LA umbilical disorders
Equine umbilical hernias- overview
Umbilical hernias are typically seen in young animals and generally either (1) are inherited or (2) develop due to umbilical infections. A few develop due to traumatic separation of the umbilical cord at birth. Congenital hernias are likely inherited if there is no sign of infection. Quarterhorse fillies, Holstein calves and pigs are predisposed. Some foals develop hernias within the first 2 months of life; these are also assumed to be due to a genetic cause.
Ventral hernias can also develop as incisional complications or direct trauma. These commonly occur when exercise is allowed too soon after abdominal surgery when the body wall is still weak and sutures have dissolved.
If a hernia develops due to trauma or incisional dehiscence, it is important to wait until a good firm fibrous ring develops before attempting repair. This generally requires about 60 days. Most of these should be referred to a surgery facility for repair due to the size and likelihood of difficult closure.
Smaller hernias (<5cm diameter) in foals may resolve on their own and this usually happens within the first 3 weeks of life. If a hernia is still present at 4 months of age, it probably isn’t going to resolve on its own. Surgery is usually delayed until the foal is weaned and is 4-6 mo of age.
Small hernias are most dangerous as intestines can slip into the hernia and get stuck. Large hernias may not ever need fixing as intestines slide in and out.
Treatment options include hernia clamps, belly bands and surgery. Hernia clamps are cheap and are designed to cause necrosis and scarring. Typically two pieces of wood are tightened across the hernia in an attempt to scarify the area. Complications include sepsis (gangrene) and evisceration. Hernia belts may or may not work better than mother nature; research is limited to non-existent. May horse owners like hernia belts.
Surgery can be performed in the field under the right conditions. Surgical repair can be done either closed (keep the hernia sac and peritoneum closed) or open (open the hernia sac and open the peritoneal cavity). Closed repair is frequently performed in horses. A fusiform incision is made around the hernia and the hernial sac dissected free of the skin (which is removed). The sac is pushed into the abdomen and the hernia sides closed over it.
Open repair is advised for bovine hernias since infection is often the cause of the hernia. After dissection to the abdominal wall, a stab incision is made into the abdominal cavity and then the hernia sac opened carefully, following the hernial ring. The stab incision should be made to one side to avoid the umbilical vessels that traverse cranially and caudally. These vessels should not be patent at this stage but may contain pus!
Body wall closure should be done with relatively large, long lasting suture in a simple continuous pattern. We use #2 PDS for most weanlings. Babies like to bounce. Bouncing is hard on the incision. PDS is the longest lasting absorbable suture we have. It maintains strength for about 45 days. Continuous patterns have been shown to be more secure under tension than interrupted patterns:
Many of us were taught to close hernias with a vest-over-pants suture or a bunch of cruciates. That was bad advice. The goal was to strengthen the closure or minimize the risk of it falling apart. A vest-over-pants (or Mayo mattress suture) creates an overlapping body wall. The problem is that the body wall doesn’t heal that way. The multiple cruciates were done in the hopes that, if one failed, the others would hold. That isn’t true either. Once one pops, all of them pop. Simple continuous suture redistributes pressure as needed. Yes, you need to tie good knots but that is true for all of them.
We do recommend continuous patterns for all 3 layers of the body wall closure. I do suture removal at 14 days but keep calves and foals restricted for much longer than 14 days (generally 3-4 weeks if at minimum). Think about it. How long does your suture last (PDS? Vicryl?) and how long does it take the body wall to heal (60 days for adult horse)? What can happen if they bounce in the time frame between when the suture is no longer strong and body wall is still weak?
This study is one of my favorites:
Comparison of incisional bursting strength of simple continuous and inverted cruciate suture patterns in the equine linea alba. Magee AA1, Galuppo LD.
OBJECTIVE:To determine the bursting strength of ventral median abdominal incisions closed by either simple continuous or inverted cruciate suture patterns.
METHODS:A 25 cm ventral median incision was made through the linea alba and a 200 L polyurethane bladder was placed within the abdomen. Either a simple continuous or an inverted cruciate pattern using 3 polyglactin 910 with a bite size and suture interval of 1.5 cm was used to close linea incisions. Closure time was recorded for each pattern. The bladder was inflated with air at 40 L/min, and the pressure at body wall failure recorded. The length of suture used for wound closure and the wound failure modes were recorded. Deviation from the linea (cm), total suture length (cm), suture length to wound length ratio (SL:WL), closure time (min), bursting pressure (mm Hg), and failure modes were compared between groups using Welch-Aspin t-tests. The effects of independent subject variables were assessed for possible effects on bursting strength using analysis of covariance.
RESULTS:Mean bursting pressure was significantly greater for the simple continuous pattern than for the inverted cruciate pattern (P = .01). Significantly less suture material (P = .0002) was required with the continuous pattern than with the inverted cruciate pattern. Mean closure time, SL:WL, deviation from the linea, and failure modes were not significantly different between groups. No significant effects were noted for independent variables in both groups on bursting strength.
CONCLUSIONS:In this model, a simple continuous closure pattern for ventral median abdominal incisions was stronger than an inverted cruciate pattern. A simple continuous pattern leaves less foreign material in the wound, which may be of benefit in reducing incisional complications.
CLINICAL RELEVANCE:Use of a continuous closure pattern for the linea alba may offer greater wound security during episodes of increased intra-abdominal pressure in horses.
Many postoperative complications are similar across species for abdominal surgery and include infection, peritonitis and hernia recurrence. The body wall is fascia and is poorly vascular. In the adult horse, it takes approximately 60 days for the hernia repair to have moderate strength. No absorbable suture lasts that long so restricted exercise is important to prevent hernia recurrence.
Richters and entrapped hernias
If the intestines are stuck, the animal will usually show signs of colic, at least initially. Eventually the animal may become depressed. In a normal (reducible) hernia, the intestines can be shoved back into the belly; if the intestines are entrapped, the hernia is not reducible. The hernia area may be painful on palpation. The area may be warmer or colder than surrounding areas.
With a Richter hernia, only part of the intestinal wall is entrapped vs the full width of the intestine being entrapped. This part of the intestinal wall can become devitalized and leak, resulting in an intestinal fistula.
- Umbilical hernias are often associated with umbilical infections in calves.
- Pigs and foals just get hernias (not always infections) and these are likely hereditary. We still do surgery on foals but owners should be advised about inheritance risk. We try to avoid surgery in show pigs.
- Use fusiform incisions, enter abdominal cavity to the side (not cranial or caudal).
- Foals with umbilical infections are sick. Since the diagnosis occurs fairly early, these animals do respond to antibiotic therapy.
- The body wall heals really slowly. Early exercise will increase the risk of hernia recurrence.
Management of umbilical disorders in the foal, In Practice, 2008- more details; nice reference for your files
Tissue Strength and Wound Morphology of the Equine Linea Alba After Ventral Median Celiotomy, Vet Surg 2000- evidence regarding how long the body wall takes to heal after surgery
Video: field anesthesia for hernia repair – designed to give you an mental image of the procedure
Video : Simple hernia repair in a horse (or dog, pig, calf, etc)- more specifics for those that want them
Video: protecting the intestines during body wall closure – cool technique that applies to all species; youtube link