Bovine Respiratory Flashcards
Sites for scope insertion with thoracoscopy
ICS 9 in the middle of the upper 1/3 of the thorax is IDEAL
ICS 7 or 8 in the middle of the middle 1/3 of the thorax may allow better evaluation of the cranioventral structures (pericardium). However, movement of the scope, at this location, is difficult and is painful for the animal.
preferably 57cm-long, 10mm diameter rigid scope with a 30° viewing angle. A shorter scope or a scope with 0° viewing angle limits evaluation
Maximim insufflation pressure with thoracoscopy
DO NOT exceed 3mmHg - will cause CV collapse
Sites for sinus trephination in cattle
A - frontal sinus
B - Maxillary sinus
C - post orbital diverticulum of frontal sinus (trephine site)
D - anterior turbinate region of frontal sinus (trephine site)
E - turbinate portion of frontal sinus
F - maxillary sinus trephine site
Most common cause of sinusitis in cattle
Following dehorning
Dental dz follows
Main cause & management of pharyngeal trauma in cattle
Cause - balling/drenching gun
Management - drain abscesses, ideally into the mouth/pharynx. If inaccessible orally need pharyngotomy (ventral midline - thyroid - basihyoid (+/- split) - dissect sternothyroid & hyoepiglotticus mm then sharp oral mucosa).
If cervical cellulitis - create multiple areas of drainage to help prevent mediastinitis.
What dz process may be a cause of pharyngeal swelling/collapse in younger calves?
Otitis media - when bilateral can cause signs referable to CN VII & CNVIII. Can also involve CN IX causing pharyngeal collapse, resp obstruction & necessitate temp trach
Recommended sx tx option for permanent DDSP in cattle
Not usually tx as rarely clinically sig
If causing dysphagia, can tx with reection of strap mm (sternothyroid & sternohyoid)
Briefly describe the steps for cleft palate repair via mandibular symphysiotomy
- GA dorsal intubate w trach
- Ventral midline incision from basihyoid to lower lips - lips should be spared (will sl ↓exposure)
- Split mandibular symphysis w blade or osteotome
- Dissect into oral cavity through a place 1.5cm away from one side of the mandible; geniohyoid muscle incised 1cm from its attachment on the mandible. Genioglossus muscle ( & soft tissue, incl mandibular salivary gland, & hypoglossal nerve), are bluntly separated with Metz. Then, oral mucosa incised. The tongue is retracted caudally with a large malleable retractor, and both mandibular rami are gently distracted to gain access to the soft and hard palates
- Soft palate first - incise margins to create 2 shelves of tissue. Nasal mucosa closed w simple continuous or a continuous Lembert pattern 2-0. Then muscular layer & oral mucosa closed w an interrupted or continuous horizontal mattress pattern. Finally, everted oral mucosa closed w a simple continuous pattern, w buried knots
- Hard palate - incise longitudinally adjacent to the maxillary bone, avoiding palatine artery, from soft palate to 1.5 cm caudal to maxillary pad. Then the hard palate is incised axially from the soft palate to the rostral edge of the defect using a No. 12 Bard-Parker blade. With a blunt periosteal elevator, the flap is detached carefully from the palatine bone, making sure not to lacerate the palatine artery. The flaps created are slid axially and sutured together with interrupted horizontal mattress sutures using 2-0 multifilament absorbable suture material.
- Finally, the abaxial portions of the flaps are sutured to the nasal mucosa using a simple continuous pattern with 2-0 multifilament absorbable suture material. The exposed bone will heal by second intention.
- Approach incision closed in 4 layers
Common cause of laryngeal dz in calves
What are the surgical tx options?
Oral necrobacillosis
Fusobacterium necrophorum and Truperella pyogenes are commonly implicated
Commonly rx in arytenoid chondritis in calves.
Sx tx options incl tracheolaryngostomy, permanent tracheostomy, and arytenoidectomy through a laryngotomy
Main difference in laryngotomy between horses & cattle
In horses, incise onlt cricothyroid membrance
Cattle incise membrane and thyroid cartilage
Sites for thoracotomy in cattle
Ideally need to have localised lesion so sx can be targeted
Lesions located in the cranial aspects of the thorax are very difficult to access as most cranial thoracotomy can only be done at the level of the fifth rib.
