#2 Parasites - Protozoal Parasites of the Digestive System.

This week, I continue the series on parasites with some information about intestinal protozoa parasites, coccidia and giardia. 

The two most common intestinal parasites in canines, besides intestinal worms, are coccidia and giardia.  Both of these organisms are protozoal and both can wreak havoc on the digestive system, especially of young puppies. 
Coccidia and giardia usually present with almost identical symptoms.  The beginning symptom is diarrhea, which usually will progress to a very watery stool and often will be bloody or blood streaked. Then you may begin to see some depression and fatigue, which are often the results of hypoglycemia and dehydration, brought about by the diarrhea.  Some pups with coccidia or giardia will refuse food and water and some won't....usually though, it's those affected with giardia that refuse food and water because giardia often causes severe abdominal cramping.

Giardia infection usually takes place as a result of a contaminated water source, however, both coccidia and giardia cysts can live in the soil for quite some time, so it is possible for puppies to pick up the cysts in the soil and ingest them that way. Both protozoa can be passed from other infected dogs in feces as well. 

Coccidia and giardia infect the host in similar ways.  Cysts are picked up from soil or passed in fecal matter from infected animals and any animal that comes into contact with the cysts can become infected by picking up the cysts on it's paws and ingesting them when it cleans itself. 
Once inside the host, giardia and coccidia begin to differentiate in how they act upon their hosts.  For an indepth look at how these two protozoal parasites behave inside the host, click on the links below.

https://www.whole-dog-journal.com/issues/20_4/features/Giardiasis-and-Coccidiosis-in-Puppies_21624-1.html

https://vcahospitals.com/know-your-pet/giardia-in-dogs

https://vcahospitals.com/know-your-pet/coccidiosis-in-dogs

Another area where these two protozoal organisms differ is how they are diagnosed.  There is a snap test available for giardia, which tests for the protien that the organisms use to encyst themselves.  Because of this, the snap test is not always reliable, as there will not be those protiens present in every stool.  The protozoa will encyst when changes in the digestive tract indicate that they are about to be expelled.  Once encysted, the protiens will dwindle and eventually there will be none left to create a positive test.  Fecal float testing can, at times, be used to diagnose giardia, but it has a very low success rate as the organism is very very difficult to see, even under a microscope.
Coccidia, on the other hand, is usually diagnosed with a fecal float test.  Still difficult to see, it is usually possible to find coccidia oocytes in the stool.  Alternatively, a blood test may help to diagnose coccidia. 

And these two parasites are also different in how they are treated.  Coccidia is treated with Albon or Ponazuril, and often an antibiotic to ensure that no secondary infections set in.  Giardia is treated with Panacur or Safeguard (a common wormer) and metronidazole, an antibiotic that not only helps to prevent secondary infections, but also appears to have some effect on the giardia organisms themselves. 

There was a controversial vaccine for giardia on the market at one time.  It was called Giardia Vax and was made by Fort Dodge.  The controversy surrounded the debate over whether or not this vaccine actually benefits the animal.  It did not prevent infection, and did not claim to.  The vaccine claimed to reduce clinical symptoms and the amount of time the animal will shed the cysts.  If the vaccine actually did this, it would be very beneficial to the animal because reduction of diarrhea would eliminate a whole host of problems associated with it, such as hypoglycemia and dehydration.  Also, reducing the amount of time the cysts are shed may also help to reduce the risks of other animals becoming infected.  However, research suggests that the vaccine has no effect on the presence of giardia in the stools of infected but asymptomatic dogs.  Further, the vaccine is now very difficult to find, so it appears as though it may have been taken off the market.   

In the end, there is no absolute cure for either of those parasites, unfortunately, except for the animal's body's own defenses.  Dogs naturally carry coccidia in their digestive systems, but what makes the animal sick is the overwhelming rapidity with which these protozoas reproduce. This happens in puppies becaue of immature immune systems.  Adult dogs rarely become ill from giardia or coccidia, but they may be carriers of the protozoa.  If given time and a little help with the medicines mentioned above though, most animals will be able to rid themselves of these organisms.