Nutritional Aspects of Developmental Orthopedic Disease

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Nutritional Aspects of Developmental Orthopedic
Disease
Paul D. Siciliano, Ph.D. Associate Professor
Equine Nutrition Dept. of Animal Science Equine
Science Program
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Overview

• DOD defined
• Bone growth and development
• Types of DOD
• Nutritional aspects
• Nutritional strategies

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DOD Defined

• Term coined in 1986
• all orthopedic problems seen in the growing
  foal
• Non-specific

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Overview

• DOD defined
• Bone growth and development

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Brief Overview of Bone Growth and Development

• Two primary processes
• Endochondral ossification
• Increases bone mass
• Accounts for long bone growth
• Modeling
• Facilitates age associated changes in bone shape

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Regions of Long Bones
Diaphysis
Metaphysis
Physis
Epiphysis
Articular Cartilage
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Endochondral Ossification
Douglas ,1992
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Taken from Turner, 1987 In Adams Lameness in
Horse, 4th Ed.
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Modeling
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Brief Overview of Bone Growth and Development

• Time course
• Large proportion o f bone growth occurs the 1st
  year of life

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Growth Plate Closure
Distal Radius 22 to 42 mo
Distal Tibia 17 to 24 mo
Distal MCIII 6 to 18 mo
Distal Phalanx Before birth
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Overview

• DOD defined
• Bone growth and development
• Types of DOD

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Types of DOD

• Physitis
• Osteochondrosis
• Cervical vertebral malformation
• Flexure deformities
• Angular limb deformities

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Physitis

• Bony enlargement of the
• metaphyseal growth plate of the
• distal metacarpus
• Metatarsus
• Radius
• tibia.
• Results from Abnormal growth on metaphyseal
  growth plate

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Physitis
Diaphysis
Metaphysis
Physis
Epiphysis
Articular Cartilage
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Physitis

• Radiographical findings
• Retained cartilage cores
• Irregularly thickened growth plates
• Metaphyseal sclerosis
• Abnormal trabecular patterns

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Physitis

• Histological findings
• Retention and crushing of hypertrophic
  chondrocyte layer
• Fractures of calcified cartilage layer or newly
  formed bone
• Crushing and translocation of the growth plate
  into the metaphysis
• Protrusion of growth plate margin in to the
  perichondrium

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Physitis

• General indicator of disturbed bone growth
• Commonly occurs w/ nutritional imbalance and/or
  trauma
• Often comes and goes w/ no consequence
• May be painful leading to flexural deformities

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Types of DOD

• Physitis
• Osteochondrosis
• Cervical vertebral malformation
• Flexure deformities
• Angular limb deformities

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Osteochondrosis

• process of abnormal cartilage and bone formation
• osteochondritis dissecans OCD
• disruption of the articular surface creating
  clinical signs referable to joint inflammation
• occurs in many joints
• prominent in the stifle and hock

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Cartilage Fragment
Osteochondrosis
Osteochondritis Dissecans (0CD)
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Osteochondrosis

• Recent research suggests some forms may be
  transient
• Some forms successfully treated by surgery

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Types of DOD

• Physitis
• Osteochondrosis
• Cervical vertebral malformation
• Flexure deformities
• Angular limb deformities

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Cervical Vertebral Malformation

• Abnormal development of cervical vertebrae bone
  and cartilage
• Narrowed or impinged vertebral canal
• places pressure on the spinal cord
• results in incoordination (e.g. wobbler)
• Tends to occur in rapidly growing horses
• Genetic predisposition??

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Cervical Vertebral Malformation
Enlarged growth plate impinging on spinal cord
Spinal cord
Cervical vertebra
Intervertebral disc
Growth plate
Douglas, 1992
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Types of DOD

• Physitis
• Osteochondrosis
• Cervical vertebral malformation
• Flexure deformities
• Angular limb deformities

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Flexural Deformities

• Congenital
• Causes uncertain
• Acquired
• Original thoughts
• Current thoughts

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Types of DOD

• Physitis
• Osteochondrosis
• Cervical vertebral malformation
• Flexure deformities
• Angular limb deformities

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Angular Limb Deformities

• Large genetic component
• Nutritions role minor
• Due to delayed or abnormal ossification of
• cuboidal bones in knee and hock
• metaphyseal growth plate
• Can be corrected to some degree
• Normal stance of new born
• Valgus stance

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Angular Limb Deformity
Diaphysis
Metaphysis
Physis
Epiphysis
Articular Cartilage
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Overview

• DOD defined
• Bone growth and development
• Types of DOD
• Nutritional aspects
• Nutritional strategies

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Water
Minerals
Energy
Protein
Vitamins
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Overview Nutritional Aspects of DOD

• Nutritional Plane
• Digestible Energy
• Crude Protein
• Calcium and Phosphorus
• Copper and Zinc
• Vitamin A
• Nutritional strategies aimed at minimizing DOD

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Nutritional Plane and DOD

• Hintz et al. (1976)
• Standardbred weanlings
• Fed ad libitum for 8 mo.
• Fed restricted (4 mo.) then ad libitum (4 mo.)
• Increased incidence of flexural deformities in
  restricted/ad libitum
• No skeletal abnormalities in ad libitum foals

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Nutritional Plane, Growth Rate DOD

• Will a ration formulated for rapid growth
  negatively affect bone growth and/or bone quality?

