Saskatchewan Equine Dentistry - MacKinnon Equine Services - Grant MacKinnon, Certified Equine Dentist

Grant MacKinnon is a certified equine dentist and one of only a handful of qualified dentists traveling and specializing in equilibration or three-point-balance. MacKinnon received his training from the Academy of Equine Dentistry, one of a few specialty schools, located in Glenn's Ferry, Idaho.

MacKinnon is committed to his dental practice and notes, "proper dental care with regular maintenance is such a small part of the overall investment we make to ensure a comfortable and cooperative riding companion".

For the purpose of substantiation, two text were chosen.

Equine Dentistry 1999, DVM G Baker, DVM J Easley (PDF scan 8,16)

Equine Dentistry: A Practical Guide 2002, DVM P Pence (PDF scan 1,2)

January 15, 2010, Grant MacKinnon performed dentistry on (name removed) horse at her request. He reduced protuberant lower 6 ramps, protuberant lower 11 ramps, 2/4 wedge smile mouth (removed 11/32" (8mm) of incisor) rounded and smoothed buccal/lingual rims safely within the following text book allowances.

In order to correctly address dental abnormalities,a horse dentist must understand anatomy of the horse and the growth and development of horse's teeth. Dr. Deb Bennett (highly respected paleontologist at the Smithsonian Institute) claims the horse's tooth is inert by age 15. Both texts speak to substantiate this claim. DVM Pence, writes that there is no blood supply after eruption (p11, scan2) and that the pulp chamber disappears by age 6 (p16, scan3) and DVM Baker and DVM Easley also provide an easy to understand comparison between human teeth and horse's teeth, claiming the lack of sensitivity in a horse's tooth is due to calcification, "fully obliterated". (p14, scan9).

"The goal of floating is to remove sharp points and round the upper buccal and lower lingual edges of the teeth. When finished, these edges should be rounded and smooth. Proper floating reduces discomfort caused by sharp edges when the horse is chewing..." or bridled (page 65, scan4,5,14)

There is a great deal of instruction available on incisor reduction. "Diamond cut off wheels are recommended when more than 2mm of tooth needs to be removed" (p108, scan6). The following graphic illustrates the relation between the cheek teeth and the incisors (p110, scan7).

"Diamond cut off wheels are very effective when a large amounts of incisors must be removed" (p200, scan11). Page 201, (scan12) is a good visual of (name removed) horse's teeth before dentistry January 15th, 2010.

"Incisors should be shortened to where the lateral excursion to molar contact (the distance the mandible is moved laterally before the upper and lower incisors start to separate) is between 5-10mm but should never remove more than 10 mm at one time". (p203, scan13)

"Proper bit seats are imperative for performance at all levels. All buccal cusps and margins should be clean and smooth". (p192, scan10,14)

The lampas is part of the horse's circulatory system (cushion of skin located on the roof of his mouth). The horse lowers his head to nip and chew grass, when his head drops below his heart, it is designed to pump blood back to the heart. "The lampas follows the growth of the incisors".

Confirmation of the above facts can be found in many, many other text. In order to maintain the integrity of material provided by the author, all references are provided as full page scanned PDF attachments.

Grant MacKinnon disputes that he has done anything wrong or improper or that in any way improperly treated (name removed) mare. In order to establish this, he requested from (name removed) to allow an independent, third party take photographs so that he has a fair opportunity to review the matter and refute any suggestion of improper treatment. As of todays day, (name removed) has refused access and instructed the barn owner to respect her wishes (as per direct e-mail contact: "I am sorry, I am caught here in the middle and cannot give you her personal information or access to her horse without her consent. Cheryl".

(name removed) implies Grant's certification is invalid, which is not true. Since the school in Glenns Ferry changed hands a few years ago, Grant started to focus his continuing education efforts toward IAED (International Association of Equine Dentistry). He is scheduled to attend courses again this year in Las Vegas, March 5,6,7. The Academy of Equine Dentistry recently included IAED's continuing education format, but they haven't re-posted Grant's name. He has faxed continuing education documents to their office a couple times. Nonetheless, Grant graduated and certified at the Academy of Equine Dentistry, one of a few specialty schools, located in Glenns Ferry, Idaho.

