What the Heck is this Disease Really?

By: Laurie Cook DVM
Originally appeared in the Spring 2017 Issue of the Southeast TDA Newsletter

First, a little “Classroom talk” is in order before discussing how our deer contract this disease along with how we treat and prevent it. This bit of information is really important to understanding how and why these organisms “thrive" in our deer pens!

When we speak of a Coccidia infection in the ruminant, it can be an infection with Eimeria, Cryptosporidium, Toxoplasma, or Neospora to list a few. Some of the above have a human health concern but for the sake of what we commonly see in our deer pens, the discussion will be limited to the form that causes intestinal disease leading to the classic diarrhea, weight loss, anorexia, and sometimes death.

Coccidiosis refers to the clinical “symptoms'' that result from an infection with one or more Coccidia. Coccidia are microscopic, spore forming, single celled organisms called Protozoans. These “protozoal parasites" infect the small intestines of domestic animals. There are MANY Genera of Coccidia with the most common we see in small ruminants, including Whitetail Deer, being the genus Eimeria. AND within this genus, there are over 10 species known to infect small ruminants, but not all are pathogenic; meaning not all protozoans are bad.

Coccidia have quite a complex Life Cycle with many stages of development. The egg is called an “oocyst” which is passed in the feces from an infected animal. When first passed, this oocyst is NOT infective. It needs to go through levels of development called sporulation (hatching). This sporulation NEEDS oxygen and moisture and how fast they sporulate is temperature dependent. The warmer the temperature, the faster they develop into the “sporulated oocyst”, which is the INFECTIVE stage! So, in the average deer pen, we will say it takes anywhere from 2 to 4 days for the oocyst to sporulate. This now infective oocyst is VERY resistant to environmental conditions with direct sunlight being the only environmental factor that is detrimental to them. These infected oocysts can survive for a year or longer if protected from sunlight.

OK, now the deer ingests this “infective oocyst" while grazing or eating treats off the ground where there is fecal matter. The infected oocyst releases what we call sporozoites that then invade the small intestinal cells. These sporozoites are kind of like strongyle larvae, they go through several stages of maturation while in the small intestine, damaging the intestinal lining and then ultimately shed the oocyst in the feces. The time from ingestion of infected oocyst to the shedding of oocyst is an average of 14 days. And the crazy (and scary) thing is, a single oocyst can produce up to 23 million oocysts during the next life cycle! Now, let’s move from the classroom to your farms.

So, we know coccidia are hardy, love a warm moist environment, are very contagious, and invade the small intestine once ingested. An active infection leads to clinical symptoms of diarrhea, dehydration, weight toss. anorexia, pneumonia and death. With that being said, there are just as many animals with “subclinical" infections in our pens. Subclinical, meaning they are "carriers” of the coccidia showing little or no symptoms while ACTIVELY shedding the oocysts! The subclinical carrier is usually the adult animals and the symptomatic ones are the Fawns or the immune compromised adult. A subclinical animal can become clinical when challenged with stress factors reducing their resistance. Stress factors are anything from weaning, shipping. overcrowding, feed change, weather or if the animal is battling another parasitic, bacterial, or viral infection. Fawns are most vulnerable because they lack a mature immune system and are totally dependent on the passive immunity they acquire from their dam’s colostrum. So, poor colostrum intake or ingestion of poor quality colostrums puts these fawns on the “Hit list” to becoming infected with coccidia and many other diseases.

So, HOW do you prevent this disease on your farm? Remember, it is far better to prevent than to treat. Avoid overcrowding, avoid feeding on the ground where there is fecal matter, lime your wet areas, “scoop poop”, and of course having good, healthy does to pass on good quality colostrum. Perform fecal checks on your fawn pens as often as you can!! Like I tell my farms, “you can’t check the poop enough living in the swamp!” DON’T let your guard down; it takes just a “blink”' to acquire a fast spreading infection leading to farm challenges and fawn losses.

How do you treat? This can be quite challenging because you are trying to ensure all the animals in your pen are ingesting the medication you put in their water. When it comes to treating the pens, I like Di-Methox solution or powder. Some of you like Corid. Whatever works best for you, BUT PLEASE READ THE DIRECTIONS ON HOW TO MIX AND ADMINISTER! More is NOT better! In my bottle feds, like Albon first then Ponazuril (Marquis) for my resistant infections. Ponazuril usually needs to be acquired from a compound pharmacy.

So what about coccidiostats to put in the feed? Adding this to feed is a preventative measure by slowing down the shedding of coccidia and is NOT a treatment. Most feed mills now are apprehensive to add to feed since now feed additives are very regulated by the FDA in an effort to restrict drug residue in our food animals. So, It you decide to use coccidiostats, use strategically and consult with your veterinarian!

In conclusion, Coccidia are another infectious parasitic disease that can be a HUGE challenge to a deer farmer and does cause loss of life and production in our industry. But again, with good husbandry and sanitation, outbreaks can be prevented. Check fecals as often as possible especially post fawning in both does and fawns, EVEN if you do not see diarrhea! Any evidence of infection treat ASAP! As I mentioned, it does not take long before you have an outbreak! And as always, observation and early detection is the KEY. And not to sound like a broken record, but “nothing bad ever came from good housekeeping” ...

Laurie Cook DVM
BDRL Whitetail Paradise Farm, Okeechobee, FL