The Case of the CoRid Caprine

Although I thoroughly enjoy helping treat dogs and cats of all various shapes, sizes, and breeds, seeing multiples of the same treatment or procedure throughout the week can sometimes become a bit monotonous.  It's times like these that I enjoy the rarity of a case involving a species other than a canine or feline.  We had such a case at the clinic this weekend involving a caprine, otherwise known as a goat.  The owner showed up at the clinic with the goat lying in the back of his truck.  It was in very poor shape, thrashing around in the bed and bleating pitifully.   The owner explained that he had taken the goat to another clinic where it had been diagnosed and treated for coccidiosis.  Coccidiosis is a disease caused by coccidian infection.  It is a parasitic disease of the intestinal tract of animals caused by coccidian protozoa.  The parasite is passed through fecal-to-oral contact and thrives in overcrowded, dirty, wet pens and unclean water.  The disease is very contagious and will quickly spread throughout a herd causing diarrhea (sometimes bloody), dehydration, and fever.  The owner confirmed that many other members of his herd had been affected by the disease as well.  The owner had been prescribed CoRid (amprolium), a coccidiostat commonly used for the prevention and treatment of coccidiosis.  The owner's goats began to improve while using the CoRid, but once again began to decline in health.  After hearing this explanation, the veterinarian knew exactly what the problem was.  He concluded the goat was suffering from polioencephalomalacia, otherwise known as polio or stargazing.  My interest in the case immediately heightened upon hearing this diagnosis.  Having learned about polioencephalomalacia in an animal nutrition class this past semester, I was interested in just how a coccidiosis infection had stemmed into polio.  The veterinarian explained that although CoRid is commonly used to rid of coccidiosis, if not dosed properly it can cause the problem we were seeing right before us.  The drug is a thiamine (vitamin B1) analogue and blocks the thiamine transporter.  By blocking thiamine uptake it prevents carbohydrate synthesis, which in turn lowers the supply of carbohydrates to neurons in the brain.  The neurons require carbohydrates as an energy source which is necessary for proper nerve function.  Without an adequate supply of carbohydrates neurological disorder and neuronal death occur.  Thiamine deficiency is one of he main causes of polioencephalomalacia, which is characterized by dullness, depression, convulsions, uncoordinated muscular movements, temporary blindness, abnormal posturing with head thrown backward accompanied by rigidity, and teeth grinding.  The goat clearly showed almost all of these signs.  The veterinarian felt that the condition had been caught early enough for successful treatment.  He administered thiamine intravenously and sent the owner home with instructions to give thiamine injections intramuscularly every 3 to 6 hours.