Dr. Tara's Trip to Nicaragua

In January 2017 I had the chance to travel to Nicaragua with a World Vets team to provide health care to working horses.  My team included vets, students, techs and volunteers from around the world. In four days we provided care for almost 500 horses! These horses are working animals that are loved by their owners and are used to pull carriages and haul food and water for their families.  The group trimmed feet, floated teeth, castrated, dewormed, provided wound and eye care and treated anything else that walked into the clinic! It was tiring but rewarding work with a fabulous group. I can't wait to go back!  Visit more about this organization at  http://worldvets.org/

Tara O'Brien, VMD



OSPHOS Overview

OSPHOS is a type of drug known as a bisphosphonate drug.  Bone constantly undergoes turnover in response to the current level of stress it is experiencing. Osteoblasts are cells that form new bone and Osteoclasts are cells that reabsorb bone.  The activity of the these two types of cells are in balance in normal bone. In abnormal bone or bone that is undergoing stress remodeling this balance is disrupted and can result in more bone being absorbed than can be laid down.  We can sometimes see the results of this imbalance on radiographs as lytic areas or even bone cysts; sometimes we also see abnormal bone that is sclerotic. MRI can also identify bone that has bruising or edema that cannot be seen on radiographs.  Bone that has this abnormal remodeling can be very painful. The active ingredient is OSPHOS is clodronate; it reduces the number of active osteoclasts reabsorbing bone and alters calcium metabolism in bone. What does this all mean?  That OSPHOS can improve bone pain associated with abnormal bone remodeling.   In a study of horses diagnosed with navicular disease with nerve blocks and radiographs 74.7% of horses were improved at least one grade of lameness by day 56 after treatment with OSPHOS with some improving up to 3 grades.  Only 3% of horses that were not given OSPHOS improved. 

How is it administered?

OSPHOS is given intramuscularly in three different injection sites. 

Are there potential complications?

All bisphosphonates have the potential to cause gastrointestinal and renal toxicity.  

We recommend observing your horse for 2 hours after the OSPHOS injection for signs of colic (pawing, rolling, looking the side, sweating, nervousness, ect).  If your horse does exhibit signs of colic we recommend hand walking for 15 minutes or until resolution or if your horse is with us we will give him or her sedation.  In the initial study 9% of horses showed signs of colic; they all resolved with minimal treatment. 

Because bisphosphonates are excreted through the kidney it is not recommended to administer it along with other potentially nephrotoxic drugs or to administer it to horses with known impaired kidney function.  What does this mean for your horse?  We will not give OSHPOS with NSAIDs such as bute, banamine, or previcoxx and we ask you to not give these medications to your horse for at least 3-7 days before and after the OSPHOS is given. Additionally we can check the kidney function with a blood test if there are concerns about your horse. Also we can give the OSPHOS with fluids to decrease its effect on the kidneys.  And we will ask you to observe your horse for increased drinking and urination after OSPHOS administration. 

Some pain at the injection site has also been observed in a small percentage of horses. 

Overall we have personally seen very few sides effects with OSPHOS. The most common side effect we have observed is abdominal pain immediately after administration.  In all cases it resolved with hand walking or sedation. 

When can my horse be treated again?

If  your horse improved but  it did not last for 6 months, treatment can be repeated at 3-6 month intervals. If you horse improved and it lasted at least 6 months it can be repeated whenever clinical signs are observed again.

Thank you for using Oakhurst Equine! Please call with any questions or concerns. We offer 24 hour emergency care if any complications arise. 

Tara O'Brien, VMD

The Importance of a Prepurchase Examination

You’ve watched the videos on-line, gone and ridden the perfect horse for you, and are so excited to bring him home!  But, wait!  What should you do first?  A Prepurchase examination.

While some may caution you that this is just a waste of time and money, let me explain why it is not.

You are investing in something that you want to use, hopefully for years to come, and be able to do the job for which you are buying him.  How do you know he will be able to do that?  While no exam is infallible, and we cannot see into the future, what we can tell you is if there is any problems with the horse today that looks like it will hinder his ability to do his job.

