4 yo Shetland Pony Mare

The pony had not been trimmed much until the time she foundered, and grazed on lush grass while under the care of the previous owner, resulting in a combination of probable metabolic and mechanical founder. Her X-rays and laminar wedge closeups appear in the posts below.

A tight regimen of frequent trimming as well as limited access to grass (using a muzzle) has been implemented, resulting in improved hoof form and a healthier body weight.  The trimming focused on lowering the heels and backing up the toes, realigning the coffin bone parallel to the toe wall, as well as bringing it closer to a ground parallel orientation. The parallel hoof wall/coffin bone is a primary factor in the prevention of founder.

BEFORE

Somewhat difficult to see in the grass, but this is where the corrective trimming started, with high heels and very long toes.  The red arrows at the toe show imminent coffin bone protrusion, along with a wide gulf  separation between its edge and the wall. The bar, (red arrow), level with the frog, is high.

1 mo.                                  3 mos.                                    6 mos.

As the hoof wall grows down, the separation (all the way around the edge of the hoof) diminishes, and the white line becomes healthy and tight, enabling it to suspend the coffin bone in the hoof capsule.

1 mo.                                                                                   6 mos.

By 6 months most of the hoof wall has grown down with less prominent rings. The remaining separation at the toe (red arrows) corresponds to the separation on the sole at the same time frame and will grow out in another month or so.

 Founder & Laminitis (Under Construction)

The following diagram comes from the May ‘99 issue of Practical Horseman:

This is a good depiction showing the progression from a healthy foot to a rotated one.  However, the heels which give us most of the information about the possibility of rotation, have been obscured.

The important information with respect to rotation, laminitis, and founder can be found in the thickness of the sensitive laminae, as well as the orientation of the coffin bone relative to them.  

1.  Healthy Foot.  The sensitive laminae (pink) are close, tight, and parallel to the insensitive laminae (white line).  The actual foot resembles the shape of the healthy, diagrammed one.  With its low heel, the coffin bone is parallel to the toe wall which is the surest way to ensure a healthy white line and healthy, tight, laminae that can solidly suspend the coffin bone and prevent founder espisode.

2.  Mildly Pathological Foot.  The wall of the coffin bone is no longer parallel to the hoof wall which causes the laminae to stretch at the bottom and begin to adopt a ‘wedge-shape’: narrower at the top at wider at the bottom. This puts constant stress on the overstretched laminae towards the bottom.

3.  Severe Pathology. Founder – Rotation with Separation.  The ‘wedge’ is extreme now, with the laminae much longer at the bottom than the top.  The bone is far out of parallel with the hoof wall.  The constant downward stress and pull on the lower part of the laminae has caused them to fail, allowing the suspension of the bone to the inside of the hoof wall to be lost and the bone to rotate. 

Restricting a horse’s diet has many negative effects, as described in the following article from KAM Animal Services.  Could the diet adopted out of necessity (if not outright desperation) by owners of insulin resistant horses and easy keepers, actually be contributing to their predisposition to laminitis? 

Read the whole article here:

http://www.kamanimalservices.com/guts.htm

Here are pertinent excerpts from the lengthy article:

By: Kate McBride Puckett
November 27, 2006

Dysbiosis, also known as “Leaky Gut Syndrome” is defined as a perforated hind gut, an excessively permeable intestine or a condition of erosion and ulceration of the gastrointestinal tract.

Symbiosis is defined as the relationship between organisms in which one organism is in an intimate association with another. A pertinent example of a symbiotic relationship is the intestinal flora of a healthy species lives in harmony with its host. As such the bacteria of the intestine is often referred to as “friendly” and helps to maintain homeostasis and many “health promoting” activities including detoxification, vitamin production, and protection against pathogens.

If this relationship is out of balance, the mere overgrowth of so-called “friendly” bacteria, dys-symbiosis or dysbiosis results and inevitably leads to holes in the gut. Dysbiosis, and subsequent increased permeability of the intestinal mucosa, in general can be caused by a myriad of causes including protozoan parasites, bacteria,  yeast, excessive antibiotic or NSAID use, parasite infestation, maldigestion, stress, and an imbalanced and restricted intake diet. The most critical point to consider with dysbiosis is the extreme damage it causes the equid by permitting bacteria, pathogens, etc. to escape the intestinal lining and enter the bloodstream. With this more permeable intestinal mucosa, essentially the filtration system of the intestines is defunct/deficient and provokes three detrimental responses to “foreigners” or pathogens leaking into the blood stream:

1.)   an Immune Function System response

 2.)  a Systemic Inflammatory System response, and

 3.)  an Insulin Resistance response (which can be measured by endocrine systems tests).

Another consequence of dysbiosis is a resistance to insulin, a recently recognized syndrome labeled “Syndrome X” or Insulin Resistance syndrome. Essentially this is a metabolic syndrome characterized by an inability to transport glucose into the cell.

