Soft tissue surgery of foals

Question 1

Synovial sepsis/Joint ill incidence

Answer 1

Very common, affects up to 1% of all foals

40% have one joint affected

40% have two joints affected

20% >2 joints affected

Question 2

Spread of synovial sepsis

Answer 2

Occurs from hematogenous spread, NOT often from trauma c.f. adults

Sepsis from pneumonia, colitis, umbilical infection —most common

Question 3

Pre-disposing factors to synovial sepsis

Answer 3

Failure of passive transfer: high risk for bacteraemia that can lead to localised infections
§ Check IgG of newborn foals - administer plasma as needed

Premature/dysmature, dystokia

Immunocompromised + systemic illness
§ Check lungs, GI

Infection at other sites: umbilical remnant infection most common

Question 4

Clinical signs of synovial sepsis

Answer 4

Most common clinical signs = joint distension

Usually febrile

Lameness may vary in foals

Depending on what is affected (bone/physis or synovial structure)

More variable initial presentation i.e. intermittent, severe/mild lameness

Question 5

Aetiology of synovial sepsis

Answer 5

Most common pathogens
○ Streptococcus
○ Rhodococcus
○ Actinobacillus
○ E. coli
○ Salmonella

Question 6

Four types of septic arthritis

Answer 6

Type S = haematogenous spread to synovial membrane

Type E = haematogenous spread to epiphysis

Type P = haematogenous spread to physis

Type T = inoculation of bacteria from trauma

Question 7

What structures can synovial sepsis affect?

Answer 7

synovial structures

bony structures within the joint (osteomyelitis)
§ often occurs if sepsis has been present for some time (weeks c.f. days)
§ if there is osteomyelitis the prognosis becomes much worse
§ surgery must also involve arthroscopic curettage of infected bone

physis – infected physis can ‘seed’ the joint infection

May have one or more joint affected

Question 8

Diagnosis of synovial sepsis

Answer 8

Synoviocentesis

Radiography

Question 9

Technique of synoviocentesis

Answer 9

Foal usually sedated + recumbent

Aseptic prep

Aseptic technique using landmarks to enter
Collection/aspiration of synovial fluid (for analysis and C/S)

EDTA most important

Question 10

Normal synovial fluid

Answer 10

Straw coloured

Viscous

Low white cell count <10 x 10^9/L
◊ Differential <15% neutrophils
◊ But can increase after e.g. joint injection up to 50-60% neutrophils

Low TP <10g/L

Question 11

Septic synovial fluid

Answer 11

Cloudy/turbid

Serosanguinous

Watery - does not ‘string’

High white cell count >20 x 109/L
◊ >90% neutrophils

Total protein: >30 g/L

Question 12

Radiography of septic arthritis

Answer 12

Look for signs of osteomyelitis in physis and epiphysis - poor prognostic sign and must be addressed at surgery

Question 13

Treatment of synovial sepsis

Answer 13

Rapid and agressive

Synovial lavage

Treat underlying illness

Antibiotics

Question 14

Needle lavage of septic joint

Answer 14

Common first line initial treatment as cheaper, but not as through as arthroscopic lavage

Only for budget cases

Allows multiple joints to be lavaged efficiently

Under standing sedation (adults) or TIVA (foals)

Question 15

Arthroscopic/tenoscopic lavage

Answer 15

GOLD STANDARD

High volume (5-15L)

After lavage, wound is debrided and usually closed primarily if possible (not too contaminated)

ALWAYS indicated if there is associated osteomyelitis

Question 16

Antibiotics for synovial sepsis

Answer 16

Systemically
□ Pen/gentamycin
□ Tetracycline (oxytetracycline) - good bone penetration
□ Ceftiofur if C&S indicate others resistant

Locally: intrasynovial/intra-thecal or regional
□ Aminoglycosides i.e. gentamycin or amikacin used commonly
® Broad spectrum coverage, high local concentration
® Usually injected into the synovial structure at the end of surgery (after lavage)
® High concentration lasts for 24-48 hours
® May be administered in the days post operatively as required

Question 17

Prognosis of synovial sepsis

Answer 17

Survival to discharge from hospital = 56-80% (varies for different studies)

Of those discharged, most (92%) survive long term

Synovial infection can affect future athletic performance
§ Only 31% - 62% of affected foals able to race (depends on study)
§ Negative outcome associated with:
□ delayed treatment
□ multiple septic joints
□ presence of multisystemic disease.

Question 18

Foal umbilical anatomy

Answer 18

Bladder and umbilicus attached

Umbilicus:

○ Umbilical aa. - L and R run caudally become round ligaments of bladder

○ Umbilical vein – runs cranially Becomes round ligament of liver/falciform ligament

○ Urachus
§ Transports urine from fetal bladder to allantoic cavity
§ Closes shortly after birth

Question 19

Patent urachus

Answer 19

Common

Incomplete closure of the urachus

Primary or acquired in few days post foaling due to excessive straining, prolonged lying down excessive umbilicus traction, or local infection

Question 20

Treatment of patent urachus

Answer 20

Dip in dilute tincture of iodine

Or no treatment if no evidence of infection

Don’t ligate

Foals require broad-spectrum antibiotics.

