Caudal Superficial Epigastric Arterial Pedicle Grafts in the Dog

A direct cutaneous arterial pedicle graft (axial pattern flap) was created from the mammary chain including glands 2 through 5 using the caudal superficial epigastric artery and vein in 4 male and 4 female dogs. All grafts survived immediate development and transfer to the recipient site which was either the flank, inner thigh, or lower limb region. A high per cent survivability rate can be expected if precautions are taken. This procedure has special application for reconstruction of extensive flank, inner thigh and inguinal skin losses.     

The Anatomic Basis for a Trapezius Muscle Flap in Dogs

The anatomy of the cervical part of the trapezius muscle and its dominant vascular supply, the prescapular branch of the superficial cervical artery, was studied by dissection and selective angiography of 16 canine cadavers. The prescapular branch of the superficial cervical artery supplies blood to the skin of the caudal half of the neck and the cervical part of the trapezius muscle and is a minor contributor to other muscles of the neck. In these dogs, the mean length of the vascular pedicles was 4.4 cm and the mean diameter was 1.0 mm. With this information, it is possible to design a broad musculocutaneous flap suitable for reconstructive microsurgery in dogs. The potential for successful incorporation of the scapular spine in such a flap remains uncertain.     

Microvascular Free Tissue Transfer of the Rectus Abdominis Muscle in Dogs

OBJECTIVE: To assess donor-site morbidity and survival of the rectus abdominis muscle with an overlying skin graft after free tissue transfer to a medial femorotibial defect in dogs. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Phase 1: 6 canine cadavers; phase 2: 7 adult mixed-breed dogs. METHODS: Phase 1: The rectus abdominis muscle was removed from canine cadavers, muscular and vascular dimensions were recorded, and angiography was performed. Phase 2: Muscular transfer was performed through anastomosis of the caudal epigastric artery and vein to the saphenous artery and medial saphenous vein. Transferred tissues were evaluated on postoperative days 3, 6, 10, and 13. Animals were examined daily until euthanasia between postoperative days 31 and 42. Postmortem angiograms were performed and tissues collected for histopathologic evaluation. RESULTS: Phase 1: Appropriate vascular dimensions for microvascular anastomosis were confirmed and surgical technique perfected. Phase 2: Muscular excision produced minimal donor-site morbidity. All muscles survived after microvascular transfer and angiography confirmed vascular patency. All of the skin grafts survived, with one graft undergoing partial necrosis. CONCLUSIONS: The rectus abdominis muscle can be successfully transferred to a medial femorotibial defect and can serve as a bed for acute skin grafting. No significant donor-site morbidity is associated with its removal. CLINICAL RELEVANCE: Microvascular free tissue transfer of the canine rectus abdominis muscle has not been previously described. This technique provides a new alternative for repair of appropriate wounds. Additional studies are needed to define its utility in clinical patients.     

Radical Lateral Body-Wall Resection for Fibrosarcoma With Reconstruction Using Polypropylene Mesh and a Caudal Superficial Epigastric Axial Pattern Flap: A Prospective Clinical Study of the Technique and Results in 6 Cats

OBJECTIVE: To describe and evaluate a technique for radical resection of the lateral body wall for treatment of fibrosarcoma with reconstruction using polypropylene mesh and a caudal superficial epigastric axial pattern flap in cats. STUDY DESIGN: Prospective, clinical study. ANIMALS OR SAMPLE POPULATION: Six client-owned cats with fibrosarcoma. METHODS: Six cats with histologically confirmed fibrosarcoma of the lateral body wall were staged using radiography and/or computer tomography scanning. Preoperative radiotherapy was used in 3 cats. All cats had the lateral abdominal wall resected and reconstructed with polypropylene mesh. A caudal superficial epigastric flap was mobilized and rotated to close the skin deficit. The animals were evaluated after surgery for wound complications, tumor recurrence, and metastasis. Outcome was assessed by patient examination and client consultation. RESULTS: Minor dehiscence of the skin flaps occurred in 2 cats, and 1 other cat was successfully resuscitated from respiratory and cardiac arrest after surgery. All tissue specimens were tumor-free at the surgical margins. Follow-up times ranged from 12 to 21 months, with a mean time of 17.2 months. None of the cats had evidence of local tumor recurrence or metastasis; outcome was judged good to excellent in all cats. CONCLUSIONS AND CLINICAL RELEVANCE: Radical lateral body-wall resection and reconstruction is an effective technique for achieving local tumor control with acceptable patient morbidity. Further studies are needed to assess whether the technique will result in improved tumor-free intervals and survival times.     

