Prosthetic mesh repair of abdominal wall hernias in horses

Repair of hernias of the abdominal wall of horses is often augmented by inserting a prosthetic mesh. In this review, we describe the various characteristics of prosthetic meshes used for hernia repair and present 2 systems that are used by surgeons in the human medical field to classify techniques of prosthetic mesh herniorrhaphy. Both of these classification systems distinguish between onlay, inlay, sublay, and underlay placements of mesh, based on the location within the abdominal wall in which the prosthetic mesh is inserted. We separate the published techniques of prosthetic mesh herniorrhaphy of horses using this classification system, ascribing names to the techniques of herniorrhaphy where none existed, and report the success rates and complications associated with each technique. By introducing a classification system widely used in the human medical field and illustrating each technique in a figure, we hope to clarify inconsistent nomenclature associated with prosthetic mesh herniorrhaphy performed by veterinary surgeons.     

Surgical repair of a congenital lateral abdominal wall hernia in a neonatal foal

A 16‐hour‐old Quarter Horse filly presented for evaluation of a soft mass in the right caudoventral lateral abdominal wall. Radiography and ultrasonography confirmed the presence of a nonreducible lateral abdominal wall hernia with small intestine located between the skin and body wall. The size of the defect itself could not be imaged and the filly was taken to surgery. A 4 cm vertical defect that appeared congenital was found in the transverse abdominal muscle and was repaired by primary apposition. This case report describes the repair and outcome of this unusual type of congenital hernia.     

Coagulation defects of aflatoxin intoxicated rabbits

Twelve New Zealand white rabbits were intoxicated with aflatoxin B1. Most rabbits developed a coagulation defect near the time of death. Immediately prior to death there were significant decreases in factors V, VII, and VIII coagulant activities and fibrinogen concentration without a change in plasma fibrin(ogen) degradation product concentration, platelet number, and detectable plasma fibrin monomers. Microscopic evidence of disseminated intravascular coagulation was present in one rabbit with marked, diffuse hepatic necrosis. Terminal serum albumin concentration was significantly correlated to plasma factors V and VII activities and fibrinogen concentration. The coagulation defect of aflatoxicosis is primarily due to diminished hepatic synthesis of coagulation factors except when hepatic necrosis is severe enough to initiate intravascular coagulation and consumption of coagulation factors.     

Surgical correction of concomitant cranioventral abdominal wall, caudal sternal, diaphragmatic, and pericardial defects in young dogs

Seven puppies with concomitant congenital cranioventral abdominal wall, caudal sternal, diaphragmatic, and pericardial defects were treated surgically when they were between 10 and 12 weeks old. Three pups had ventricular septal defects that were not corrected. Diaphragmatic herniorrhaphy without extension of the diaphragmatic defect was performed in 6 pups. In one pup, paracostal extension of the diaphragmatic defect was necessary to decrease tension on the diaphragmatic closure. All pups were healthy at 6-month follow-up examinations, but 2 of 3 pups with ventricular septal defects had moderate generalized cardiomegaly evident on thoracic radiography. Early surgical correction of the congenital defects in these pups was usually simple because there were few or no thoracic adhesions, the dogs were small, the defects were small in 6 of 7 dogs, and the costal arch was pliable in each dog.     

Herniation of the abdominal wall in pregnant mares

Abdominal wall hernia was detected in 4 pregnant mares. Antemortem diagnosis of the specific abdominal wall lesion was difficult. Ventral deviation of the abdomen, associated abdominal wall edema, and pain indicated rupture of the prepubic tendon. Three mares examined at necropsy did not have a rupture of the prepubic tendon but did have herniation of the abdominal wall. Abdominal pain was severe and was compounded by incarceration or entrapment of viscus.     

Evaluation of small-intestinal submucosa implants for repair of meniscal defects in dogs

OBJECTIVE: To assess the effects of porcine small intestinal submucosa (SIS) implants on the healing of meniscal lesions in dogs. ANIMALS: 16 adult Greyhounds of both sexes. PROCEDURE: Unilateral osteotomy was performed at time 0 to disrupt the medial collateral ligament attachment, and two (1 cranial and 1 caudal) 4-mm circular defects were created in the avascular portion of the medial meniscus. One defect was filled with an SIS graft, and the other defect remained empty (control). Three months later, the identical procedure was performed on the contralateral limb. Three months after the second surgery, dogs were euthanatized, and meniscal tissue specimens from both stifle joints were collected for gross, histologic, biomechanical, and biochemical evaluations. RESULTS: Regenerative tissue was evident in 4 (2 SIS-implanted and 2 control) of 16 defects examined histologically. In 3 defects, this thin bridge of tissue was composed of immature haphazardly arranged fibrous connective tissue with a relatively uniform distribution of fibroblasts. Aggregate modulus, Poisson ratio, permeability, and shear modulus were not significantly different between control and SIS-implanted defects either 3 or 6 months after surgery. Hydroxyproline content also did not differ between SIS-implanted and control defects at 3 or 6 months. CONCLUSIONS AND CLINICAL RELEVANCE: Implantation of porcine SIS into experimentally induced meniscal lesions in dogs did not promote tissue regeneration.     