This resonates in the horse because an increased risk of several digestive and metabolic disorders has been associated with feeding (high carbohydrate and sugar) meals of grain and molasses.  Post eating, the pancreas produces insulin to lower blood sugar levels, however with the consequent flooding of sugar into the blood due to dysbiosis, this results in reactive “rushes” of insulin that either cause decreased future insulin levels leading to high blood sugar (diabetes), erratic insulin levels leading to low blood sugar (hypoglycemia), or Syndrome X, whereby insulin receptors in the liver, muscle and fat cells become damaged and cannot transport glucose effectively. These blood sugar conditions also cause the adrenal glands to produce increased cortisol levels catabolizing proteins and weakening and inflaming connective tissue and lamellar structures within the feet.  The cells become resistant to insulin and the glucose from the feed can no longer penetrate the cells. In turn, the horse suffers from inflammation, laminitis, and/or founder.   This metabolic syndrome also causes a general build up of lactic acid (due to stress and poor oxygenation) that interferes with muscle function, endurance,
metabolism, immunity, and hoof health, exacerbating laminitis.

Essentially the equine digestive system is a complicated system designed to process frequent small amounts of food.  By confining horses, the amount, frequency and type of feed available for them to consume is now determined by humans. Before what was a continual input from grazing, has become a once a day feeding of unvaried, unbalanced large quantities of feed. 

The causes of dysbiosis include: high starch meals, infrequent feedings and confinement during feeding times (Equine stomachs constantly produce hydrochloric acid which eats away at the mucosal lining if empty), response to chronic pain, heavy exercise (Horses contract their abdominal muscles under stress forcing the stomach’s hydrochloric acid into the upper stomach), NSAIDS and Steroidal drugs (These drugs prevent prostaglandin production, key components of the protective mucosal lining of the GI tract), and parasites.

The clinical signs of dysbiosis are varied.  Typically the horse eats grain, but will not eat hay, has a rough coat, suffers weight loss and has dificulty gaining weight, is often anxious, stressed, nervous, and objects to working or to the saddle itslef, is often sore to the touch to the bladder 21 acupunture point and is reactive to palaption along the gut sagittal line.

Once dysbiosis occurs in the equid, this essentially opens the door to many equine diseases. In addition to the aforementioned diseases founder, laminitis, inflammatory diseases i.e. arthritis, and metabolic disorders i.e. insulin resistance; dysbiosis also contributes to Cushing’s disease, endotoxemia, Diabetes mellitus, azoturia, colitis, inflammatory bowel disease, irritable bowel syndrome, infectious enterocolitis, celiac disease, bacteremia, Chronic Obstructive Pulmonary Disease (Heaves), liver disease, and colic. Most often these conditions manifest in the horse as colic, which is often recurrent and unrelated to management. Chronic weight loss and chronic diarrhea may also result from leaky gut syndrome.

Further it has a devastating effect on the liver as it is recruited to filter all “contaminated” blood from the intestine. Signs of liver dysfunction, which include tight, sore muscles, weak, easily injured tendons and ligaments, poor hoof quality, eye disorders and irritability will appear before the liver has time to increase liver detoxification enzyme production (detectable via blood tests) and thus excess free radicals are left to circulate in the blood exacerbating chronic disease i.e. laminitis.

Treatment and Prevention of dysbiosis is fairly straight forward and a simple way to avoid such grave consequences. First off, return your horse’s life to him. Permit your horse to be a horse as close to its natural state as possible. Relocate your horse “out” with ample running room, grazing, and companionship. Offer plenty of high quality grass hay and frequent small low starch meals. It is always best to prophylactically prepare/protect your horse’s gut prior to any stressful situations: deworming, vaccinations, shipping, shows etc. Maintain a well-balanced feed for your horse with appropriate Calcium/phosphorus ratios as close to 1:1 as possible. Have horses teeth checked and floated regularly and try to keep the horse’s daily regime predictable and prompt as possible. “The more boring your horses daily life, the better”.

”Insulin Resistance” is a trendy diagnosis made by lay people with regards to their own horses, based on information they glean from the internet. It is suspected as a cause in laminitis and founder, and horses are removed from most or all pasture, depriving them of their natural grazing needs in an attempt to remove sugars from the diet. I believe it is possible that this actually can cause the horse to experience even more stress and thus puts in motion a vicious cycle.Below are some excerpts from an article in The Horse, in which Tia Nelson DVM, discusses her experience in reducing signs of insulin resistance (such as cresty necks) in some horses, simply by improving their hoof form.

As she says, it is important to manage horses’ diets, especially easy keepers, but it can be very helpful to eliminate poor hoof form as a contributing factor. There is more on Insulin Resistance in a study posted on this blog, linked on this page here

Read the whole article here

“People usually don’t recognize that there are only two factors affecting the foot–genetics and environment,” says Nelson (Tia Nelson, DVM, a farrier and veterinarian from Helena, Mont). “The footing, the farrier, the food the horse eats, the ability to utilize the nutrients in the food, etc., are all part of the environment. These things are intertwined, and it can be hard to separate them.”

She says some of her cases looked like they were insulin-resistant (with cresty necks, prone to founder, etc.), but weren’t. When she was able to get their feet comfortable so they could get regular exercise, their glucose and insulin levels came down and their feet got better–without medical treatment.

“Fixing the mechanical cause of pain in feet that led to stress–that raised their cortisol(a “stress hormone”) levels–resolved their problems,” she explains. “When a horse gets painful feet, the cortisol levels go up, probably due to the stress and the ulcers that develop due to the stress. Stress hormone levels go up in any horse that’s in pain. If his feet are out of balance and the stress on them starts to lead to founder, he’ll be in pain.

“There are some horses, however, that are truly insulin-resistant,” Nelson says. “It is our job to learn how to balance feet and get the horse comfortable again and to run bloodwork to check for these things”.