Term
| What is the soft, unpigmented tissue covering the hoof in utero? |
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Definition
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Term
| When is the hoof developed during gestation? |
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Definition
| Fully developed by 3 mos. gestation |
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Term
| What is the coronet? What should it not be confused with? |
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Definition
| Boundary between skin of pastern and hoof. NOT a physical structure; do not confuse with coronary band, which is located AT the coronet. |
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Term
| What is the coronary band? |
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Definition
| 1.5 cm. bulging band of epithelium (transitional btw skin and hoof) and underlying corium. Can be palpated. |
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Term
| Is the sole weight-bearing? |
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Definition
| No. The hoof wall + frog are weight-bearing. |
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Term
| What are sloping and club feet? |
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Definition
Sloping foot: excessively acute toe angle (much less than 50 degrees in the fore, and 55 in the hind).
Club foot: excessively obstuse toe angle (greater than 50 fore, 55 hind). |
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Term
| What tissue forms the ungual cartilages? |
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Definition
| Hyaline at birth, changes to fibrocartilaginous in adult. |
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Term
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Definition
| Purulent infection of lateral (aka ungual) cartilages. Seen rarely in draft horses. |
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Term
| What plexuses are associated with the hoof? |
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Definition
1) Coronary venous plexus (in coronary corium): assoc. with axial surface of lateral cartilage.
2) Palmar venous plexus (in solar dermis): assoc. with axial surface of lateral cartilage.
3) Dorsal venous plexus: in laminar corium. |
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Term
| What are 2 regions (histologic) of epidermis in hoof? |
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Definition
1) Stratum corneum (keratinized, "dead", insensitive)
2) Stratum germinativum (contains both Stratum basale - proliferating cells - and Stratum spinosum - in the process of keratinizing). Sensitive. |
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Term
| What are the sensitive tissues in the horse hoof? |
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Definition
| Stratum germinativum (living part of epidermis) and corium (dermis). |
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Term
| Hoof wall epidermis is produced from what 3 regions? |
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Definition
1) Periople
2) Coronary
3) Laminar |
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Term
| What are the layers of the hoof wall epidermis? |
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Definition
1) Stratum externum (aka stratum tectorium): produced by periople germinal epidermis; waterproof layer.
2) Stratum medium: tubular and intertubular horn produced by coronary germinal epithelium. This is what actually forms the horn of the hoof wall.
3) Stratum internum: where laminar germinal epithelium interdigitates with laminar dermis. Does not make hoof wall; just connects the hoof wall horn with the underlying dermis. |
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Term
| How fast does the hoof grow? |
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Definition
| Wall is formed at rate of 6mm/month. Thus it takes 9-12 mos. for the toe to grow out. |
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Term
| To which structure(s) does the subcutis of the coronary corium attach? |
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Definition
| Extensor tendons and lateral cartilages. |
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Term
| How many primary and secondary laminae are there? What are they formed by? |
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Definition
| 600 primary; 100 secondary for each primary lamina. These are formed by the laminar epidermis of the stratum internum. |
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Term
| What is founder? What are some causes? |
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Definition
| Laminitis. Can be caused by: grazing lush pasture, carb overload, postparturient metritis, endotoxemia, colic, enteritis. |
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Term
| Compare and contrast horn of hoof wall vs. sole vs. frog. |
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Definition
Hoof wall: produced by coronary germinal epithelium.
Sole: produced by sole germinal epithelium. Softer due to being 30% water. Does not bear weight.
Frog: produced by frog germinal epithelium. Not completely keratinized; 50% water. Cushions foot as it lands heel first. |
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Term
| What is the coronary cushion? |
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Definition
| Coronary subcutis of coronary corium. Contains collagen, elastin, fat, and cartilage. Contains coronary venous plexus. |
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Term
| What is the digital cushion? |
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Definition
| Collegen + elastin under/around frog, DDF, and lateral cartilages. Dissapates shock. Contains tubular glands that exit to frog (only place that "sweats" on solar surface). Acts as pump to return venous blood from foot. |
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Term
| Which arteries supply blood to the digits and hoof? |
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Definition
| Mostly the median palmar + plantar arteries, with some contribution from lateral palmar artery. Superficial palmar/plantar arch supplies fetlock joint and associated tissues. Arterial circles at distal P1 and P2. Terminal arch is formed from anastomosis of medial and lateral digital arteries in sole canal of P3. Branches of terminal arch go through P3 bone to supply laminar and coronary corium of hoof. |
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Term
| Is the proportion of heel to sole greater in the horse or cattle/pigs? |
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Definition
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Term
| What is the parapedal groove, and in which animal is it found? |
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Definition
| Groove on medial aspect of hoof wall (where horn is thinnest) of cow. |
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