|Saturday, April 8|
|Saturday, April 8|
|Race 1||Waiver Claiming – $2,500||$6,100|
|Race 2||Waiver Claiming – $4,000||$6,600|
|Race 3||Waiver Maiden Claiming – $8,000||$7,800|
|Race 4||Maiden Claiming – $5,000||$6,400|
|Race 5||Waiver Claiming – $3,500||$6,800|
|Race 6||Claiming – $15,000||$11,300|
|Race 7||Waiver Claiming – $2,500||$6,400|
Reddam Racing’s Irap became the first maiden to win the $1 million Toyota Blue Grass (G2) for 3-year-olds on Saturday, holding off Practical Joke by three-quarters of a length before a crowd of 32,610.
Trained by Doug O’Neill and ridden by Julien Leparoux, Irap covered the 1 1/8 miles on a fast main track in 1:50.39 in the 93rd running of the race. It was the second victory in the race for Leparoux, who won the race in 2013 with Java’s War.
The victory was worth $600,000 to Irap, a Keeneland sales graduate, and also gave him 100 points toward the $2 million Kentucky Derby Presented by Yum! Brands (G1) to be run May 6 at Churchill Downs.
Irap has 113 points and a spot in the starting gate for the Kentucky Derby that is limited to the top 20 point getters that pass the entry box.
Wild Shot took the lead out of the gate and set fractions of :23.79 and :48.34 with Irap in closest pursuit.
On the turn, Irap took over and opened a daylight advantage with Practical Joke making his first move. However, through the stretch, Irap never wavered and held off the two-time Grade 1 winner. Favored and previously undefeated McCraken was another 3 lengths back in third and 2½ lengths in front of J Boys Echo.
Tapwrit finished fifth with It’s Your Nickel sixth and Wild Shot seventh.
Practical Joke picked up 40 Kentucky Derby points to give him 74, McCraken doubled his total from 20 to 40, and J Boys Echo added 10 points to give him 63.
Irap is a Kentucky-bred son of Tiznow out of the Storm Cat mare Silken Cat. Two times graded-stakes placed prior to his victory, Irap increased his earnings to $772,600 with a record of 8-1-3-1.
Irap returned $64.60, $22.40 and $6.80. Practical Joke, ridden by Joel Rosario, returned $5.60 and $3.20 with McCraken, ridden by Brian Hernandez Jr., paying $2.40 to show.
Racing resumes Sunday with a nine-race program beginning at 1:05 p.m. ET. Headlining the program is the $150,000 Adena Springs Beaumont (G3) for 3-year-old fillies that goes as the eighth race with a 4:57 p.m. post time.
J. Paul Reddam (whose Reddam Racing is owner of 31-1 longshot winner Irap. He and trainer Doug O’Neill watched the race from Santa Anita.)
“(When the horses were coming down the stretch) We thought, ‘Oh this is looking good’ and then in the stretch when we saw he actually had a chance, we all just started yelling and screaming. It seemed like the wire was taking forever to get there. When he made the lead I thought that son of a gun is going to hit the board here. Then, about the eighth pole I was thinking man we have a chance to win here because McCraken had backed out of it and a couple other horses didn’t fire for whatever reason. I really have got to say (trainer) Doug (O’Neill) did a fantastic job – he and his team. It’s just fantastic feeling when you don’t think you are going to (win).”
Doug O’Neill (winning trainer)
“He’s a son of Tiznow, and he has a ton of ability. The fact he was still a maiden was kind of unfortunate, but he’s always been a talented horse. (Jockey) Julien (Leparoux) gave him a great ride. Unbelievable.”
“That’s the plan. As long as he stays injury free, that will be our next move.”
Jack Sisterson (assistant to Doug O’Neill, winning trainer of Irap)
“A lot of credit to the Reddams. He (Irap) went to Sunland Park and didn’t run quite as well as we expected. Doug said, ‘This horse is better than this, so let’s send him to Keeneland.’ And sure enough, he showed up on the day.
