How often should you deworm a horse?

Answer 1

Deworming A HorseThere is no one-size-fits-all worming program for horses. The "every 6-8 weeks" deworming program that has been in use for 30 years was layed out to target mainly a specific type of parasite that was the most problematic back then but that is no longer the main concern. It was also layed out with different deworming drugs in mind. This program is no longer the most effective or most appropriate deworming program. Most horses only need to be dewormed from 2-4 times a year to control parasites. The number of dewormings and the times to deworm will be based upon environmental conditions, the horses own immunity to parasites and the management practices such as keeping a horse stalled or picking up feces out of paddocks at least every other day. To determine an appropriate deworming program, horse owners should discuss their horse keeping situation with their vet and have fecal egg counts performed to determine which of their horses typically shed large numbers of parasite eggs and which tend to control their parasite burden with little chemical assistance. For the US this means that after the spring deworming in the northern US or fall deworming in the southern US a fecal sample should be collected and tested and the number of parasite eggs per gram of feces determined. If the horse was last dewormed with ivermectin, this sample should be taken 3 months after deworming. If the horse was last dewormed with moxidectin, then the sample should be taken 4 months after deworming. (These time periods allow for egg shedding to have begun again after the effects of the last deworming.) Then based upon the rate of egg shedding of each horse, a deworming program for that particular horse can be layed out. Many horses require deworming no more than twice a year to minimize parasite loads.

You should deworm every six weeks and ensure you are rotating dewormers to prevent wormer immunity.

Answer 2

The recommendations for deworming horses have changed in the last few years. Due to the widespread development of parasite resistance to two of the 3 families of dewormers commonly used and the fact that the old "deworm every 6-8 weeks rotating dewormers" plan was based on targeting a specific parasite that is no longer the main threat and on the use of old dewormers and doesn't take into account the effects of the currently used broad-spectrum dewormers, the current recommendation is to deworm strategically. This means focusing on the times of year when parasites are an issue based upon geography/environmental conditions and on deworming AS NEEDED based upon fecal egg counts.

It is known that horses can develop quite strong resistance to certain parasites when mature and around 50% of adult horses maintain low parasite burdens with a minimum of deworming. Another 30% tend to carry moderate burdens and need to be dewormed slightly more frequently and 20% are high egg-shedders and need to be dewormed around 4 times a year. Foals are a different story and recommendations for them are based upon their increased susceptibility to parasites.

The choice of dewormers is also more complicated than "just rotate" because in more than 90% of areas tested world-wide, strongyles (the main parasite of concern in adult horses) are resistant to fenbendazole (panacur) and in around 50% of areas they are resistant to pyrantel (strongid). So the only drug choices still highly effective for strongyles are typically ivermectin and moxidectin which are in the same drug family. Fenbendazole and pyrantel should ONLY be used in situations where fecal egg counts have been done prior to dosing and again 10-12 days after dosing to determine that they are still effective in a given population/herd.

The basics of deworming are that all horses should be dewormed spring and fall for bots and tapeworms, therefore with a combination of either ivermectin and praziquantel or moxidectin and praziquantel. Beyond that, fecal egg counts need to be performed at specific intervals (3 months after dosing with ivermectin or 4 months after dosing with moxidectin) to determine if any further deworming is necessary during the season when parasite reinfection rates are highest. Whether or not to deworm is based upon the number of eggs per gram of feces with over 200 eggs per gram bein moderate and indicating need for further deworming and over 500 eggs per gram indicating a high burden and likely a horse with a lower resistance to parasites. Seasonal conditions in which parasite reinfection rates are going to be high are when temperatures exceed 45 degrees but are lower than 85 degrees Fahrenheit. So for climates where winters are snowy and cold, deworming is typically not recommended during the winter months and in climates where the summer is extremely hot, deworming is not typically recommended. This is because the weather controls parasite reinfection rates at those times and the goal is to minimize the use of deworming drugs to help slow the development of resistance to the drugs that we have as there are no new deworming drugs set to hit the market anytime soon.

If we don't minimize our use of chemical dewormers by practicing strategic deworming, we will end up with parasites that are resistant to all of our deworming drugs before we have anything new to use.

