JUNE 2024 THE RIDER /31 Founder In Horses


By Jaime Thomas BSc. Chronic and acute lameness


issues are at the forefront of med- ical concerns for horse owners everywhere. “Founder” is among the most common forms of lame- ness in horses and one that all caretakers need to watch out for. Founder is the common


name for laminitis, a condition defined as inflammation of the laminae within the hoof. This condition is painful, causing lameness in horses, and involves damage to the laminar connec- tion between the hoof wall and the coffin bone. The term founder is often


used colloquially to refer to any form of laminitis. Veterinarians use the term more specifically to describe ongoing laminitis that also involves rotation/sinking of the coffin bone.


Hoof Anatomy The laminae are the two


layers of finger-like protrusions that interlock with each other (like Velcro) to anchor the hoof wall to the coffin bone. The coffin (a.k.a. the pedal


or P3) bone is the first bone in the leg to absorb the impact of walk- ing, and its proper position is crit- ical to circulation within the lower limbs.


In cases of laminitis, the


laminae strain and start to sepa- rate, which is very painful. Dys- function in the laminae results in less support of the coffin bone, which can allow it to rotate out of position.


When the coffin bone ro-


tates abnormally, intense pressure is exerted on the sole of the foot. In extreme cases, it can rotate so far it penetrates the sole of the foot. Horses with this condition may show signs of distress and discomfort and require prompt veterinary attention.


Image by Dr. Ana Mesa PhD, Mad Barn Equine Nutritionist


Causes Founder is often influenced


by both metabolic and environ- mental factors acting on their own or in combination with each other. Common causes include:


Diet Changes: Overconsump- tion of grain products and other concentrates is associated with laminitis and founder.


Endocrine disorders:Hormonal imbalances including Equine Metabolic Syndrome (EMS) and Cushing’s Disease (Pituitary Pars Intermedia Dysfunction) are as- sociated with an increased risk of laminitis.


Obesity: All equines can be af- fected by laminitis and founder regardless of their weight. How- ever, horses and ponies that are overweight are more at risk of pedal bone rotation and damage to their hooves because of the extra weight their feet must sup- port.


Acute illness: Bacterial infec- tions and their related symptoms


can impair the laminae, including • Diarrhea • Inflammation in the small intes- tine (enteritis) • Pneumonia • Salmonella or Clostridia infec- tion • Potomac Horse Fever • “Bastard” (systemic) Strangles • Lyme Disease


Black walnut exposure: The use of black walnut (Juglans nigra) shavings as bedding is a known cause of laminitis. After the horse is exposed to black walnut shav- ings via oral ingestion or skin contact, laminitis may develop within 24 to 48 hours.


Signs and Symptoms of Founder Some of the most common


symptoms of founder include: • Sudden onset of lameness in both front limbs • Resistance to walking or mov- ing • Strong digital pulse • Heat in the hooves • Shifting weight back and forth between legs • Reluctance to pick up the feet


• Standing with the legs camped out in front of the body or with all four


legs under the body


(sawhorse stance) • Lying down more frequently


Signs to look out for that


can indicate chronic laminitis and impaired hoof integrity include: • Dished appearance to the front of the hoof • Divergent growth rings (rings of growth on the hoof that are very tight at the toe and wide at the heel) • Widened white line/hoof sepa- ration • Foot abscesses that develop a few weeks after the initial acute laminitis episode


How is Founder Diagnosed? A veterinarian will typi-


cally complete a thorough physi- cal examination that includes assessing the behaviour, weight, height, temperament, body con- dition score, body temperature, and vital signs of the horse. Some of the exams used to diagnose founder include: • A lameness exam, which may include nerve blocking • Hormone level testing • Diagnostic imaging such as X- rays


Treatment of Founder Any sudden onset of lame-


ness is a medical concern and prompt veterinary assessment provides the best chance of a pos- itive outcome. The treatment strategy for founder aims to re- lieve immediate symptoms, then resolve the underlying cause.


Diet


oped acute founder due to en- docrine


In horses that have devel- causes


(such as


metabolic syndrome or Cush- ing’s), it is advised to stop feed- ing all grain products and remove the horse from pasture. Hay should be soaked before feeding until it can be analyzed for hy- drolyzable carbohydrate levels, as high sugar can trigger another laminitic event. It is recom- mended to work with a nutrition- ist to formulate an appropriate feeding plan.


Medication Veterinarians


generally


start treating founder with non- steroidal anti-inflammatory drugs (NSAIDs) or other types of painkillers to relieve pain and in- flammation. Horses with endocrine dis-


orders may require specific med- ications to treat their endocrine imbalance and prevent future laminitic episodes.


Cold Water Therapy To reduce inflammation in


the foot, a veterinarian may sug- gest immersing the horse’s foot in ice water for 72 hours to main- tain a consistent temperature


under 40 degrees Fahrenheit. This is appropriate for grain overload and cases involving widespread inflammation, as it slows toxin delivery to the lami- nae by reducing blood circulation in the hoof. However, cold water ther-


apy for endocrinopathic laminitis after pain has appeared is contro- versial because blood circulation is already impaired in these horses.


Corrective Trimming and Shoeing Horses with founder should


be made comfortable to bear weight on the rear portion of their affected hooves. This involves a realigning trim with short toe and heels moved back as far as the foot will allow. Specialized shoes such as heart bar shoes, shoe pads or wedges may help make the horse more comfortable. A foundered horse should also have a soft place to stand or lie down to relieve the pressure on their weakened hoof laminae.


Surgery Horses with founder may


benefit from surgery on their deep digital


flexor tendon


(DDFT) to relieve tension on the structure and help prevent further rotation of the coffin bone. This procedure is contro-


versial and is generally reserved for cases with severe contraction of the musculotendinous unit.


Jaime Thomas is a graduate of the University of Cal- gary and has extensive ex- perience working as a researcher and writer in the nutraceutical industry. She is a dedicated horse owner who enjoys staying current with advances in equine health and nutrition to bet- ter serve the horses she cares for and interacts with.


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