Mesh repair of a large traumatic lateral abdominal wall hernia in an 8‐day‐old foal

An 8‐day‐old French trotter colt was admitted with a traumatic lateral abdominal wall hernia with reducible intestinal content. A 15 cm long full thickness tear was identified in both the internal abdominal oblique and transverse abdominal muscles. This case report describes the surgical repair of the hernia using a polypropylene mesh.     

Effects of local anesthetics on healing of abdominal wounds in rabbits

The influence of lidocaine and bupivacaine on the breaking strength and histopathologic appearance of wounds in the ventral abdominal midline (linea alba) of rabbits was studied. In control rabbits, group 1 (n = 24), skin and subcutaneous tissues were incised, permitting direct infiltration of the linea alba with normal saline solution. The linea alba was then incised, and wound margins were apposed in layers, using absorbable suture material. Group 2 rabbits (n = 24) were given 0.5% lidocaine, group 3 rabbits (n = 24) were given 2% lidocaine, and group 4 rabbits (n = 24) were given 0.5% bupivacaine, rather than saline solution. Eight rabbits from each group were killed 6, 12, and 18 days after wounding. Eight 1.0-cm wide transverse strips were removed from the abdominal wall of each rabbit. Two strips were used for histopathologic evaluation and 6 were tested for failure, using a mechanical testing device. Breaking strengths in group 1 averaged 0.66 kg, 1.35 kg, and 1.57 kg at 6, 12, and 18 days, respectively. None of the test groups had significantly different (P greater than 0.05) breaking strength results as compared with that in controls. The histopathologic appearance of tissues infiltrated with local anesthetics did not vary consistently from that of tissues infiltrated with normal saline solution. Local infiltration of lidocaine and bupivacaine does not alter substantially the healing of midline abdominal incisions in rabbits.     

Biocompatibility of three-dimensional chondrocyte grafts in large tibial defects of rabbits

OBJECTIVE: To evaluate biocompatibility and effects of implantation of 3-dimensional chondrocyte-agarose autografts in tibial defects in rabbits and to compare in vitro and in vivo chondrocyte-agarose constructs with respect to cell viability, differentiation, and matrix production. ANIMALS: 24 adult New Zealand White rabbits. PROCEDURE: Three-dimensional constructs with (grafted group) or without (control group) autogenous chondrocytes were implanted into tibial defects of rabbits and cultured in vitro. During an 8-week period, defects were evaluated radiographically, grossly, histologically, biochemically, and immunohistochemically. In vitro constructs were evaluated histologically, biochemically, and immunohistochemically. RESULTS: Tibial defects had significantly higher radiographic densitometry values at 4 and 6 weeks after implantation in grafted group rabbits, compared with control group rabbits. Number of observed centers of endochondral ossification was significantly greater in defects of grafted group rabbits, compared with control group rabbits. On day 14, glycosaminoglycan concentration was significantly higher in tibial defects of grafted group rabbits, compared to defects of control group rabbits or in vitro constructs. At weeks 2, 4, and 8, glycosaminoglycan concentrations were significantly lower in the in vitro control constructs, compared with other groups. Collagen type I was present in bone and bony callous in defects of grafted and control group rabbits. Collagen type II was identified in cartilaginous tissues of grafted and control group rabbits. Collagen type X was associated with hypertrophic chondrocytes. Only type II collagen was found in the in vitro chondrocyte constructs. CONCLUSIONS AND CLINICAL RELEVANCE: Chondrocyte-agarose grafts are biocompatible in large tibial defects and appear to provide a cell source for augmenting endochondral ossification.     

Ultrasonography of the abdominal wall before and after laparotomy in cows

The ultrasonographic appearance of the normal abdominal wall in the flank region was investigated before and after exploratory laparotomy in five cows (group A). The results were compared with those after surgical correction of left displaced abomasum in 10 cows (group B) and of caecal dilatation in another 10 cows (group C). We hypothesized that in group C and group B, wound healing would be impaired because of the higher risk of complications compared to group A. A 10.0 MHz linear transducer was used to examine the abdominal wall immediately before exploratory laparotomy and for 10 days (groups B, C) or 30 days (group A) postoperatively. The thickness of the individual layers of the abdominal wall was determined. The skin and the individual muscle layers could be well differentiated via ultrasonography in all the cows preoperatively. In group A, the total thickness of the abdominal wall ranged from 2.80 to 3.40 cm; the skin and the subcutaneous tissues were 0.60 to 0.80 cm, the external abdominal oblique muscle 0.50 to 0.70 cm, the internal abdominal oblique muscle 0.50 to 0.70 cm, the transverse abdominal muscle 0.50 to 0.75 cm, and the transverse fascia and peritoneum were 0.20 to 0.30 cm. Groups B and C had similar findings. There was no significant difference in the course of healing, the thickness of the abdominal wall or thickness of the individual layers during healing among the three groups of cows. Features of healing included subcutaneous emphysema in 19 cows, seroma in 19 and haematoma in 2 cows. However, the occurrence of these events did not differ significantly among the three groups. Ultrasonographic examination of the wound on day 10 postoperatively was unremarkable in 24 cows. A seroma was still present on day 15 postoperatively in one cow of group B.