“Julien (Leparoux) rode him perfect, and it worked out. You have to toy with this horse. He’s such a thinker. As a 2-year-old, he always showed talent. When Julien came to gallop him Wednesday, he said, ‘This is a nice horse.”
“He’ll obviously stay here at Keeneland like Nyquist did last year. (Keeneland was) really accommodating to us with Nyquist here. I really believe horses thrive here at Keeneland.”
Julien Leparoux (winning rider of Irap)
“It’s great (for a horse to break his maiden) in the Blue Grass. The plan was to be sitting second. He was very relaxed. We had the trip that we wanted. He (trainer Doug O’Neill) wanted me to start going at the half-mile pole. He said if a horse came up to him, he might (pull back) back a little.
“(In the stretch) I felt confident but I knew they were coming. He never gave up. I knew he was going to run good. He runs good every race. We talked and we had the perfect trip. It came to reality.”
Joel Rosario (rider of runner-up Practical Joke)
“It was nice where I was and he responded very well turning for home, but it was too tough to beat the horse on the lead. I thought for a second I was going to get him but the winner kept on fighting and had another gear.”
Chad Brown (trainer of Practical Joke)
“He showed a lot of heart. I was disappointed with the trip but that was due to the (outside) post. (Jockey) Joel (Rosario) really didn’t have a chance to tuck him in. The winner really ran a courageous race. He really ran fantastic and I thought my horse did, too. Post is so important and today even though it was a short field, it hurt us because he had to go wide. I am proud of his effort.”
Brian Hernandez Jr. (rider of third-place finisher and beaten favorite McCraken)“We had a good trip. He (McCraken) ran his race, and it was a good third today. He ran with some well proven horses. We will just go on from here.”
Ian Wilkes (trainer of McCraken)
He declined to comment immediately after the race.
Robby Albarado (rider of fourth-place finisher J Boys Echo)
“He got bumped around some, but he ran a decent race.”
Dale Romans (trainer of J Boys Echo)
“I thought we’d win the race, but he ran a credible race. You can go back in history and look at horses that run third or fourth in this race and come back and do well.”
“I was hoping he would move forward off the other (last) race (when he won the Gotham-G3). We’re gonna go. He’s a good horse, and we’ll see what happens. Twenty horses in a mile and a quarter race; a lot of stuff can go right.”
Jose Ortiz (rider of fifth-place finisher Tapwrit)
“He broke well, maybe a step behind. Going into the first turn I was in a good spot behind Rosario (on Practical Joke) so I tried to follow him the whole way. When I tried to keep up with a half-mile remaining, I didn’t have too much horse. I don’t think he liked the track too much. When I hit the backside I was kind of nervous already.”
Todd Pletcher (trainer of Tapwrit)
“He seemed to run kind of flat. I thought he saddled beautifully and behaved really well in the post parade and the gate. He had his head in the air a little bit and missed the break a touch. Then he got stuck four or five wide all the way around there. It seemed like he struggled with the race track a little bit. He just ran kind of evenly and flat the whole way.”
“We’ll see how he comes out of it and talk to everyone, but we feel like he’s that caliber of horse. As long as we don’t find any major reasons (not to), we’ll certainly take him to Churchill (Downs) and see how he trains there.”
Kenny McPeek (trainer of sixth-place finisher It’s Your Nickel)
“You don’t know ‘til you try. We were the second-longest shot on the board and the longest shot won it. My horse is a nice horse. We’e probably going to go a little more conservative with him, and at least we know. We didn’t fail. We learned.”
Corey Lanerie (rider of seventh-place finisher Wild Shot)
“My horse broke well and the plans were if we didn’t see a lot of speed in the race to try and go to the front, and if somebody beat us to it then it was fine to sit off of it. I was loving my trip to the half-mile pole, I thought I had a lot of horse and when the eventual winner (Irap) came to me, I thought, ‘Oh, not this early.’ I thought it was a little early but he won the race so he made the right move. I didn’t have enough to go on with him, but he (Wild Shot) will come back and run another race. He’s a good horse.”