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January 17, 2010, 9:47 a.m. (name removed) called the MacKinnon Equine's Calgary office to schedule three more horses in for a dental appointment;

January 17, 2010, (name removed) called later in the p.m. Grant returned (name removed) call, complaining that "her horse had not eaten for three days" and that "the nerves were exposed in the teeth"; he made arrangements with (name removed) to meet her at the barn the next evening;

January 18, 2010, 6:26 p.m. Grant met (name removed) at Diamond Willow Horse Boarding Facility, Cochrane AB. (name removed) complained that the horse had not eaten in three days (Grant's observations: horse was in good condition, no evidence of dehydration or starvation) ... She stated she was worried that the incisors did not come together (Grant manually showed (name removed) that the incisors did in fact come together and that the horse was putting his tongue between her molars holding the incisors apart -- a common behavior when conducting an oral examination) ... (name removed) noted a concern with excessive salivation while riding (Grant explained that the reorganization of the propreception takes some individual horses longer to adjust) ... (name removed) mentioned that the horse was unable to eat hay (Grant observed the horse was normally eating hay that night) ... (name removed) said that the bit seat was excessive (when Grant explained about bit seats, (name removed) stated that her horse was not a reining horse, and did not need a bit seat -- bit seats: Grant gradually rounds the #6 tooth at an angle so that the pouchy flesh of the bars, cheeks or tongue does not get pinched between the bit and the tooth, when the rider engages the action on the bit) Because the main concern was focused around the horse's inability to ingest food, or water of any kind, Grant took the following pictures before leaving that night;

In MacKinnon's opinion, these are not pictures of a horse that has been unable to eat or drink for three days.

January 27, 2010 Grant received the following e-mail (MacKinnon's initial response is in red text)

From: (name removed)
To: (name removed)
Subject: Equine Dentistry Gone Wrong (the following information is now posted on (name removed) Facebook page, and (name removed) continues to refuse MacKinnon an opportunity to publicly respond to her accusations.)
Date: Wed, 27 Jan 2010 17:21:26 -0700

To all my horsey friends,

You are receiving this email because I feel very strongly that the pain that my best equine friend is enduring should not be repeated with your horse. I can only hope that by sharing my experience you have the opportunity to learn from my mistake. Following are the events that have transpired over the past week during what I thought was a routine floating:

Day 1) Call from my stable and learned that my mare Sierra was now being floated at 9:00pm rather than 9:00am by Grant MacKinnon. If (name removed) was interested in watching the dental procedure why was she not in attendance at 9:00 a.m., or anytime thereafter? It is important to Grant that horse owners be in attendance while their horse's teeth at are being worked on so he can spend time explaining the differences they will experience the days following the dental procedure. I would have been there for the procedure had I known it had been rescheduled around my working hours. Grant did not have addresses or telephone numbers to contact owners, the barn made all the arrangements.

Day 2) Caught Sierra for a ride. It was very odd that she was not eating the hay on offer but in her shelter. This is not unusual, see the following article for clarification: Http://www.mackinnonequineservices.com/articles/13.PDF . Quote: Horses left untouched or merely floated were the comparative study group. FEED CONSUMPTION HIGH. Horses left untouched or merely floated, eat aggressively; bolding their oats, rushing through their oats, or pushing all other horses away. It was noted that horses with teeth that cause them pain, push others away from the feed until they have had time to eat since it takes them longer to chew their food. Other horses eat constantly. Horses that are unable to chew their food up completely before they swallow have voids in their system caused by large particles of unchewed food. The voids in their system cause the horse to feel hungry all of the time, therefore needing to eat constantly, never feeling satisfied.) While riding she salivated excessively dripping large white globs on the arena floor despite a very soft not metallic happy mouth snaffle. Grant's research finds that in over 1200 bitted horses annually, salivation is directly related to the bit and the freedom of movement of the jaw during riding. She was sweating excessively compared to normal and was not interested in her feed. Grant is unable to speak to how (name removed) rode her horse that night (re:sweating), but not being hungry when (name removed) fed at that hour, could speak to the horse's being well, (not hungry). The horse's condition noted by MacKinnon on January 18th appeared that the horse was figuring out the new mastication patterns, common with good dentistry. When I let her out she did not go to her hay as per usual (again, a positive, and attributed to good dentistry, providing the condition is maintained).