The caudal lung lobes can be reached through a partial rib resection or intercostal approach from ribs 7-9
Considerations for thoracotomy
STANDING always preferable - v high mortality rates w GA esp in lateral. GA may be necessary for lesions when extensive pleural debridement near the mediastinum is required, when likelihood of creating potentially fatal bilateral pneumothorax is ↑. DO IN STERNAL
Can be done via an intercostal space or rib resection technique
Cattle usually have imperforate mediastinum so should’t get bilateral pneumothorax
Mostly will be marsupialising abscesses - many walled off enough that if sutured to the skin before opening, drainage occurs outside without causing pleural contamination or significant pneumothorax. Wounds heal by second intention
For non-septic processes, need to try re-establish negative pressure after closure - Drain & Heimlich valve in the dorsal thorax is optional but ↑ comfort by ↓ PO pneumothorax
Briefly describe rib resection and intercostal approaches to thoracotomy in cattle.
Thoracotomy through an intercostal space allows limited manipulation but sufficient for simple drainage, lavage, limited debridement of the pleural space, and marsupialisation of an abscess adhered to the parietal pleura if PO access to the thorax is not required
Intercostal approach to thoracotomy - skin incision is centred over the lesion in a proximal to distal direction & the ICS should be incised at the cranial aspect of a rib (to avoid intercostal neurovascular structures immediately caudal to each rib)
Rib resection technique - incision started 20 cm dorsal (or more dorsally if larger lesion) to the CC junction centred over the longitudinal middle of the rib.
DO NOT incise ventral to the CC junction to prevent inadvertent transection of the cranial epigastric vessels.
Dissect through SQ, then the latissimus dorsi mm dorsally & intercostal muscles deep & ventral to latissimus dorsi muscle.
Sharply incise the periosteum, & elevate circumferentially
Transect rib proximally w Gigli wire subperiosteally around the rib, then rib is removed by dislocating at CC junc.
Can also use osteotome/mallet or oscillating bone saw or large rongeur
The axial rib periosteum + parietal pleura is incised to enter thorax
** care re pericardium if performing 5th/6th rib resections
Describe the surgical approach for adult cattle with reticular diaphragmatic hernia
Sx approach is 2-fold
- Standing left flank rumenotomy - hernia is confirmed through a left-flank laparotomy. A rumenotomy is performed to remove FBs from the reticulum but without dislodging it from the thoracic cavity. Routine closure of the rumen & abdomen, then feed restrict to keep the rumen small for the second surgery, which is planned in 2 to 3 days.
- GA cranioventral laparotomy - 30-cm crescent-shaped incision from xyphoid process. The herniated reticulum is carefully freed from adhesions & diaphragmatic hernia sutured
Acquired pneumothorax corrected by inflating the lungs as the last suture knot is tied
Approach to pericardial drainage with TRP/pericarditis
Lateral thoracotomy - standing or GA (GA in lateral recumbency w pericarditis is assoc w ↑ mortality, ∴ STERNAL recumbency if GA is absolutely essential (standing preferable))
A reticular FB may enter thorax from either left or right side, ∴ accurate dx essential; Pre-op US
Most common approach to pericardium→ enter thorax at left ribs 5 or 6 or ICS or ribs 6/7
Skin incision at least 20cm long
Pericardium is often adhered to the regional pleura if the disease is advanced. ∴ incising into the pleural cavity must be carefully performed although cattle have separate pleura from the pericardium when no adhesions are present
Find the FB before draining the pericardium, failure to remove will rx in tx failure
Idiopathic septic pericarditis is rare but possible - no rad FB - other than FB removal, management similar
For both - pericardium sutured to the skin at the incision edge w large (#2 or #3), monofilament, absorbable, or nonabsorbable sutures w interrupted or continuous pattern
Pericardium then incised & drained manually. Can be thick/caseous purulent exudates that must be manually removed from the pericardium in longer standing dz.
Lavage w warm isotonic fluid.
Reinflate lungs & use a drain to ↓ pneumothorax & PO pain/morbidity
The pericardial cavity may be left open to drain or be partially closed and managed with drains if this allows appropriate lavage and adequate drainage