In the morning, Irish War Cry is calm and collected; in the afternoon, sometimes, he can be wound up tight.
In the week leading up to the Grade 2, $750,000 Wood Memorial presented by NYRA Bets, trainer Graham Motion knew he needed to get his chestnut colt to settle down. Motion made a slight equipment change for the race, put his faith in new rider Rajiv Maragh, and nervously sat back and watched to see what would happen.
In a performance that stamped his ticket to the Kentucky Derby, Irish War Cry reverted to the sterling form that won him the Grade 2 Holy Bull Stakes this past winter, stalking the pace in the Wood set by favorite Battalion Runner and taking command in the stretch to draw away and win the 93rd running of Aqueduct Racetrack’s signature race on Saturday.
Off as third choice in a field of eight, Irish War Cry completed the 1 1/8-mile race for 3-year-olds in 1:50.91 on Aqueduct’s main track. Owned by breeder Isabelle de Tomaso, Irish War Cry beat Battalion Runner by 3 ½ lengths.
After the race, Motion struggled to find words.
“That was more like it; I’m speechless,” he said, pausing, excitement in his voice. “I’ve never understood why he would not relax, this horse. He’s very classy, he’s very sensible.”
When he won the Holy Bull in February, Irish War Cry, a New Jersey-bred son of Hall of Fame runner Curlin, knocked off champion Classic Empire and Gunnevera in seemingly effortless, front-running fashion.
The Grade 2 Fountain of Youth was his logical next step, but as a commanding even-money favorite in that race, Irish War Cry chased the pace set by Three Rules and inexplicably disintegrated, finishing 21 ¾ lengths behind Gunnevera.
Motion had no answers, although he believed Irish War Cry was too keyed up to run effectively. Motion returned the colt to his base at Fair Hill in Maryland the week leading up to the Wood, put a Figure 8 bridle on him, and put Maragh on his back three mornings in a row.
“I’ve never had a jockey get on a horse in the morning before,” said Motion, who teamed with Maragh when Main Sequence won the 2014 Grade 1 Sword Dancer Invitational at Saratoga and Grade 1 Joe Hirsch turf Classic at Belmont in that horse’s championship year. “Me and the agent [Tony Micallef] thought it was sensible to do it.”
Whatever he did, it worked. When the gate opened, Irish War Cry broke from his outside post in the field of eight and went three wide as long shot True Timber chased Battalion Runner into the first turn.
On the backside, Irish War Cry settled into a steady stride through a quarter-mile in 23.50 seconds. Maragh allowed his mount to ease up toward Battalion Runner after a half-mile in 47.34, and the race was on.
As the two leaders entered the far turn, Irish War Cry drew abreast of Battalion Runner and the pair dueled into the lane, when the winner moved to the lead with a single left-handed crack of the whip and a vigorous hand ride by Maragh.
“He could have maybe waited even longer,” Motion said of Maragh.
“He was always in a smooth rhythm,” Maragh said. “He relaxed real easily. He did everything I wanted him to do without a lot of effort. He did it all in rhythm. He wasn’t rank at all. He settled beautifully. By getting on him in the mornings, I didn’t think I’d have a hard time getting to settle because he goes so easy and comfortable. We ran good together today.”
Second choice Cloud Computing failed to reach contention and finished third, 3 ½ lengths behind Battalion Runner. He was followed home by True Timber, Bonus Points, Glenrichment, Mo Town and Stretch’s Stone.
Irish War Cry paid $9 for a $2 win bet. In winning the Wood, he earned 100 qualifying points to guarantee himself a starting position in the Kentucky Derby. Battalion Runner picked up 40 Derby qualifying points for his runner-up finish. Cloud Computing finished third, adding 20 points to the 20 he earned for his second-place finish in the Grade 3 Gotham.
Motion said the only decision to make now was whether to work Irish War Cry at Fair Hill before the race or ship straight out.