Evaluation of Experimental Transection and Partial Excision of the Caudal Cruciate Ligament in Dogs

The caudal cruciate ligament (CaCL) of one stifle joint in seven dogs was transected and a 2 to 4 mm section was removed. Six months after surgery, none of the dogs were lame. Thigh muscle circumference, stifle range of motion, and internal tibial rotation in the operated limb were not significantly different from the preoperative measurements or the contralateral, unoperated limb. A caudal drawer motion was consistently present in the stifle joints with a transected CaCL. A radiographic evaluation of the operated stifle joints did not reveal osteoarthritic changes; four of seven stifle joints had an irregular fat pad 6 months after surgery. Results of a joint fluid analysis revealed a slight increase in synovial cells within treated stifle joints; inflammatory cells were not observed. The only gross morphologic change in stifle joints with a severed ligament was enlarged knobby remnants of the CaCL. Articular cartilage defects or osteophytes were not observed. Results of a histologic examination of the CaCL remnants revealed synovial cellular capping and intraligamentous fibroplasia. Based on a limited number of dogs, it was concluded that isolated transection of the CaCL produced minimal clinical and pathologic changes in the stifle joint during a 6 month period.     

Evaluation of Fenestration for Treatment of Degenerative Disc Disease in the Caudal Cervical Region of Large Dogs

Seventeen large dogs (15 Doberman pinschers, one Labrador retriever, and one German short-haired pointer) with pain and gait abnormalities resulting from caudal cervical intervertebral disc degeneration were treated by disc fenestration. Four dogs recovered completely, two dogs appeared to have recovered but nerve root compression and pain returned 3 years later, five did not recover completely or did not improve, and six became progressively worse. In the dogs that recovered, preoperative myelograms showed that traction on or flexing the neck relieved the spinal cord compression. Such manipulation did not relieve slight persistent compression in the dogs that did not improve nor did it relieve severe compression by disc herniation or spinal canal stenosis in the dogs that became progressively worse. The return of nerve root compression after 3 years in two dogs was attributed to incomplete removal of dorsal anulus fibrosus. It was concluded that disc fenestration alone provided inadequate treatment of caudal cervical degenerative disc disease in large dogs.     

Evaluation of a Transcondylar Toggle System for Stabilization of the Cranial Cruciate Deficient Stifle in Small Dogs and Cats

Objective— To evaluate use of a transcondylar toggle system (TCTS) for stabilization of the cranial cruciate ligament (CrCL) deficient stifle in small dogs and cats. Study Design— Prospective clinical study. Animals— Small dogs (<7 kg; n=14) and cats (2) with CrCL‐associated lameness of <3 months duration and a tibial plateau angle <32°. Methods— Affected animals had an extracapsular CrCL repair using the TCTS. Lameness score, muscle atrophy, osteoarthritis (OA) score, and range of motion (ROM) were evaluated preoperatively, and at 6 weeks and 7–10 months postoperatively. Results— Operative time was 75 ± 16 minutes. Fifty‐six percent required >1 bone tunnel attempts. One dog required revision at 2 weeks because of suture loosening. All stifles were stable at 6 weeks postoperatively. Fifteen animals were available for follow‐up (7–10 months). Lameness improved significantly at 6 weeks (P<.0001), whereas muscle atrophy was worse at 6 weeks (P=.008) but improved at 7–10 months (P<.0001). OA scores were unchanged at 6 weeks (P=.08) but were significantly worse at 7–10 months (P<.0001). ROM remained unchanged at 6 weeks (P=1) and 7–10 months (P=.6). Conclusions— The medially placed toggle provides a reliable short‐term proximal anchor for the extracapsular suture with outcomes similar to other extracapsular techniques. The aiming device and drill bit are not recommended in their current form. Clinical Relevance— The TCTS appears to be a well‐tolerated technique for proximal suture anchoring in extracapsular CrCL repair in small dogs and cats where instrumentation and anatomic constraints preclude other techniques.     

