Monday, April 16, 2018

New School of Thought on Parasite Management

         Often as the Small Ruminant and Equine Extension Agent I get calls regarding horses and parasites. In recent years the industry has begun to see a shift in the way we approach and handle internal parasites of many species, particularly horses.  In the past, parasite management in adult horses was largely based on knowledge that is now considered to be outdated. The purpose of this article is to discuss the new approach to parasite management in adult horses. It is important to note that these are merely researched based suggestions and it is still important for one to work closely with their veterinarian in developing a farm specific parasite program.
         In order to fully understand the scope of the parasite issue, horse owners must understand the parasites at hand, dewomers, and resistance. It is important to understand why these changes in parasite managment have occurred. Recent research has demonstrated the following:
1.    Switch in type of parasite focus. Large strongyles have for the most part been eradicated and new parasites of focus are small strongyles and tape worms. A recent survey performed in the Southeast United States, focusing on small strongyles, found that 95% of herds demonstrated a resistance to panacur, 53% of herds were resistant to Anthelcide ® and 40% of herds were resistant to Strongid ®. Horse owners should note that small stronglyes affect all grazing horses so focus should not be for complete eradication but rather to treat only when needed. Small stronglye parasites are low pathogenic, meaning they only produce a disease when parasite loads are high.
2.    Increase in anthelmintic (dewormer) resistance across the board, which is the ability of worms to survive treatment; this problem has occurred due to old school of thought where one should rotate type of dewormer every two months and the lack of accurate dosing resulting from not having a true weight of the horse.
3.    Adult (over age of 3) horses vary greatly in regards to needing to be dewormed due to immune response.

Dewormers can be grouped into 3 drug classifications: Benzimidazoles, Pyrimidines, and Macrocyclic Lactones. Knowing the drug classification of a dewormer can help owners to stop rotation of dewormers.  The table below denotes these classifications and common horse dewormers that fall into their category.
Drug Class
Common Dewormers
Fenbendazole (Panacur ® ) and Oxybendazole
Pyrantel (Strongid ® )
Macrocyclic Lactones
Ivermectin and Moxidectin (Quest ® )

         There are many factors to consider when developing a parasite management protocol for your farm. When working with your veterinarian these are a few things horse owners should take into consideration:
1.    Ivermectin is a larvicidal (will kill larvae) and a boticide. If used every 6 months large strongyles will be eliminated from your farm. It is equally important when introducing a new horse on farm one should deworm them immediately, stall them for a minimum of 4 days to prevent worm contamination.
2.    Horses develop an immunity to roundworms.
3.    Eggs can last for years in the environment so preventing contamination is essential.
4.    Perform fecal egg counts. Fecal egg counts will provide one with the type of parasites and load of parasites. Knowing what worms and how many are present one can determine how to treat or even if treatment is necessary.
5.    Fecal egg count reduction tests can provide horse owners with information necessary to determine if a dewormer is still working on farm.
EPG = Egg Per Gram
                EPG Pre-treatment – EPG 14d post-treatment  x 100 = FECRT      
                           EPG pre-treatment
6.    Products containing praziquantel (Equimax ®) are effective against tapeworms. Tapeworms are carried by the pasture mite which dies after first hard frost. So, deworming with a product containing praziquantel is recommended yearly.
7.    Pasture management is a vital aspect of parasite management. Overpopulating and overgrazing pastures will inevitably lead to parasite transmission. Picking up manure piles in pastures instead of dragging them are now considered better options to reduce contamination. 

Monday, April 9, 2018

Common Pasture Pond Weeds

If you are noticing green, floating material in your pasture pond during this time of year, you are not alone.  Chances are this floating green mess is one of two things: duckweed or watermeal.  These plants seem to disappear in the late fall, but they overwinter on the bottom waiting until the spring to resurface.  Both plants reproduce quickly so it is important to take action promptly or risk de-oxygenation of the water, which leads to fish kills.   These plants spread easily on the feathers of water fowl, the coats of cattle or other livestock as well as on boats, paddles and other equipment.  Please refer to the bulleted list below for help identifying and treating the problem in your pond.  

·      Free floating
·      1/8 to ¼ of an inch in width
·      Roundish in shape
·      Single (hair-like) root hanging from each plant
·      Recommended Control Methods: Diquat or Fluridone

  • Free floating
  • Less than 1mm in diameter
  • Rootless
  • Feels gritty when rubbed between fingers
  • Recommended Control Method: Fluridone

For more information on these plants or any other aquatic weeds and their control, please contact your local Cooperative Extension Office.  As always, when using chemicals to control weeds, make sure to follow the directions on the label and observe the fishing, swimming, and drinking restrictions.

Monday, April 2, 2018

Fescue Toxicosis

Almost everyone that owns a horse is aware that the endophyte-containing tall fescue variety, Kentucky 31, and pregnant horses (or any breeding animal for that matter) don’t mix, but few people know why.  Kentucky 31 tall fescue is the most commonly grown fescue type in North Carolina.  It has been used as a forage for over 50 years and is one of our most hearty and resilient grasses.  It is a cool season, perennial grass that is resistant to drought, overgrazing and is quite nutritious.  It is also one of the most commonly used grasses for soil stabilization due to its extensive root system.  Unfortunately the property that makes the grass so hearty is also what affects the animals that graze it.  Kentucky 31 contains an endophyte fungus that causes the grass to survive and thrive where most other grasses would not, and also causes vasoconstriction along with many other health issues in the animals that eat it.  The constriction of blood vessels can cause poor thermoregulation (including heat stress), loss of limbs due to poor circulation, low feed intake and rate of gain, low birth weight and weaning weight, birthing problems, poor reproduction and poor milk production in all livestock species.  

