Dr. Chris Riley

The new veterinary school at Roseworthy is currently in the process of hiring staff and building their facility.  One of the newest faculty is Dr. Chris Riley. 

He is an Australian who taught in Canada for many years and then migrated back to Australia.  His expertise is large animal surgery.  He is helping veterinarians in our area with difficult cases and showing us some surgical techniques. 

He is a very knowledgeable source of information, and a second or third opinion.  Here he is showing Alison how to do a surgery. 

Chris is fun to work with and we really appreciate his input with a few cases here at APEC.

Fractures or broken incisors>>

Roundworms

In talking to Dr. Mary Carr of Primary Industries I found out that she is seeing a large increase in ruminant parasitism this year.  She attributes this to the sequential heavy rains we have had all summer that have kept the eggs going in what normally would be a very dry environment.  The equine parasites will most likely follow suit.
So enter a nice 8 month old colt with a very recalcitrant respiratory infection.  He was one sick weanling.  He was referred to us to do follow-up from treatment for the infection.  He was better, but he still had an ongoing infection.   His history included several recent wormings for a known sighting of parasites in his feces. 
The common most visible parasite is round worms or ascarids or Parascaris equorum if you want to get technical.  This is what they look like when a horse passes them:
Figure 1 freshly passed roundworms

They are about 5 inches or 12 centimeters long and round just like good fishing worms.  Tape worms can look like that but they are flat.
Round worms pass eggs that on a fecal flotation examination look like this:


Figure 2 Roundworm eggs (4 brownish in color)

The life cycle is typical in that the hardy eggs are shed and the foal picks them up often in the breeding or foaling shed and the larvae hatch and migrate throughout the body, but especially through the liver and lungs and then the larvae return to the intestine where they mature into the worms you see in the first picture.  Those worms reside in the intestine, and in large numbers can obstruct the intestine and cause colic and death. 

There is some suspected resistance to the ivermectin dewormers but the accepted treatments for roundworms include: ivermectin and the benzimidazoles including fenbendazole and oxibendazole and even daily wormers such as Wormtec 30 may play a role in preventing larval migration and killing adults.  The recommended interval to worm is variable but if you see adult roundworms or the eggs with fecal examination then the damage is done and the larvae have migrated through the horse.   Most foals should receive their initial worming after two months of age.  The maximum interval  between worming in foals should be two months.
Another method of reducing worm burden is to pick up the feces in the paddocks twice weekly.  The good news is that most horses develop immunity to roundworms in their first year of life so that it is rare (but not impossible) to have round worms in adult horses.
 
Our case of the “respiratory weaner” started to pass these adults after being on daily wormer for two days.  The daily wormer will not kill migrating larvae so foals also need one of the other products.  Most likely his immune system was down due to chronic infection and the overwhelming worm burden. 
The bottom line is that foals and weanlings need to be monitored and wormed regularly and we all need to be aware of the potential increase in parasites due to environmental factors that favor the parasites this year.  Don’t be blaming Al Gore for this one; not that blaming Al Gore for a few things isn’t all bad, but the worm thing was around for a lot longer than global warming…. Don’t get me started.