Dr. Darin Madson - Pig Lameness and Diagnostic Lab Views

Veterinary Diagnostic LaboratoryIowa State University

Feeding for Optimal Bone Strength2013 Allen D. Leman Swine Conference

What we are seeing at the diagnostic laboratory

Darin Madson

[email protected]


What we are seeing

• Increased clinical investigations/submissions• Suggesting an issue or production concern• Different from “normal/routine” submissions

• Suboptimal clinical lameness assessments• With improper sample submission

• Wide variation in bone quality

• The gamut of lameness etiologies found• Metabolic condition, OCD, and Mycoplasma sp.


Bone – “the organ”

• Bone is constantly being remodeled

– Throughout life; even after growth as stopped

– Bone is dynamic tells a story!• Mechanical stress• Decreased nutrition• Environmental stress• Disease

– Can be seen microscopically• Arrest and reversal lines


What is metabolic bone disease?

• Disturbances related to:1. Vitamin D

2. Calcium

3. Phosphorus

4. Parathyroid hormone

• Results in1. Depletion of bone mineral storage

2. Delayed formation/modeling

Can be combinations of these



• Terminology– Rickets

• Abnormal endochondral ossification in a growing animal– Defective mineralization of growing bone

– Osteomalacia• Similar to rickets, but in adult animals

– Defective mineralization of bone remodeling

– Fibrous osteodystrophy• Extensive bone resorption with replacement by fibrous connective

tissue

– Osteoporosis/Osteopenia• Reduced bone mass

– Quality of remaining bone is normal



Common mechanisms:

1. Inadequate dietary supplementation of vitamin D3

2. Inadequate absorption of phosphorus due to low phosphorus in diet, phosphorus bound to phytate and therefore unavailable, and inadequate or ineffective phytase usage

3. Imbalance of feed calcium to phosphorus ratio; improper formulation of Ca:P ratio in diet (should be roughly 1.2:1)

4. Inadequate dietary calcium can also contribute to rachitic lesions, though these are also often confounded by accompanying osteoporosis.


Potential industry issues

• Swine diets maximum growth• Not bone strength

• Ingredient costs• Alternative feedstuffs• Variability in feedstuffs

• Amount of ingredient• Process for inclusion (pelleting)

• NRC values (outdated?)


Clinical signs

• Clinical signs are variable• Sudden death (found dead)

• Tremors/seizures (CNS like disease)

• Muscle fasciculations/tetany

• Weakness

• Lameness

• Painful gait and reluctancy to move

• Bone fractures

Metabolic bone disease

Veterinary Diagnostic LaboratoryIowa State UniversityMadson et al. 2012

Clinical signs


Rachitic rosary

Broken bone


Diagnostic testing

• Assessing rib strength

Rickets (growing pigs)

Phosphorus Rubbery bones

Calcium Fragile bone; Break easy, but snap

Vitamin D Rubbery bones


Diagnostic testing• Bone analysis

– Need to know the processes• Wet weight or dry-fat free!!!

Swine; rib boneBone ash 58-62 %Bone density 1.4-1.5 g/ml. Bone ash Calcium 32-39%

Bone ash Phosphorus

13-22%

Dry, fat free

Swine; rib boneBone ash 25-30 %Bone density 1.4-1.5 g/ml. Bone ash Calcium 32-39%

Bone ash Phosphorus

13-22%

Wet weight


Diagnostic testing

Deficient (below 25%)

Normal (25-35%)

Above noraml (>35%)

0 10 20 30 40 50 60 70 80 90 100

Bone Ash - Summary of 169 porcine cases

Total

number of test results within each range

Wet weight


Diagnostic testing • Serum

– Calcium– Phosphorus– Alkaline phosphate (ALP)

» Increased with bone resorption

Analyte Vit D deficiency

Calcium deficiency

Phosphorus deficiency

Calcium⬇ ⬇ ⬆, ⬌

Phosphorus⬆, ⬌ ⬆, ⬌ ⬇

ALP⬆ ⬆ ⬆


Diagnostic testing

• Serum Vitamin D– Heartland Assays. Inc (Ames, Iowa)

– Ron Horst

Age of animal 25-OH-D3 ng/mlNeonate 5-1510 days 8-233-4 weeks old 25-30Finishing pigs 30-35Mature 35-70Parturition 35-100

Darin’s Thought

Stay above 15 ng/ml


Diagnostic testing

• Urine?

Hagemoser et al. 2000


Vitamin D research - ISU

• Main goal– Assess vitamin D levels across different ages of pigs in the

Midwest

• Two different time points – Once in January (2011)– Once in July (2011)

• Ages of animals assessed in the surveillance– 3 week old pigs– ~11 week old pigs– Market hogs– Gestation sows– Boars

8 samples from 15 sites in each age group at each time point

1,200 total samples tested600 samples tested in January 2011600 samples tested in July 2011



Results

5 ng/ml

15 ng/ml

35 ng/ml

ANOVA - * & ** indicate significant differences between January and June samples (p < 0.01)

**

*


2719 total samples


Vitamin D research – ISU take 2

Objective of proposal– Assessing the quality of vitamin D from

multiple suppliers overtime

• 5 feed manufactures• Sample bulk vitamin D 1x per month

– Mixed from multiple locations

• Sampling for 12 months– October 2011-September 2012



Vitamin D research – ISU take 2

• Results– No company was found

to be significantly lower than 500,000 IU

• No difference in US vs. Foreign vitamin D manufactures

– Month was found to be significant

• P= 0.0022• Storage???



Confounding issues

• Lameness failures– Clinical assessment

– Age, weight, feed, growth rate, and watching them walk

– Gross assessment– It is more than hacking off a limb– Sample submission is key

– Complexity– Correct samples– Other differentials– Knowing what to look for


Confounding issues

OsteochondrosisYtrehus et al. 2007


Confounding issues

Mycoplasma hyosynoviae

Hygroma formation


Take home points• Lameness is an industry issue

– Multiple factors are associated• Infectious or nutritional• The “insult” may have occurred previously

• Clinical assessments are important• Multiple samples are needed• Location can vary significantly in clinical pigs

• Understand potential confounding problems– Are the findings the “real” cause of the lameness


QUESTIONS?Thank you for your attention!

Dr. Darin Madson - Pig Lameness and Diagnostic Lab Views

Health & Medicine

bone quality

bone density

organ bone

bone ash phosphorus

bone ash calcium

optimal bone strength

diagnostic testing urine

low phosphorus