Digits
Joint Luxations
Tendon and ligament lacerations/injuries
Hypertrophic osteopathy
Trauma/fractures
Joint Luxations
Signalment
Breeds – No breed predilection, although sporting and working dogs are predisposed to digit injuries in general.
Gender – No gender predilection
Age – Usually middle aged to older
Etiology - Dogs may get their digits caught on various obstacles, resulting in trauma and luxation or subluxation of the metacarpophalangeal joint, P1-P2, or P2-P3 joints.
History
There is often an acute onset of lameness if the digit is caught on an obstacle. Dogs may initially improve, and when work or activity is resumed, there may be a consistent or intermittent lameness which is exacerbated by exercise.
Clinical Findings
Varying degrees of lameness may be apparent. The affected joint(s) is (are) generally swollen and painful with manipulation. Chronic injuries may have palpable fibrous tissue. Varus and valgus stresses may result in excessive motion when the affected joint is isolated and extended. Comparison with neighboring joints or the contralateral limb at the same joint may be useful to evaluate normal joint motion.
Diagnostics
Radiographs of the affected area should be made to evaluate the degree of luxation/subluxation and to rule out fractures or osteoarthritis. It is difficult to image the area with ultrasound or MRI due to the small size of the structures and the limited area. Infiltration of the area/joint with local anesthetic may be useful to be certain that the cause of the lameness is the digit, especially if other musculoskeletal conditions are found elsewhere in the limb.
Treatment Options
Depending on the stage of injury (acute vs chronic), the extent of injury, and the intended use of the dog, various treatments may be instituted. For example, dogs with chronic injuries that are house pets may be treated conservatively with splinting, bandaging, and anti-inflammatory medications. Working or sporting dogs with acute injuries may benefit from primary repair of collateral ligament and joint capsule damage, followed by appropriate splinting or support. If osteoarthritic changes are the predominant cause of the lameness rather than instability, arthrodesis of the joint may be performed, or if the digit is not one of the main weight bearing digits, amputation of the digit may be performed, especially at the P2-P3 level.
Tendon and ligament lacerations/injuries
Signalment
Breeds – No breed predilection, although sporting and working dogs are predisposed to tendon and ligament lacerations in general.
Gender – No gender predilection
Age – Usually younger to middle aged
Etiology - Lacerations of the superficial and deep digital flexor tendons are more common than lacerations of the extensor tendons. Dogs may be running in a field and suddenly cry out and demonstrate lameness with lacerations with glass, metal, fences, etc.
History
There is often an acute onset of lameness if the limb is injured by sharp objects such as metal or glass. Lacerations are usually obvious with skin lacerations and bleeding. Owners may be concerned about excessive hemorrhage since these areas are usually quite vascular.
Clinical Findings
The area of acute laceration is usually obvious with skin trauma, hemorrhage, and often gross contamination of the wound. Isolated chronic lacerations of individual flexor tendons may appear to have a "dropped" or "cocked up" toe as a result of unopposed tension by the digital extensor tendons.
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Diagnostics
Radiographs should be made of the affected area to be certain that no fractures or luxations of joints are apparent. Following appropriate initial wound management, debridement and flushing of the area, a deep tissue culture may be obtained.
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Treatment Options
Initial wound management is critical to success. Debris should be removed, necrotic tissue debrided, and the wound should be thoroughly irrigated to reduce contamination. A deep tissue culture should be taken. Primary repair of the tendon may be performed if it is within the first 6 hours of injury and the wound can be adequately cleaned. Wounds that cannot be adequately cleaned, or older wounds, may benefit from delayed repair. In these cases, tagging the ends of the tendon(s) with a colored monofilament suture may be useful to locate the ends of the tendon when repair is performed. Standard tendon repair suture patterns may be performed, such as a locking loop or three-loop pulley, to approximate the tendon ends. Smaller, multiple horizontal mattress sutures in the epitendon give additional strength. The foot should be immobilized in a flexed position for the first 2-3 weeks to allow early healing. Over the course of the next 6-8 weeks, strategies to increase the amount of tension and weight bearing on the healing tendon should be employed that increase the amount of tensile and weight bearing forces on the tissue, without causing re-rupture of the tendon. Gradually increasing extension of the foot with a non weight bearing sling, such as a carpal flexion bandage, may be used from week 2 to week 4. A splint, orthotic, or external fixator may be used between weeks 4 to 8 to gradually increase the amount of weight bearing on the limb, without exceeding the strength of the repair. Failure often occur if the animal is suddenly released from a bandage or splint with complete weight bearing. For a successful outcome, the stresses must be gradually applied to stimulate healing and strengthening without exceeding the strength of the healing tissue. Nonsteroidal anti-inflammatory agents may slow healing and should be used judiciously. Fluroquinolone antibiotics are contraindicated in the treatment of tendon or ligament healing unless a life-threatening infection is present and there are no other reasonable choices.
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Hypertrophic osteopathy
Signalment
Breeds – No definitive breed predilection
Gender – No gender predilection
Age – Usually middle aged to older
Etiology - This is a condition of bones of the distal limbs, associated with masses in either the thorax or abdomen. Most, but not all masses, are neoplastic. Cases associated with parasitism have been reported. Some have postulated an imbalance of sympathetic and parasympathetic input to vasculature in the area as a cause of the periosteal reaction.
History
Dogs have lameness, reluctance to move, and firm swelling of the bones of the distal limbs. Other signs related to thoracic or abdominal masses may also be present.
Clinical Findings
Lameness, reluctance to move, and firm swelling of the bones of the distal limbs are found on examination. Other signs related to thoracic or abdominal masses may also be present.
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Diagnostics
Radiographs of the phalanges and metacarpal bones show extensive periosteal reaction along the cortices. As the condition progresses, lesions may be noted in more proximal bones. Additional diagnostics should be performed to locate the primary source of the problem in the thorax and abdomen.
Treatment Options
Treatment of the primary condition may result in improvement of the lesions, but sometimes incomplete resolution is possible. Symptomatic treatment of lameness with anti-inflammatory medication may be beneficial.
Trauma/fractures
Breeds – Any breed
Gender – No gender predilection
Age – Any age
Etiology – Trauma. Many cases occur as a result of automobile trauma, getting the foot caught in things such as a gate or fence, or being stepped on.
History
Often owners witness trauma, such as a fall, hit by automobile, being stepped on, or another sudden traumatic event that results in sudden onset of severe lameness.
Clinical Findings
Fractures of the metacarpals and phalanges result in pain on manipulation and crepitation during manipulation of the area.
Diagnostics
Radiographs are generally diagnostic, but it is important to separate the toes when taking radiographs to clearly define each digit because multiple fractures are often present in the foot. CT evaluation may give additional details.
Treatment Options
Some fractures of the metacarpals and phalanges may be managed with external coaptation, especially if the inner digits are not involved. Some palmar displacement of the healing bones often occurs if care is not taken to prevent early weight bearing. lnternal fixation is necessary to restore anatomy and function in working and sporting dogs, and if all digits are involved. Options include plates and screws, small intramedullary pins, or mini external skeletal fixators.
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