Diseases of the Musculoskeletal System

Casey Conway & Jeannie Stall, R.V.T.

Credits: A. Summers

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vet.upenn.edu

Justanimal.com

The Musculoskeletal System

Movement and shape in animalsSystem of pulleysDisruption:

TraumaDegenerative dz InflammationPoor conformationNeoplasia

Long-Bone Fractures75% occur from HBC Indirect violence, bone dz., repeated

stressOpen or closedSimple or comminuted Stable or unstableQuickly assess patient, tx shock, etc. Stabilize (bandages,etc), care when

moving

Long-Bone Fractures

Clin. SignsHx Trauma, Pain, Lameness, swelling

DxX-rays, 2 views , opposite limb

Tx – reduction and fixation asap if stableSplints, casts, intramedullary pins, bone

plates , external fixators

Fractures

Cruciate Ligament Injury

Anterior and posterior cruciate ligamentStabilize the stifle joint

Rupture of the cranial cruciate ligament possibly the most common injury to the stifle of the dog and major cause of DJD

May rupture, or may tear Middle-age, obese, inactive, or athletic

Cruciate Ligament Injury

Clinical SignsNon-wt bearing on rear leg – painTibia rotates internally when bears wt If recent – swellingAcute with onset

Dx - Cranial drawer movementTibial compression testX-rays

Cruciate Ligament Injury

Tx – Surgical stabilization of the stifle joint

Damaged tissue must be removed Restricted exercise post-op

then gradually increase exerciseWatch opposite stifle for rupture/dzNsaid therapy for arthritis/DJD in sx joint

Patellar Luxations

Medial LuxationToy, min, large breedsTraumatic luxations – any breed

Lateral LuxationToy, min breedsLarge giant breeds

Palpation and x-raysSurgical correction and extensive rehab.

Hip Dysplasia-- “Ball & Socket”

Acetabular- most cases (Socket)Excessive slope of the dorsal rim of the

acetabulum, failure of the femoral head to press correctly into the developing cup (damage to the dorsal rim), painful, unstable joint.

Femoral ( Ball)Femoral neck is shortened, dec. coverage

by acetabular rim. Joint lacks support from acet., damage and instability.

Hip DysplasiaClinical Signs

Vary with age. Young 5-8 mo. Mature w/chronic dz

Difficulty rising, stiffness that goes awayPain on palpation of dorsal pelvic areaLameness, waddling gait, young reluct. to

standDx – x-rays!

OFA 7 grades OFA Cert. 2yr– under anesthesia

Hip Dysplasia

•Tx –Conservative•Moderate exercise

•Wt control

•Nsaids, steroids

•Nutriceuticals ( Glucosamine/Chondroitin)

•Surgical•FHO (Femoral Head Ostectomy)

•Total hip replacement

•Pelvic osteotomy

Hip Dysplasia

L-C-P Disease (Avascular Necrosis)

a.k.a.-- Legg-Calve-Perthes dz.Small-breed dogs, unknown causeFemoral head and neck necrosisX-rays, surgical removal of femoral head

and neckEarly, active use of limb post-opGenetic predisposition may exist Animals may have both hips involved

Osteochondrosis Dissecans

Degeneration or necrosis of bone and cartilage followed by reossification

Lameness in lg-breed dogs (3-18mo)X-raysRest and wt controlSurgically remove the cartilage flap/miceMay have a hereditary component

Osteochondrosis Dissecans

Panosteitis

• Intermittent lameness – shift from leg to leg

• Med to lg breed dog – German Shep

• Cause unknown, viral – self- limiting

• Clincal signs: Anorexia, fever, wt. loss, reluctance to move

• Dx: Pain on deep palp., X-rays

• Tx: Analgesic, Anti-inflammatory drugs

• Recur, not seen over 2 yr old

Luxations

Secondary to trauma, tearing of joint capsule and round ligament

X-rays, closed reduction, open reductionSlings: hip=Ehmer shoulder=Velpeau

to stabilize joint then limit exerciseSurgery may be necessaryOsteoarthritis may develop in that joint

Inflammatory Myopathies

Bacterial myositis, rarely occurringAfter bite wound or surgical procedureStaphylococcus and Clostridia spp.

Protozoal myositisCysts form within the muscle of

toxoplasmosis + cats,- rupture or immune response results in clin.

signs of muscle hyperesthesia - (hypersensitivity to stimulation)

Immune-Mediated Myopathies

• Polymyositis – dogs and cats, weakness, hyperesthesia, fever, megaesophagus, muscle atrophy. Dx: Biopsy Tx: Pred.

• Masticatory muscle myositis - muscle contains special fiber that has antigenic properties possibly shared with bact. Infections elsewhere may incite an immune response that affects these fibers. Swollen, painful, atrophy and fibrose. Glucocorticoids.

