Using a Microscope for Animal Fecal Analysis

This information may also be important to breeders and raisers of horses, rabbits, cats, dogs, primates and cattle. Two of the biggest problems confronted by a goat farmer are worm and coccidia infestations. These two parasites alone kill more goats than all other illnesses combined. Surprisingly, many goat raisers do not have an established program of regular, systematic microscopic examination of goat “pills” (feces) for these parasites. Analyzing the feces for these parasites is a simple operation and should be incorporated into the overall program.

Coccidia is a protozoan parasite. Coccidiosis, the malady caused by this protozoan, can be one of the most economically devastating diseases in many livestock species. It can be especially harmful to recently weaned kids and, occasionally, results in losses in other age groups. It causes a watery diarrhea which is sometimes bloody and can even be a life-threatening problem to an especially young animal. The presence of coccidia in the intestines of an individual does not mean the animal is actually suffering from coccidiosis as coccidia are everywhere. In fact, it is almost impossible to find an animal without some coccidia. These protozoans only cause disease when their numbers become so great that damage is done to the host.

At left is a highly magnified view of coccidia sporogony. This is the infective stage of the coccidia when it is consumed by the animal. Species of coccidia are determined by looking at the structure of this stage. The oocyst contains two sporocysts, and this is typical of the genus Isospora (and Toxoplasma, although Toxoplasma oocysts are much smaller). Sporulated oocysts of the genus Eimeria contain 4 sporocysts.

Materials and Supplies

To examine your animals for worms, eggs and coccidia you will need a microscope and some basic supplies. You do not need an elaborate microscope. A simple instrument like the Richter Optica HS-3M-3 will allow you to see worms, worm eggs and coccidia. If you want two eyepieces, the Richter Optica HS-3B is a good option. Some investigators use elaborate microscope slides called McMaster slides. These are chambered with a grid pattern overlay and will provide a more scientific and precise value of the infestation but you do not need these special slides to determine if there is a problem or not. Other supplies that you will need are plain microscope slides, cover slips, cheesecloth or a strainer, test tubes (or 12cc syringe covers), a stirring rod (a pencil or chopstick works well), fecal flotation solution (sugar or salt can be used) and a test tube holding rack. For the rack, you can punch holes in a cardboard box or a styrofoam block or use any device that will hold the test tubes in a vertical position.

Fecal Analysis Methods

1. Mix up the flotation solution. It should be saturated. This means that you dissolve as much solid in the water as it will hold. You can use a variety of chemicals including salt or sugar. Saturated sugar is prepared by dissolving a pound (454 grams) of sugar in 1 1/2 cups (355 ml) of water, and saturated salt takes a pound (454 grams) of salt in 4 4/5 cups (1140 ml) of water. If there are salts left in the bottom of the liquid, pour off the saturated liquid into a new container.
2. Collect fresh feces. Use an old pill bottle or a small jar for each animal. Be sure to label the container with the date, time and animal that provided the specimen.
3. Place 3 or 4 fresh goat pellets (one to three grams) into a test tube and pour in just enough flotation solution to cover them.
4. Mash them up in the liquid with your stirring rod. Add more of the solution and pour it through the strainer or cheesecloth to remove the large particles. Now, pour the strained liquid into a clean test tube.
5. Next, fill up the test tube to the very top with more liquid. Place a microscope cover slip over the top. There should be no air between the cover slip and the liquid. Over time (20-30 minutes) the eggs will float up to the top and adhere to the glass plate.
6. Carefully remove the cover slip and lower it at an angle over a microscope slide with the sample sandwiched between both pieces of glass.
7. Examine the specimen for worm eggs and coccidia oocysts. Start with the lowest power (40x) on your microscope and carefully move up to 100x and even 400x if you see something interesting. An illustrated chart would be helpful in identifying them. Note, you will also be looking at other debris. Do not confuse it with parasites.
8. You should be able to see coccidia oocysts, nematode eggs, and some tapeworm eggs. Nematode eggs are shed by a large number of nematodes (worms), most of which cannot be easily distinguished from each other with this type of procedure. This group is referred to as strongyle eggs and worming recommendations can be based on the quantity of strongyle eggs present. Since fecal counts only estimate the parasite load, there is no clear cut level when worming should be undertaken. As a general guide, a level of about 500 eggs per gram of feces would indicate that worming is required for sheep, goats, or cattle. A better way of deciding when to treat would be to monitor fecal samples every 4-8 weeks and worm when there is a dramatic rise in egg counts.

Remember there are different treatments for various parasites. In some cases a change of environment (to a new pasture) may be all that is needed. When worming medications are used, be sure to use one that is effective against the parasite(s) for which you are treating. It is counterproductive to treat for everything, when you only need to treat for a couple specific parasites. If you are unsure of the extent or type of infestation, consult a vet.

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