Hormones Play A Role In Foal Rejection 

Foaling can be a high-stress situation with a lot of variables that may go wrong, from dystocias to ill foals. Though most mares have an innate mothering mentality, some mares reject their offspring and the exact reason is unclear, making it difficult to prevent.

Drs. Dalia Berlin, Amir Steinman and Tal Raz conducted a study using eight Arabian mares who behaved normally after foaling and 15 Arabian mares who typically “rejected” their foals. Rejection includes refusing to let the foal nurse, indifference toward the foal and even attacking the foal. The Arabian was chosen specifically  for the study as rejection behavior in mares has been well documented in the breed.

Each mare had blood drawn at the first and third day after foaling; the blood was tested for progesterone, prolactin and estradiol, which are reproductive hormones. The most significant difference between the two groups was the estradiol-to-progesterone ratio the first day after foaling was significantly lower in mares that rejected their foals than in mares with normal maternal behavior.

The exact role the hormones play in maternal behavior is unclear, but the ratio of hormones in mare that rejected their foals increased in the three days post foaling, suggesting that the hormones may normalize and the rejection behavior may diminish.

The study team notes that the creation of hormonal treatments for rejecting mares is premature as the optimal concentration for each hormone is yet unknown.

Read more at EQUUS.

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Small Strongyles Showing Resistance To Last Effective Class Of Dewormer

Martin Nielsen, DVM, Ph.D., Dipl. ACVM, Schlaikjer professor of equine infectious diseases in the Gluck Equine Research Center, presented his research on small strongyles at the University of Kentucky's Equine Research Showcase in February.

He spoke about current data showing resistance among cyathostomins (small strongyles) to the three main groups of anthelmintic (anti-parasitic) drugs.

“The small strongyle parasite, which is the type of parasite that all horses get, is the primary parasite category, the one that we are always deworming for,” Nielsen said.

The first class of anthelmintic drugs introduced and administered to combat small strongyles was the benzimidazoles in the 1960s. Because this class of drugs has been in use the longest, there is  wide-spread resistanceto these drugs.

“It is very rare to find these products still working,” Nielsen said.

Pyrantel salts began experiencing resistance in 1996 and Nielsen said it is also likely to find small strongyles resistant to Pyrantel dewormers today.

Macrocyclic lactones (ivermectin and moxidectin) are our “last resort,” with good efficacy, but there have been some questionable early signs of emerging resistance reported, according to Nielsen. In 2020, routine data collected from a farm in Central Kentucky confirmed resistance to macrocyclic lactones among small strongyles.

Nielsen shared data showing that macrocyclic lactones were 100 percent effective against small strongyles in a group of U.S.-bred yearlings, but the same dewormers administered to a group of imported, Irish-bred yearlings failed to remove small strongyle parasites.

“There's no doubt, looking across this data, that we have clear-cut, proven resistance to ivermectin in these imported parasites,” Nielsen said. “The problem is, if we have resistance to everything, what can we deworm with?” he said.

He described that the efficacy of moxidectin was also evaluated against the resistant parasites. Despite this drug being potentially more potent than ivermectin, it did not overcome the resistance and did not provide better efficacy.

Nielsen closed with a final note that ivermectin and moxidectin resistance is occurring in small strongyles. This case was only discovered due to the meticulous testing procedures in place on this particular farm. Without regular testing of deworming efficacy, drug resistant parasites will go undetected and farms will be left without opportunities to intervene before it is too late. Good parasite control starts and ends with testing the dewormers being used and this must be done every year.

Read more here.

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Scientists Discover A Genetic Anomaly In European EHV-1 Outbreak

The EHV-1 outbreak in Europe and the United States has many horse owners on high alert. As there is no definitive reason why some horses become ill and others don't, it's imperative that all horse owners manage their barn as though an outbreak is possible.

Multiple European laboratories testing recent samples of the equine herpes virus have found an anomaly with the positive samples: the virus doesn't contain the N752D amino acid substitution in the DNA polymerase, which has previously been associated with neurological disease.

Lab employees are working to identify which genetic group these samples belong to. This will assist in tracking virus spread and differentiating it from the other EHV-1 strains in circulation. Past research has shown that there are 78 strains of EHV-1 that have been isolated over the last 35 years and most neurological isolates had the N752D substitution.

The FEI Veterinary Epidemiology Working Group reported that the virus is expected to remain in circulation as EHV-1 spreads more slowly than other equine diseases like equine influenza. The group also advised that to safely conduct equestrian events, event organizers and competitors take certain extra precautions. Event size should be restricted, pre-travel health certificates should be issued, and events should encourage health monitoring and separation between horses.

Read more at HorseTalk.

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The Blueberry Bulletin: A Young OTTB Learns His First Lessons In Retirement, And Teaches A Few

This is the first installment in a series following the early training of OTTB Underscore, fondly known as Blueberry. Blueberry was the subject of a popular column in the Paulick Report soon after editor-in-chief Natalie Voss adopted him via the Godolphin Lifetime Care Program in late 2020. You can read about his origin story here. 

If you like a good OTTB training series, check out our Thoroughbred Makeover Diaries series, which tracks Jonathan Horowitz on his road to the 2021 Retired Racehorse Thoroughbred Makeover here.

Although I have spent many years writing about off-track Thoroughbreds (OTTBs), working professionally with on- and off-track Thoroughbreds, and cheering on friends with their OTTBs at horse shows, Blueberry is the first Thoroughbred who has been all mine.

