Bovine teat surgery Flashcards
Outline the anatomy of the teat?

What kind of sedatives can you use before teat surgery?
Xylazine - alpha 2 agonist
Detomidine
How and how much xylazine would you give a fractious dairy cow (250 DIM) before teat surgery?
- For fractious cows, an increased dose should be used - the maximal dose of Xylazine being 0.3mg/kg. This will make the animal recumbent. Therefore for teat surgery it might e advisable to use a reduced amount
- Dose range of Xylazine = 0.05-0.3mg/kg (0.25-1.5ml/100kg BW)
- Xylazine at higher doses will be effective in ~5 minutes and lasts for several hours
What advantages/disadvantages of using a sedative do you consider/discuss with the client?
- Xylazine can be reversed if an overdose is administered (not common in farm animals to use the reversal atipamezole is not licensed but will reverse it)
- Safety of the vet!
- No milk or meat withdrawal time
- Can make the cow lay down which is not ideal for teat surgery

What methods of restraint should be used for teat surgery?
Lift backleg
Tail jack
Tie back leg
Kickbar
What are the methods of LA for teat surgery?
Methods:
- Method used for LA administration depends on the site or nature of lesions
- Use 23 or 25 G 1-5cm needed
- Teat cistern infusion
- Ring block
- Inverted V block
- IV regional anaesthesia

When would a teat cistern infusion of LA be used?

Describe how a ring block is performed?

How is an inverteed v block performed?

How is regional anaesthesia performed for teat surgery?

Name other methods of local anaesthesia that can be used for teat surgery?

Discuss procaine and perhaps why it is not the best choice for teat surgery and what would be better?
Procaine:
LA licensed for farm animals
Contains epinephrine therefore causes vasoconstriction and increase the risk of tissue sloughing and necrosis
Especially bad with ring blocks and IV regional anaesthesia
Lidocaine:
Use through cascade as not licensed
No epinephrine
MRLs (28 days meat, 7 days milk)
Outline NSAIDs for use in cattle?

Which peripheral nerves do you need to block for cranial and caudal teat surgery?
For cranial teat surgery (front two quarters): L1 and L2 +/- T13 - paravertebral block
For caudal teat surgery (back two quarters): use epidural
What are common causes of simple lacerations of the teat?
Treading on teats
Dog bites
Stocking density
Slippery floors
Poorly maintained
Barb wire
Housing/cubicles caused
Discuss a self retaining teat canal?
- Allows for passive milk let-down for 7-10 days when required by removal of the central stylet
- Bare in mind the cannula being present allows easy migration for infection to track through so need adequate mastitis control
- Return to regular milking ASAP as is less traumatic than manual milking and reduces risk of trauma and infection
- Stitches from surgery can be removed in 7-10 days
Discuss a milk tube/catheter?
- Placed when needed to allow passive milk let-down
- Use for full thickness perforated lesion and want to suture full thickness tightly
- Place cannula for something to suture over
- Developed for cows with injury that cannot enter the parlour
- Allows them to be milked without manual or mechanical milking
- Risk that end of cannula is open
- Surgical cannulas have stylet placed inside so not open
- These will fall out - just use for surgery then remove
- Source of infection into the teat if left open
- Want teat sphincter to close ideally 15 minutes after milking!

What is recommended after surgery?
Drying off after surgery:
- Recommended for the affected quarter if there is a large amount of swelling or if the animal resents machine milking
- Reduces risk of wound breakdown in large deep lacerations
What are the layers of the teat wall?
- Mucosa: thin layer around the teat cistern
- Submucosa
- Connective tissue - highly vascular
- Muscle - circular and runs longitudinally
- Skin
What is the surgical technique for superficial lacerations?
- No milk leaking from teat canal and only skin or shallow muscle lacerations
- Can simply apply a teat bandage after thorough cleaning and drying
- Protects wound from further injury and infection whilst healing occurring
- Easily replaced
- Can use a staple gun and staple remover for superficial lacerations
- Much cheaper option if lesion not full thickness
What is the prognosis for superficial teat lacerations?
- Prognosis worse for superficial lesions more than 4 hours old and extremely poor for >12 hours old
- Lacerations at the base of the teat heal better than those at the distal end
- Vertical lesions heal better than horizontal lesions
- Teat sphincter and streak canal are difficult to repair and so have poor prognosis
- Deeper wounds can cause sinus formation
- Require immediate three-layer suture repair
- Prognosis better if laceration does not enter the teat canal!
- Sign of milk in quarter after surgery indicates successful surgery
What is the aftercare for superficial teat lacerations once surgical mended?
- Systemic and intramammary antibiotics for all full thickness lacerations or injuries to teat end
- Machine milking can occur after surgical repair as long as swelling not too severe
- Pre-milking by hand found to be detrimental to wound healing due to abnormal pressures being generated
- Protect with teat bandage between milkings or if the cow id being dried off until healing complete
Describe surgical technique for deeper teat laceration?
- Initial debridement of laceration important to remove infection or necrotic tissue and ensure clots etc are dislodged
- Could be done with scissors or scalpel blade etc until healthy tissue present
- Assess blood supply to tissue flaps
- Remove if considered compromised as could turn necrotic
- Some severe lacerations of teat end can cause the teat sphincter to be separated from the surrounding skin, usually by a large haematoma
- Undermine all skin to reveal raw teat end which should be left open for second intention healing