So what does a thorough pre purchase examination entail?  There is no standard exam form that is out there.  Every Veterinarian has his/her own way of performing this type of examination but there are basics that should be included.  They are:  a thorough physical examination including assessment of the eyes, teeth and oral cavity, heart, lungs, skin, weight and body condition scoring.  Palpation of limbs, back, neck, application of hoof testers, a neurological exam, and notations on feet, shoeing, and conformation.  Evaluation of the horse in motion, on hard surface, soft surface and even under saddle where appropriate.  Performance of dynamic flexion tests of all four limbs.  Breeding soundness exams if you are intending to breed the animal.  This encompassing examination is usually extensive and can take over an hour alone to perform.

At this point, you and your Veterinarian can determine if additional information is needed.  Pre purchase exams do not always include radiographs, but may be an important part of the process.  After all, you are trying to protect your investment.  And our patients cannot tell us, “You know, doc, sometimes it hurts here…”  What imaging, such as radiographs or ultrasound, can tell us is if there something underlying that may not be causing pain or lameness at this time, but can put the horse at increased risk for having problems in that location in the future.  Without imaging, I cannot see into a joint or ligament and know if there is anything in there that may be a problem.  Additionally, in young horses that may not have a lot of miles on them, some may have some developmental issues with the bones, tendons or ligaments, which may show lameness only once they are put into some serious work.  Many people choose to not radiograph young horses, because they are young and have not done anything yet, but this may be a mistake.  It also may change how you feel about purchasing a horse for a particular job.

What about resale or insurability?  These questions often come up when purchasing a horse in order to train and resell it down the road.  If you do not know what is going on with the joints and the next buyer does decide to radiograph to horse and finds a problem, then it will affect resale.  You will want to know before buying what is happening to prevent a surprise in the future.  Even if the horse does not show lameness now, it may affect its future performance or resale value.  The insurance companies will also want to know about any predisposing conditions, especially if trying to insure your horse for loss of use.

Buying a horse can be an emotionally charged situation when you’ve already fallen in love with them.  A pre purchase exam will help bring to light any problems this horse may have that will affect his ability to do his job from a third party prospective that is not emotionally invested in the horse.  It is not the Veterinarian’s job to pass or fail a horse, but merely to point out any problems so you may make an informed decision on whether or not you want to purchase this horse.

Often times, a horse that is presented for a prepurchase examination has a subtle (or not so subtle!) lameness that maybe the seller was not aware of.  At this point, I usually stop the examination and explain to the buyer that this no longer is a pre purchase exam and is now a lameness examination.  The purpose of this is twofold.  One, it is the responsibility of the seller to present a sound horse.  If the problem is solved and it was a minor issue, then the buyer may wish to look at the horse again in the future to see if it still meets their needs.  Two, the onus of finding the cause of the lameness is on the seller, not the buyer.  If the buyer chooses to continue and “work up” the cause of the lameness, then, at the end of the day, they have paid to solve the problem on a horse they do not own.  It should be the seller’s responsibility to solve the lameness and present a sound horse to the buyer.  This is another reason the pre purchase examination is so important.

There are many additional items you, as a buyer, can request during a prepurchase exam, such as routine blood work, drug screens, Coggins test, endoscopic exams if the horse is making a breathing noise when it exercises, and more in-depth imaging, etc.  Discussing your concerns about a particular horse, intended use, resale or insurance needs, and financial constraints are important to discuss with your Veterinarian before you get started.

With a thorough exam, a pre purchase exam will help you make the most informed decision you can about an investment that should last for years to come.


Sylvia Ouellette, DVM dip ABVP (Equine)


Shipping horses across state lines or internationally

“Help, my horse is leaving for fill in the state tomorrow and the hauler says I need a health certificate!!.”  We as Veterinarians are often called to examine a horse that will be “leaving tomorrow” to go to another state.  While we understand that life gets in the way and there are many things to consider when you are preparing to move your horses, you need to plan ahead for this situation.

As much as it may be an emergency to you, we cannot make the lab run the necessary bloodwork any faster.

In order to write a health certificate, or Certificate of Veterinary Inspection, for interstate transport in the United States, we first need to obtain a negative Coggins Test on your horse and examine your horse to make sure it is healthy enough for transport.  Already have a Coggins Test completed within the last 6-12 months?  Then yes, we can examine your horse, fill out the paperwork and you can be on your way shortly.  (Some states differ on whether they require a negative test 6 OR 12 months from date of travel)

If you do not have a completed Coggins Test, then that is a different story.  Coggins testing can performed by a couple different methods.  Agar gel immunodiffusion (AGID) is the “gold standard” for Coggins testing and when you are transporting horses internationally, that is usually the required method.  The test can take 3-4 days minimum to get the results back, and you will need the original Coggins paperwork sent with the health certificate for transport.  The other way is with a c-ELISA test, which is usually quicker and can be completed sometimes within 24-48 hours, depending on the proximity to the lab in order to get the original paperwork back on time.

