Snowshoe Hare Parasite Control

Last Review Date: November 29, 2017


I.  Purpose

The purpose of this Standard Operating Procedure (SOP) is to outline the parasite control plan for snowshoe hares housed outdoors at the Fort Missoula Field Research Station (FMFRS).

II.  History

Snowshoe hares are susceptible to tapeworms (Taenia pisiformis), pinworms (Passularus abiguus), stomach worms (Obseliscoides cuniculi), protozoa (Eimeria sp.), roundworms (Trichostrongylus sp.), and ascarids (Ascaris sp.). Indeed, upon necropsy of a hare from the FMFRS captive colony, cystercercis (Taenia pisiformis) was discovered in an individual. Exposure to the tapeworm most likely occurred prior to capture and captive management and in this form of tapeworm infestation the parasite larvae are encysted in sacs (cystercercus) within the the abdominal cavity and do not become active until ingested by a predator. The only way to determine if any other snowshoe hares are infested with Taenia pisiformes is by necropsy as the parasite larvae are not physiologically or metabolically active in this state.  Elimination of encysted tapeworm larvae in the captive population would be stressful to the animals, potentially may not be successful as the parasites are sequestered from exposure to the parasiticide, and as cycstercercus poses no health threats to the animals or the husbandry staff, and thus this course of action will not be undertaken.

The current housing strategies (communal enclosures divided by sex or housed individually in home cages outside) for the captive snowshoe hares provides the animals with a more naturalistic setting but does potentially expose them to parasites carried by wild rodent populations. To monitor and control any parasite infestations, a periodic fecal floatation regimen will be instituted and deworming will occur as needed. Parasite eggs become dormant during the late fall and winter when temperatures drop consistently below 40 ºF and become patent again in the spring when temperatures are consistently above 40 ºF.

III. Materials/Equipment

A.  Personal Protective Equipment (PPE) includes lab coats and gloves. 

B.  Ovum Flotation Dry – a zinc sulfate solution

C.  3-5 mm plastic tube

D.  Microscope slide covers

E.   Microscope slides

F.   Microscope

G.  Fecal samples

1.  If snowshoe hares are housed communally, collect samples from about the
     enclosure, group the samples, and batch test

2.  If snowshoe hares are housed individually, collect a sample from each cage
     and test individually

IV. Parasite Fecal Testing Schedule

Group or Individual fecal samples will be collected on the following schedule:

A.  Last week of March
B.  First week of July
C.  First week of November

Parasite Fecal Testing

A.  Communal Fecal Samples (If any of the communal fecal samples is positive for
      parasite eggs all the animals in the affected enclosure will be treated with a

1.  Place communal samples in a container and crush the feces to make one
     homogenous sample

2.  Place approximately 1 cc of homogenous stool sample into the bottom of a
     five 5 cc plastic tubes

3.  Fill the tubes with Ovum Floatation Dry to the brim

4.  Cover the tubes with a microscope slide cover

5.  Allow to sit for 10 minutes

6.  Remove the slide covers and place on microscope slides

7.  Examine each slides under a microscope on low power to look for parasite

B.  Individual Fecal Samples (when testing individual fecal samples, note which
     sample is positive for parasites and that individual animal will be treated with a

1.  Place each sample in a 5 cc plastic tube and crush the feces with the wooden
     stick of a q-tip or a similar device

2.  Repeat steps #2-7 above

VI.  Parasite Treatment Based on Ovum Identification

A.  Pinworms; Piperazine citrate: 100 mg/ml of drinking water for 1 day

B.  Coccidia; Albon (Sulfadimethoxine): 75 mg/kg by mouth for 5 days or Amprolium
     9.6% (Corid™): 0.5 ml/500 ml of water

C.  All other GI parasites; Ivomec 1% injectable or Noromectin 1% injectable (generic
      version); 0.1 ml by mouth or placed on bare skin.