Veterinary Pathology of Skeletal system

1. Veterinary Pathology
of Skeletal system

2. Bone Tissue
 Osteoproginator cells  Growth factors – TGF-β
 Chondroblasts – somatomedin…somatotropin hormone
 Osteoblasts – PTH  Osteocyte
 Fibroblasts - FGF
 Hemopoietic stem cells  Osteoclast – 2-3 to 100
nuclei
 Bone Matrix (Osteoid)
 Collagen type I – 90%
 Noncollagenous proteins (glycoproteins and proteoglycans)
 Bone Minerals
 Calcium, phosphorus, carbonate, sodium, magnesium
Hydroxy-apatite crystals Ca5(PO4)3(OH,F,Cl)

3. Generalized Developmental Disorders
Chondrodysplasias (Chondrodystrophies,
achondroplasia)
 Disproportionate Dwarfism
 Cranio or spondylodysplasia
 Rhizomelic (proximal), mesomelic (middle),
and acromalic (distal)
 Dextor Bulldog – aborted before 7 months
 Telemark Lethal – cranium domed,
hydrocephalus
 Snorter Dwarfism – Herford – short legged
 Primordial Dwarfism

4. Bulldog Calf

5. Brachycephalic Snorter Dwarfism

7. Osteogenesis imperfecta
 Brittle bone disease is a group of
hereditary conditions –
 Abnormal development of type I collagen
 Skin abnormality
 Growth plate normal
 Bone deposited
is deficient
• Decrease in
Apatite crystals

8. Localized Developmental Disturbances
 Limbs
 Hemimelia – mid section of limb (radio-ulna)
 Syndactalia – fusion of the toes
 Polydactalia – increase in the number of digits
 Ectrodactalia – split-hand (dogs and cats)
 Adactalya – absence of digits
 Sternum
 Ribs
 Pelvis
 Vertebrae
 Cervical

9. Metabolic bone Diseases
 Hormonal Influences
 Pituitary (dwarfism – gigantism)
 Thyroid/Parathyroid
 Estrogens and Androgens
 Glucocorticoids

10.  Osteoporosis
 Osteomalacia
 Rickets
 Hyperparathyroid Disorders
 Renal Osteodystrophy

11. Osteoporosis
Ostopenia
 Reversible lesion not disease
 Bone quality and quantity is
affected
 Imbalance in resorption and
formation
 Bone with large cancellous
bone areas are usually affected
 Bones usually light and fragile

12.  Causes
 Starvation
 Disuse
 Senile
 Intestinal Parasitism
 Calcium and Phosphorus deficiency
 Copper deficiency – lysyl oxidase – cross linking of
collagen
 Vitamin C deficiency
 Lactational

13. Osteoporosis

14. Pathogenesis
 RANK receptor - ligand
interaction activates nuclear
factor қB  osteoclasts
 Macrophage colony stimulating
factor
 RANK pathway is regulated by
a molecule called
osteoprotegrin (OPG), secreted
by osteoblasts.
 OPG is “decoy receptor” that
can occupy RANK ligand and
thus prevent its binding with the
RANK receptor
 When RANK ligand binds to
OPG rather than RANK
receptor on osteoclast
precursor, formation of
osteoclasts and their bone
resorption is curtailed

15.  Estrogen stimulate production of OPG –
decrease in the production of osteoclasts –
decreased bone resorption
 During menopause decreased estrogen level
increases the production of decoy receptor OPG
by osteoblasts
 Decreased production of estrogen cases
increase in IL-1, IL-6, TNF
 Stimulate the production of RANK ligand and
MCSF, both of which cause increased osteoclast
formation

16. Rickets and Osteomalcia
 Rickets… immature skeleton
 Osteomalcia . . . Mature skeleton
 Failure of mineralization
 Vitamin D deficiency
 Functions:
 Stimulates intestinal absorption of calcium and
phosphorus
 Required for normal mineralization of epiphyseal
cartilage and osteoid
 Collaborates with PTH in the mobilization of calcium
from bone
 Stimulates the PTH-dependent reabsorption of
calcium in the distal renal tubules

18.  Lesions:
 Bone deformities and fractures….calves,
lambs
 Rickets…dis of bone and cartilage under
going ossification.
 Growth plates are thickened
Osteomalacia is disease of only bone in
adult…… resulting kyphosis / scoliosis etc

19. Osteosis
(Degeneration & Necrosis)
 Ischemia followed by fracture
 Ostitis

20. Inflammatory bone Diseases
 Osteitis: osteomyelitis or periostitis
 Causes
 Fusobacterium necrophorum (foot rot)
 Extension from synovial surfaces (poll evil, fistulous
withers, joints, teeth cutting, dehorning, periodontal
disease)
 Primary periostitis – osteophytes – exostoses
 Hematogenous – young animals:
 Sataph. Aureus, Actinomyces pyogenes, Salmonella spp.,
Klebsiella spp., E. coli, Streptococci, Mycobacterium
 Actinobacillus bovis and ligniersii, Aspergillus
fumigatus

21. Viral infections of bones
 Infectious canine hepatitis
 Metaphyseal hemorrhages
 Canine distemper
 Metaphyseal sclerosis
Osteomyelitis

22.  Tumors of the bones
 Fracture healing

23. Developmental Disturbances of Joints
 Luxations and subluxations
 Hip dysplasia – humans, dogs, rarely
cattle

24. Noninfectious Arthritis
 osteoarthritis
 Rheumatoid
 gout
Urate crystals

25. Degenerative joint Disease, degenerative
arthritis, osteoarthrosis, and osteoarthritis
 Primary (unknown cause)
 Secondary (injury to joint cartilage or
subchondral bone)
 Nutritional
 Traumatic
 Developmental
 Articular plates soften, fibrillate, and ulcerate.
Subchondral bone is eburnated (bone sclerosis)
 Osteophytes develop at joint margins and
remodeling of joint structures occur
 fibrous or bony union of opposing bones

26.  Ring bone arises in interphalangeal joints,
especially of forelimbs

27. Intervertebral Disks
 Spondylosis
(ankylosing
spondylosis) –
osteophytes develop
in intervertebral space
 Herniation of
intervertebral discs
(dogs and humans –
sciatica) Degenerative Osteoarthritis

28. Infectious Arthritis
 Sheep
 Erysipelothrix rhusiopathiae
 Streptococci
 Haemophilus agni
 Staphylococci
 E. coli
 Mycoplasma spp.
 Chlamydia psittaci
 Goats
 Retroviruses
 Mycoplasma spp.
Cont……..

29.  Cattle
 Streptococci
 E. coli
 Actinomyces pyogenes
 Salmonella spp.
 Mycoplasma bovis
 Haemophilus somnus
 Horses
 Actinobacillus equuli
 Streptococcus spp.
 E. coli
 Klebiesella spp.
 Rhodococcus equi
 Salmonella spp.
 Dogs
 Staphylococci
 Streptococc
 E. coli
 Borrelia burgdorferi
 Blastomyces dermatitidis

30. Purulent arthritis
 Usually hematogenous----pyogenic
bacteria

31. Fibrinous arthritis
 Synovial fluid increase, turbid and mucinous
 Petechiae on membranes
 Infiltration of mononuclear cells
 Villi enlarged and branched
 Granulation tissue
 Erysipelothrix rhusiopathiae and
Corynebacterium rubrum