dimanche 13 août 2017

The purebred producer of Canadian horse

The purebred producer of Canadian horse
Introduction
Canadian horse is one of the most, if not the most, ancient breed of North America. They have been very useful in the construction of our country, the country of which they bear the name. They were the perfect little farm horse: enduring, strong and gentle. This may be the reason why their nickname is “the little iron horse”. But today, replaced by tractor and hydraulic machine, they lost their initial purpose. Some breeders are working hard to revitalize the breed and to make it popular again, starting by showing how good riding horses they are. Canadian horse is a small breed that is just starting to recover from being almost extinct. The subjects that will be looked at here are: History of the breed, registration book, phenotype, temperament, environmental impact on the breed, genetic disease and future of the breed.

Le noir Dynamo Kafka


History
Canadian horse is believed to be the first breed of horse in North American. In fact, it was the first studbook ever created in North America, in 1889 (Khanshour and al, 2014). According to some evidence, Canadian foundation horses were introduced to Canada by King Louis XIV around 1665 (lechevalcanadien.ca, 2008; Prystupa and al, 2012). There was no information left on the breeds sent to New France at this time. Recent research on DNA of multiple horse breeds, found that Canadian horse were closely related to draft horses, especially Percheron and Breton (Khanshour and al. 2014). Belgians and dales ponies were also closely related to Canadian. There were around 100 foundation horses from different breeds that were the base of the breed creation. They evolved in a rude climate in an isolated area and were bred with no influence of other breeds or blood lines (chevalcanadien.ca, 2008). By 1784, the breed counted around 30 000 individuals (Gendron, 1993). The combination of a massive export for war and the industrialization of the agriculture almost bring the breed to extinction (Oklahoma state university, 1998). The livestock of Canadian horses through the world was estimated to 5000 individuals in 2015 (Leprince, 2015). The breed is still recovering of the great lost they had back then. There are now breeders of Canadian horses outside the Canada; United States and France (clrc.ca, 2014; lechevalcanadien.ca).There is also Canadian horses that are sold to particulars in Europe (France, Germany and Swiss) and everywhere in the USA.
There is some evidence that Canadian horse was a foundation breed for many other North American breeds as: American Saddlebred, Standardbred, Northern plain mustang, but especially important in the development of the Morgan (Khanshour and al, 2014).


Registration Book
Canadian horse registration is a closed book separated in two categories: purebred and grade horses.
Purebred: Studs should be at least 96,9% purebred Canadian and mares should be at least 93,8% purebred (clrc.ca, ND).
Grade: Geldings of at least 75% Canadian (no studs are allowed) and mares that are between 75% and 93,7% purebred (clrc.ca ND).
To be eligible for registration both foal parents should be registered, have a blood type certificate for the sire, have a parentage certificate and the name of the foal should begin by the right letter (each year of birth has a letter) (clrc.ca, NhasD).
The registration name should always be: The breeders’ breeding name, the name of the sire and the name of the foal (beginning by the year letter). For example: Windigo Noireau Héritier, the horse came from the Windigo breeding facility, sired by Noireau and born in 1998. All of his future foals will also wear is name in the middle.

JP Casselman Wilfrid Dazzler, stallion


Phenotype
The breed standard is divided into 8 points; head, neck, shoulders, body, forequarters, hindquarters, legs and general exterior appearance (lechevalcanadien.ca, 2008).
Some important characteristics of the breed are (lechevalcanadien.ca, 2008; Oklahoma state university, 1998):
-Mane and tail: Abundant, long, dense and wavy
- Body:  Short and strong back, Medium sized neck large at its base, long muscled shoulders, deep chest, strong and muscled back end, slightly sloped croup.
-Legs: Strong, straight front legs, angulated hind legs, articulations well defined, short canon bones, strong large hoofs, thick and lean fetlock, medium sized and strong pasterns.
-Head: Short, straight lined and lean, short and thin ears, large and bright eyes, large nostrils, small lips, well-defined cheeks and flat forehead.
Stand from: 14 to 16 hands, but taller horses start to be seen.
Average weight: from 1000 to 1400 lbs
Colours, starting from the most common to the less common: Black, bay, chestnut, palomino, buckskin and grey. Blaze and white socks are also seen and accepted.

JP Casselman Wilfrid Dazzler, stallion


Temperament
Canadian horses are calm, intelligent and have a vivid personality. They are loyal and trusting companions with great reliability.

