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
How should the layers of the teat be sutured?
- Mucosal: continuous sutures using 4-0 or 5-0 polygactin 910 (Vicryl)
- Submucosal: connective tissue and muscle, use continuous sutures again
- Skin: simple interrupted or horizontal mattress using 2-0 or 3-0 prolene
- Sometimes submucosa and skin are sutured as single layer but this will increase swelling and thickness of scar tissue, making the wound more likely to breakdown
Discuss teat amputation?
- Commonly done in farm practice with irreversible trauma and severe or gangrenous mastitis
- Used if teat ripped off more than 3/4
- Use scalpel and restraint
- Could use Burdizzo above the cut to improve haemostasis
- Can use LA or lumbosacral epidural
- Prognosis of surgery on teat lesion are not great, therefore amputation common
- Show cow, might try to fix rather than remove
- Depends on value of the cow and ability of other teats
- Good if present during first 4 hours during first intention healing - get an idea of how long ago the laceration happened
What is the process of teat amputation?
- Allow milk to drain prior to surgery and give prophylactic intramammary antibiotics
- Place rubber tourniquet (thick elastic band) at base of the teat, trim out the milk sinus with scissors and close the defect with three suture layers
- If teat necrotic or still infected then trim/crush and remove devitalised tissue with a Burdizzo and leave the area open to drain
- Can leave elastic band on for 24-48 hours to prevent haemorrhage
Discuss mid teat abnormalities?
- May be caused by chronic inflammation, milk calculi (teat peas), neoplasia (bovine papillomatosis) or a congenital obstruction
- Teat peas can be due to chronic Staph infections and therefore necessary to treat the underlying cause and consider viability of surgery in some cases
- Lesions should be fragmented and removed via the teat streak canal using a papillotome and forceps:
- Large teat lesions may need open teat surgery
What is this used for?
Hudon’s teat spiral/Alligator forceps:
- Feel teat for pea inside teat canal
- Slows down milking - not known where they come from e.g. haematoma, Staph infection, calculi
- Can just crush either side of pea sometimes
- Otherwise use Hudson’s teat spiral/Alligator forceps
- Use LA
- Insert into teat canal
- Get pea inside spiral
- Difficult to keep teat sphincter intact therefore not very useful in returning to full functioning teat after
- Alligator forceps can just be inserted up teat canal to grab pea
- More effective in not stretching the teat sphincter
What is this and what is it used for?
Teat knife:
- Used to repair sphincters or ‘hard milkers’ of teat spiders (scar tissue as base of teat)
- Teat spiders can be due to trauma or congenital
- Insert knife into teat to open and increase milk flow
- Can also be used for ‘blind milker’
- Teat with membrane covering end of teat in heifers
- Can use for ‘hard milkers’ by inserting up teat canal to cut streak canal
- Twist 90 degrees and repeat
- Creates a cross cut in teat canal
- If this is the original problem then will continue to milk etc
- BUT risk of infection is very increased as no tight streak canal to prevent contamination
List some abnormalities of teats?
Supernumerary teats:
- Common inherited condition
- Can be in isolation or attached to normal teats
- Teat removal carried out for animals >3 months old must be done by a vet
- Optimal time is less than 4 weeks old - can be done by farmer
- LA advised in all cases
- If left then can interfere with milking and increase mastitis risk as well as altering the cosmetic appearance
Conjoined teats:
- Supernumerary teats attached to a primary teat and have accessory glands
- Conjoined teats need removal due to milking interference and mastitis risk
- Surgical intervention by elliptical incision parallel to long axis of the primary teat
- Dissect down to the annular ring
- Isolate the sinus of accessory teat to transect it at its junction with the gland cistern
- Close wound in three layers
- Good prognosis but heritability is a concern
Congenital atresia:
- Blind quarter found at a cow’s first lactation
- Causes: trauma from suckling, infection from flies
- Can occur at the distal end of the teat, teat cistern and annular ring
- Results in minimal or no milk from one or more quarters
- May need ultrasound or contrast radiography to see cause and extent
How is teat removal done?
Teat removal:
Inject 1-5 ml of LA to site of removal and apply haemostats for 2-3 minutes before removal
Crush base of supernumerary teat/s using artery forceps or Burdizzo - depending on size of the animal
Excise tissue using scalpel in a craniocaudal direction
Apply topical antibacterial spray and wound dressings