Tumors of Bone

• Dogs: 8000 cases/ yr - 85-90% involve osteosarcoma

• 90% of all animals dx with bone cancer die despite treatment

• Primary bone cancer in cats is less common

• 90% of bone cancers in cats are osteosarcomas

• Survival rates after amputation appear to be better for cats than those for dogs

Tumors of the Bone

• Clinical signs: Lameness, wt. loss, pain, swelling

• Dx: x-rays, biopsy, chest x-rays (metastasis)

• Tx: Amputation, follow-up with medication.

• Radiation therapy for pain control

• No recommended drug therapies exist for cats

• Bone cancer is fatal

• 12 mo with aggressive trt.

• Drug therapy is expensive

Tumors of the Bone

Subsolar Bruising (Corns)

• Trauma to the sole w/subsequent hemorrhage between the sensitive and insensitive soles

• Acute onset of lameness

• Bruises are often bilateral

• Sole pain is evident with hoof testers

• See the bruise

• Proper shoeing/trimming – Nsaids Prevented by proper foot care

Hoof Abscess

• Acute, severe lameness

• Foreign body penetration into the hoof – bact

• Heat in foot, coronary band

• +/- palmar digital pulse

• +/- fetlock and pastern swelling

• Localized pain with hoof testers

• Dx: visualize draining tract

• Sometimes x-ray

Hoof Abscess

Tx: Localize pain and pare out abscessEpsom salt soaks+/- drawing agent (Ichthammol)Abx usually not indicated, unless kept in

dirty unsanitary conditionsBe aware of tetanus !!

Routine prophylaxis via annual

vaccinations

Navicular Syndrome

• QH, TB, Warmblood

• 6-8 yr, older

• Inflammation and erosion of navicular bone

• Clinical signs: chronic, bilateral lameness

• Lameness may be intermittent

• Pointing, pain over frog with testers

• Dx:

•nerve blocks

•X-rays

Navicular Syndrome

Tx: Nsaids

(Non-steroidal anti-inflammatory drugs)

-can cause gastric ulcerationCorrect hoof imbalance & maintain proper

hoof careSupport heelsSurgery

Thrush

•Bacterial infection of sulci of frog

•Wet, dirty conditions, feet not properly maintained

•Foul-smelling black discharge

•Usually not lame unless severe

•Clean feet, remove necrotic tissue

•Apply topical astringents

•Easily prevented, daily management

Fractures

Pastern Chip FracturesProximal Sesamoid FractureAthletic performance X-rays Surgery / arthroscopic repairExtensive recovery

Bucked Shins

• New bone production on the cannon bone

• 2 yo TB – sudden onset of hard training

• Tearing of periosteum – new bone deposition

• Forelimbs, bilateral, lameness

• Hard, warm, painful swelling on dorsal aspect of cannon

• REST, Nsaids, decrease high-speed training

• Prevent by modifying training regimen

Laminitis

Inflammation, avascular necrosis of the sensitive laminae of the hoof

Grazing lush pasturesGrain overloadMetritis/retained placentaExcessive weight bearing on

alternate (supportive) limb

Laminitis

• Occurs when an insult causes blood to bypass dermal laminae via shunts

• Possibly due to endotoxins

• Extreme vasoconstriction, lack of blood supply causes sensitive laminae to die

• Sensitive laminae separate from insensitive laminae and the coffin bone rotates away from the hoof wall, because of the pull of the deep digital flexor tendon.

Laminitis

Laminitis

Clinical SignsBounding pulses in the palmar digital

arteriesHooves may feel warm “Saw-horse” stancePain over toe with testers

Dx: Lateral x-rays May show rotation of the coffin bone

Laminitis

• Treatment•Correct underlying/predisposing factors•Bute for pain•Banamine to bind endotoxins•Cold water hose•Shoeing with proper padding•Elevate heels•Deep bedding• Isoxuprine•Acepromazine for vasodilation •Nitroglycerine around coronary bands

Laminitis in Sheep and Goats

Lush pastures and high-concentrate feeds

Systemic illness can predisposeC/S: Lameness, warm feet, recumbentDX: C/S, x-rays Tx: Nsaids, tx primary underlying causeCan be preventedSlowly increase feed and or turnout time

White Muscle Disease

•Nutritional Muscular Dystrophy• Lack of selenium in the diet•Antioxidant, protects cell membranes from damage by free radicals•Cardiac form: dyspnea, recumbancy, tachycardia•Skeletal muscle form: stiff gait, muscle tremors while standing, hunched appearance, dysphagia

White Muscle Disease

•Dx:•Lab results and whole-blood selenium

concentrations from herd• Tx:• Injection of vit E/selenium•Avoid stress/exertion•Many areas of US are selenium deficient –

can supplement – but careful not to create toxicity

Hip dysplasia--bilateral