Day 3) I went to feed her oats as temperature outside had dropped. This is when I noticed she could not eat. She lipped the oats in her mouth and tried to chew, but could not. Day 3, is January 18th, Grant personally observed the horse eating beet pulp and hay. Her mouth could not close around her chewing, and her cheeks were swollen like a chipmunk. MacKinnon's dental instruments are specially designed with guards, specifically to prevent soft tissue damage, this claim is highly unlikely a result of a dental procedure. This reported swelling was neither observed or reported to MacKinnon at the barn. MacKinnon performs over 120 equilibration's each month, this (swelling) has never been reported. Within seconds her spill pile was huge. She was extremely frustrated and it was very evident that her normal chew pattern could not function (professional terminology, not used by lay people). She presented her upper lip like a parrot mouthed horse and kept rolling her tongue trying to push the oats along. This behavior was not observed in Grant's presence on the day she claims while eating beet pulp or hay. She was extremely frustrated and tried to push the oats out again as she could not masticate (professional terminology, not used by lay people). And push them through to normal digestion (???). Upon bringing her to the barn I noticed that her gums were bright pink, very stressed, and her incisors had been cut down to the gums. The picture (name removed) attached to the original e-mail does not show red and swollen gums as she claims (see pictures)

Her palate is now 7/16” below her incisors which scrapes against anything she tries to eat. If the lampus extends 7/16" below the incisors, this picture is inaccurate. That would make the #1-3 tooth (shown in the above pictures), four times that length (inconceivable). If a vet is prompting her, this information is incorrect . . . Many practitioners don't understand the horse's lampus. It is located in the roof of his mouth directly behind the upper incisors. Many assimilate it to a human and assume it should look the same (it's not). The lampus is designed to be a return pump, for blood, out of the oral cavity, since horses are designed to gain their fodder with their head lower than their heart. A healthy lampus should extend slightly past the incisors, it works as a pump. The way soft tissue (of the lampus) settles into place, similar to the frog in a horse's hoof. If a farrier trims only the hoof wall and leaves the frog untouched, the frog will re-adjust quickly from the pressure of the ground he walks on. Examination of the frog visually, changes in only a few days. The same thing happens to the "roof of the horse's mouth" when food passing over the lampus. It will gradually recede. Her incisor bite does not close. Not true, on the 18th of January, Grant manually demonstrated to (name removed) that once the tongue was moved out of the way, the incisors met normally in the middle (in a mirror image. MacKinnon was unable to insert a thumbnail between the closed incisors.) Her upper incisors in her number 1 quadrant are even shorter than in the number 2 quadrant. (again terminology?) her claims are inconsistent with her own pictures. The pictures above, (picture 1 and picture 3) are the two teeth (name removed) is comparing, they are the same length according to her own pictures. I can feel a very aggressive bit seat which has been taken down excessively (according to who?).

This picture is of a horse chewing, you can tell by the position of the jaw in relation to the skull and the proportion to the masseter muscle. Movement to the right exposes the upper left cheek teeth. To the untrained eye, this may look like swelling.

She never had her bit interfere previously and is not a reining horse needing a bit seat to this degree. This picture shows a scar located at the commissar of the mare's lips, this is consistent with excessive, repetitive bit pressure and the reason a bit seat was designed (back in 1820 there is documentation of the benefits of bit seating), contrary to her understanding or prompting from a vet. I called Grant MacKinnon that afternoon and left a message. Spoke to him that evening where he proceeded to say that horses had no nerves in their teeth (Grant told her that there were no nerves in "that part" of the horse's tooth) and it may take 12-24 hours for her new propensity (I said, propreception, not propensity), what he calls her (I said, orientation in space and time without a visual) sense of space and time, to adjust. When I mentioned that it had been 48 hours he called it a very unique situation and was quiet and unable to offer explanation (Grant had already explained, she did not seem to understand, repeating himself would have been demeaning to her). He offered to visit the next day. On day three she was eager to very sloppily eat a beat pulp mash. 2g bute. When turned out she opted for no hay, went over to the waterer and hovered. When after several minutes she attempted to drink she shot back but did not leave the waterer. She was very focused on the water but on the second attempt pulled back like a horse cribbing, but was not able to get any water in due to the sensitivity of her reduced teeth (this is inaccurate according to the design of horse's teeth) Pulp chamber is a dynamic structure located in the equine incisor, which remains in the proximal two-thirds of the incisor tooth, it recedes with age and abrasion, in turn is back filled with secondary dentin, which is evident on the occlusal surface (lower centrals, at 8yrs of age and beyond). To "expose" the pulp horn (root), more than one-third of the entire length of the incisor would have to be removed. For example: a quarter horse's central incisors are approximately 3" long at five year old, therefore the pulp chamber is 3/8" below the gum line. As the tooth erupts (small particles of tooth grid away as he nips grass throughout his life), the pulp chamber will recede at the same rate with time and abrasion. After 15 minutes of this she gave up on watering. Her cheek teeth gums were swollen out an inch and her front incisor gums were protruding with inflammation. This statement is not consistent with proper dentistry.

