Pleasure Horse 

 Show or Boarding Horse

Encephalitis Annual Annual
Tetanus Annual Annual
Rhino Flu Twice Yearly Semi Annual or Quarterly
Rabies Annual Annual
Strangles Annual Semi Annual
Pneumabort K Show Season
PHF If Traveling
West Nile Annual Annual

Pregnant Mares Have their Own Vaccine Program

Foals Have Their Own Program

De-Worming Program

  • De-worming should be based on each horses specific situation.
  • Roating de-wormers frequently may cause resistance to all de-wormers used.
  • Some infrequent rotation better keeps resistance away.
  • In some situations, frequent de-worming is not necessary
  • De-worming every (Interval Program) 6 weeks is an easy way to remember and a fairly effectly program.
  • Use Strongid, Panacur, Anthelcide or Ivermectin all year; Then use Zimectrin Gold once in December.
  • You will be more effective by worming monthly in the warm months and wet months and minimally in the dry and cold months, than using the regular 6 week program. (Strategic De-worming Program)

(EXAMPLE: 4/15, 05/15, 06/15, 8/15, 10/15 and use Zimectrin Gold in December)

  • Foals and pregnant mares need special de-worming programs.
  • All de-worming programs lose value if not double checking, by testing a fecal in lab (fecal flotation) at least 2 times per year!
  • A good source for other vaccine and de-worming recommendations is the website of the American Association of Equine Practitioners (

A better way to control Equine parasites

Understanding the parasite life cycle- How do horses get worms in the first place?

The most important and damaging parasite in horses are small Strongyles. Adult Strongyles live in the large intestine and the females lay eggs which pass into the environment in the horses’ manure. The eggs hatch n the environment and small wormlike larvae emerge. The larvae will molt twice and the third stage (L3) larvae climb up the blades of grass where they are eaten by a grazing horse. Once ingested by a horse the larvae burrow into the intestinal lining. The larvae can stay in their capsules for a few weeks to a year waiting for the fright conditions to hatch out and repeat the cycle. Large numbers of larvae can hatch at once causing diarrhea that can be fatal. Even small numbers of larvae can cause colic, weight loss, poor growth, loss of condition and rough hair coat.

Because the life cycle involves grazing, stalled horses are at lower risk however, because the encysted stage can last 2 years or longer we still find horses with significant worm burdens that have been in stalls 24 hours a day for over 2 years.

These parasites have evolved for maximum survival. The fecal pile is moist and dark providing the protection for developing larvae. During the hot, dry summer months the larvae will die quickly due to desiccation (drying). The parasites are capable of conserving energy and they can survive northern winters with ease.

How does parasite resistance develop?

Many times it is by error. If a horse weights 800 pounds and you only give him a 750 pound dose the horse will not receive adequate medication and some of the parasites will be left in the intestine. These parasites that have been exposed to inadequate levels of product can develop a genetic code for resistance that they can also pass along to future generation of worms. Some horses make the job of deworming easy while others toss their heads, spit out paste and otherwise do their best not to take their medication. Think about all the times that you dewormed your horse and when you were done there was paste on the horses’ lips, the side of their face and your shoe.  Do you really think that he got the full dose? Or how about the horse that spit the entire tube out, you only had one tube for each horse so you didn’t go back to the store for another? Many farms don’t have a deworming program; horse A is dewormed today, horse B is dewormed 2 weeks later and horse C is never dewormed. The horses are constantly exposing each other and resistance develops quickly in these cases. Let one of those horses move to a new farm and he takes his resistant worms with him depositing the eggs on the new pastures. Once you have resistance to a drug using more the drug is of no benefit. This is why deworming and parasite control should matter to you.

How parasitised are my horse?

A scoring system was developed by parasitology experts: A low shedder has 150 or fewer eggs, a moderate shedder has 150-500 is a moderate shedder and those with 500 or more are high shedders. Approximately 20% of the horses on any farm have good immunity to parasites and these horses will be in the low shedder group, most of these horses only need to be dewormed twice a year. Another 20% of the population has poor immunity and fall in the high shedder classification. These high shedding horses will need to be dewormed at least every 90 days for 4 – 6 times a year. The remaining horses will fall into the moderate shedder classification and will require deworming about 3-4 times per year. By identifying which horses are in which category most owners can reduce their deworming bill in half.

It is important to identify the horses that are at most risk. High parasite loads will cause damage to the intestinal wall and predisposed these horses to colic. In additional the horses that are shedding high numbers of parasite eggs are contaminating your pastures only to be shared with other horses on the farm. Many dewormers on the market have been around for decades. Resistance hs developed as a result of repeated exposure and misuse of these products. The only way to know if a product is working is the test horses after deworming.

  1. Fall is the most important time to test horses to determine which category they belong in, high or low shedders.
  2. Spring and fall are the most important times to deworm horses.
  3. You must test positive horses to know if resistance to a product is present on your farm.
  4. Bring a fresh fecal sample in a zip-lock bag or air-tight container for testing. Keep samples cool until testing.
  5. The best time to test is 4 months after Moxidectin, 3 month after Ivermectin and 9 -10 weeks after Pyrantel or Benzimidazoles.
  6. Test all new arrivals coming to the farm BEFORE you allow them to go out to pastures.
  7. When giving de-wormers be sure to give the right dose.
  8. Only deworm horses that require deworming based on fecal egg counts.

Cook, Charlene B., DVM “A Rational Approach to Parasite Control”. Central Georgia Equine Services Newsletter. September 2009  19 January 2011 <