Environmental Impact on the Breed
The environment in which the Canadian horse had evolved had a big impact on the genetic of the breed. Indeed, with the long and hard winter of the Quebec Province, only the more rustic and the strongest could survive. Winter was really cold and feed were not as accessible as it is today, horses needed to live in extreme cold with minimal feeding requirements, or less. In time of extreme cold, digestible energy given to horse should be raised by 2,5% for each degree Celsius below -15°C (Cavanagh and Ternan, 2014). As such increase in feeding wasn’t really possible back then, horses that were good at storing fat easily (easy keeper) were the ones that had better chance to survive and to be useful. Horses that were insulin resistant were also advantaged in those climates (Treiber and al, 2006) because it is probably caused by a “thrifty” genotype (Kaczmarek and al, 2016). This was related to obesity, which gave them some “reserve” for the hard winter. Those horses that were more resistant and that passed through winter more easily were probably more fertile and were more “wanted” as breeding animals, because they were in better shape and ready to work for all winter.



Genetic Diseases
There is neither major genetic disease, nor breed specific disease identified in the Canadian horse breed. On the other hand, there are some genetic predispositions in the breed for developing some metabolic diseases. This means that those diseases are not breed specific, but some genetic factors in that breed can enhance the chance of developing them. This would be why some Canadian horse has more chance of developing those diseases than Arabian, for example.
Those metabolic diseases we talk about are: insulin resistance (IR), laminitis and Cushing's disease (CD). What was an amazing asset for survival back then is what can make them more prone to develop metabolic diseases today. Let me explain, it was hard to have good hay at winter back then, so horses that were good at storing fat were advantaged. Today, good quality hay is easily available at winter, so those horses are now easily obese, which can be detrimental to their health. In human, metabolic syndrome is now believed to be an inherited autosomal dominant trait. This may also be the case with horses, further research could be interesting. As we have seen in the environmental section, horses with easy keeper genetic and with IR were advantaged in survival. This may be why these problems are more encountered with Canadian breed.

Insulin resistance: Insulin resistance occurs when tissues become more resistant to insulin (they are less responsive to it), which make them absorb less glucose. Glucose will then be higher in the blood. Obesity is an important factor in the development of IR: obesity and IR are positively correlated (Treiber and al, 2006). IR is believed to be determined by a number of genetic factors (Kaczmarek and al, 2016) with an alimentary trigger: high carbohydrate diet, which exacerbates IR (Treiber and al, 2006).  So it is really important when you have a horse that has more chance to carry some thrifty genes to take extra care about his nutrition. Keep an eye on the quantity of food he receives, making sure to meet is nutritional requirements, but avoiding overfeeding (so obesity is avoided). As seen previously, Canadian horses are genetically closer to draft and pony breeds which means that they probably have more efficient and slower metabolism just like them (Cavanagh and Ternan, 2014). Looking at the minimal nutritional requirement from the National Research Council will be a good starting point to manage their food intake properly.

Laminitis: Laminitis is a major disease among equine population. Laminitis occurs when there is inflammation in the lamellar part of the foot. Blood flow is disrupted and lamellae start to necrosis and detach from the hoof wall. This removes support for the third phalange and causes it to flip. The exact mechanism is not 100% known but there are some suspicions of a major gene or genes expressed dominantly (Treiber and al, 2006) that could explain why two obese horses, fed the same thing and housed in the same environment will not both develop laminitis. Again, thrifty genes could be a part of the problem. Like with IR, nutrition is really important, but also trimming: making sure to avoid running heels and long toe kind of foot (Loving, 2009). So treatment for this disease consists in making sure to have good feeding management and taking care of the hoof properly. In other words, balanced diet and balanced feet (short toes, balanced trimming).



Cushing's disease: Equine pituitary pars intermedia dysfunction (Cushing's disease) is a progressive endocrine disease that often starts with older horses (McFarlane, 2007). It is in fact a dysfunction of the pituitary gland that changes the secretion of ACTH hormones and cortisol (The Pituitary Foundation, 2015), causing some change in horses’ metabolism. Cushing's disease is believed to be a genetic disease that has environmental triggers (McFarlane, 2007). Every horse can develop CD, but some breeds are at greater risk. Again taking care of the nutritional side is really important, but putting an extra care on the healthiness of the environment and keeping a balanced trim are also important in the management of CD. The drug pergolide is also often used to keep CD under control (petmd.com, ND).
So in summary, those diseases are not 100% caused by one thing, it may be a dominant gene or a combination of genes that are influenced by the environment of the horse and by his nutritional management.