Day 4) My veterinarian was very concerned that her incisors had been taken down 11/32 which converts to 8.7mm. This article refers to the Dental Associations standards for dentistry that contradicts her claims (see graph in the attached article) http://www.mackinnonequineservices.com/articles/31.pdf. Many of the vets and dentists I have since talked to have explained that there is a 3-4 fold relationship between the incisors to the molars, so this would be putting approximately an additional inch of pressure on her molars. The bio mechanics of the mouth does not support this claim, the incisors are the furthest point from the pivot, call the TMJ. Between the incisors and the TMJ, lie the molars. Reducing the incisors 11/32" could only, at most, put an additional 11/32" pressure on the molars. Providing that the molars were touching at commencement. My vet with Moore & Co met with me to give me much information on how to manage my horse now and to deliver the heavy duty pain killer and anti-inflammatory drugs that my mare would need in order to eat comfortably and bring down the swelling in her gums and cheeks. Grant MacKinnon came out to assess the situation; however did not look at her teeth before informing me that he was the most highly educated dentist and continually fixed all the veterinarian’s work. Grant did not say that he fixed all the veterinarian's work. When I asked him to show me if her pulp root was exposed he explained to me that horses did not have a pulp root. Not true, as explained above He said that she had a wedge true. This was not noted on her previous dental record or by myself after regular checks when competing this summer. To an untrained lay person or even a general practitioner, it is not unusual that the wedge would not be observed. I asked why he had an 8 year old mare on the invoice and whether this would have impacted the amount of tooth he reduced. She is a 15 year old mare. He claims someone told him she was 8, though did not recall who or whether the person that informed him was either a male or female. (name removed) refused to listen to any explanation offered by MacKinnon, (name removed) preferred to disclose everything she knew. He offered no help, but asked if he could take photos. He did not believe she had been off feed for a couple days. He offered no comment on her difficulty consuming the beat pulp in front of her. (name removed) claimed in the above paragraph that the horse was eager to eat, MacKinnon observed the horse eat both beat pulp and hay.

Day 5) Two injections of painkiller plus start on antibiotics to fight inflammation and possible pulp root exposure. In the morning when hay was presented she mouthed it around until it was wet and fell out of her mouth. More mash, and Masterfeed Golden Year feed was a hit as she could crumble it on her sore molars.

Day 6) One injection painkiller, one powder packet of painkiller. Hydration was much worse than the day before, the beat pulp was not enough liquid to keep her fully hydrated. Some of the dentin (dark cap on a horses pulp root) on her corner incisor in quadrant 3 fell out and I became concerned with the limited amount of dentin in tooth 101. (see the last photo) This picture is of quadrant 2, not 3. But dentin does not fall out, (see-above explanation re: pulp chamber), however what is important is that the tooth (name removed) is referring to is showing the remnant of the infundibulum cup, a seprate structure within the tooth (see figure below)

I hauled her into Moore & Company where her blood work confirmed she was dehydrated and needed a tubing of water into her stomach of 10 liters. The intern gasped when she saw my mare’s lack of bite and the veterinary professionals on call gave me an indication that this was more aggressive than they have seen before. They are finding these cases to be more rare as the knowledge among the industry improves. She cannot close her incisors by a good margin. (this has been addressed above)

Day 7) Some good news – it is very thin, but she does still have a very thin layer of dentin. None of this makes sense according to the structure and design of the horse's tooth The cheek teeth have been floated down to “piano keys.” Her transversal ridges, as in a normal tooth, are completely gone in her lower arcades. This is accurate and the way dentistry is performed to maximize anterior/posterior movement of the mandible The filing is very close to the inner structures of her tooth causing the sensitivity. (impossible, according to the tooth's nerve structure) This is compounded with heavy loading on her molars, rather than loading on her incisors or in a balanced position. (this is a justification by practitioners that choose not to perform incisor work because of the difficulty and precision required to do it right) There is nothing to do as we cannot take any more tooth off to put her into a balanced position. The horse was in balance when I left the barn, further dental work would take her out of balance She was tubed with water twice more, and moved onto her new painkiller that will be safe to give for long term. She yawns a lot trying to relieve the pressure (name removed) may have seen the horse yawn, and interprets it as "relieving the pressure". This is typical, in a horse's mouth that was out of balance, put into balance and getting used to the adjustment. The key now will be to keep her hydrated and wait for her incisors to erupt to close her bite. This could take several months to several years. This is not true, I guarantee they are touching right now Some horses will not recover, how would she know this??? though with her new found keenness for Goldenyear crunchies I am hoping that we’ll be able to keep weight on her. Water remains the primary concern. Any suggestions for keeping water lukewarm and a horse consuming is appreciated.

