Bovine teat surgery

Question 1

Outline the anatomy of the teat?

Answer 1

Question 2

What kind of sedatives can you use before teat surgery?

Answer 2

Xylazine - alpha 2 agonist

Detomidine

Question 3

How and how much xylazine would you give a fractious dairy cow (250 DIM) before teat surgery?

Answer 3

• 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

Question 4

What advantages/disadvantages of using a sedative do you consider/discuss with the client?

Answer 4

• 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

Question 5

What methods of restraint should be used for teat surgery?

Answer 5

Lift backleg

Tail jack

Tie back leg

Kickbar

Question 6

What are the methods of LA for teat surgery?

Answer 6

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

Question 7

When would a teat cistern infusion of LA be used?

Answer 7

Question 8

Describe how a ring block is performed?

Answer 8

Question 9

How is an inverteed v block performed?

Answer 9

Question 10

How is regional anaesthesia performed for teat surgery?

Answer 10

Question 11

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

Answer 11

Question 12

Discuss procaine and perhaps why it is not the best choice for teat surgery and what would be better?

Answer 12

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)

Question 14

Outline NSAIDs for use in cattle?

Answer 14

Question 15

Which peripheral nerves do you need to block for cranial and caudal teat surgery?

Answer 15

For cranial teat surgery (front two quarters): L1 and L2 +/- T13 - paravertebral block

For caudal teat surgery (back two quarters): use epidural

Question 16

What are common causes of simple lacerations of the teat?

Answer 16

Treading on teats

Dog bites

Stocking density

Slippery floors

Poorly maintained

Barb wire

Housing/cubicles caused

Question 17

Discuss a self retaining teat canal?

Answer 17

• 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

Question 18

Discuss a milk tube/catheter?

Answer 18

• 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!

Question 19

What is recommended after surgery?

Answer 19

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

Question 20

What are the layers of the teat wall?

Answer 20

• Mucosa: thin layer around the teat cistern
• Submucosa
• Connective tissue - highly vascular
• Muscle - circular and runs longitudinally
• Skin

Question 21

What is the surgical technique for superficial lacerations?

Answer 21

• 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

Question 22

What is the prognosis for superficial teat lacerations?

Answer 22

• 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

Question 23

What is the aftercare for superficial teat lacerations once surgical mended?

Answer 23

• 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

Question 24

Describe surgical technique for deeper teat laceration?

Answer 24

• 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

Question 25

How should the layers of the teat be sutured?

Answer 25

* 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

Question 26

Discuss teat amputation?

Answer 26

* 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

Question 27

What is the process of teat amputation?

Answer 27

1. Allow milk to drain prior to surgery and give prophylactic intramammary antibiotics 2. 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

Question 29

Discuss mid teat abnormalities?

Answer 29

* 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

Question 30

What is this used for?

Answer 30

**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

Question 31

What is this and what is it used for?

Answer 31

**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

Question 32

List some abnormalities of teats?

Answer 32

**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

Question 33

How is teat removal done?

Answer 33

**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