starvation of parasite -- energy processes

Ovicidal: Ova are inactivated early follwing treatment

Cytoplasmic microtubules disappear in tegumentary and intestinal cells.

Secretory processes, e.g., from Golgi apparatus and acetylcholine release, are impaired.

Microtubular function may be common to all of these processes.

Adverse effects

Teratogenic effects have been shown for albendazole, cambendazole, oxfendazole, and parbendazole. If these drugs are to be used in early pregnancy, it must be for good reason and at the lowest recommended doses.

Acute toxicity is extremely difficult to produce with these drugs and LD50s are almost impossible to define for drugs such as thiabendazole and fenbendazole. They are regarded as safe up to 20 to 30 times the recommended dose. The earliest sign of toxicity noted in horses with mebendazole is a slight diarrhea.

The following SOP is used to train technicians to place the feed on cages.

Fenbendazole Treated Feed

1. When treating full service microisolators arrange ahead of time to receive autoclaved cages with no food on the weeks you are giving medicated chow (Wks 1,3 & 5).
   1. Enter boxes of food into animal room when necessary by spraying and wiping outside of container with 1:18:1 Clidox and then bring to room to be treated.
   2. To enter into hood where change stations are normally used, remove food bag from box, spray down with 1:18:1 Clidox and place in hood. Food can then be added to each cage as needed, using only enough for one week.
2. The entire treatment regime lasts for 6 weeks as follows:
   1. WEEK 1:
      1. Change cages, tops and racks, discarding all old food.
      2. Place sufficient medicated food for 1 week in hopper, check daily and give more if needed.
      3. Change card holders
      4. Change room exhaust filter and wipe area with 1:18:1 Clidox.
      5. Wash all surfaces including walls, ceiling,floor, tables,change stations, carts, food barrels, census books, sharps containers, waste cans, etc with 1:18:1 Clidox. Send as much as possible to the washroom.
   2. WEEK 2:
      1. Top off remaining medicated feed from cages with normal chow
         
   3. WEEK 3:
      1. Everything the same as week 1.
         
   4. WEEK 4:
      1. Everything the same as week 2.
         
   5. WEEK 5:
      1. Everything the same as week 1.
         
   6. WEEK 6:     
            1. Everything the same as week 2.
      
   7. Week 7:
            1. Everything the same as week 1.
      
   8. Week 8:
      1. Everything the same as week 2.