Future of the Breed
The breed may be small, but it has a really great genetic diversity, which means they are still a viable breed, with a really low inbreeding index (Khanshour and al, 2014). This is a good indicator of the genetic health of the breed. Moreover, they carry some rare alleles (Khanshour, 2014), which make them even more interesting, genetically speaking.
The Canadian horse is a big part of our history, an important pillar in the development of our country. It would be so sad to lose such a big part of our heritage. They have been recognized as part of the heritage by Quebec government in 1999 and have become the national breed in 2002 (lechevalcanadien.ca, 2008). Despite these facts, government is inactive in the saving of the breed. They do not actively do something to help concretely the breeders or the breed. It is too bad they don’t help preserve this national treasure.
With the agricultural revolution and the rural exodus, breed that was used in the past for agricultural work lost their popularity. Canadian horses may have similarities with draft breeds but they are physically different. They are lighter which make them more suitable for riding. Let’s be honest, they may not be a grand prix breed, or a race champion breed, but these horses are the all-around horses by excellence. They are perfect for the rider that wants to have fun and try a bit of everything. They are enduring, strong and reliable horses. A study of equine Canada showed that 75% of adult equestrian were pleasure riders (equestrian.ca, 2011), which means that 75% of the equestrian should have a lot of fun owning a Canadian. Despite the fact that they are not grand prix horses, they can be competitive against other breeds, especially in dressage. They are seen more often in the show ring and they are not so disadvantaged by their rustic physic.

Canadream Kelbeck you and me (aka toque) at Devon horse show


Some breeders try to go in that way: breeding Canadian horses that are a bit lighter and taller than their predecessor. This is made in an attempt to make them a bit more sportive, so they will be a bit more competitive. Playing with the phenotype of a breed needs to be done carefully. One reason is because we don’t want to denature the breed in a way that the breed doesn’t look the same anymore. A second reason is that changing a phenotype need to be done by breeding horses that are phenotypically similar (Equine Genetics Workbook, 2013). This needs to be done the right way, because if not, it can lead to inbreeding. Inbreeding can be good if done properly (horses free of genetic diseases, avoid pushing the inbreeding too far, etc.), but as the breed as a really low inbreeding coefficient and a great genetic variety it would be sad to lose that. Breeders make incredible efforts to revitalize the breed and to make them popular again. Breeding horse is not easy, especially with rustic breeds because people are more attracted by tall, delicate and shiny sports horses. But there are still passionate peoples out there that try to save the breed.

Canadream Alex Shining Star on the cross country course

This breed deserves saving, for their part in our history, but also because they really are good horses that have a lot to offer. It is a healthy breed, with a lot of genetic diversity. Canada should start to be proud of their national breed and start to rediscover them.

Conclusion
In conclusion, the Canadian horse is a little national treasure. It is a breed that has a great part in the history and construction of the Canada. Canadian horses have been great partner to all farmers trying to survive in the New France, helping them in their daily lives. Losing that heritage would be a shame. Especially knowing that the breed is so healthy, genetically and physically speaking. They may have a genetic predisposition to some metabolic diseases, but a proper management of their nutrition and their environment should really help reduce the chance of developing these problems. Knowing that the breed is at risk due to their thrifty genes will leave a chance to their owner to start a good management routine right at the start. This should not stop someone from buying a Canadian horse, every breed has their little or big genetic problems. The Canadian horse has a lot to offer for their future owners, capable of offering them a lot of pleasure in multiple disciplines and able to compete at a good level, especially in dressage.
We should never forget this adage: We raise for our children the horse of our fathers.

Canadream Kelbeck Belle-de-mai


Bibliography
Article
Anas Khanshour, Rytis Juras, Rick Blackburn, E. Gus Cothran, 2015, The Legend of the Canadian Horse: Genetic Diversity and Breed Origin, Journal of Heredity 2015:106(1):37–44

Dianne McFarlane, 2007, Advantages and limitations of the equine disease, pituitary pars intermedia dysfunction as a model of spontaneous dopaminergic neurodegenerative disease, Elsevier

Jaclyn Mercedes Prystupa, Pamela Hind, E. Gus Cothran, Yves Plante, 2012, Maternal Lineages in Native Canadian Equine Populations and Their Relationship to the Nordic and Mountain and Moorland Pony Breeds, Journal of Heredity, 2012:103(3):380–390

Katarzyna Kaczmarek, Bogdan Janicki, Maria Głowska, 2016, Insulin resistance in the horse: a review, Journal of Applied Animal Reasearch, Vol. 44; NO. 1, 424–430

Kibby H. Treiber, David S. Kronfeld, Tanja M. Hess, Bridgett M. Byrd, Rebecca K. Splan, W. Burton Staniar, 2006, Evaluation of genetic and metabolic predispositions and nutritional risk factors for pasture-associated laminitis in ponies, Scientific Reports: Original Study, Vol 228; NO 10, P. 1538-1545

Book
Cavanagh and Ternan, 2014, From the horses’ mouth nutrition, feed and feeding, matrix multimedia
S.Loving, Nancy, DVM, 2009, Nouveau manuel vétérinaire pour propriétaire de chevaux, edition vigot, translated from English by Patrick Morin, DVM, originial version : All horse system go, 2006
Website
Canadian livestock record corporation, no date, Horses Eligible for Registration
Canadian livestock record corporation, 2014, Members Listed by Province
Equine Canada, 2010, People in The Industry in 2010

Leprince, Jean-Michel, 2015, Le cheval canadien va-t-il disparaître?