Evaluation of Fibular Head Transposition for Repair of Experimental Cranial Cruciate Ligament Injury in Dogs

Unilateral cranial cruciate ligament excision and fibular head transposition (FHT) were performed on 30 adult dogs. Vertical ground reaction forces were determined using force plate data before and after surgery. Cranial drawer motion, tibial rotation, and varus-valgus motion were measured at monthly intervals. Radiographic, gross, and histological examinations of the stifle joints that had been operated on were performed 3 weeks, 4 months, and 10 months after surgery. A scoring system was used to evaluate lameness, osteophyte formation, and meniscal damage. Rank correlation coefficients were calculated between variables tested in pairs. Cranial drawer motion and abnormal tibial rotation were present in all of the joints that had been operated on. Peak vertical force and associated impulse were not restored during the study time period. Meniscal damage was noted in 25% of the dogs at month 4 and in 50% of the dogs at month 10. Progressive gross and histological deterioration of the articular cartilage was observed in all joints. Positive correlations were noted between the degree of stifle joint instability and meniscal injury or radiographic changes. FHT did not control cranial drawer motion and rotational instability, was not successful in restoring limb function, and did not prevent joint degeneration, especially meniscal damage.     

Superficial Osteitis and Sequestrum Formation as a Result of Skin Avulsion in the Horse

Metatarsal injuries with exposed bone are described in seven horses. Superficial osteitis and sequestrum formation occurred in six of the seven horses. The basic pathophysiology includes local vascular stasis leading to ischemic necrosis of osteocytes and establishment of bacterial infection within dead bone. Radiographic features of superficial osteitis and sequestrum formation include reactive periosteal new bone formation, an area of radiodense necrotic bone (sequestrum) surrounded by a radiolucent zone of granulation tissue, which in turn, is surrounded by an area of increased radiodensity (involucrum). The presence of a sequestrum may usually be confirmed radiographically by 12–14 days after injury. Surgical management included wound debridement, wound irrigation, bandaging or casting, sequestrectomy and skin grafting. Five of the seven patients required sequestrectomy, in one the sequestrum disappeared without removal. Mixed bacterial populations were commonly found in the wounds. No specific etiologic agent was associated with sequestrum formation.     

Xylenol Orange as a Vital Stain to Determine the Viability of Skin Flaps in Dogs

Intravenous injection of xylenol orange results in generalized violet staining of vascularized skin. The precision of xylenol orange vital staining was compared to fluorescein sodium vital staining and to assessment of skin flap viability by visual observation (color). Skin flaps in the experimental dogs were evaluated by each method at 0, 24, 72, and 120 hours after surgery and subsequently compared to the length of skin flap that remained viable at 216 hours. No significant differences between methods were found at any time interval; however, assessment of skin flap viability was significantly more precise at 24,72, and 120 hours in comparison to the 0 hour assessments. The use of xylenol orange to assess vascular integrity of skin is precise, but no advantage over fluorescein sodium vital staining or assessment by visual observation was noted.     

Axial Pattern Flap Based on the Cutaneous Branch of the Superficial Temporal Artery in Dogs: An Experimental Study and Case Report

