Bones 1

Some bone disorders of ‘medical’ interest

Richard A. Squires Lecture 1 of 3 17 Aug 09

We are not going to consider the bone marrow at this stage…

From: Ettinger & Feldman Textbook of Veterinary Internal Medicine – Diseases of the Dog and Cat. 6th Edition. Chapter 279.

Associated Clinical Problems • Lameness: owners wont notice lameness if bilat symetrical/all 4. Will notice discomfort, getting up slowly

• Exercise intolerance:

sometimes think CHF,

then its bone

• Bone pain:

Elicit pain when pressing on bone  many of the bone diseases

• Fever: inflammatory

 going into multiple

organ failure and die

• Pathological fractures:

secondary to weakness

of bone leading to it breaking

• Deformity / Small stature: metaphysis; varus/valgus; small stature

swellings at

From: Ettinger & Feldman Textbook of Veterinary Internal Medicine – Diseases of the Dog and Cat. 6th Edition. Chapter 279.

Andrew will cover bone disorders associated with angular and other obvious deformities… Ruth will cover most of the causes of small stature

The Biggies… • Osteomyelitis (bacterial, fungal) • Bone cancers • Malignant or benign • Primary, metastatic or ‘multifocal’

• ‘Metabolic’ bone diseases – Well balanced diets  don’t see as much – Feeding carnivores just meat  masses too much phosphorous  stops Ca being absorped  nutritional hypoPTH

Weirdies you also need to know a bit about… • Panosteitis (=enostosis) – Something inside the bone

• Metaphyseal osteopathy • Craniomandibular osteopathy • Secondary hypertrophic osteopathy – Maries Dz  periosteal new bone formation

• Hypervitaminosis A  CATS • Various inherited disorders

Some others… • Bone cysts • Bone infarcts • Multiple cartilaginous exostoses • Others

DAMNIT-V

Bone disorders can be confused with… • Disorders of joints • Disorders of muscles • Neurological disorders

• Some metabolic disorders

General diagnostic approach

Signalment • • • •

Age: usually older Breed: little vs big dogs: terriers vs Large breeds Sex: 2/3 panosteitis male Neutering status : D + C dont live long enough to show neutering status effect

History • Duration / Onset • Intensity / Progression – Intermittent – Constant – Shifting  shifts from leg to leg (lameness) – Worsening  bone cancers get worse over time

• Better with exercise? After rest?

History • • • •

Diet? Any supplements? Vaccinations? Siblings / Parents? Some Dz are familial  affected same time by same disease

• Previous illnesses? Trauma? • Therapy? Response to therapy? – Can give idea on kind of Dz process

Physical examination • Distance exam (gait, attitude) • Bones • Muscles • Joints • Assess for pain, lack of symmetry, crepitus

Diagnostic imaging • Radiology • Computed tomography • Magnetic Resonance Imaging • Nuclear imaging

From: Ettinger & Feldman Textbook of Veterinary Internal Medicine – Diseases of the Dog and Cat. 6th Edition. Chapter 279.

Haematology / Serum biochemistry • Leukogram • Anaemia of inflammatory disease – Can happen quickly

• Calcium – Ionized Ca in blood drops  detected and PTH pumped out to bring isonized Ca back to normal – Hypercalcemic : some bone tumours release Ca into system

• Phosphorus • Alkaline phosphatase : normally higher in adult in large breed dogs growing quickly

• Globulin – Multiple myeloma can prod immunoglobulin light

+/- Other blood tests • • • •

Ionized calcium PTH / PTHrP Vitamin D metabolites Serum protein electrophoresis

• FeLV / FIV

Bone biopsy / histopathology • Can achieve definitive diagnosis • Grading of some tumours helps with prognostication – How aggressive it looks – Some tumours grading can give Px

• Prone to operator error: inappropriate sampling of reactive bone instead of cancer – Jim sheedy needle ... Need to get into middle...the more luscent centre

Cytology / Microbiology • Osteomyelitis • Aerobic & anaerobic • Not recommended to culture pus from externally draining tracts

Why? – Osteomyelitis can drain from sinuses  sinus tract open to outside world becomes colonised with skin bacteria : <50% of time org you culture from

DAMN V

IT-

DAMN V

IT-

Infectious, inflammatory, idiopathic, immune-mediated, iatrogenic, inherited

DAMN V

IT-

Infectious, inflammatory, idiopathic, immune-mediated, iatrogenic, inherited

Panosteitis (=enostosis) idiopathic

From: Ettinger & Feldman Textbook of Veterinary Internal Medicine – Diseases of the Dog and Cat. 6th Edition. Chapter 279.