170 KENTUCKY DERBY QUALIFYING POINTS AT STAKE AS WINNER AWARDED WITH 100
ARCADIA, Calif. (April 8, 2017)–Set down while well off the pace leaving the half mile pole, Gormley kept to his task through the lane en route to a half length win in Saturday’s Grade I, $1 million Santa Anita Derby. Ridden by Victor Espinoza, trained by John Shirreffs and owned by Jerry and Ann Moss, the Malibu Moon colt got the mile and one eighth in 1:51.16 while picking up 100 Kentucky Derby qualifying points.
“I think the key was Espinoza rating Gormley and then making his big move,” said Shirreffs. “This is very exciting. It’s thrilling to have a Kentucky Derby horse and it’s for the same owners as (2005 Kentucky Derby winner) Giacomo. Royal Mo (third place finisher, also trained by Shirreffs and owned by the Mosses) ran really big. If he had a better post position, you wonder how he would have done.”
Fourth in the Grade II San Felipe Stakes here on March 11, Gormley was off at 6-1 in a field of 13 3-year-olds and paid $14.40, $7.20 and $5.00.
“Today, the big difference is that he was ready,” said Espinoza. “He’s really quick out of the gate and today the plan was to take him back and make him run, because it seemed like there was a little bit of speed in the race. I had a little bit of a hard time taking him back but all I had to do was jerk him one time, a bit harder than I wanted, and that’s all it took.
“He relaxed very nice. Down the backside, I started laughing to myself because I knew I was in a good position and I knew all the horses in front of me were going to stop…The only problem is his size. He’s not a very big horse but he’s tough and that’s what I like about him. He works really hard and that’s what it takes.”
A winner of the Grade I FrontRunner Stakes in his second start on Oct. 1, Gormley took the Grade III Sham Stakes two starts back and now has three graded stakes victories included in an overall mark of 6-4-0-0. With the $600,000 Derby first prize, he now has earnings of $920,000, while his stablemate, third place finisher, Royal Mo, banked $120,000 and collected 20 Kentucky Derby qualifying points.
“It’s been such a great time bringing both of these horses up and they both came through beautifully today,” said Jerry Moss. “It was fantastic to see Royal Mo do so well today. Gary (Stevens) rode him perfectly. He was the pacesetter for a while even…We’re just delighted.”
Ridden by Corey Nakatani, Jerry Hollendorfer’s Battle of Midway pressed the issue throughout and finished second, a half length in front of Royal Mo. Off at 7-1, Battle of Midway paid $7.80 and $5.40.
“He ran really well,” said Nakatani. “I wish we could’ve gotten a breather at some point, but it didn’t work out that way. He ran dynamite.”
Royal Mo, who broke from the far outside, pressed the pace along with Battle of Midway and Reach the World, and prevailed by a half length over Reach the World in the end. Off at 11-1, Royal Mo paid $7.60 to show.
Fractions on the race were 22.66, 46.55, 1:10.92 and 1:37.55.
Note: Along with 100 points being awarded to the winner and 40 to the runner-up, 20 Kentucky Derby qualifying points went to the third place finisher and 10 were awarded to Reach the World, who ran fourth.
|April 8 – Santa Anita|
|Doc Curlin||Wgt-120||Race 1||Allowance Optional Claiming $40,000|
|Dog Gone Lenny||Wgt-123||Race 3||Maiden Special Weight|
|Radish||Wgt-120||Race 4||Evening Jewel S.|
|Mopotism||Wgt-121||Race 6||Santa Anita Oaks (Gr 1)|
|So Conflated||Wgt-124||Race 8||Santa Anita Derby (Gr 1)|
|You Missed It||Wgt-120||Race 9||Providencia S. (Gr 3)|
|Green With Eddie||Wgt-124||Race 10||Echo Eddie S.|
|April 9 – Santa Anita|
|Blabimir||Wgt-122||Race 3||Claiming $25,000|
|April 7 – Santa Anita|
|Ocean Dream finished 5th beaten 5 1/4 lengths||Race 5|
All those tubes of anthelmintics (deworming drugs) look pretty similar lined up on a store shelf, but the drug classes within them vary significantly. How do you know which type of dewormer to choose and whether the one you’re administering to your horse is doing its job? We’ve learned that each horse and farm requires an individualized parasite control program, but confusion about words like benzimidazole and cyathostomin likely still exist.