In pregnant mares there are a whole host of reproduction related problems that are caused by fescue toxicosis.  Abortions may occur around the time the mare is expected to foal.  She may have a prolonged gestation period, sometimes by as much as 30-40 days, which can cause major birthing issues due to the foal continuing to grow over the extended period.  Thickened placenta and retained placenta can be caused by fescue toxicosis.  Most commonly however, is agalactia, or poor milk production, as previously mentioned.    

These are obviously major issues that we want to avoid, so most farms with broodmares either avoid fescue all together or do their best to manage their livestock on it.  Replacing toxic fescue with a novel-endophyte fescue is the most recommended management tool.  In the past, it was recommended to replace the Kentucky 31 with an endophyte-free variety of tall fescue, but since the endophyte is what makes the grass so great, in recent years there have been several different varieties of tall fescue developed that contain an endophyte but not the endophyte that is toxic; we call this novel-endophyte fescue.  This gives us the best of both worlds, a hearty, nutritious grass that we do not have to worry about letting our animals graze.  Converting your toxic fescue pastures to novel-endophyte pastures is a long term project, but can be accomplished relatively easily.  Contact your local extension office or Soil and Water office to find out how to get started.  If completely renovating your pastures is not something that seems like an option for your farm, dilution can make a difference in toxicity levels.  You can dilute the Kentucky 31 by overseeding with legumes or another cool season grass such as Orchardgrass or Brome.  This will at the least cut down on the amount of toxic fescue that your horse in ingesting.  The last management tool is to simply remove the pregnant mare from the tall fescue pasture during the last 60-90 days of gestation.  This means either putting her on a pasture composed of another grass type or dry-lotting her.  In either case she should be closely monitored for signs of fescue toxicity.

If you think you may have fescue toxicity issues on your farm you should contact your vet immediately.  Getting a management plan together by working with your vet and your local extension agent is key to finding what will work best for your farm.

Tuesday, March 27, 2018

Introducing Horses to Spring Pasture

As the weather starts to feel like Spring, grass is beginning to break dormancy and horses will have access to green pastures.

Read the following article for tips on introducing horses to spring pasture.

Monday, March 19, 2018

Algae in Horse Troughs

Since temperatures are starting to rise, you’ll start to see an increase in algae growing in your horse tank.  Algae needs three things to be successful.  They are water, sunlight, and a nutrient source.  The nutrient source could be from any organic material that has blown or gets dropped into the trough such as manure or horse saliva.
While most algae don’t pose a direct health concern, certain types of blue-green algae release toxins that can lead to colic and scours.  Large amounts of algae might make the water less palatable to your horse which could lead to reduced water intake.  Keeping algal blooms to a minimum in your troughs is always a good idea.  Some solutions to your algal problem could be shade, chemicals, barley straw, biological control, or scrubbing.
Placing a shade structure over troughs can help reduce sun exposure, therefore slowing algae growth.  However, this incurs a cost and time and might not work in all trough locations.  For chemical control, unscented chlorine bleach can be added to troughs at a rate of 2 to 3 ounces per 100 gallons of water.  Chlorine burns off gradually in the heat, so you will need to repeat this weekly.  You can also add copper sulfate to reduce algae growth.  It comes as a blue crystal and often needs to be dissolved in warm water before being added to the trough.  For a 300-gallon trough, dissolve half a teaspoon in 1.5 ounces of warm water, and then pour the solution into the trough.  You’ll want to mix it up really well just like with chlorine before the horses are allowed to drink it.  If your horses share their water trough with other animals, you want to remember that copper is very toxic to sheep!  Do not use copper sulfate if your horses share their water source with sheep.  Zinc sulfate is another option.  You can dissolve 1 cup in 1 gallon of warm water before adding to a 100-gallon trough.  There are other commercial additives to kill algae in troughs.  Many include copper sulfate as an ingredient.  Always follow the label on any chemical, not only because the label is the law, but also to keep your animals safe. 
Although not fully understood, when submerged in water and exposed to sun, barley straw emits a chemical that slows algae growth.  It won’t kill existing algae, but will prevent new growth.  How quickly it works depends on the water’s temperature, with it taking several weeks at 50o Fahrenheit but only one to two weeks when water temperatures rise to about 70Fahrenheit.  University Researchers recommend using about 10-25 grams of barley straw per meter of surface area.  Don’t add more straw than this if fish live in the trough, because it can deoxygenate the water, and will kill your fish.  Place the straw in netting and anchor it at the bottom of the trough.  Premade balls are available for purchase from most pond supply stores.
Adding gold fish to your troughs can help reduce algae, although in areas with abundant bloom the fish might not be able to keep up.  Regular gold fish are fairly cheap and work well.  Some people like to use plecostomus, which are known algae eaters.  If you’re using fish, keep in mind that oxygen availability in a trough is often low and might not support very many fish.  Troughs need to be deep enough so the water does not become too hot, and ice will need to be broken daily in the winter.  You will need to check your trough often for dead fish that might release toxins into the water.  Don’t forget about them when you turn your trough over to clean it by hand.  They are also sensitive to the chlorine found in county water.  You will need to put them in another container and let the chlorine dissipate from the fresh water for several days before returning the fish back to the trough, so that you don’t kill them.
Emptying and scrubbing troughs is very effective, although time consuming. Use a scrubbing brush or old stiff grooming brush for best results, and rinse out before refilling.  This is my personal choice for algae removal on my farm, because it is cheap.  Whatever method you decide is best for your situation, working to maintain algae-free water will help keep your horse drinking this spring and summer as the temperatures continue to rise.