Pet MD, 1999-2017, Cushing ’s Syndrome in Horses
The Canadian horse breeders association, 2008, Breed Info
The Canadian horse breeders association, 2008, List of Member
The Oklahoma State University, 1998, Breeds of Livestock - Canadian Horse
The pituitary foundation, What is the pituitary gland?, 2015



vendredi 16 décembre 2016

observation comportementale - budget de temps alimentaire

Observation comportementale
Cheval: Sonara                Race: Canadien X QH             Âge : 10
Mode de vie : au moment de cette observation (le mode de vie change selon les saisons et la température), la jument vit sur un pré d’herbe 24/7 (herbe et eau à volonté) avec 9 autres chevaux de tous âges (poulain, adulte, vieux), race, sexe (pas d’étalon ou de jument pleine). Les chevaux rentrent le soir pour avoir leurs grains et retournent dehors. Ils passeront la nuit à l’intérieur que s’il y a de la pluie forte et très froide.
Éthogramme de repas
Les feuilles d’observations sont en bas de page.
J’ai traduit certaines sections et changé certains titres pour ajouter des comportements observés qui n’étaient pas initialement sur la fiche.
Sonara a été calme tout au long de l’expérimentation. Par contre, ses mouvements d’oreilles pourraient suggérer un peu d’anxiété. Cela pourrait ne pas être relié à la prise de nourriture, mais au fait que son box est juste à côté de la porte et qu’elle regardait souvent dehors (la porte reste ouverte). Ses mouvements fréquents d’oreille pourraient venir du fait qu’elle reste attentive à ce qui se passe à l’extérieur. Il n’y a pas de gros changement dans son comportement durant les étapes : avant, pendant et après la prise de nourriture. Il y a pourtant quelques légers changements:
Avant: elle me regardait plus souvent, sachant que la nourriture était avec moi, attendant patiemment que je lui apporte sa nourriture.
Pendant : Un seul comportement, MANGER ! Elle ne pense qu’à manger à cette étape, le reste lui est indifférent.
Après : Elle commence à bâiller après avoir mangé (est-ce que manger peut rendre les chevaux plus endormis, comme nous ? Cela pourrait être un bon sujet de recherche.). Elle continue de me regarder, probablement pour savoir si elle va avoir plus de nourriture. Un nouveau comportement est qu’elle se lèche les lèvres quelques fois (se lécher les lèvres indique un changement d'état émotionnel).
Je suis heureuse avec son comportement lors des repas, pas d’impatience, pas d’anxiété ou de gros stress, alors je n’ai pas de changement à faire face à cela.
Budget de temps
Budget de temps (sans travail)


Budget de temps (avec travail)


Budget de temps (quand elle dort au box)


La section autre inclue : grattage/interrelation avec les autres chevaux, courir, marcher en groupe, se gratter et se rouler.
Le budget de temps de Sonara est proche de celui des poneys Camargue (lorsqu’elle est au pré 24/7). C’est logique puisque la jument est dehors 24/7, comme les poneys Camargue qui sont gardés sous des conditions semi-sauvages. Sonara se couche normalement au même endroit et dans la même plage horaire tous les matins (vers 10h) et profite d’un bain de soleil. Par la suite, elle passe la plupart de son temps à manger et un peu en position stationnaire (lorsque son estomac est plein) à somnoler avec d’autres chevaux (qui se tiennent normalement en groupe, souvent par paire, tête à fesses pour chasser les mouches). À d’autres moments de la journée, elle peut s’amuser avec les autres en faisant la course, en se gratouillant, en se roulant ou en se grattant sur un arbre. Elle passe aussi du temps à se déplacer en groupe, pour changer de section de pré (il semble que les chevaux aient différentes sections d’alimentation dans le pré. Ils semblent avoir un parcours bien défini. Par exemple : toutes les nuits ils sont sur le plateau du fond, derrière la lisière d’arbres, le matin ils sont dans le petit pré de droite, ils se déplacent ensuite sur le plateau de gauche où il se repose et se couche, etc. Ils respectent généralement ce parcours).

