Sx conditions of the equine foot

Question 1

What is another name for navicular syndrome?

Answer 1

Palmar heel pain

Question 2

Changes in the bone and synovial structures with navicular syndrome are similar to what process?

Answer 2

Osteoarthritis

Question 3

What ligaments develop lesions with navicular syndrome?

Answer 3

DDFT, collateral suspensory ligament, and impar ligament

Question 4

What does the impar ligament connect?

Answer 4

The navicular bone to P3

Question 5

Where do adhesions develop with navicular syndrome?

Answer 5

Between the DDFT and the navicular bone

Question 6

What is the most common cause of forelimb lameness in the horse?

Answer 6

Navicular syndrome

Question 7

You are presented with a quarter horse showing signs of bilateral lameness with a short, choppy stride. The lameness is exacerbated when on a hard surface and trotting in circles. With this breed of horse and description of lameness, what is your primary differential?

Answer 7

Navicular syndrome

Question 8

What two breeds of horses are predisposed to navicular syndrome? What breed has a low prevalence of navicular syndrome?

Answer 8

QH and TB are predisposed. Arabians have a low prevalence.

Question 9

What structure exerts the main force on the navicular bone in navicular syndrome?

Answer 9

The DDFT

Question 10

What is the main contributor to navicular syndrome?

Answer 10

Poor conformation

Question 11

What are the two types of poor conformation that cause navicular syndrome?

Answer 11

(1) long toe + under-run heels

(2) Small hoof/heavy body

Question 12

T/F False negatives common with hoof testers in a horse with navicular syndrome

Answer 12

T

Question 13

What are the 5 views you use in a horse you suspect has navicular syndrome?

Answer 13

DP, LM, sky view, DMPLO, and DLPMO

Question 14

Why are there many false negatives with radiographs and navicular syndrome?

Answer 14

Because rads only detect mineralized tissues and not all horses will have radiographically detected changes

Question 15

What are navicular syndrome lesions that can be detected by radiography?

Answer 15

(1) Flexor cortex erosion/cyst like lesions (lollipops)
(2) Loss of portico-medullar distinction due to medullar sclerosis
(3) Enthesiophytes
(4) . Mineralization of DDFT and/or collateral suspensory ligament

Question 16

Which imagining modality has good soft tissue contrast and the best osseous detail?

Answer 16

CT

Question 17

What is the gold standard for imagining of navicular syndrome?

Answer 17

MRI

Question 18

What is the most common structure with navicular syndrome lesions detected by MRI?

Answer 18

Lesions of the DDFT

Question 19

What are the types of lesions on the DDFT that are detectable with MRI?

Answer 19

(1) dorsal fraying at the level of the navicular bone
(2) Sagittal splits
(3) Core lesions at P1 and P2

Question 20

What are the treatment options for navicular syndrome?

Answer 20

(1) corrective trimming/shoeing
(2) intra- synovial medications
(3) Firocoxib
(4) Bisphosphonates
(5) PD neurectomy
(6) Navicular bursoscopy

Question 21

What corrective trimming/shoeing is done on a horse with navicular syndrome?

Answer 21

(1) Square toe to ease break-over

(2) Raise heels with wedge to correct hoof pastern angles

Question 22

What shoe is preferred in horses with navicular syndrome and why?

Answer 22

Aluminum because they’re lighter and less concussive forces are transmitted to the foot

Question 23

What joints/structures can you inject intra-synovial medication and what is the preferred agent for navicular syndrome?

Answer 23

The DIPJ and/or the navicular bursa with triamcinolone

Question 24

T/F Repeatedly injecting triamcinolone into the DIPJ and/or the navicular bursa increases the duration and efficacy

Answer 24

F Repeat injections decreases in efficacy and duration

Question 25

What is the MOA for firocoxib?

Answer 25

Cox-2 selective

Question 26

Why is firocoxib a good anti-inflammatory to use on a horse with navicular syndrome?

Answer 26

It causes less adverse effects in the GI and the kidneys

Question 27

What is the MOA of bisphosphonates like Tildren and Osphos?

Answer 27

Reduces osteoclastic activity

Question 28

T/F Biphosphonates provide consistent results when treating navicular syndrome

Answer 28

F Excellent marketing, inconsistent results

Question 29

When is a PD neurectomy indicated and when is it contraindicated for treatment of navicular syndrome?

Answer 29

If the horse is responsive to a palmar distal nerve block its indicated. Its contraindicated if there is a pre-existing lesion in the DDFT or flexor cortex of the navicular bone

Question 30

Why is a PD neurectomy contraindicated in a horse with navicular syndrome if they have a lesion in the DDFT or flexor cortex of the navicular bone?

Answer 30

Because the horse won't feel pain and can eventually rupture the DDFT due to overuse

Question 31

T/F Re-innveration never occurs with a PD neurectomy

Answer 31

F it can occur within 6 months

Question 32

What are the main indications for a navicular bursoscopy in a horse with navicular syndrome?

Answer 32

(1) adhesions between the navicular bone and the DDFT (2) Dorsal fraying of the DDFT (3) Navicular bursitis

Question 33

You've been treating a horse for laminitis and despite your best efforts, there has been progressive rotation of P3. What is the surgical treatment and what does it prevent?

Answer 33

DDF tenotomy. Prevents sole perforation

Question 34

What are the two indications for surgical treatment of laminitis?

Answer 34

(1) Progressive rotation of P3 despite conservative efforts | (2) To correct severe FLD that developed due to chronic laminitis

Question 35

What does a DDF tenotomy do to help with laminitis?

Answer 35

It reduces the pulling of the DDFT in a palmar/plantar direction

Question 36

What are the two approaches you can use for a DDF tenotomy, which is preferred and why?

Answer 36

(1) Mid metacarpus and mid pastern (2) Mid metacarpus is the preferred approach because its easier, its associated with better outcomes, and it allows for a 2nd tenotomy at the level of the pastern if needed

Question 37

How can you asses the blood supply of an equine hoof?

Answer 37

A digital venography