Lameness is an important economic problem in all sectors of the cattle industry. One of the main problems is laminitis, which leads to changes in claw conformation and results in chronic lameness, weight loss, reproductive losses and early culling.
Subacute/subclinical laminitis, mostly seen in cattle, is a systemic disease in which the foot is one of the main targets because it’s extremely vascular and has a rich nerve supply. Inflammatory mediators and endotoxins cause disruptions in horn growth, alterations in blood flow and stimulation of pain receptors, leading to pain and lameness.
Laminitis is a multifactorial condition associated with nutrition, body weight, claw conformation and size and normal weight distribution. In general, healthy feet are highly dependent on normal rumen fermentation.
Structure and weight distribution
The foot consists of two digits, and at the end of each digit is a claw. The “medial” is the inner claw, while the “lateral” is the outer claw. In a perfectly normal back foot, the outside claw is slightly bigger than the inside claw and bears more weight than the inside claw. Most often, lameness will occur in the outer claw, particularly in the back legs. More weight being placed on the outside claw makes this area susceptible or prone to concussion due to weight-bearing forces.
The back legs are a rigid, boney system going through the pelvis. There’s not much flexibility between the outside and inside claws. In the back legs, the normal weight distribution ratio of a heifer is 60:40 between the outside and inside claw.
The front legs are a muscular structure attached through the chest, allowing them much more flexibility between the two claws than the back legs. The weight distribution ratio is 50:50, although the medial claw bears slightly more weight than the back under normal conditions.
The third phalanx (P3) is located inside the foot. On the outside of P3 is the horn structure of the claw. It’s suspended within the claw by ligaments, including the distal cushion, and normally gives when the animal walks.
[inline_image file=”86038581d6bd1b9d3158359337ce3067.jpg” caption=”Screw claw is a heritable defect that causes severe lameness in cattle when the outer wall of the hoof curves like a corkscrew.”]
“When it bears weight, the P3 doesn’t sink down evenly. It sinks down more to the inside and causes concussion and bruising to the corium. This is the most common site for sole ulcers,” said Dr. Sarel van Amstel, retired professor in the Large Animal Clinical Sciences Department at the University of Tennessee’s College of Veterinary Medicine.
Nutrition
Nutritionally, many different factors can contribute to laminitis, including an incorrect fiber to grain ratio. For example, many producers in the Midwest run cattle on harvested cornstalks during the fall and winter months. Cattle load their rumen with whole corn, a highly fermentable carbohydrate, eventually leading to rumen acidosis. This has a large impact on the blood supply in the foot, and laminitis begins to develop.
Rumen acidosis causes inflammation and production of endotoxin, which reduces the ability of the blood to carry oxygen.The formation of keratin, which are intracellular filaments acting as a support scaffold in the cell, partially fails. Claw horn becomes softer. Softer feet bend more easily as weight is applied. When more weight is applied to the outside wall of the foot, it begins to roll or curve inward, causing lameness.
“Rumen health and foot health go hand in hand,” said van Amstel. “A healthy rumen is dependent on a good, quality roughage. Hay needs to be no shorter than an inch.” Structured roughage in the rumen stimulates receptors in the wall of the rumen.
“If it is chopped or milled too fine, those receptors won’t be stimulated. Cattle will not chew their cud sufficiently, and saliva will not be produced in sufficient quantities,” explained van Amstel.
Saliva is the main component that buffers the acid produced by fermentation in the rumen. Lack of saliva leads to acidosis, poor blood circulation and laminitis.
If you are preconditioning cattle to laminitis, such as running cattle on cornstalks where they can develop acidosis, look at your trace minerals. Copper, zinc and biotin are very important for the formation of keratin. Keratin’s role inside the cell is similar to scaffolding, making the cell strong. Supplementing these trace minerals will help combat acidosis and ensure quality keratin growth for healthy feet.
In a situation like running cattle on cornstalks, it’s best to use chelated minerals. Chelated minerals are trace minerals that have been attached to an amino acid, which is an organic compound, and have high bioavailability.
“In the gut, chelated mineral formulation will be absorbed best. For example, zinc oxide may have a low bioavailability compared to some of the chelated forms. You may have a normal book value of zinc levels, but that does not mean that’s what the animal is going to absorb depending on formulation,” said van Amstel.
Laminitis versus screw claw
Laminitis has often been mistaken as screw claw when purchasing cattle. Screw claw is a heritable defect that causes severe lameness in cattle when the outer wall of the foot curves like a corkscrew. Observed in young cattle around 10-11 months of age, the claw begins to curve and eventually twist like a corkscrew. This improper weight distribution places parts of the foot’s sidewall in direct contact with the ground, causing lameness through development of a sole ulcer or white line disease.
“Claw curving or twisting in laminitis usually manifests later, around 2 to 3 years of age,” said van Amstel. “Laminitis is a chronic disease, and symptoms of systemic disease are usually absent.”
In recently calved cows, sole hemorrhages may be seen, which may progress to other sole and horn lesions such as a sole ulcer, white line disease and other horn lesions denoting a poor-quality horn, such as vertical and horizontal wall cracks.
Compared to screw claw, laminitis is not heritable, although heritable laminitis was reported in the Jersey breed. Laminitis is a nutritionally and environmentally induced disease. It’s primarily related to nutrition and systemic problems, such as mastitis and metritis, and aggravated by weight bearing,” van Amstel emphasized.
[inline_image file=”64d008aaef9e4ae9900133925742c211.jpg” caption=”Improper weight distribution places parts of the foot’s sidewall in direct contact with the ground, causing lameness due to the development of a sole ulcer or white line disease.”]
“Heritable screw claw is based on an abnormal angle of (second phalanx) and P3 bones inside of the foot, which should be straight. When P3 is slightly angled toward the inside, the weight and pressure on the outside claw wall is going to be more than normal. The wall, particularly at the heel, will turn inward and curve similar to laminitis,” said van Amstel.
Horizontal “hardship” grooves that run across the toe can be used to depict laminitis. “It almost causes a ripple effect if you look at the top part of the toe,” he said. “It shows that there have been interruptions of horn growth because of laminitis. Foot quality can also be a factor to observe, such as if the foot is not smooth or is peeling. This can be a result of cattle with zinc and copper deficiencies.”
Husbandry
Exercise is very important to maintain the blood circulation in the foot. Cattle must be provided enough space to do so. Placement and size of feed bunks are also important to note. “If the feed bunk is too high or wide, the animal must propel their body forward, twisting their feet to the outside in reach of food. Over time, the added pressure to the inside of the claw causes it to roll,” said van Amstel.
“These days, we see a lot of foot warts,” said van Amstel. Foot warts are a disease contracted in muddy, slurry conditions. The area around feed bunks and bale feeders often serves as a breeding ground for foot warts.
“It can be a huge problem in feedyards when cattle are standing in slurry conditions. I usually recommend adding a foot bath in situations where animals are really exposed to slurry,” concluded van Amstel. — Rudy Pooch