Do not use chemicals to cauterise the cord in order to close the opening.

Adv to use gentle antiseptic solutions such as chlorhexidine (0.05%) or povidine iodine (0.1%) to clean the area without causing more destruction.

Do not use strong iodine solutions - will cause cell destruction.

Surgery indicated in a small no of cases where it will not close on its own

Question 21

Patent urachus surgery

Answer 21

Involves umbilical resection and cystoplasty

Required if it persists despite conservative tx (>7d)

Fusiform incision in skin around umbilicus

Umbilicus and urachus dissected out

Follow caudally -> bladder

Clamp and resect tip of bladder

Close bladder in 2 inverting layers (cushings)

Urinary catheter for couple of days post op

Question 22

Omphalitis/Omphalophebitis/Omphaloarteritis

Answer 22

Infected umbilical cord

can occur at or around the time of birth or develop in the days to weeks following birth

involves the blood vessels and not just the urachus.

umbilicus can become enlarged and swollen

the absence of swelling and a discharge externally does not mean that the umbilicus is not infected

Signs can just be unexplained fever, lethargy or off suck

Question 23

How do you differentiate between patent urachus and umbilical infection

Answer 23

Clinical signs and ultrasound

Question 24

Diagnosis of umbilical infection

Answer 24

Palpation (not useful alone to determine course of action)

Ultrasound
§ Umbilical v. <1 cm
§ Umbilical a. <1.3 cm
§ Umbilical aa. + urachus <2.5 cm

CBC

Blood culture

IgG

Question 25

Treatment of umbilical infection

Answer 25

Surgical vs medical

Surgical indicated if:
- clinician preference
- progress not attained medically
- Signs of systemic disease
- U/S shows widespread/severe infection
- No response to Abx or recurs
- Concurrent joint sepsis or widespread sepsis

Question 26

Surgical procedure for treating umbilical infection

Answer 26

Suture umbilical opening closed first to prevent contamination of site

Elliptical incision around umbilicus

Dissect off body wall

Then incise linea alba cr and cadual to umbilicus

Identify the umbilical vein running cranially -> trace to a normal section (not thickened) and ligate

Repeat with both umbilical arteries

body wall closed in 3 layers (linea alba, s-cut and skin)

Cover wound with stent (sutured on) or body bandage

Question 27

Uroperitoneum

Answer 27

Quite common
○ Prevalence 0.5-2%

Often occurs during parturition (rapid and forceful); can occur in septic/recumbent foals (monitor)

Rapid and forceful parturition in horses
○ Ruptured bladder in foals
○ Fractured ribs in foals
○ Occasionally ruptured bladder in mare

Tears most common dorsally

Question 28

Surgical treatment of uroperitoneum - cystoplasty

Answer 28

• Dorsal recumbency - midline laporotomy
• May need to reflect prepuce to extend laporotomy caudally
• Drain abdomen of urine slowly first
• Midline (dorsal tear) of bladder edges resected
• Then repaired with inverting absorbable sutures (none left in lumen
• Resect other umbilical remnants
• close bladder tip - double layer inverting (Cushings)
• Close linea alba, s-cut, and skin)

Question 29

Pre-cystoplasty considerations

Answer 29

Stabilize

Correct Hyperkalemia
§ Can cause muscle tremors and cardiac arrythmias
§ Goal = < 5.5 mEq/l prior to surgery

Broad spectrum abx

Question 30

Cystorrhaphy

Answer 30

To repair a tear in the bladder

check full extent of bladder—some can be quite long and difficult to exteriorize

Can use fluorescein to visualize tear if small via catheter

Excise margins; culture neck of bladder before closure

Question 31

Umbilical hernia

Answer 31

Common (around 2% TBs); most are congenital

Usually chronic, small, uncomplicated

Size: commonly measured in ‘finger’ width

Usually cosmetic but serve as a potential site of bowel incarceration (8-10% referred for emergency surgery)

Should be easily reducible
○ If not - gut or omentum may be trapped
§ CS = colic, oedema/clammy skin over hernia site
§ Need surgery relatively urgently -> open sx under GA

Question 32

Treatment of umbilical hernia

Answer 32

<5cm; reducible
§ Reduce hernia daily to check size and ensure nothing entrapped
§ Frequently close as foal matures
§ Hernia clamps not advised as can entrap bowel
§ If not closed by 4 months; surgery

> 5 cm; non reducible
§ Surgery
§ Will not close on its own; strangulation risk high
§ Elliptical incision, invert sac or cut out, close body wall, sub-q and skin

Question 33

Simple hernia surgery in foals

Answer 33

1. elliptical skin incision around the hernial sac - leave enough skin to close easily afterwards
2. carefully dissect skin from hernial sac - try not to penetrate
3. invert the sac (into abdomen)
4. pre-place mattress sutures to close the hernia
5. tie all mattress sutures at the end -> appositional closure of the abdomen wall
6. close subcut and skin
7. add stent or body bandage - young animal will be lying on wound

