Common Diseases and Pathologies	191

Disorders of muscles and tendons

Muscular, tendinous, or ligamentous injuries are commonly sustained by animals, but they are often difficult to diagnose unless the traumatic incident has been witnessed by the owner. An experienced practitioner may detect subtle differences in heat which may indicate increased blood supply, possibly indicative of inflammation due to trauma. The fact that muscular injuries are often overlooked is perhaps due to the difficulties that imaging muscular structures presents, and the perceived transient nature of the injury.

Individual muscle fibre

Endomysium

Perimysium

Epimysium

Muscle anatomy (normal)

195 Diagram of a muscle unit.

Skeletal muscle injury

Injuries to muscle come in two recognized forms, the bruise (contusion) and the strain. The term ‘bruise’ suggests haemorrhage and muscle fibre disruption as a direct result of trauma, as opposed to a strain, which is defined as stretching or tearing of the groups of fibres, and is perhaps more consistent with abnormal or excessive movement of a muscle beyond its normal range of movement. Muscular injury can cause considerable pain during normal locomotion. Trauma to muscles can result in damage to individual muscle fibres, disruption of the fibril units of muscle, and damage to the vascular supply of the muscle unit, leading to considerable haemorrhage, which further disrupts its continuity. Usually, strains tend to be a little less severe than contusions.

Fortunately, muscle heals readily as it has a very good blood supply. However, this occurs only if the connective tissue surrounding each muscle fibre (the endomysium) remains relatively intact (195). If this is not the case, as a result of severe trauma leading to catastrophic haemorrhage, scar or fibrous tissue is laid down, disrupting the normal architecture of the muscle. Scar tissue does not possess the properties of the muscle fibre, i.e. its capability to stretch and contract. Scar tissue, therefore, retards the muscle as a whole, reducing its ability to stretch and contract and, therefore, affecting the motion of the dog.

Muscular injury is invariably caused by trauma, which may or may not be witnessed by the owner. Unlike many orthopaedic diseases, there is no age, breed, or sex predilection.

Treatment

Treatment, if trauma is witnessed, should include the immediate application of a cold compress to the area concerned. The cold compress can take any form, from a specially-designed ice pack to a can of drink! However, the compress, whatever it is, should always be wrapped within a

192 Chapter 7

towel or similar, to prevent skin trauma as a result of excessive vasoconstriction. For the same reason, a compress should only be applied for short periods of time − not more than 5 minutes − and repeated for as long as the heat persists after the injury (196). If the affected area is superficial, the length of time that the compress is applied should be reduced.

NSAIDs are often administered during the early post-injury period to reduce the inflammation and the pain, although this can often be counterproductive, as the animal automatically feels improvement, moves more readily, and, therefore, does not allow time for healing.

The healing process relies upon the recruitment of mesenchymal cells which migrate to the traumatized area and lay down collagen, forming the initial scar

tissue ‘scaffold’. This allows future remodelling from one side of the injury to the other. During this time, exercise restriction should be advised, or there may be a replacement of muscle tissue by fibrous tissue, leading to shortening of the muscle and abnormal locomotion. This is an area where physical therapy and massage can help enormously. If trauma is suspected, the dog should be taken as soon as possible to the veterinary surgeon for a diagnosis and quick referral to a therapist. If there is a form of intermittent or difficult to diagnose lameness, the likelihood is there is soft tissue involvement. A good therapist will be able to identify the affected muscle and target the exact area/s requiring treatment. The earlier a therapist can see any dog with muscular trauma, however small, the

7

7

3

3

7

7

3

3

196 Cold compression of muscular trauma. These are the maximum times for cold be applied – to be repeated if heat returns. Areas of deep muscle 7 minutes, areas of superficial bone 3 minutes; do not exceed these times.

Common Diseases and Pathologies	193

better and quicker the recovery will be, and fewer secondary compensatory issues will have time to develop. Correct massage techniques will enable scar tissue to be broken down and fibre alignment reestablished, maintaining a balanced muscular system (see Chapter 6).

stasizing in the early stages of the disease process. The most common sites for this particular neoplasm are the metaphyseal regions of the long bones, at the proximal

Tendon rupture

It is not uncommon for penetrating injuries to the superficial structures of the limbs, poorly protected by muscle units to result in partial or complete rupture of a tendon. Chronic, extreme overextension of a tendon may produce a similar outcome. Diagnosis is relatively straightforward: the lacerated tendon ends can often be observed through the skin wound, or the diagnosis can be made following debridement under anaesthesia.