Coggins testing is for the disease Equine Infectious Anemia.  Why is this disease so important that the United States of America wants every horse tested that is being transported?  Because it is a potentially fatal viral disease with a high degree of morbidity (highly contagious) in horses, donkeys and mules with no known cure.  This disease was thought to be eradicated within the US, but now isolated cases every year have been turning up.  When horses are diagnosed with this disease, they are usually humanely euthanized due to the disease and to prevent spread.  Horses that survive become chronic shedders of the virus and would need to remain on lifelong isolation to protect others around it.  To keep the USA free of this disease, the government instituted this protocol to protect the horse population. 

What does Equine Infectious Anemia look like?  Some of the clinical signs may include:  fever, depression, weight loss, anemia and petechial (pinpoint sized) hemorrhages on the mucous membranes, swelling of legs, lower chest and abdomen, decreased appetite, fatigue, rapid weight loss, or nasal bleeding.  Transmission is usually by blood or in-utero passage from a mare to a foal.  Blood transmission can occur by blood-sucking insects (such as horse flies, deer flies and mosquitoes), or by blood transfusions or contaminated needles.

Equine Infectious Anemia is a reportable disease.  If positive, your horse must be reported to the state Veterinarian and the federal Animal and Plant Health Inspection Service (APHIS).

When traveling internationally, we need even more time to get your paperwork together.  In addition to a Coggins test, many countries have additional diseases that require testing.  Also, the paperwork will need to be sent to a USDA office for approval prior to shipping which can take an additional week to obtain.  Please plan accordingly.

If you are unsure about requirements, please call your Veterinarian’s office.  They will be able to help you plan, call the states you will be traveling to in advance to acquire the necessary permit numbers and protocols necessary.  Good communication and planning will help to make your travels worry free.


Sylvia Ouellette, DVM dip ABVP (Equine)



September 6, 2016

Class IV Laser Therapy

by Sylvia Ouellette, DVM, Diplomate ABVP

Laser therapy has been around for decades but has gained popularity in equine medicine in the last few years. What is laser therapy? Lasers use light energy to stimulate the tissue in the body to heal. The unit of energy that is delivered is a Joule. Each laser is designed at a different Wattage and wavelength that will deliver the Joules that you need depending on the amount of time used on a specific area. Cold lasers are defined as a laser that delivers 0.5 Watts or less. Anything over 0.5 Watts is considered a class IV laser. Surgical and cutting lasers are also in the same category as class IV. At our clinic we utilize a 15 Watt Class IV laser. It allows us to deliver therapy with a deeper tissue penetration and in a shorter amount of time. Research has determined how many Joules are needed to treat certain problems in the horse and that is what dictates how long and what Wattage we need to use. Why do lasers work? The simplified version is that the cells absorb light and stimulate the mitochondria within them to produce Nitric Oxide (among other factors) which increases energy production and initiates a cascade of local and systemic therapeutic signaling which increases cell activation, growth factors, inflammatory mediators and expression of protective anti-apoptotic (anti-cell death) proteins. The results of this cascade of events is what leads to increased healing in chronic wounds, decreased inflammation and pain reduction. Lasers are helpful in reducing inflammation in both acute and chronic conditions, such as tendon and ligament inflammation or tearing, chronic osteoarthritis, and joint or tendon sheath swelling. We have also had great success in healing extensive wounds and lacerations with minimal swelling in a reduced amount of time. The wound below is an example of healing using only Class IV Laser therapy in the areas that could not be sutured. No skin grafting was necessary to close this wound, and other than daily bandaging, the laser helped to reduce the inflammation and continue to help the skin heal over the gaping wound within only a couple of months. 


Picture number 1 is the original injury - June 16, 2016. Note the bone is exposed. Picture number 2 you see tissue is completely covering the bone - July 6, 2016. And in Picture number 3 only a small portion is left to heal - September 1, 2016. 