Quand elle doit passer du temps en box, son budget de temps est similaire au groupe “box individuel, paille et foin à volonté ». Il y a de petites différences entre ce groupe et la situation de ma jument : elle n’est pas à l’intérieur 24/7 (elle passe normalement plus de temps dehors qu'à l'intérieur, sauf par temps extrême) et elle n’est pas nourrie à volonté à l’intérieur. Elle a 2kg de foin dans un filet « slow feeder » (trou de 1 pouce) pour la nuit, elle mange normalement sa ration en 1 à 2h. Elle passe plus de temps à manger quand elle est dehors, elle se couche toujours dehors, mais pour de plus courte période, profitant du temps à l’intérieur pour se reposer. Il n’y a pas vraiment de changement dans ses interactions avec les autres chevaux lorsqu’elle dort en box VS lorsqu’elle est dehors 24/7. Même à l’intérieur, elle passe du temps à interagir avec son voisin de box (oreilles couchés, botter la cloison du box, renifler les autres chevaux nez à nez, couiner, etc.).


Je trouve son budget de temps parfait quand elle est dehors 24/7. Ce qui n’est pas toujours possible vu notre situation géographique ; nous avons des froids extrêmes, chaleurs extrêmes, beaucoup d’insectes piqueurs, etc. J’aimerais donc qu’elle puisse passer plus de temps à manger au box. Le problème est que cette jument est une « easy keeper » ; trop facile à garder en surpoids. Comme elle a eu 2 épisodes de fourbure à ce jour, elle doit rester mince et éviter la suralimentation. Il m’est donc impossible de lui donner un accès illimité au foin. Par contre, j’aimerais tester le trempage du foin. Ce qui pourrait permettre de retirer une partie des sucres hydrosolubles et donc réduire l’apport calorique du foin et me permettre de lui en offrir plus.




Behaviour observation assignement - feed time ethogram

Behaviour observation
Horse: Sonara      breed: Canadian X QH     Âge: 10    
Living situation: for now (it depends on the season and weather), outside in a large pasture 24/7 (so water and grass ad libidum), in a group of 9 horses from all age (foal, adult, old), breed, sex (no stallion or suited mare). Come in for concentrates, and return outside. Spend the night inside if there is heavy/cold rain.
Working 3-4 times a week (return to work after 6 months of rest for injuries(abscess, laminitis, tendon injury)), muscular work, on line (not ridden for now, as she needs to rebuild muscle)
Feeding ethogram
Results for feeding ethogram are on the bottom of the page.
NB: I change some section’s name to add some behaviour that I saw and I wanted to note as, for me, it was relevant.
Sonara seems pretty calm all the time of the experimentation. But her ear movements can show a bit of anxiousness. This could not be related to the feed itself as her stall is next to the door and she was looking outside (the door is left open for better aeration). There is no big change in her behaviour before, during and after feed time, but there is slight change: Before: She looked more at me, knowing I had the feed, waiting patiently for me to bring the food.
During: One behaviour, eating! More concentrate on her food than anything else.
After: She starts yawning after eating (is eating can make horses sleepy as we do? This could be a great searching project). She still looked at me (maybe looking if I had more food?). New thing is also that she licks her lips sometimes.
I’m happy with her behaviour at feeding time, no impatience, no anxiousness, no big stress, so I don’t really want to change anything about it.
Time Budget
Time budget (when not worked)


Time budget (when worked )


Time budget (when sleeping inside)


Other section includes: grooming/interaction with other horses, running, trekking, scratching, rolling.
Sonara time budgets are close to Camargue ponies time budget. It is logical fit as this mare is actually 24/7 outside, so her time budget is close to Camarague ponies who are also outdoor in natural condition. She normally lay in the same spot every morning (around 10 o’clock) and enjoy a sunbath. Then she spends more of her time eating, some time standing with other horses (they normally stand together, close enough to chase flies). At different moments of the day she can take a good run with the group, groom with a conspecific, roll or scratch herself on a tree. She also spends time trekking, when the group change of eating spot (there are different eating sections in the field, they seem to have a pattern of eating, ex: every night they are in the back section of the field, in the morning they are in the right side section of the field, etc. They seem to respect this pattern.).
 On the day she needs to sleep inside, her time budget is similar to “individual stall, straw and hay ad libidum” group. There is a slight difference between this group and the reality of this mare: She’s not inside 24/7 and she’s not fed ad libidum inside. She has 2 kg of hay in a slow feeder (1” holes) for the night, she normally eat it within 1 or 2 hours. But she took this “no feed time” inside to lay down, so she spends more time eating when she’s out for the day, she still lay down outside, but a shorter time.  The behaviour displayed with other horses when she’s out is pretty similar to when she’s 24/7 out. She also spends a bit of time interacting with her neighbour’s horse in her stall (pinned ears, kicking, sniffing, nose to nose touch, squealing).