It is important that you know what these terms mean, the basic characteristics of common equine parasites, as well as the main mechanisms of action and effects of the common deworming compounds. So we’re here to help.
While there are great differences among the important internal parasites, they share a fundamentally similar life cycle: They all spend part of their lives in the horse and part of their lives in the environment.
A quick review: Adult worms live and lay their eggs in the horse’s intestine. These eggs pass from the horse into the environment with the manure. On pasture, the eggs hatch over time, releasing larvae that develop to a point at which they are “infective” and a horse ingests them, bringing us back to how the worms gained access to the intestines in the first place. The infective larvae mature within the horse into adult worms, and the cycle repeats.
“In the environment, parasite eggs flourish and develop into infective larvae when temperatures are between 45° and 85° Fahrenheit,” explains Martin Nielsen, DVM, PhD, Dipl. EVPC, ACVM, co-author of The Handbook of Equine Parasite Control, chair of the AAEP Parasite Control Subcommittee, and an equine parasitologist, veterinarian, and assistant professor at the University of Kentucky’s Gluck Equine Research Center, in Lexington. “When these conditions exist during the year depends on location, but one thing we know is that eggs and larvae actually survive much better in cold than hot conditions. There is no such thing as a killing frost for these parasites.”
Large strongyles Historically, veterinarians considered the large strongyle Strongylus vulgaris (bloodworm) to be the most important equine parasite. Bloodworms were common, and they caused a life-threatening problem in horses called thromboembolic colic, in which worms enter, damage, and block the arteries that supply blood to segments of intestine. Over the past 40 years, much of our parasite control efforts went into eliminating these worms, and to a great extent we were successful. Thromboembolic colic, and bloodworms, are now rare in managed horse populations. But those same efforts have caused severe drug resistance in other worm populations.
Small strongyles (cyathostomins) These parasites are common in almost all horses. They are small, threadlike worms that can sometimes be seen in manure after deworming. Small and large strongyles share the classic life cycle described, but small strongyles show one important difference: Their larvae burrow into the intestinal wall and stay there for extended periods in a dormant state until the environment is optimal for reproduction, at which time they emerge. This makes the species more adaptable. It also protects them from most of our deworming compounds, which cannot penetrate the intestinal wall well enough to kill the encysted larvae there. Small strongyles are now resistant to many of our common dewormers. The only good news is that these parasites do not cause severe disease unless they are present in extremely large numbers.
Ascarids One of the most important parasites in young, growing horses is Parascaris equorum, a large, pale roundworm resembling a bean sprout. This parasite is primarily of clinical concern in horses younger than 6 months old; adult horses can ingest ascarid eggs, but their acquired immunity prevents infection.
Ascarid eggs are extremely hardy in the environment, living for years on pasture. When temperatures warm above 45°F, the larvae develop to an infective stage within the eggs that the horse ingests. The eggs are coated with a sticky substance that enables them to adhere to all types of surfaces, including fences, walls, and the mare’s udder. Mouthy, curious foals can pick them up from these surfaces or as they nurse. Once ingested, the eggs hatch in the small intestine, and the larvae penetrate the intestinal wall and enter the bloodstream. They enter the liver, travel to the lungs, and then back to the intestine, where they grow to be adults and lay eggs. The whole cycle takes about 2 ½ months.
These parasites are not actually worms but the larval stage of a fly that looks a bit like a honeybee. Botflies buzz around horses’ legs and lower bodies, depositing their sticky pale eggs on the hair. Horses lick areas where the eggs have adhered, ingesting them in the process.
