Degenerative Joint Disease in Horses

Question 1

What is the difference in roles of type a and type b synoviocytes?

Answer 1

type a- phagocytose cell debris and wastes in the joint cavity
type b- production of matrix components including hyaluronan, collagens and fibronectin

Question 2

What is Degenerative Joint Disease (DJD)?

Answer 2

multifactorial disorder of the joints that causes degeneration of articular cartilage, new bone formation and bone lysis (osteoarthritis)

Question 3

What can cause Degenerative Joint Disease? (4)

Answer 3

Trauma/ over use
Infectious inflammation such as Septic Arthritis
Non infectious inflammation
Developmental disease due to abnormal loads

Question 4

What do we mean when we say DJD is an inflammatory process?

Answer 4

Insult/ Injury causes recruitment of inflammatory mediators such as IL-1 and TNF-a which activate PGE2 to cause matrix degeneration

Question 5

How do we diagnose DJD?

Answer 5

Analgesia- intra articular ‘nerve block’
Diagnostic Imaging- Radiography, Ultrasound, MRI
[can use arthroscopy to asses cartilage health but this is rarely used- not needed]

Question 6

Why is DJD hard to diagnose using synovial fluid analysis?

Answer 6

Pretty much identical in appearance and cell count to normal synovial fluid

Question 7

How does DJD appear on radiographs? (5)

Answer 7

No joint space between the femoral condyle and tibia
New bone deposition on medial femoral condyle
Soft tissues may appear swollen
Meniscus may mineralise
Effusion of the joint space
Increased bone density

Question 8

What are the aims of DJD treatment?

Answer 8

Reduce pain and stop inflammation
Chondroprotection to arrest or slow down cartilage degeneration

[just remember DJD cannot be fully cured!]

Question 9

What treatment strategies can be used for patients with DJD? (5)

Answer 9

Weight control
Exercise modification/ physiotherapy
Strategic analgesia to increase comfort
Joint supplements
Surgery- salvage procedures

Question 10

How do NSAIDs work to reduce inflammation in DJD?

Answer 10

Inhibit the COX pathway to prevent prostaglandin synthesis which in turn decreases synovitis and cartilage degeneration

Question 11

What are the side effects of using NSAIDs for DJD? (3)

Answer 11

GI ulceration
Nephritis
Protein losing enteropathy

Question 12

What first line NSAIDs are recommended to use for DJD in horses?
What are the alternatives?

Answer 12

Phenylbutazone- can use Suxibuzone which is a precursor that’s activated in the body and is more protective
Flunixin meglumine- can use Meloxicam alternative but is more expensive

Question 13

Apart from NSAIDs, what else can we use for pain management in DJD?

Answer 13

Intra articular corticosteroids

Question 14

What are the three mechanisms of action of Intra articular corticosteroids for DJD treatment?

Answer 14

Inhibit prostaglandin synthesis by blocking the cyclooxygenase pathway
Inhibit synthesis of cartilage degrading cytokines such as IL-1 and TNF-a
Inhibit cartilage degrading enzymes such as MMP1

Question 15

What side effects are associated with using corticosteroids to treat DJD? (3)

Answer 15

• Increased risk of iatrogenic joint infections due to the reduced inflammatory defence mechanisms
• Laminitis
• Possible negative effects on cartilage metabolism & healing (needs more research)

Question 16

Which corticosteroids are recommended for DJD in horses and why?

Answer 16

Triacinolone acetonide
Isoflupredone acetate
Methylprednisolone acetate

[corticosteroids with acetate and acetonide are more lipid-soluble and have a longer duration of action]

Question 17

What is the role of Glycosaminoglycans in DJD?

Answer 17

given as an I/M injection to help rebuild the ECM of the cartilage and stimulate HA production

Question 18

Give an example of a glycosaminoglycans that can be used in the treatment of DJD?

Answer 18

Polysulphated glycosaminoglycan (Adequan)
Pentosan Polysulphate (Cartrophen)

Question 19

What is the role of Sodium Hyaluronate in the treatment of DJD?
How is it administered?

Answer 19

helps confer visco elasticity to the joint fluid (lubricity) and has some anti-inflammatory function
Intra articular or Intravenous

Question 20

What is Tiludronate (Tildren) and what is it used for?

Answer 20

non nitrogenous biphosphate that can inhibit bone resorption by causing osteoclast apoptosis and has some anti- inflammatory properties

Question 21

What is the main disadvantage to using Tiludronate?

Answer 21

Some evidence it can cause colic when given suddenly so must be given via a constant effusion IV

Question 22

What is Hydrogel and how is it used to treat DJD?

Answer 22

Synthetic, non degradable hydrogel that can be administered via intra articular injection where it integrates into the synovial membrane to line the joint cavity and change loading capabilities of the joint

Question 23

What are the advantages and disadvantages to using mesenchymal stem cell injections for the treatment of DJD?

Answer 23

advantages- readily available (obtained from equine blood), effective
disadvantages- induces an immune reaction so can create inflammation

Question 24

What surgery can be done to ‘treat’ DJD in horses?

Answer 24

Arthrodesis/ Facilitated Ankylosis- removal of the cartilage and stabilizing by fusing the bones across the joint