Call Oakhurst Equine Veterinary Services to inquire about our Laser Therapy protocols and to see if your horse is a candidate for Laser Therapy. 503-554-0227.

September 5, 2016

parasite pop quiz! 

by Flynn Magorian, BVMS

Dear Oakhurst clients,  we have a little quiz for you, do you know your parasites? Are your horses on the best program possible? Get ready for some true/false questions and answers. Please don’t hesitate to call us if you have questions, we can help you come up with an effective worming protocol.


  1. Large Strongyles are the most dangerous parasite for horses. True or False?

  2. There is a single wormer that kills all equine parasites.  True or False?

  3. It is better to underdose my horse than overdose on dewormer.  True or False?

  4. Horses naturally aquire immunity to Ascarids (round worms) after 18 months of age. True or False?

  5. The best way to manage pastures is to spread manure on them. True or False?

  6. Hot dry weather kills parasite eggs better than freezing temperatures. True or False?

  7. Small strongyles are becoming resistant to all available dewormers. True or False?

  8. All horses on the same property will have the same worm burden. True or False?

  9. A negative fecal exam means I never need to deworm my horse. True or False?

  10. I’ve always used the same product, it works, so i don’t need to change it. True or False?

  11. Moxidectin (Quest) should not be used on foals less than 6 months. True or False?



1. Large Strongyles are the most dangerous parasite for horses. False

Almost all dewormers effectively kill large strongyles, therefore they are quite rare and pose little threat to regularly dewormed horses.


2. There is a single wormer that kills all equine parasites.  False

Moxidectin plus praziquantel (Quest Plus) works well against encysted small strongyles, large strongyles and tapeworms. But does not work well against ascarids in foals, especailly as it should not be used on foals less than six months. It is also important to switch classes of wormer to prevent resistant worms from developing on your property.


3. It is better to underdose my horse than overdose on dewormer.  False

Underdosing horses leads to resistance by only killing the most susceptible parasites and leaving the strongest ones to reproduce.


4. Horses naturally acquire immunity to Ascarids after 18 months of age. True

Young horses are very susceptible to ascarid impactions, and should be wormed regularly with fenbendazole (panacur) at a 10 mg/kg dose for 5 days in a row to kill them.


5. The best way to manage pastures is to spread manure on them. False

Spreading manure on your pastures can actually increase the parasite burden on your farm, unless the weather is hot and dry enough to effectively kill all the eggs.


6. Hot dry weather kills parasite eggs better than freezing temperatures. True

More parasite eggs are killed in hot dry weather then freezing temps.


7. Small strongyles are becoming resistant to all available dewormers. True

The adult version of small strongyles are fairly easy to kill while the encysted form are only susceptible to moxidectin, for the time being


8. All horses on the same property will have the same parasite burden. False

Younger horses often have higher worm burdens because they have less immunity, and just like people, some horses have less immunity and some have more.


9. A negative fecal exam means I never need to deworm my horse. False

Fecal egg counts can quite often have false negative results, meaning that they come back negative but testing a different fecal ball or a different pile of manure from your horse would actually have a positive result.  Knowing that, all horses should be wormed a minimum of twice per year.


10. I’ve always used the same product, it works, so i don’t need to change it. False

Using the same product over and over breeds resistance in your parasite  population. It also doesn’t kill all stages and types of parasite. Rotating wormers and using the appropriate one for the age of your horse is important.


11. Moxidectin (Quest) should not be used on foals less than 6 months. True

Horses less than 6 months of age have a higher incidence of adverse reactions, including ataxia, depression/lethargy and recumbency.  Very old and very thin or sick horses should also avoid moxidectin.

August 31, 2016

New Hats

Visit our contact page to order. $15.00 each. 

August 2016

Dr. Jack's Baby Pigletts! 

reserve yours - visit our contact us page 

August 2016

new! Visit our office to see what we have on our shelves! 

Platinum Performance Products


Oakhurst-Grindstone-Giacomo Hats

Ask for Platinum Performance Samples and a $2.00 off Coupon on Zoetis Wormers!

July 2016

We have a new website!

Let us know what you think!? Email us your suggestions and send a picture of you and your horse doing what you love most! We want to make our website an interesting place to visit and provide educational topics and links with the kind of information you want to know more about! We look forward to hearing from you!

Dr. Flynn Magorian, Editor