Once consumed, the eggs quickly hatch within the mouth, and the larvae burrow in the tissues and stay there for several weeks until the horse swallows them and they attach to a very particular location within the stomach, where they spend the winter months. When conditions are right in the spring, the larvae release and are passed into the environment in the manure. They burrow into the soil and pupate, emerging later as adult flies to lay eggs and repeat the cycle. Our sources say the internal larval stages of bots probably cause no real problems for horses. The biggest problem associated with bots is likely the annoyance the adult flies cause.
The only dewormers that control bot larvae are moxidectin and ivermectin. But aggressive use of these drugs to eliminate bots might also increase resistance in other parasites.
Doug Thal, DVM, Dipl. ABVP
In large numbers, these parasites can cause ill thrift and poor growth. When you administer a dewormer to a heavily parasitized youngster, large numbers of these worms can die simultaneously in the intestine and drift downstream, forming a tangled mass that blocks the intestine and causes severe abdominal pain. This life-threatening episode is known as ascarid impaction. Managing and cleaning the environment where foals reside helps reduce the number of eggs they ingest, but it is almost impossible to prevent infection in young horses altogether.
Pinworms Unlike the parasites described previously, pinworms do not cause serious disease. Pinworm adults live in the colon. Instead of laying eggs that are passed into the environment through manure, female pinworms actually leave the intestine and lay their eggs on the skin of and around the anus. The eggs irritate the skin there and cause itchiness. In rubbing his tail base and anus on stall walls, fences, trees, etc., the horse deposits the eggs back in the environment. The next horse to lick the object will ingest the eggs, and the cycle will repeat itself.
Historically, pinworms were primarily a problem in younger horses, but today they are seen more in adult horses, too. “There is evidence that pinworms are developing drug resistance and new approaches to managing them are needed,” cautions Craig Reinemeyer, DVM, PhD, president of East Tennessee Clinical Research Inc. and co-author of The Handbook of Equine Parasite Control.
Tapeworms These are very different from other equine internal parasites, and most of the common dewormers do not affect them. One important difference is that tapeworms have an indirect life cycle; they must spend time within a second “intermediate host,” a tiny oribatid mite, to complete their circuit. These mites live in large numbers on pasture and ingest tapeworm eggs that horses shed in manure. The eggs hatch into larvae within the mites, and the larvae grow.
Grazing horses inadvertently eat the mites containing the infective larvae, and during equine digestion the larvae are released and travel to a specific location within the intestine—the point at which the large and small intestines meet (called the ileocecal valve). Here the larvae mature into adults over six to 10 weeks and begin shedding segments containing eggs that are passed in the manure.
It’s difficult for veterinarians to detect tapeworms. “They are usually not diagnosable using fecal floatation techniques, and the available blood tests have some problems, too,” says -Reinemeyer.
The mites live only on moist, growing pasture, so these areas are more prone to harbor tapeworms, and drylot situations and arid environments generally aren’t affected. Tapeworms are thought to contribute to a condition causing colic—irritation and blockage of the ileocecal valve area where they gather. But they can live in small numbers there and usually not cause a problem.