When I took an internship and later a part-time job at the Secretariat Center some 13 years ago, the whole notion of working with off-track racehorses was somewhat different. Many people with OTTBs believed they needed to “restart” them, taking them back to the very beginning of training and almost rebreaking them to saddle, as if the experience would be entirely new and overwhelming for the horse otherwise. Now, from what I understand, the philosophy has shifted – it's best to capitalize on what the Thoroughbred already knows. They have been ridden before, they've trailered frequently, and they've been groomed, bathed, clipped and handwalked extensively through their lives. This isn't the same as starting a green horse, and the training trajectory shouldn't be the same.

Until now, my education as a horse owner comes from a Percheron/Thoroughbred cross mare named Jitterbug who I started under saddle when she was five years old and eventually brought through the lowest levels of eventing, dressage, and jumpers. She was a case who had to be taken from the ground up. Jitterbug was a formerly feral horse who spent her first three years with little to no human contact, and that has drastically impacted the way she has progressed in her training. Accepting a saddle and rider was no problem for her; taking instructions like 'Trot' and 'Turn' was a personal affront. She reminded me loudly and often that she was bigger, smarter, and faster than I am, and that working with me was always her choice and not her obligation. Some of this is down to being a mare, but a lot of it is down to having grown up independent of human kindness or authority. It took years and lots of help of my esteemed trainer Stephanie Calendrillo of Graystone Stable to even begin trotting crossrails, let alone polish her into the productive citizen she is today.

I already knew that Blueberry would have a different concept of the horse/human relationship and as we have begun our early ground work, he indeed tries very hard to do what he is asked. We've learned to lunge, ground drive, long line, walk forwards and backwards over poles, and have conquered minor skepticism of tarps, plastic, puddles, tires, umbrellas, and pool noodles – all with great ease. I think part of his success, besides his very hands-on beginning, was that I entered into each new task with some idea of what aspects could be new or unsettling for him, but behaved as though I expected him to be familiar with the new task.

Most racehorses haven't been crosstied in a grooming stall before, but this is common practice in riding stables. Almost all of them have become used to standing quietly while tied to the back wall in their stalls in the mornings, though. The main difference, I reasoned, would be pressure on two sides of the halter instead of one, but the principle would be the same – Blueberry should know that this was time to stand quietly, and that if he hit the slack on one tie, he could move himself easily to relieve that tension. On our first afternoon, I clipped him in, ensured the quick release hardware worked, and pulled the barn door closed just in case he became upset and broke out. Then I went to work grooming him as though this was perfectly ordinary. The first time he stepped to one side and felt the tension increase, I gently tapped his shoulder to direct him to move sideways to create slack. From there, I let him figure it out—and he did. We'd spend short periods in the grooming stall at first, and gradually increased our time there, sometimes taking a break from grooming for me to put equipment away so he would see that this is a time for relaxation.

Blueberry on his first day of long line work

We've progressed this way with each new obstacle or task, and through a combination of a great brain and past experience, he has met every expectation with minimal confusion and almost no anxiety.

That doesn't mean my years of study have left me without fault, of course. I had some idea of what to expect from a retired Thoroughbred based on my past experience, I thought, but I believed I came into the process relatively free of faulty preconceptions about what the experience would be like.

Well. Horses have a way of teaching you things about yourself that you didn't realize you needed to know, and mine has already taught me that I came in with a lot of management stereotypes in the back of my brain. Here are a few of the ones Blueberry pointed out by proving them wrong:

  • Thoroughbreds will struggle to gain weight. Blueberry arrived in late November with some race fitness to him still, about four weeks after his last breeze. For my purposes, I wanted him to gain a little weight but he didn't need much. He was going onto 24-hour turnout, and I assumed that with winter looming it would be an uphill battle to improve his condition even a little bit. In roughly a month, he looked fantastic with two modest grain meals a day. Granted, he lost some ground again during the extreme cold and precipitation in February, but made it up again similarly easily.
  • Thoroughbreds may struggle in extreme cold if they enter turnout mid-winter with a slick coat. I got a light sheet for Blueberry in December but found my draft mare's clothes were way too big for him so I had didn't have a ton of different blanket choices to work with at first. I worried about this — would he shiver and shake without a puffy medium weight and neck cover? No, as it turned out. In fact, he runs warm and even before his winter coat grew in, I had to be more cautious about letting him get overheated with a blanket than too cold without one.
  • Barefoot Thoroughbreds will immediately and constantly abscess and chip their feet, especially in a wet winter. Blueberry arrived barefoot and my plan is to keep him that way as long as I can to let his soles toughen up before he begins under saddle work in another couple of weeks. So far we've had one bruise in four months and while I anticipate he'll need shoes when he starts real work, that's a much better record than I thought we'd have.
  • Horses, including Thoroughbreds, are bonkers for treats. Did not imagine this was a misconception, but Blueberry tells me with great authority that only red and white mints are treats. Carrots, apples, horse cookies, green and white mints, and even candy canes (yes, that's right – a mint in a different shape) are not edible and must be thrown out of a grain pan immediately.

I believe that no matter what type of work you're doing, horse training is a two-way street: if the horse isn't also teaching you something, you're probably doing it wrong. So far, Blueberry is a patient, kind teacher and I hope to be the same for him as we progress in our journey together.

For more of Underscore's OTTB journey, follow his Facebook page.

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