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Nutritional Plane, Growth Rate DOD

• 12 QH APH weanlings (5mo)
• Treatments
• Rapid growth ration (n6)
• Formulated for .9 kg of body wt gain/d
• Slow growth ration (n6)
• Formulated for .34 kg of body wt gain/d

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Nutritional Plane, Growth Rate DOD

• Measurements
• body wt. gain monitored weekly
• bone mineral-density via dual energy x-ray
  absorptiometry (DXA)
• 0, 60 and 120d

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Dual Energy X-Ray Absorptiometry (DXA)
Focal determination of bone mineral content
density
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Regions of Interest
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Body Weights of Weanlings/Yearlings Fed For
Rapid or Slow Growth
Treatment x Time P lt .001
Time P lt .001
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ROI
BMD
Distal Radius
Metaphyseal/physeal
RGSG
Epiphyseal
RGSG
Distal McIII bone
Metaphyseal/physeal
RGSG
Epiphyseal
RGgtSG
Distal MtIII bone
Epiphyseal/physeal
RGgtSG
PI
RGSG
PII
RGSG
Plt.05
Plt.1
Pgt.1
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Rapid Growth
Slow Growth
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Nutritional Plane, Growth Rate DOD

• Increasing nutritional plane
• Increases bone growth
• Bone mineral density was unchanged or slightly
  increased
• Increased clinical signs of joint pain
  (transient)
• Significance of above findings?

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Nutritional Plane, Growth Rate DOD

• Conclusions
• Avoid situations leading to compensatory growth
• Formulate balance rations aimed at moderate
  growth
• Avoid over-conditioning

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Digestible Energy DOD
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Digestible Energy

• Implications in DOD
• excess digestible energy?
• lack of sufficient energy?
• source (e.g. starch, fat, fiber)
• Increasing energy has also been shown to enhance
  skeletal development

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Digestible Energy DOD

• Weanling TBs fed 70, 100 130 of digestible
  energy and protein requirements
• cereals used as primary energy source
• Abnormal columnar organization of chondrocytes in
  130 group
• skeletal lesions similar to hypothyroidism
• Longitudinal bone growth reduced in 70 group,
  and slightly increased in 130 group relative to
  the 100 group

Glade and Belling, 1984
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Digestible Energy DOD

• Hoffman et al. (1999)
• Starch and sugar vs fat and fiber containing
  supplement
• Foals/weanlings consuming the fat fiber
  supplement had lower bone mineral content of the
  3rd metacarpal bone

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Digestible Energy DOD

• Savage et al. (1993)
• Increasing DE alone
• Increased incidence of osteochondrosis in
  weanlings
• Mechanism is unclear
• Not related to growth rate
• Nutrient to Calorie imbalance?

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Digestible Energy and DOD

• Increased DE increases bone mineral density of
  third metacarpal bone
• Thompson et al. (1988)
• foals and weanlings fed 50 above controls
• Ott and Asquith (1986)
• yearlings fed 20 above controls

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Digestible Energy and DOD

• Thompson et al. (1988)
• increasing DE w/o increasing CP may impair bone
  quality

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Digestible Energy and DOD

• Relationship between DE and DOD is unclear
• Balance of other nutrients relative to DE may be
  important in preventing DOD

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Protein and DOD
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Protein DOD

• Excess Protein often implicated, but not
  substantiated
• Schryver et al. (1987)
• Protein defiency (9 CP)
• Impaired Ca turnover in bone
• Impaired long bone growth
• Protein excess (20 CP) was not detrimental to
  bone growth and development, nor was it
  advantageous to growth
• Confirmed by Savage et al. (1993)

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Crude Protein DOD

• Insufficient crude protein is more likely to
  create problems than excess crude protein

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Ca, P DOD
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Ca P and DOD

• Deficiencies have major impact on bone growth and
  development
• 120 of NRC (1989) requirements may be prudent in
  susceptible herds
• Ca 0.6 to 0.8
• P 0.3 to 0.5

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Ca P and DOD

• Optimum ratios???
• Never more P than Ca
• Stay w/ in 2 Ca 1 P (if possible)
• 1.251 suggested as optimum
• Excess Ca a problem??