If large hernia then refer

Question 34

Post op considerations for umbilical hernia surgery

Answer 34

Keep covered for 3-4 days

Elective clean surgery - shouldnt need antibiotics

NSAIDs indicated

RESTRICT exercise for 2-3 weeks - prevent pull through of sutures

Question 35

Hernia repair with elastrator rings

Answer 35

If used, for SMALL hernias only (<1 finger width)

Fibrous tissue fills the gap but this is not a true repair

3-4 weeks for hernia skin to slough off

Significant risk of getting gut trapped in the ring if done standing, or can necrose skin and leave an open hole into the peritoneum

Question 36

Inguinal hernia

Answer 36

Congenital, likely hereditary

Cause = congenitally enlarged vaginal ring (internal ring of inguinal canal

Usually easily manually reducible

Most are self-resolving within 6mo

Low risk of bowel incarceration

Tell owner to reduce manually SID

adv re-signs to look for if ruptures or bowel becomes incarcerated
- Cold, clammy feel to scrotum
- Colic/depressed
- Irreducible

Question 37

Inguinal hernia in adult horses

Answer 37

Entire adult males (large inguinal rings/canal)

Post jumping/breeding

Usually non-reducible, often strangulating intestine

Question 38

Inguinal hernias in foals

Answer 38

Foals - rare that intesting incarcerated/strangulated

Ruptured hernia -> vaginal tunic ruptures (often during birth)
§ Intestine can then travel sub-cutaneously
§ Swollen, non-reducible, cold, clammy oedematous scrotal skin, colic signs

Both require urgent surgery (referral) at this stage

Question 39

Elective castration of foal with reducible scrotal hernia

Answer 39

Need CLOSED castration

Twist vaginal tunic -> bowel into abdomen

Ligate as low as possible, prevents recurrence

Question 40

Signs of colic in foals

Answer 40

Back up constantly

Tail flag

Dull/not nursing

Abdominal distension

Show typical signs of colic

Question 41

Common causes of colic in foals that may require surgery

Answer 41

Enteritis

Small intestinal mesenteric volvulus

Meconium impaction

Ascarid impaction

Intussusception

Congenital anatomic abnormalities (atresia ani; atresia coli)

Question 42

Specific considerations for foal with colic:

Answer 42

More challenging to diagnose as can not perform rectal exam etc
§ Rely on u/s + rads

Perceived increased risk of intra-abdominal adhesions post op
§ Perhaps not more so than adults?

Beware if has pyrexia – may be enteritis or sepsis rather than surgical lesion?
§ But also seen with SI volvulus etc

Abdominal distension – common
§ Can measure with tape at specific points on abdomen to detect changes
§ If severe can cause dyspnoea

Naso-gastric reflux in foals – does not always indicate mechanical obstruction (unlike adults)
§ Do pH test – acid reflux from stomach vs basic reflux from SI

Common DDx for colic/distension
§ Uroperitoneum
§ Enteritis

Question 43

Surgical stomach disorders of foals

Answer 43

Gastric outlet obstruction/pseudo obstruction - relatively rare

§ Result of severe ulceration

§ Most tx medically

§ Surgery possible but quite difficult, high risk of complications, ££££

Question 44

Small intestinal lesions in foals

Answer 44

Hernias that entrap SI (rare
§ Scrotal, inguinal
§ Diaphragmatic

SI obstructive lesions
§ ascarid impactions

SI strangulating lesions
§ SI volvulus
§ intussusceptions

Question 45

Ascarid impactions in foals

Answer 45

Not so common these days

Parascaris Equorum

Usually weanlings 4-24 months
® Often thin/unthrifty appearance
® Impaction follows anthelmintic tx by 1-5d

Surgery indicated if complete obstruction present
® Enterotomy and evacuate then close
® Occasionally enterectomy if bowel devitalised

Question 46

SI volvulus in foals

Answer 46

most common surgical lesion of foals esp <3mo

Variable length of intestine rotates around its long axis

Often jejunum and ileum involved

In some cases, entire SI rotates around root of mesentery -> massive ischaemia
-> Poor prognosis due to large amount of gut that is compromised

Question 47

Clinical signs of SI volvulus in foals

Answer 47

pain becomes severe- often recumbent,

SI and abdominal distension,

no movement of SI on U/S,

increased RR and HR,

injected MM,

can be pyrexic

Question 48

Intussusceptions in foals

Answer 48

Foals/young horses

Simple obstruction first -> strangulating as more gut drawn in

Typical ‘bulls eye’ appearance on u/s

Question 49

Clinical signs of atresia ani/atresia coli

Answer 49

Foal colic

Failure to pass meconium/no meconium staining

Question 50

Diagnosis of atresia ani/coli

Answer 50

May be able to digitally palpate atresia ani, but not always

Barium enemas may be helpful for both , but sometimes are difficult to interpret, especially with atresia coli

Often diagnosed via exploratory celiotomy

Always look for other congenital abnormalities (i.e. contracture ect)

Question 51

Treatment of atresia ani

Answer 51

If complete rectal pouch

persistent anal membrane incised or small circular piece of skin removed + rectal wall sutured to skin

Prognosis for life favourable, but normal anal function may not be obtained

Question 52

Treatment of atresia coli

Answer 52

euthanasia