OBJECTIVE: To determine the anatomic guidelines and viability of an axial pattern flap based on the cutaneous branch of the superficial temporal artery (STA) in dogs. Application of the flap in a clinical patient is reported. STUDY DESIGN: Flap viability in control and experimental groups was determined 7 days postoperatively. ANIMALS: A total of 14 mature, mesaticephalic dogs; 1 clinical patient. METHODS: The cutaneous branch of the STA and vein were incorporated in the flaps of the experimental groups (group A, n = 5; group B, n = 4) and were ligated in the control group (n = 5). Flap length was extended in experimental group B. Seven days postoperatively, the length and area of tissue that remained viable in each flap was determined and compared with similar measurements performed intraoperatively. Cutaneous fluorescence was also used postoperatively to assess flap perfusion. The flap used in the clinical patient had the same dimensions as flaps developed in group A. RESULTS: Mean survival length (+/- SD) of STA flaps [group A, 9.1 (0.8) cm], was significantly increased (P < .05) compared with control flaps [7.0 (0.6) cm]. Percentage flap length survival (+/- SD) of STA flaps [group A, 91.8 (8.9)%], was significantly increased (P < .05) compared with control flaps [71.6 (7.0)%]. Mean percentage area of survival (+/- SD) of STA flaps [group A, 93.1 (7.5)%], was significantly increased (P < .05) compared with control flaps [73.5 (7.4)%]. Group B flaps had a mean survival length of 10.4 (1.1) cm, percentage flap length survival of 69.5 (4.8)%, and mean percentage area of survival of 69.1 (6.5)%. There was no positive correlation between the area of flap fluorescence at days 0, 1, and 3, and the area of flap survival. Application of the flap in a clinical patient allowed primary wound reconstruction with 100% survival. CONCLUSION: A flap based on the cutaneous branch of the STA may be a source of skin for reconstructive procedures of the maxillofacial region in dogs. CLINICAL RELEVANCE: Knowledge of the anatomic landmarks and expected viability of a STA axial pattern flap is essential before consideration of its use as a reconstructive surgical technique.     

The Intraosseous Blood Supply of the Canine Radius: Implications for Healing of Distal Fractures in Small Dogs

The intraosseous vascular anatomy of the radius was studied in 12 pairs of canine cadaver limbs. Six pairs of specimens were obtained from small-breed dogs (less than 6 kg) and six pairs were obtained from large-breed dogs (18 to 30 kg). All specimens were studied after arterial injection with India ink. Samples were fixed, frozen, then sectioned and processed using a modified Spalteholz technique. In all specimens, the intraosseous blood supply arose from the nutrient artery with its associated branches and the metaphyseal arteries. In small-breed dogs, there was decreased vascular density at the distal diaphyseal-metaphyseal junction compared with large-breed dogs. The reduced vascularity corresponded to the region associated with a poor prognosis for fracture healing in small-breed dogs. This regional association suggests that a decreased vascular supply in the distal radius may contribute to a higher frequency of delayed union and nonunion in smaller dogs.     

Peripheral Nucleated Red Blood Cells as a Prognostic Indicator in Heatstroke in Dogs

Background: Heatstroke in dogs is often fatal and is associated with a high prevalence of secondary complications. Peripheral nucleated red blood cells (NRBC) occur in dogs with heatstroke, but their association with complications and the outcome is unclear.
Hypothesis: Peripheral NRBC are common in dogs with heatstroke and have prognostic significance.
Animals: Forty client-owned dogs with naturally occurring heatstroke.
Methods: Prospective, observational study. Dogs were followed from presentation to discharge or death. Serum biochemistry and coagulation tests were performed at presentation. CBC and evaluation of peripheral blood smears were performed at presentation and every 12 hours. The relative and the absolute NRBC numbers were calculated.
Results: Presence of NRBC was observed in 36/40 (90%) of the dogs at presentation. Median relative and absolute NRBC were 24 cells/100 leukocytes (range 0–124) and 1.48 × 10³/μL (range 0.0–19.6 × 10³/μL), respectively. Both were significantly higher in nonsurvivors (22) versus survivors (18) and in dogs with secondary renal failure and DIC versus those without these complications. Receiver operator curve analysis of relative NRBC at presentation as a predictor of death had an area under curve of 0.92. A cut-off point of 18 NRBC/100 leukocytes corresponded to a sensitivity and specificity of 91 and 88% for death.
Conclusions and Clinical Importance: Relative and absolute numbers of peripheral NRBC are clinically useful, correlate with the secondary complications, and are sensitive and specific markers of death in dogs with heatstroke, although they should never be used as a sole prognostic indicator nor should they replace clinical assessment.     

Evaluation of Iron Deficiency Using Reticulocyte Indices in Dogs Enrolled in a Blood Donor Program

Background

People donating blood more than twice annually are at risk of developing iron deficiency. Little is known about the iron status of dogs enrolled in blood donor programs.

Hypothesis

Dogs donating blood ≥6 times annually will show evidence of iron deficiency based on their reticulocyte indices.

