Sx conditions of the equine foot Flashcards
What is another name for navicular syndrome?
Palmar heel pain
Changes in the bone and synovial structures with navicular syndrome are similar to what process?
Osteoarthritis
What ligaments develop lesions with navicular syndrome?
DDFT, collateral suspensory ligament, and impar ligament
What does the impar ligament connect?
The navicular bone to P3
Where do adhesions develop with navicular syndrome?
Between the DDFT and the navicular bone
What is the most common cause of forelimb lameness in the horse?
Navicular syndrome
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?
Navicular syndrome
What two breeds of horses are predisposed to navicular syndrome? What breed has a low prevalence of navicular syndrome?
QH and TB are predisposed. Arabians have a low prevalence.
What structure exerts the main force on the navicular bone in navicular syndrome?
The DDFT
What is the main contributor to navicular syndrome?
Poor conformation
What are the two types of poor conformation that cause navicular syndrome?
(1) long toe + under-run heels
(2) Small hoof/heavy body
T/F False negatives common with hoof testers in a horse with navicular syndrome
T
What are the 5 views you use in a horse you suspect has navicular syndrome?
DP, LM, sky view, DMPLO, and DLPMO
Why are there many false negatives with radiographs and navicular syndrome?
Because rads only detect mineralized tissues and not all horses will have radiographically detected changes
What are navicular syndrome lesions that can be detected by radiography?
(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
Which imagining modality has good soft tissue contrast and the best osseous detail?
CT
What is the gold standard for imagining of navicular syndrome?
MRI
What is the most common structure with navicular syndrome lesions detected by MRI?
Lesions of the DDFT
What are the types of lesions on the DDFT that are detectable with MRI?
(1) dorsal fraying at the level of the navicular bone
(2) Sagittal splits
(3) Core lesions at P1 and P2
What are the treatment options for navicular syndrome?
(1) corrective trimming/shoeing
(2) intra- synovial medications
(3) Firocoxib
(4) Bisphosphonates
(5) PD neurectomy
(6) Navicular bursoscopy
What corrective trimming/shoeing is done on a horse with navicular syndrome?
(1) Square toe to ease break-over
(2) Raise heels with wedge to correct hoof pastern angles
What shoe is preferred in horses with navicular syndrome and why?
Aluminum because they’re lighter and less concussive forces are transmitted to the foot
What joints/structures can you inject intra-synovial medication and what is the preferred agent for navicular syndrome?
The DIPJ and/or the navicular bursa with triamcinolone
T/F Repeatedly injecting triamcinolone into the DIPJ and/or the navicular bursa increases the duration and efficacy
F Repeat injections decreases in efficacy and duration
What is the MOA for firocoxib?
Cox-2 selective
Why is firocoxib a good anti-inflammatory to use on a horse with navicular syndrome?
It causes less adverse effects in the GI and the kidneys
What is the MOA of bisphosphonates like Tildren and Osphos?
Reduces osteoclastic activity
T/F Biphosphonates provide consistent results when treating navicular syndrome
F Excellent marketing, inconsistent results
When is a PD neurectomy indicated and when is it contraindicated for treatment of navicular syndrome?
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
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?
Because the horse won’t feel pain and can eventually rupture the DDFT due to overuse
T/F Re-innveration never occurs with a PD neurectomy
F it can occur within 6 months
What are the main indications for a navicular bursoscopy in a horse with navicular syndrome?
(1) adhesions between the navicular bone and the DDFT
(2) Dorsal fraying of the DDFT
(3) Navicular bursitis
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?
DDF tenotomy. Prevents sole perforation
What are the two indications for surgical treatment of laminitis?
(1) Progressive rotation of P3 despite conservative efforts
(2) To correct severe FLD that developed due to chronic laminitis
What does a DDF tenotomy do to help with laminitis?
It reduces the pulling of the DDFT in a palmar/plantar direction
What are the two approaches you can use for a DDF tenotomy, which is preferred and why?
(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
How can you asses the blood supply of an equine hoof?
A digital venography