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Copper and DOD
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Proposed Mechanism
Cu-deficiency
Impaired lysyl-oxidase
Impaired pyridinoline cross-links
Impaired apposition of new bone mineral
Increased bone fragility
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Osteochondritis Dissecans (OCD)
Cartilage Fragment
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Current NRC (1989) Cu Requirements for Growing
Horses

• 10 ppm
• Justification?
• Satisfactory growth w/ 9 ppm (Cupps and Howell,
  1949)

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Post NRC Research Regarding Cu

• Knight et al. (1985)
• Low dietary copper associated with increased
  incidence and severity of DOD

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Post NRC Research Regarding Cu

• Knight et al. (1990)
• 32 vs 15 ppm Cu
• Decreased incidence of osteochondrosis
• No inferential stats
• Did not protect all horses
• Some horses fed 32 ppm had lesions whereas some
  fed 15 ppm did not

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Post NRC Research Regarding Cu

• Hurtig et al. (1993)
• 8 vs 25 ppm Cu
• Increased incidence of osteochondrosis w/ 8 ppm
  Cu
• 8 ppm deficient relative to NRC
• Weanlings were group fed therefore n 1

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Post NRC Research Regarding Cu

• Pearce et al., 1998
• Supplementation of mares, during the last ½ of
  gestation, grazing pasture (4.4-8.6ppm) with 0.5
  mg Cu/kg body wt (30 ppm).
• reduction of radiographic indices of physitis
  articular lesions in foals
• Lesions had minor clinical significance
• Supplementation did not completely prevent
• Supplementation of foals had no effect

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Cu DOD Hurtig et al. (1993) Pearce et al.
(1998)

• Distribution pattern of lesions is atypical and
  not reflective of patterns typically diagnosed in
  practical settings.

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Copper and DOD

• No definitive evidence that higher concentrations
  (20 to 30 ppm) of copper prevent osteochondrosis
  and other DOD
• Copper deficiency is probably not a major cause
  of osteochondrosis in horses

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Copper and DOD

• Although not a major cause, Cu deficiency can
  still cause osteochondrosis
• Diets containing less than 10 ppm should be
  supplemented.

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Zn DOD
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Zn DOD

• Deficiencies result in osteochondrosis
• 75 to 100 ppm (mg/kg) may be prudent in herds
  susceptible to DOD
• High levels of Zinc interfere w/ Cu in other
  species
• ZnCu 3-41

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Vitamin A DOD

• Kronfeld et al., 1990
• Vitamin A fed _at_ 100 1000 Xs the NRC
  requirements was associated with DOD in a small
  group (n4) of growing fillies

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Nutrition and DOD Summary

• Many unanswered questions
• Multiple nutrients may be involved
• Balance of all nutrients should be considered
• DOD is multifactorial
• Nutrition may not be involved at all

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Nutritional Strategies Aimed at Minimizing DOD

• Rations should be balanced to promote a
  consistent growth curve

Requires periodic updating of the ration
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Nutritional Strategies Aimed at Minimizing DOD

• Target growth rates
• ideal?
• Reach mature body wt. and size in a time frame
  consistent w/ intended use

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Nutritional Strategies Aimed at Minimizing DOD
Avg. Daily Gain, lbs/d
Month of Age
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Nutritional Strategies Aimed at Minimizing DOD

• Balancing rations
• Get Help!
• Resources
• Universities
• Cooperative extension
• Feed Manufactures
• Private consultants

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Nutritional Strategies Aimed at Minimizing DOD

• Identifying Red Flags
• Feed selection
• High quality forage is a must
• Grain mix concentrates formulated specifically
  for growing horses
• Improper use of supplements

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Nutritional Strategies Aimed at Minimizing DOD

• Identifying Red Flags
• Feed amounts
• Forage
• Minimum of 1 lb / 100 lb BW / d
• Fed to appetite is best
• Concentrate
• 1 lb / 100 lb BW / d
• Max. 8 to 10 lbs /d

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Nutritional Strategies Aimed at Minimizing DOD

• Periodic evaluation
• clinical signs
• dont panic
• double check ration
• other factors involved?
• Body wt. and condition

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Nutritional Strategies Aimed at Minimizing DOD

• Slowing growth so as to align w/ your target
  growth rate is o.k.
• Starvation strategies DO NOT work!

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Conclusions

• Nutritional Plane
• Avoid inconsistent growth
• Advantages of high planes?
• Digestible Energy
• Relationship unclear
• Maintain in balance with other nutrients
• Crude Protein
• Deficiency is a problem

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Conclusions

• Calcium Phosphorus
• Adequate amounts
• Ratios
• Copper
• Deficiency can cause OC
• Not the silver bullet
• Avoid diets containing gt 10 ppm

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Conclusions

• Zinc
• Adequate supplementation
• 75 to 100 ppm
• Vitamin
• Avoid toxicities

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Conclusions

• Balance rations for consistent growth
• Evaluate periodically
• Dont Over-react

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