Soft tissue surgery of foals Flashcards
Synovial sepsis/Joint ill incidence
Very common, affects up to 1% of all foals
40% have one joint affected
40% have two joints affected
20% >2 joints affected
Spread of synovial sepsis
Occurs from hematogenous spread, NOT often from trauma c.f. adults
Sepsis from pneumonia, colitis, umbilical infection —most common
Pre-disposing factors to synovial sepsis
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
Clinical signs of synovial sepsis
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
Aetiology of synovial sepsis
Most common pathogens
○ Streptococcus
○ Rhodococcus
○ Actinobacillus
○ E. coli
○ Salmonella
Four types of septic arthritis
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
What structures can synovial sepsis affect?
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
Diagnosis of synovial sepsis
Synoviocentesis
Radiography
Technique of synoviocentesis
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
Normal synovial fluid
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
Septic synovial fluid
Cloudy/turbid
Serosanguinous
Watery - does not ‘string’
High white cell count >20 x 109/L
◊ >90% neutrophils
Total protein: >30 g/L
Radiography of septic arthritis
Look for signs of osteomyelitis in physis and epiphysis - poor prognostic sign and must be addressed at surgery
Treatment of synovial sepsis
Rapid and agressive
Synovial lavage
Treat underlying illness
Antibiotics
Needle lavage of septic joint
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)
Arthroscopic/tenoscopic lavage
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
Antibiotics for synovial sepsis
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
Prognosis of synovial sepsis
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.
Foal umbilical anatomy
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
Patent urachus
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
Treatment of patent urachus
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
Patent urachus surgery
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
Omphalitis/Omphalophebitis/Omphaloarteritis
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
How do you differentiate between patent urachus and umbilical infection
Clinical signs and ultrasound
Diagnosis of umbilical infection
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
Treatment of umbilical infection
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
Surgical procedure for treating umbilical infection
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
Uroperitoneum
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
Surgical treatment of uroperitoneum - cystoplasty
- 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)
Pre-cystoplasty considerations
Stabilize
Correct Hyperkalemia
§ Can cause muscle tremors and cardiac arrythmias
§ Goal = < 5.5 mEq/l prior to surgery
Broad spectrum abx
Cystorrhaphy
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
Umbilical hernia
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
Treatment of umbilical hernia
<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
Simple hernia surgery in foals
- elliptical skin incision around the hernial sac - leave enough skin to close easily afterwards
- carefully dissect skin from hernial sac - try not to penetrate
- invert the sac (into abdomen)
- pre-place mattress sutures to close the hernia
- tie all mattress sutures at the end -> appositional closure of the abdomen wall
- close subcut and skin
- add stent or body bandage - young animal will be lying on wound
If large hernia then refer
Post op considerations for umbilical hernia surgery
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
Hernia repair with elastrator rings
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
Inguinal hernia
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
Inguinal hernia in adult horses
Entire adult males (large inguinal rings/canal)
Post jumping/breeding
Usually non-reducible, often strangulating intestine
Inguinal hernias in foals
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
Elective castration of foal with reducible scrotal hernia
Need CLOSED castration
Twist vaginal tunic -> bowel into abdomen
Ligate as low as possible, prevents recurrence
Signs of colic in foals
Back up constantly
Tail flag
Dull/not nursing
Abdominal distension
Show typical signs of colic
Common causes of colic in foals that may require surgery
Enteritis
Small intestinal mesenteric volvulus
Meconium impaction
Ascarid impaction
Intussusception
Congenital anatomic abnormalities (atresia ani; atresia coli)
Specific considerations for foal with colic:
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
Surgical stomach disorders of foals
Gastric outlet obstruction/pseudo obstruction - relatively rare
§ Result of severe ulceration
§ Most tx medically
§ Surgery possible but quite difficult, high risk of complications, ££££
Small intestinal lesions in foals
Hernias that entrap SI (rare
§ Scrotal, inguinal
§ Diaphragmatic
SI obstructive lesions
§ ascarid impactions
SI strangulating lesions
§ SI volvulus
§ intussusceptions
Ascarid impactions in foals
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
SI volvulus in foals
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
Clinical signs of SI volvulus in foals
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
Intussusceptions in foals
Foals/young horses
Simple obstruction first -> strangulating as more gut drawn in
Typical ‘bulls eye’ appearance on u/s
Clinical signs of atresia ani/atresia coli
Foal colic
Failure to pass meconium/no meconium staining
Diagnosis of atresia ani/coli
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)
Treatment of atresia ani
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
Treatment of atresia coli
euthanasia
