The Musculoskeletal System Movement and shape in animals System of pulleys Disruption: Trauma Degenerative dz Inflammation Poor conformation Neoplasia
Long-Bone Fractures 75% occur from HBC Indirect violence, bone dz., repeated stress Open or closed Simple or comminuted Stable or unstable Quickly assess patient, tx shock, etc. Stabilize (bandages,etc), care when moving
Cruciate Ligament Injury Anterior and posterior cruciate ligament Stabilize 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 Signs Non-wt bearing on rear leg – pain Tibia rotates internally when bears wt If recent – swelling Acute with onset Dx - Cranial drawer movement Tibial compression test X-rays
Cruciate Ligament Injury Tx – Surgical stabilization of the stifle joint Damaged tissue must be removed Restricted exercise post-op then gradually increase exercise Watch opposite stifle for rupture/dz Nsaid therapy for arthritis/DJD in sx joint
Patellar Luxations Medial Luxation Toy, min, large breeds Traumatic luxations – any breed Lateral Luxation Toy, min breeds Large giant breeds Palpation and x-rays Surgical 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 Dysplasia Clinical Signs Vary with age. Young 5-8 mo. Mature w/chronic dz Difficulty rising, stiffness that goes away Pain on palpation of dorsal pelvic area Lameness, waddling gait, young reluct. to stand Dx – 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
L-C-P Disease (Avascular Necrosis) a.k.a.-- Legg-Calve-Perthes dz. Small-breed dogs, unknown cause Femoral head and neck necrosis X-rays, surgical removal of femoral head and neck Early, active use of limb post-op Genetic 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-rays Rest and wt control Surgically remove the cartilage flap/mice May have a hereditary component
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 reduction Slings: hip=Ehmer shoulder=Velpeau to stabilize joint then limit exercise Surgery may be necessary Osteoarthritis may develop in that joint
Inflammatory Myopathies Bacterial myositis, rarely occurring After bite wound or surgical procedure Staphylococcus and Clostridia spp. Protozoal myositis Cysts 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 % 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 abscess Epsom salt soaks +/- drawing agent (Ichthammol) Abx usually not indicated, unless kept in dirty unsanitary conditions Be 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 ulceration Correct hoof imbalance & maintain proper hoof care Support heels Surgery
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
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 pastures Grain overload Metritis/retained placenta Excessive 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.
Clinical Signs Bounding pulses in the palmar digital arteries Hooves may feel warm “Saw-horse” stance Pain 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 predispose C/S: Lameness, warm feet, recumbent DX: C/S, x-rays Tx: Nsaids, tx primary underlying cause Can be prevented Slowly 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