Camelid surgery - general/other

Question 1

What treatment for bilateral choanal atresia was described by Pader et al - JAVMA 2017

Answer 1

Endoscopically guided (scope in mouth & retroflexed round SP to see back of membrane) - membrance punctured via nostril w 14g catheter & tissue dilator to expand for 10 mins. Revised dt obstruction, w 4mm ETT through each hole & left in place 14d as stents. No repeat obstruction once removed

Question 2

CSs and diagnosis of choanal atresia

Answer 2

CSs - Can be partial or complete & uni or bilateral (complete bilateral will die v shortly after birth as can never take a breath - they may be able to mouth breath with difficulty - obv cant nurse simultaneously so commonly aspirate milk & get AP. Usually puff out cheecks to help force air down trachea

Can be seen concurrent w other nasal cavity deformity

Dx - plain rads can be suggestive. Can place 5-10ml of barium (seems a bad choice) into the nasal cavity with 3-5Fr catheter in sternal w the head elevated - this accumulates in the caudal nasal cavity & doesn’t pass into the nasopharynx

Failure to pass tube from ventral meatus caudally also dx

Doesn’t mention nasal endoscopy but surely this is a v useful dx test?

Question 3

CSs & treatment of CCN

Answer 3

• associated with dietary changes and excessive carbohydrate ingestion
• classic presentation is acute-onset blindness & depression. Usually spotted wandering aimlessly or into fencing etc. Later, circling & head tremors may develop. CN exam - absent or reduced menace response with normal or reduced PLRs: ophthalmic examination will reveal no obvious cause for the absent menace suggesting cortical blindness.
• Bloods/CSF usually normal (CT- diffuse encephalitis)
• Tx - thiamine hydrochloride at 10-15mg/kg q 4 hours, continued until several d after resolution of CSs. Supportive and nursing care; IVFT & thiamine can be added
• Preds for depression; poss reduce cerebral edema.
• Recover usually within 24 hours of starting tx ot not at all
• Early tx is vital to the chances of success

Question 4

Give 2 treatment options for choanal atresia.

Answer 4

1. GA; ventilate via tracheostomy. Palpate junction between hard & soft palate windex finger, & w other hand, a 3.5– 6cm (1/8– to 1/4-in.) trocar-tipped IM pin inserted into the nostril through ventral meatus, w tip directed toward the finger within the mouth. Pin pushed through the plate & may be felt in the nasopharynx through the soft palate. Thread a silastic tube over the IM pin then withdraw the pin; Tube needs to be larger diameter than the original IM pin & must be sutured to the ventromedial aspect of the nostril and cut off flush to prevent the tube from catching on objects during feeding. Repeated on the opposite side. Tubes left in 3-4 weeks to allow epithelium to cover newly created orifices. Tracheostomy until tubes removed.
2. Midline trephine opening through nasal bones directly dorsal to the choanae. The choanal area is visualised through the nasal cavity on either side of the nasal septum. The choana is penetrated with a scalpel and the orifice enlarged using rongeurs
3. Pader JAVMA 2017 descr. more minimally invasive approach with a scope retroflexed around the palate from the mouth then visualised penetration via the nose w 14g catheter, then enlarged w tissue expanders. Re-obstructed so catheter balloons placed & inflated in defect & maintained 2wk

Question 5

Most common cause of facial nerve defecits in camelids

Answer 5

Most common cause in llamas in middle ear dz - exam for FB, inflammation/infection etc

ABs eg gent 1mg/kg TID may be used

CSs depend on location of the trauma eg branches over the masseter will rx in muzzle signs only, trauma to the zygomatic arch may only involve the auriculopalpaebral branch (eye and eyelid only), more proximal lesions will involve more of the nerve (eg paracondylar process fracture in horses)

Ear droop, muzzle deviation, feed drops from the lips, nostril failure to dilate, inability to blink and exposure keratopathy,

Question 6

List of ddx for neurological disease in camelids

Answer 6

1. Heat stress (poorly adapted for hot/humid climates)
2. Meningeal worm - Odocoileus virginianus - USA
3. Cervical vertebral injuries
4. Otitis media/interna
5. CCN/polioencephalomalacia
6. Listeriosis
7. Meningitis
8. EHV-1
9. Ryegrass toxicity

Question 7

Egs of viral encephalitides in camelids

Answer 7

Equine herpesvirus (EHV-1) reported as causing blindness & encephalitis in alpacas and llamas; ddx for camelids kept in close proximity to horses

West Nile Virus reported in camelids in the US, causing acute onset of progressive neurological signs and is usually fatal. (PCR & immunohistochemistry of brainstem).

Eastern equine encephalitis (EEE) also usually fatal. Occurred on the east coast of the US where the disease is typically found in other species.

Question 8

Clinical features of Ryegrass staggers

Answer 8

caused by ingestion of an endophyte growing within ryegrass

Endophyte produces tremorgenic toxins = lolitrems, increased during dry weather. Rye grass staggers is dx of exclusion based on history and characteristic clinical appearance of head tremor; difficult to demonstrate toxic levels of endophyte in pasture.

Normally recover when removed from affected pasture: but, permanent damage manifested by ataxia and head tremor may remain following prolonged exposure

Question 9

Clinical features, dx and tx of meningitis

Answer 9

Most often following FPT neonates; meningitis dramatically worsens px.

Affected crias may develop seizures but most often are extremely depressed, or found sleeping more & more.

Tx mannitol. BS-antibiosis such as penicillin/gentamicin combinations while awaiting blood and/or CSF culture results together with intensive fluid and electrolyte therapy. If meningitis is suspected, third generation cephalosporins have quite good penetration into the CSF. Florphenicol is another antibiotic for consideration in such cases

Question 10

Clinical features, dx and tx of listeriosis

Answer 10

Not common in camelids but it does occur. As in other small ruminants, px guarded.

Usually acute onset w rapid progression incl seizures. Most present with lateralising signs–circling, ataxia, leaning to 1 side, nystagmus, but also recumbency, depression & seizures. CSF may show increased protein & CK & characteristic monocytosis.

Tx -supportive care–IVFT as most unable to eat or drink, anti-inflammatories, thiamine & nursing. Oxytetracline at 20mg/kg IV SID for 5 days, or high dose penicillin IV could also be used (80,000 IU/kg IV q6).

Most cases fail to respond to tx & dx can be confirmed at necropsy

Question 11

Clinical features, dx and tx of otitis media/interna

Answer 11

May be an extension of otitis externa but is more often presumed to be dt ascending infection up the Eustachian tubes in the absence of otitis externa. Spinous ear ticks have been associated with several cases

Normally present with a head tilt +/- facial nerve deficits (droopy ear, flaccid facial muscles–animals tend to pack food in the affected cheek, drop food or drool saliva–ptosis, inability to blink +/- exposure keratitis). Some may be ataxic or circling. Vestibular signs can be more severe including nystagmus, circling and leaning to one side.

CSF analysis is useful to rule out listeriosis or other causes of vestibular disease. Radiographs are useful if bony changes are present: however, soft tissue involvement can be extensive and only CT will show these

Surgical drainage & intensive medical management

CT is advised for guiding sx tx (lateral approach to a bulla osteotomy). Haemorrhage and permanent facial nerve deficits are potential complications of this surgery although px generally good. Various bacteria have been isolated from otitis cases including A pyogenes, Staphylococcus and Bacillus most frequently.

Question 12

Newborn cria. What is the diagnosis?

How can this be managed?

Answer 12

Imperforate vulva

Causes straining to urinate

Corrected easily with dorsal to ventral midline incision. No closure required. Urine flow should prevent healing