Panosteitis • Relatively common in medium to giant breed dogs • 6 – 18 months • 2/3 are male • Acute onset intermittent lameness in one or more limbs (no trauma Hx) • Each episode ~ 2 weeks. Can go on for 2 - 9 months • Worst of them need to be

Panosteitis • Pain can be detected in long bone shafts (ulna, humerus, radius, tibia, femur)

• Lameness may be accompanied by anorexia, lethargy, pyrexia and weight loss. Can be quite ill. – Can have a fever

• A concurrent blood eosinophilia may be present

Panosteitis • Aetiology unknown • Disease process begins in medullary bone marrow, in vicinity of nutrient foramen – Why here? Swelling compromising blood flow in artery going to foramen to feed bone?? We dont know!!!

• Genetic predisposition, certainly. – Viral (CDV)? – Dietary?

DAMN V

IT-

Infectious, inflammatory, idiopathic, immune-mediated, iatrogenic, inherited

Metaphyseal osteopathy (hypertrophic osteodystrophy, HOD) • Young, rapidly growing dogs of larger breeds • Great Dane, Weimaraner, Boxer, Irish setter, GSD • ~ 3 – 4 months of age • Metaphyseal swelling + pain, +/- fever, inappetence

Metaphyseal osteopathy (hypertrophic osteodystrophy, HOD) • Idiopathic acute, suppurative inflammation and necrosis of metaphyseal bone • Trabecular microfractures and resorption leading to the lucent line

Metaphyseal osteopathy

From: Ettinger & Feldman Textbook of Veterinary Internal Medicine – Diseases of the Dog and Cat. 6th Edition. Chapter 279.

Metaphyseal osteopathy

From: Ettinger & Feldman Textbook of Veterinary Internal Medicine – Diseases of the Dog and Cat. 6th Edition. Chapter 279.

DAMN V

IT-

Infectious, inflammatory, idiopathic, immune-mediated, iatrogenic, inherited

Craniomandibular osteopathy

From: Ettinger & Feldman Textbook of Veterinary Internal Medicine – Diseases of the Dog and Cat. 6th Edition. Chapter 279.

Craniomandibular osteopathy • Young terriers, WHWT, Scottish, Cairn, Boston. Occasionally other breeds • Autosomal recessive in WHWT, sporadic in other breeds. Predisposition rather than direct cause? • 3 – 8 months • Swelling and pain of jaw, drooling, prehension difficulties, pain on opening mouth – hungry...inflamed and sore if you palpate, might try bite you. If cant open mouth...muscles of mastication will atrophy: point on head  occipital crest. Sometimes cant open mouth...might have to do surgery.

Craniomandibular osteopathy • Self-limiting by about 1 year of age – Can use carprofen/meloxicam/soft food/small kibble

• Lesions regress but if petrous temporal bone / tympanic bulla is severely affected, jaw movements may be permanently affected and rostral hemi-mandibulectomy may be needed – Wont fully regress.

DAM

NITV

DAM

NITV

Neoplastic, nutritional

DAM

NITV

Neoplastic, nutritional

Nutritional secondary hyperparathyroi dism

From: Ettinger & Feldman Textbook of Veterinary Internal Medicine – Diseases of the Dog and Cat. 6th Edition. Chapter 279.

Nutritional secondary hyperparathyroidism • Diets with excessive phosphorus, insufficient calcium, or both. Often exclusively, or nearly exclusively, meat / offal (Ca:P of 1:16 - 1:35 instead of 1.0-1.2:1)

• Osteopenia results from excessive bone resorption. Eventually, folding (pathological) fractures occur

Nutritional secondary hyperparathyroidism • Confine / rest during first few weeks of dietary correction to avoid pathological fractures – Cage rest good idea: jump from furniture can break bones

• Feed a good quality diet with calcium carbonate supplementation to raise Ca:P to 2:1. Feed for 2 – 3 months then withdraw the supplement

Hypervitaminosis A

From: Ettinger & Feldman Textbook of Veterinary Internal Medicine – Diseases of the Dog and Cat. 6th Edition. Chapter 279.

Hypervitaminosis A • Typically mature, older cats fed a diet very rich in liver • Osteopathy with fusion of cervical vertebrae due to confluent exostoses. May also involve long bones. • Can be managed with dietary change, but vertebral fusion and neck stiffness will likely remain

Rickets • Rare • Insufficient Ca or P ingestion or absorption • Hypovitaminosis D • Inborn error of Vitamin D metabolism

Renal osteodystrophy – ‘rubber jaw’ • Uncommonly seen • More likely in youngers than adults, so assoc with familial renal diseases • Thickening and pliability of maxilla and mandible. Jaw can sometimes be ‘sprung’ between fingers • Renal 2y HyperPTHism and failure to synth 1,25 Vit D3