Treatment

Treatment is invariably surgical, with appositional and deep supporting sutures both being used to facilitate healing (197). The healing process is similar to that of muscle, but slower, as the blood supply is poorer. It is very important to coapt the limb after surgery for up to 3 weeks, by which time considerable atrophy of the associated muscle groups will have occurred. Carefully managed physical therapy and massage can help to assist the primary and secondary, compensatory muscular conditions.

Neoplasia

Neoplasia, the formation of ‘new and abnormal growth, specifically in which cell multiplication is uncontrolled and progressive’, is a well-recognized cause of lameness in the dog. Neoplasia can technically stem from any cell of the body, including the bones, joints, and any of their constituent parts.

The most commonly diagnosed bone tumour is osteosarcoma, which accounts for 90% of long bone tumours in large and giant breed dogs. Osteosarcoma is an aggressive neoplasm, invariably meta-

Suture used to repair laceration to tendon

197 Surgical repair of a ruptured tendon.

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humerus, distal radius, distal femur and proximal tibia (198), away from the elbow and at the knee. It is postulated that wear and tear, excessive load, and genetics may play a part in the disease.

Osteosarcoma is locally invasive, causing an intense periosteal reaction in conjunction with lysis or erosion of the cortex. This renders the bone weak, and prone to pathological fracture. The condition is known to be extremely painful and, due to its rapid progression and metastasis, the prognosis is grave. Diagnosis is tentatively made by palpation and radiographs (199, 200); the disease differs from severe OA as it does not cross from one bone to another. It is imperative that a physiotherapy practitioner be aware that, should a prominent bony swelling be palpated, at any of the aforementioned predilection sites, immediate consultation with a veterinary surgeon is required.

Treatment

The treatment of choice in many circumstances involving vertebral trauma, intervertebral disc disease, and spinal cord trauma will involve surgery and a prolonged post-operative recovery period. It is, therefore, highly likely that a physiotherapy practitioner would be involved in a post-surgical rehabilitation programme of some kind during their professional career. Certain situations exist, however, where surgery may be deemed inappropriate, due to the age of the patient, or the

Treatment

Treatment is usually palliative; amputation, limb sparing, bisphosphonate medication, and chemotherapy are often instigated in an attempt to prolong life. To assist any secondary muscular problems, carefully managed physiotherapy and massage can help enormously.

Spinal disease

Several disease processes of the spine arise in dogs. Pathologies of note include discospondylitis (infection of the intervertebral disc and the adjacent vertebrae), intervertebral disc disease (displacement of the intervertebral disc, leading to spinal cord trauma of varying severity), chronic disc degeneration (201), spondylosis deformans (see later), and neoplasia. It should be emphasized that if a dog is being treated by a physical therapist and spinal disease is suspected, physiotherapeutic treatment should be halted and veterinary advice sought immediately. Such cases should only be treated under strict veterinary supervision.

Proximal	Distal femur
humerus

Proximal

tibia

Distal radius

198 Predilection sites for osteosarcoma.

	Common Diseases and Pathologies		195

199 Ventrodorsal radiograph of the hip of a dog showing osteosarcoma of the proximal femur. Note the periosteal new bone (arrow) and bone lysis within the cortex of the femur (arrow head).

200 Lateral radiograph of the elbow showing osteosarcoma of the proximal ulna. Note the areas of bone lysis and destruction of the cortex (arrow).

201 Radiograph showing calcification of the intervertebral disc.

owner’s financial constraints, e.g. in cases of chronic disc degeneration or disc disease (types 1 and 2). The physiotherapy practitioner may, in such circumstances, be asked to provide crucial conservative treatment to maintain the quality of life

of the affected animal by ensuring a reasonable level of movement, and preserving mobility for as long as possible. Treatment should be specifically designed for the region of the spine affected (cervical, thoracic, lumbar).