These recommendations are based upon Dr. Craig Reinemeyer's presentation at the 2009 American Association of Equine Practitioners conference. These are for adult horses. Again, foals are more susceptible to parasites and besides simply concentrating on strongyle control, we must also concentrate on ascarids. Ascarids are showing resistance to ivermectin and pyrantel...add that to the resistance of strongyles to fenbendazole and pyrantel and you see that it is more difficult to plan a deworming program that is going to be effective for foals because of the chance that the drugs you are using may only target one of the two common parasites of foals.

Answer 3

The frequency for deworming horses depends on their age, their environment and their own natural resistant to parasites.

Horses under 18 months of age need to be dewormed frequently because they are more susceptible to parasites, the parasites have different life cycles and because parasites have been developing resistance to the commonly used deworming drugs. This means that in order to treat all the likely parasites infecting young horses, different dewormers need to be used at different times to effectively control infections.

Adult horses tend to be more resistant to parasites and 50% or more of adults require deworming only twice a year (spring and fall), for small strongyles, bots and tapeworms as well as less common parasites in certain situations. Other adult horses do not develop as strong an immunity and may need to be dewormed 3-4 times a year.

Some environments and management practices also help to reduce the chances of reinfection with parasites. Very hot (over 85 degrees Fahrenheit ), dry climates reduce the survival time of infective small strongyle larva in the environment. Stalls are also poor environments for parasites and horses kept in stall are less likely to be reinfected. Removing feces from paddocks/pastures at least every other day reduces the number of parasite eggs and larva in pastures, thus reducing reinfection risks. Rotating horses off of pastures for 6 months or more also reduces reinfection risks for small strongyles because infective larval stages don't survive indefinitely.

Ascarids are the exception to hot, dry environmental conditions and time significantly reducing reinfection. Ascarid eggs can survive for 10 years or more in the environment and area concern for young horses and very old horses.

Horse owners need to base deworming decisions off of the results of fecal egg counts, environmental conditions, horse age and seasonal parasite risks. It is also important to know what deworming products are effective against what parasites and what products have resistance issues in a particular area. An equine veterinarian should be consulted to assess each horse and determine an appropriate deworming regimen.

Answer 4

You should deworm your dog at least every four months. This could depend on what parasites are relevant in the area that you live. Many places in the United States see dogs with heartworm infections and a monthly heartworm prevention is ideal. These preventions also deworm dogs for other parasites which could include tapeworms, hookworms, roundworms, and whipworms.

Answer 5

You shoud worm your horse every 6 weeks. You should also rotate your wormers as not all wormers will kill all types of worms. Rotating wormers also will keep worms from developing a resistance to any particular worming drug.

Answer 6

It is generally recommended to de-worm a horse every 2 months (or 6 times a year). Depending on your area, you may not need to de-worm your horse as often. Speak to your vet to see what they think.

Answer 7

How often a horse should be dewormed depends on age, environmental conditions, management practices and the horse's own resistance to parasites. Deworming programs should be designed for each horse based upon a consideration of the risk factors for parasites for that particular horse, including the results of fecal egg counts which help to determine an individual horse's reinfection status and natural resistance to parasites. Immatures horses (under 18 months) are less resistant to parasites and often require frequent deworming, but adult horses may need as few as 2 dewormings a year or as many as 3-4 dewormings a year.

Horse owners should consult their veterinarian to determine an appropriate deworming program for their horses.

Answer 8

How often a horse should be dewormed depends on age, environmental conditions, management practices and the horse's own resistance to parasites. Deworming programs should be designed for each horse based upon a consideration of the risk factors for parasites for that particular horse, including the results of fecal egg counts which help to determine an individual horse's reinfection status and natural resistance to parasites. Immatures horses (under 18 months) are less resistant to parasites and often require frequent deworming, but adult horses may need as few as 2 dewormings a year or as many as 3-4 dewormings a year.

Horse owners should consult their veterinarian to determine an appropriate deworming program for their horses.

Answer 9

How often you deworm a horse will vary according to the horse itself and the parasite load it may be carrying. To determine if you should deworm you need to do a Fecal Egg Count Test (FECT) to determine if the horse has a parasite load and if so what type of parasites it is carrying. Once the test results come back you'll know if the horse needs to be dewormed. If so you'll also know which deworming drug (anthelmintic) to choose. After you have dewormed the horse you should then do a Fecal Egg Count Reduction Test (FECRT) to see if that particular dewormed was effective or not. This should be done twice a year at minimum.

Also, regardless of if a test comes back clean you should use a product containing Praziquantel once a year during the fall to kill off possible tapeworms as they don't typically show up on FECT's/