|Parasite||What Horses it Affects||Prevalence||Health Concerns it Causes||Drug Resistance|
|Large strongyles, bloodworms (Strongylus vulgaris)||All horses||Rare in managed horse populations||Severe colic, thromboembolism (blood clots in the arteries), and intestinal damage||No reported resistance|
|Small strongyles (cyathostomins)||All horses 6 months of age and older||Widespread throughout the United States, but more prevalent in moist environments.||Weight loss, lack of appetite, diarrhea, fever, lethargy, dull hair coat, poor performance, etc.||Widely resistant to benzimidazoles, somewhat resistant to pyrantels, early evidence of macrocyclic lactone resistance|
|Tapeworms (Anoplocephala perfoliata)||All horses 6 months of age and older||Widespread throughout the United States, but more prevalent in moist environments.||Ileocecal impactions and spasmodic colic||No reported resistance|
|Roundworms, ascarids (Parascaris equorum)||Primarily foals younger than 6 months||Widespread on breeding farms||Airway inflammation, small intestinal impaction, ill thrift, poor growth||Widespread macrolide lactone resistance, early evidence of pyrantel resistance|
|Pinworms (Oxyuris equi)||All horses||Widespread but less common in managed adult horse populations||Intense tail rubbing, skin irritation around the anus, pruritis||Reported resistance to several classes, some macrocyclic lactone resistance|
|Threadworms (Strongyloides westeri)||Primarily foals younger than 4 weeks||Widespread throughout the United States, but more prevalent in moist environments.||Possible unthriftiness, diarrhea||No reported resistance|
|Bots (Gasterophilus spp.)||All horses||Widespread during summer||Annoyance||No reported resistance; however, most anthelmintics are ineffective against insects|
Property management techniques are the true cornerstone of effective parasite control and are more important than drug administration. There are many management points to consider, (See “Creating a Parasite Control Program“), but here we will focus on the common anthelmintic drugs used in horses:
Benzimidazoles A class of compounds called benzimidazoles have been a mainstay of equine parasite control for more than 40 years. These chemicals interfere with worms’ energy metabolism on a cellular level, causing a slower kill of the parasites than the so-called paralytic compounds we’ll describe next. Examples of benzimidazoles include fenbendazole (Panacur) and oxibendazole (Anthelcide EQ). These continue to have good efficacy against ascarids, but small strongyles are now mostly resistant to this class. For this reason, use these drugs primarily in foals.
Pyrimidines These drugs (pyrantel pamoate/tartrate, known by the trade name Strongid) act at the junction between parasites’ nerve cells and muscle cells, causing paralysis and rapid kill of worms. Pyrantel does not penetrate the intestinal wall and, so, will not kill encysted strongyles or any parasite stage outside the intestine. There is now significant resistance to pyrantel among strongyles. Pyrantel comes in several forms: a paste, a fluid, and at low levels in a pellet (continuous dewormers like Strongid-C). Double-dose pyrantel is labeled for tapeworm treatment, with no evidence of resistance. It is generally very safe for all ages and classes of horses. While some study results have implicated continuous dewormers in resistance development, Reinemeyer estimates they still might have a niche role “for selected horses on the farm, for a selected time period, but never for life.”
Macrocyclic lactones (ivermectin and moxidectin) Ivermectin has been around for about 30 years and has been our most relied-upon dewormer, but now there is evidence that certain parasites are developing resistance to it.
Ivermectin and moxidectin also work by paralyzing worms. But unlike the other drug classes, macrocyclic lactones also kill external parasites such as lice, mites, and larval skin forms involved in summer sores. Moxidectin can penetrate the intestinal wall and kill encysted strongyles, and it probably is the most effective compound for this purpose.
“Diatomaceous earth and other ‘natural’ products have to date not been shown to effectively kill parasites.”
Dr. Craig Reinemeyer
Praziquantel This drug kills only tapeworms and is currently marketed in combination with either ivermectin or moxidectin. Praziquantel is probably also being overused, especially in regions that have very few tapeworms.
Other compounds “Diatomaceous earth and other ‘natural’ products have to date not been shown to effectively kill parasites,” Reinemeyer adds. If you rely on these products, you might be putting your horses at risk.
With these basics in mind, consider your own unique circumstance and ask yourself some questions: What is your current deworming program and how do you evaluate its efficacy? Have you changed your approach as the industry has become more aware of drug resistance? Have you done all you can do to reduce the number of worms your horses ingest? What worms are likely to be a problem for your horses, given your geographic region and management?
By understanding worms and their life cycles, along with the drugs used to combat them, you can take a smarter approach to parasite control, helping slow the onset of drug resistance while still protecting your horses’ health. Work with your veterinarian to develop a targeted parasite control plan tailor-made for your situation.
Doug Thal, DVM, Dipl. ABVP, is an equine veterinarian with 18 years experience in clinical practice. Thal Equine (www.ThalEquine.com) is his full-service equine hospital near Santa Fe, N.M.