Bovine Reproduction. Группа авторов
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that the navicular bone be removed. A half‐inch drill is used to facilitate curettage of the joint surface, drilling from the heel incision toward the extensor process and following the surface of the joint [6]. Further debridement of the joint is necessary using a large bone curette. Curettage is complete when you can't remove any more necrotic bone. Use a squeeze bulb to lavage the surgical site with a broad‐spectrum antibiotic or antiseptic saline solution. Place a wooden block on the healthy claw, pack the joint with medical‐grade honey, and bandage the hoof [7] (Figure 16.15).
Figure 16.15 Dressing change post DIP joint currretage. Notice the gauze packing ingress at location of the extensor process of the third phalanx and eggress at the heel bulb.
Parenteral antibiotics are administered daily, and bandage changes and joint lavage are performed every other day up to four times. Beads of bone cement mixed with an antibiotic can be placed in the joint space to facilitate healing, but they should not be placed until there is a healthy granulation bed and no more purulent discharge. When the surgical wound has closed with granulation tissue, the limb is casted above the fetlock for five to six weeks. After the cast and hoof block are removed, the animal should have a recuperative period. The patient should show at least 80% improvement in lameness over the initial presentation after the convalescent period; some lameness is to be expected.
Corkscrew Claw
Corkscrew claw (CSC) is observed in the young adult beef animal and usually involves the lateral claw of both hindlimbs. In some breeds, such as Brahman and Brahman crosses, it can occur on the medial claw of both forelimbs. Because CSC can be seen in calves and yearlings, some practitioners believe that this is a heritable condition. However, it appears that this is a management‐induced problem, in our opinion, even in younger animals. Offering overabundant feed can lead to rapid skeletal growth and subsequent epiphysitis and rotational limb deformity. This results in abnormal load bearing and compensatory changes in the hoof. Therefore rapidly growing animals may express CSC. To prevent structural changes to the phalanges secondary to CSC, corrective hoof trimming must occur during the active growth phase. In the fully grown adult, CSC cannot be cured, only managed [8] (Figure 16.16).
Figure 16.16 Corkscrew claw on the lateral claw of a Brahman bull.
It is unknown whether bone remodeling in the distal phalanx is the cause or effect of CSC. In some patients with CSC, the second and third phalanges become misaligned and the third phalanx becomes narrower with an abaxial curvature. This leads to abnormal load bearing, which affects the white line and leads to separation. In other patients with CSC, the growth rate of the middle to caudal portion of the wall is faster than the fore portion of the toe, which causes the animal to bear weight on the abaxial wall, predisposing to bruising, abscessation, and sole ulcers.
Correction of CSC involves balancing the weight‐bearing surface of both claws. It is best to trim excess from the medial claw just until the white line is apparent. Next shorten the affected claw to the same length as the normal claw. Remove the upward deviation and rotation of the wall with a grinder or nippers. The heel is often higher in the CSC and it should not be lowered. Bevel the sole to encourage wall contact with the sole surface. At this point, there may not be very much area for bearing weight, but it will encourage more favorable wear for the hoof wall. Corrective hoof trimming should occur every four to six months.
Interdigital Dermatitis, Digital Dermatitis, and Interdigital Pododermatitis
The hoof problems of interdigital dermatitis, digital dermatitis, and interdigital pododermatitis are often lumped together, but each condition has its own etiology, tissue involvement, and disease progression. Interdigital and digital dermatitis are often not serious problems unless left to become chronic. Interdigital pododermatitis can progress rapidly and cause serious economic loss if left untreated.
Interdigital dermatitis is a localized inflammatory process involving the interdigital space. In the early stages, the skin has a greasy appearance and some erosion can occur, particularly in the heel bulb area. Digital dermatitis (hairy heel wart) is another low‐grade inflammatory process with pronounced change when allowed to become chronic. The epidermal layer becomes overproductive, at first producing excessive hair growth that stands out from the skin, and progressing to small papillary projections giving the appearance of wart‐like growths. As the condition becomes chronic, the dermis can become very proliferative [9], making for an unsightly lesion. These conditions respond well to treatment via footbath. Care should be taken in the choices of medications recommended in footbath treatments as some products may cause environmental contamination with improper disposal [10]. A copper sulfate solution is considered environmentally safe. In chronic lesions that are extremely proliferative, surgical resection and topical treatment may have to be provided before resolution can occur.
Interdigital pododermatitis, commonly called foot rot, can be an acute, aggressive infection that progresses to deeper structures quickly. While systemic antibiotics are rarely indicated in the treatment of digital or interdigital dermatitis, they should always be administered in patients with foot rot. Bandaging with a broad‐spectrum antiseptic or antibiotic is recommended when treating each of these three conditions.
Interdigital Fibroma
Interdigital fibroma is a condition most often observed in heavier weight beef breeds, particularly older bulls with widely placed claws. Occasionally, cows will develop fibromas as well. If the condition is allowed to persist, the “corn” can become ulcerated and infected due to continued contact with the ground (Figures 16.17, 16.18 and 16.19).
Figure 16.17 Digital dermatitis (hairy heel wart).
Figure 16.18 Interdigital fibroma can be misleading; this one does not appear to be significant until observed from the solar surface.
Surgical removal is necessary to resolve the fibroma. Anesthesia of the interdigital area can be provided by four‐point block or the use of a tourniquet and intravascular anesthesia. Removal of the prolapsed tissue is accomplished by sharp dissection followed by extraction of the fat pad. Cautery of the vascular bed is sometimes required to control excessive hemorrhage. A bandage is applied with a sterile gauze pack and changed after three days. As an aid to healing, especially in the individual with splayed toes, it is helpful to wire the toes together to reduce swelling and decrease granulation bed formation. The second bandage can be removed in 4 days, with complete healing expected within 10 days of surgery.