I find her time budget perfect when she’s out 24/7. But when she’s in for the night I would love her to spend more time eating, the problem is, she’s an easy keeper who had 2 episodes of laminitis in her life so she needs to be kept slim. For now, it’s not really possible to give her more hay. I need to test if soaking the hay to remove some hydro soluble carbohydrates could help her access more hay without giving her too many calories.




dimanche 21 août 2016

Form VS use - Navicular and laminitis disease


Introduction
As we have been studying since the beginning of this class, human management of horses do not always fit the horse needs and is more designed to accommodate the human needs. Bad management and unsuitable use of the horse can create problems to the horse. Laminitis and navicular syndrome are two inflammatory disease that are handicapping health issues. They are serious illness that may end a horse athletic career or even be life threatening. Mechanism of those diseases, their link to human management and their prevention and curative techniques will be revised here.

1-      Navicular and laminitis, what is it? What are the causes, symptomes and treatments

Both diseases are affecting the feet, usually mainly the foreleg feet. Both can create a major limp, end the career of a horse or in extreme case his life. Laminitis affects the laminae and the distal phalanx (cf fig 1 ) and navicular affects the sesamoïde (navicular) bone, navicular bursa and deep digital flexor ligament (cf fig 1).

Fig. 1                                                                       
  
Figure 1 : Part of the hoof, with laminae structures
From: http://lakesidelivery.co.uk/laminitis/
(2014)

Laminitis
Laminitis is a disease affecting the laminae of the foot. Laminae is a dermis structure that provide an attachment between the inside of the foot and the hoof wall (Hood and al, 2013). In laminitis, this structure gets inflamed and causes great pain to the horse (McCurnin, 2010). When laminae get inflamed for too long, they can lead to a degenerative state where the dorsal laminar attachment detach from the insensitive laminae of the hoof wall. Distal phalanx (coffin bone) can then dethatch from the wall and rotate toward the solar surface, in severe cases it can rotate so much that it can perforate the sole. All this will altere the intern mechanic of the foot, which will result with a blood flow dysfunction within the foot. As consequences, it will cause problem with the wall cornification and growth (Hood and al. 2013). It can occur on the two front feet or all four feet, but sometimes, it can occur in one foot only, but this is more rare. This disease is more often seen in adult horses over one years old (McCurnin, 2010). Horse developing laminitis can have the following symptoms: hot hoof, reluctance or difficulty to move, increased digital pulse, they stand in a way that put weight on the hind limb (front limb are stretched in front of them and back end is more under them than usual), white line can begin to separate from the wall, founder ring can appear on the hoof wall and in severe case, the hoof can appear deformed (Hood and al. 2013, McCurnin, 2010, Loving, 2009).



Causes
The causes of laminitis are not 100% sure, there is a lot of good suspicions but not much proof. On the other hand, a lots of conditions can raise the chance to develop this problem. Those conditions do not mean that the horse will systematically develop laminitis, but it will increases the chances. When a horse has serious inflammatory problem or serious infection, it can result in an endotoxemia, which can increase the chances of developing the disease (McCurmin, 2010). This problem can also be caused by giving too much concentrates or sweet feeds, often offered to show horses to raise their energy intake. It can also be caused by an hormonal imbalance, like cushing disease or insulin resistance (McCurmin, 2010, Loving, 2009). A lot of other causes are suspected: dehydration, electrolytic imbalance, colic or mechanical problems like extreme bruises, overload of one foot or contusions on the foot (Loving, 2009).



Treatment
Treatments for all severity of laminitis will focus in reducing the inflammation (with medication or/and cold therapy) of the hoof and facilitate the digital blood flow (Loving, 2009). It will also focus on making the horse as comfortable as possible, by giving him analgesic medication for the pain and by using an external support for the distal phalanx (McCurmin, 2010, Loving, 2009).

Mechanical support for the distal phalanx can be provided by a lot of tools, like heart bar shoes, leather degree pad (often used with heart bar shoes), boots with gel pad, special boots that can be fixed to different degree pads. A more rudimentary but efficient tool is Styrofoam pad fixed with duck tape (Loving, 2009). Good trimming of the foot will be extremely important in the treatment part to make sure that pressure is well distributed and to reduce the deformation of the foot.
Oui c'est le même pieds, avant et après un parage

Concentrates and sweet feed need to be eliminated and a fat horse needs to lose weight to reduce pressure on the feet. Blood tests can be performed to look if the horse as any metabolic problems. If so, management of those problems will be necessary (Loving, 2009).
Comfort care are also important as the laminitic horse is in great pain and will spend more time lying down, so deep bedding is necessary.
Treatment for mild cases of laminitis will focus on rebalancing the hoof, rebalancing the diet, and manage pain and inflammation. For moderate cases orthopedic shoeing and reduction of intense activity can be added to the previous strategies and for more severe cases euthanasia can be the best option as horses will suffer too much.