This is a picture of a different horse, a bay colored horse with different front teeth.

Lessons I have learned: Even if you have a referral on your equine professional, ALWAYS be there for the procedure. (name removed) is correct, MacKinnon has always requested his clients not only be in attendance but to make the effort to learn how their horse's teeth work, both before and after dentistry and understand the importance of annual maintenance. Call for several references from experts in the field just to be sure – this would have prevented my situation. Call the Dental Academy or institution your dentist is from and ask whether your dental professional is fully certified and goes back to upgrade and have their work critiqued. Mackinnon encourages horse owners across the country to fully educate themselves. The best thing the horse industry can do is to encourage horse owners learning the complete facts. In Grant case, since the school in Glenns Ferry changed hands a few years ago, Grant started to focus his continuing education efforts toward IAED (International Association of Equine Dentistry). He is scheduled to attend courses again this year in Las Vegas, March 5,6,7, 2010. Grant is a proud member of IAED. The Academy of Equine Dentistry recently included IAED's continuing education format, but they haven't re-posted Grant's name. He has faxed continuing education documents to their office a couple times. Nonetheless, Grant graduated and certified at the Academy of Equine Dentistry, one of a few specialty schools, located in Glenns Ferry, Idaho.

Industry standard equine dental procedures recommend taking 1mm down on the incisor at a time, IF there is a need for incisor correction. This is to check to make sure they are not going to go through the dentin and hit the pulp root. The pulp root is closer on older horses than younger horses. According to the text documents present above, (name removed) reference to "the industry standard" is inaccurate.

3mm incisor correction is considered extreme or aggressive and is the maximum reduction recommended for 1 session. If more correction is needed, this will be performed at 6 month to 1 year intervals to give your horse a chance to adjust According to the text documents present above, (name removed) reference to "maximum reduction" is inaccurate.

There is a very sensitive relationship between the incisors, molars and TMJ. This must be completely understood by your equine dental professional. Ask them about this before they begin. This it true. The above documents confirms this certification requirement.

If your equine professional uses a diamond saw, like the image attached, ask a lot of questions about what they are doing before they begin

If your horse has a “wedge” it is common practice to only reduce the incisor that is too long and leave the shortened one to erupt into a normal position on its own. Reducing the other incisors to match the short one risks encountering pulp root, and can drastically affect the relationship with their molars and TMJ. This statement confuses a number of issues. The above documents clearly address the "how to, when to and why to" of incisor reduction.

The dental professionals I have consulted with strongly recommend conventional floating of the molars BEFORE making any incisor corrections if incisor corrections are warranted. My horse’s incisors were cut first, and therefore are now not able to come together because of the drastic reduction. The reason (name removed) incisors were reduced first was because her horse's teeth had not been properly addressed in the past. The incisors were excessively long and would not allow the horse to comfortably fit into the speculum. The horse's mouth would have had to open that much more to properly address the molar tables. Side note: (name removed) was not in attendance. (name removed) did not come to the barn after work that evening and the barn workers were sitting in the office.

My horse will need to endure the next 2-3 years before her teeth wear to a point that they are able to effectively masticate again. Not true, inaccurate and impossible to make this correlation to equine dentistry. It will be a long wait before her incisors erupt into a normal wearing pattern again. I will be trying topical pain desensitizer to encourage her to drink. This statement is sooooooooooooo erroneous -- I must reiterate: Dr. Deb Bennett (highly respected paleontologist at the Smithsonian Institute) claims the horse's tooth is inert by age 15. Both texts speak to substantiate this claim. DVM Pence, writes that there is no blood supply after eruption (p11, scan2) and that the pulp chamber disappears by age 6 (p16, scan3) and DVM Baker and DVM Easley also provide an easy to understand comparison between human teeth and horse's teeth, claiming the lack of sensitivity in a horse's tooth is due to calcification, "fully obliterated". (p14, scan9). If anyone has any suggestions or a similar experience they would like to share please contact me. If you are aware of a movement or an organization aimed at certifying equine dental practitioners, please contact me at (name removed)

Thank you for your time and I hope that your horse does not go through the same experience as mine. Signed (name removed)

Note: All names and references to the original source of this document has been removed at the request of the Privacy Commissioner due to an official complaint by the original source.

Does My Horse
Need a Dentist?

It might just be
his teeth!

Does My Horse Need a Dentist?

It might just be his teeth!

Does My Horse
Need a Dentist?

It might just be
his teeth!