Prognosis
It depends if there is a distal phalanx rotation, and if so, of the severity of this rotation (McCurnin, 2010). The more severe is the rotation, more dark is the prognostic. Horse can live well with a small rotation but can not often return to a full athletic career. More rarely, rotation can recover completely and the distal phalanx can return to zero degree of rotation. But owner still needs to keep an eye on his horse’s foot.

Navicular syndrome
Navicular syndrome is a wide term used to talk about the degenerative process of the navicular structure. Those structures are the sesamoïde bone (navicular bone), the navicular bursa, the deep digital flexor tendon, and the multiple ligaments that support the navicular bone (Loving, 2009). In most cases, navicular syndrome occur in the front feet and make the horse lame. This syndrome is degenerative and progress with time.  Horses between seven and fourteen years old are more at risk to develop this affection, but younger horses in intensive use can also develop it.
Symptom of this affection can be: short and stiff strides (Rose, 1995), foot tends to land toe first, horse will trip frequently, frequent bruises and abscesses, feet can appear smaller and contracted heels can develop (Loving, 2009).



Causes
Multiple factors can cause inflammation and lead to this degenerative problem. Bursitis or bone remodeling caused by repeated pressure between the flexors tendons and the sesamoïde bone or an increased load on the heels are some example of those factors (Loving, 2009). Recent study by Dr. Robert M. Bowker conclude that this problem is about all the feet, not only about the navicular structures (Loving, 2009). There are many structures in the foot and each one of them are related to each others. If one structure have a problem, it can cause a domino effect and affect the others.
Some characteristics can enhance the chances of a horse to develop navicular syndrome. Hereditary conformation problems like straight pastern or really small feet, comparatively to the body mass (Rose, 1995). Horses that are trained for disciplines where they are subject to repeated impact on the feet are also more at risk as it stresses the internal structures of the hoof (Rose, 1995). Some breeds tend to develop this syndrome more easily than other, Quarter Horse and Thoroughbred, for example, tend to be more at risk than Arabian (Loving, 2009, Rose, 1995). Bad hoof care and balance are also a factor, as they can put abnormal biomechanic stress on the navicular structures.



Treatment
The most important part of the treatment is to provide great foot care for the horse (Rose, 1995). Well balanced trim or shoeing is really an important step in the management process. It is important to provide good support at the back of the foot (Loving, 2009), this is why egg bar shoes are often used,
as they do not form a “U” shape like normal shoes but are in “O” shape, which provide the support needed to the heels. Some iron shoes coated with plastic can be used to help reducing the impact in the foot. More recently, synthetic flexible shoes appeared on the market, some of them are full shoes with frog support and have the advantage of being flexible and help to absorb choc (Loving, 2009).
In complement of a good hoof care, other strategies can be used to help managing this syndrome. Injectable drug like Polysulfated Glycosaminoglycan can delay the degeneration of the cartilage matrix. Intra-articular injections with corticosteroid can also provide pain relief to the horse. When none of the previous strategies can help pain management, palmar digital neurectomy can be performed (Loving, 2009). This procedure consist in removing the palmar digital nerves to remove the pain. This surgery can have many side effects, one of them is that horses will lose sensation in his foot, which can lead to concussion an bruising (Grant, 1997). This can also cause some horse to trip more often (Grant, 1997). owner should ask about them before taking any decision (Rose, 1995).  Navicular horses should be exercised and kept moving as this can help to keep a good blood supply and a good articular cartilage lubrication in the feet.



Prognosis
It depends of the severity of the damage of the navicular structures. The more severe are the damages, more dark is the prognostic. Some horses can have an athletic career, while some can’t. It really depends of the severity of each case and the ease to manage the pain.

2 - Human management, how is it responsible of these two diseases
 Human management methods are not always suitable to horses need, bad management and care can create handicapping problems for horses. It is important to know what can lead a horse to illness and try to avoid those practices.
Bad equine care and management can raise the chances of a horse to develop laminitis. Horses are often given too much concentrates and sweet feeds for their need. Hay and pasture are frequently too rich for the horses needs as well. This herbivorous animal is not conceived to ingest much of those simple sugar, he is designed to ingest cellulose, a complex sugar, which will slowly be degraded on the hind gut (Janis, 1976). Simple sugar like fructose and carbohydrate are absorbed too quickly by the small intestine, they are too easily available for the body and can cause inflammatory responses. As seen previously, constant inflammation can lead to laminitis. Feet care are not always at their best, sometimes it is because the feet are not well balanced (long toe, running heels) (Loving, 2012), they can be trimmed too short (which can lead to concussion laminitis) and sometimes hoof cares are not provided as often as it should (so feet are too long and deformed). There is also suspicion of dehydration and electrolytic imbalance in the possible cause for laminitis (McCurmin, 2010), horses need to have constant access to fresh water, which is not always the case. Horses that are showed can also be at risk of this, because stress and intense activity can lead to dehydration. Moreover, water in show can taste different than at home, which can prevent a horse to drink.



Bad management can also lead to navicular syndrome. Like in the laminitis causes, bad foot care is a major cause of the disease. Long toe, running heel type of foot can put more tension on the deep digital flexor tendon. In consequence, the tendon put more pressure on the sesamoïde bone and can lead to a premature use and to inflammation (Loving, 2012). Nutrition also plays a role in the management of navicular syndrome, as discussed above, too much weight on too small feet can enhance the chance of developping this problem. There is less bearing surface on the small hoof that can distribute the pressure, and there is more weight to carry, leading to more stress on the foot structures. Horses are also asked to perform in a lot of disciplines like reining, dressage, show jumping, eventing, barrel racing, etc. Those disciplines need fast speed, big jumps or both, this is putting more stress on the horse’s feet than if he was just walking around.
Good attention to management could help to reduce the horse’s risks of developping those diseases. Simple details can be looked at every day to try to have a more suitable horse management.


3-Prevention
 When we talk about preventive techniques, good practice can be to keep the hoof well balanced, to keep the horse fit and with a good weight (Loving, 2009). Horse should be kept moving, offering him frequent turnout will help to keep the foot structure strong and healthy. Too often, owner will keep their horse in a stalls to prevent them from injuries and not having to run after them in the field, but lack of movement can actually cause more bad than good and lead to more injuries (McGreevy, 2012). In the nutrition side, horses should always have access to fresh water, to avoid dehydration.  A good prevention to foot problems is also to be really careful not to give horses feed that is too rich for their needs, and if they need it, to fractionate the portion in multiple meals. Keeping horses in overweight is a bad idea, easy access to rich hay, concentrates and sweet feed have led many horses to obesity and andotoxemia, two major factor in the development of laminitis. Keeping an eye on the horses intake and needs is a good management strategy. In the contrary, horses that are put on a severe diet can develop other problems like gastric ulceration (McGreevy, 2012) or important muscular loss. Deprivation of enough hay or locomotion can lead equine to stereotypies and ulceres (McGreevy, 2012). Management should always take in consideration the behavioral need of the horse as well, because mental health is as important as physical health.
New fashion in the American horse industry is to have big muscled horses with small feet. There is less bearing surface on those small hooves to distribute the pressure, and more weight to carry as muscles are heavy. This put more pressure on the internal structures of the foot. These horses are then asked to perform at great speed, which will also increase the pressure on these tiny feet (Loving, 2012). All this can lead to navicular syndrome and this kind of breeding selection should be avoided in an attempt to produce healthy athletes. Owner must try to reduce chocs on the feet at the lowest possible level. Shoeing is often used to reduce the wear of the hoof, which work great for that purpose, but in the other hand, it reduces the expansion of the feet. This function is important in the choc absorption mechanism of the feet, and shoeing reduce that. So it’s a double-edged knife that should be taken into consideration before taking this decision.



Conclusion
Navicular syndrome and laminitis are two different diseases of the foot that can be related to  human use and management. Horses management is complex and requires knowledge from caretakers. It is important to find the right balance between the horses and the human needs in a way that enhance the welfare of the horse. Needs of the horse should always been taken in account before any decision making.



Bibliography
             Hood, David M. and Larson, Connie K. Building the equine hoof, by Zinpro performance minerals, 2013 zynpro corporation.
             McCurnin, Dennis M. and Bassert, Joanna M. Clinical textbook for veterinary technicians, P. 1068 - 1317, seventh edition, Saunders Elsevier, 2010
             S.Loving, Nancy, DVM, nouveau manuel vétérinaire pour propriétaire de chevaux, 2009, edition vigot, translated from English by Patrick Morin, DVM, originial version : All horse system go, 2006
             Rose, R.J, navicular disease in the horse, 1995, paper presented at the world equine veterinary association meeting held at Yokohama, Japan, published in the journal of equine veterinary science, volume 16, number 1, 1996
            Janis, C, The evolutionary strategy of the equidae and the origins of rumen and cecal digestion, museum of comparative zoology, Harvard university, Cambridge, Massachusetts, February 8, 1976
            McGreevy, P, Equine behavior a guide for veterinarians and equine scientists, second edition, saunders Elsevier, 2012
            Grant, Barrie, Neurectomy for navicular, Oct 1, 1997, http://www.thehorse.com/articles/10603/neurectomy-for-navicular