Animals

Thirteen dogs enrolled in a blood donor program donating ≥6 times over the preceding 12 months and 20 healthy nondonor control dogs.

Methods

Prospective observational study. Mature red blood cell (RBC) indices, reticulocyte indices, serum iron, serum ferritin, and total iron‐binding capacity (TIBC) were compared between groups.

Results

Packed cell volume (median 47%, range 40–52%, P < .01), hematocrit (median 46.4%, range 40.3–52.5%, P < .01), and reticulocyte count (median 16,000/μL, range 9,000–38,000/μL, P < .01) were significantly lower in the blood donor dogs. No statistically significant differences were noted in the mature RBC indices between groups. Both reticulocyte mean corpuscular volume (median 88.8 fL, range 83.4–95.5 fL, P = .03) and reticulocyte hemoglobin content (median 24.6 pg, range 23.1–26.6 pg, P < .01) were significantly lower in the blood donor group. Serum iron and ferritin were similar between groups; however, TIBC was significantly higher in the control group (median 403 μg/dL, range 225–493 μg/dL, P = .02).

Conclusions

The findings in dogs donating ≥6 times annually suggest the presence of iron‐deficient erythropoiesis in this population.     

Clinical Results Following Nonoperative Management for Rupture of the Cranial Cruciate Ligament in Dogs

Eighty-five dogs were diagnosed as having rupture of the cranial cruciate ligament. They were managed by restriction of activity to leash walks for 3 to 6 weeks, weight loss if indicated, and analgesic medication as needed. Twenty-four of 28 dogs that had a body weight of 15 kg or less (85.7%) were considered to be clinically normal (no lameness and normal range of motion in stifle, 21 dogs) or improved (3 dogs) after an average follow-up period of 36.6 months. Lameness in the remaining four dogs persisted or worsened over an average period of 8.2 months (minimum 6 months), and surgical replacement of the cruciate ligament was performed. Eleven of 57 dogs that had a body weight of 15 kg or greater (19.3%) were classified as normal (4 dogs) or improved (7 dogs) after an average follow-up period of 49.1 months. Lameness in the remaining 46 dogs persisted or worsened over an average period of 10.2 months (minimum 6 months), and surgical replacement of the cruciate ligament was performed.     

Evaluation of a Urine Cortisol:Creatinine Ratio as a Screening Test for Hyperadrenocorticism in Dogs

The authors collected urine specimens in 31 normal dogs, 25 dogs with hyperadrenocorticism, 21 dogs in which hyperadrenocorticism was suspected but was not present, and 28 dogs with a variety of severe, nonadrenal diseases. Cortisol and creatinine were measured in unextracted urine by radioimmunoassay and spectrophotometry, respectively, and the cortisol:creatinine ratio was calculated for each specimen. The mean ± SD urine cortisol:creatinine concentration ratio in the dogs with hyperadrenocorticism (103.1 ± 100.7) was significantly (P < 0.001) higher than that in the normal dogs (13.1 ± 7.0). The mean urine cortisohcreatinine ratio in dogs initially suspected of having hyperadrenocorticism (16.3 ± 7.0) was significantly (P < 0.001) lower than the ratio in dogs with hyperadrenocorticism, but was not significantly different than that in the normal dogs. The mean urinary cortisohcreatinine ratio in the dogs with nonadrenal disease (82.8 ± 97.7) was significantly (P < 0.001) higher than that in both the normal dogs and dogs in which hyperadrenocorticism was initially suspected, but was not different than the ratio in the dogs with hyperadrenocorticism. The sensitivity of the urine cortisohcreatinine ratio as a diagnostic test for hyperadrenocorticism was 0.92. The specificity was high in the normal dogs (0.97) and the dogs initially suspected of having hyperadrenocorticism (0.95), with ≤ 5% having false-positive results. However, the specificity was very low (0.21) in the dogs with moderate to severe nonadrenal disease, with 79% having false-positive results. Similarly, both positive and negative predictive values and diagnostic efficiency were high in the normal dogs and dogs suspected of having hyperadrenocorticism but were low in the dogs with nonadrenal illness. When the results of the cortisol assay used in the study were compared to results obtained by two other commercially available cortisol radioimmunoassays, a high correlation between results was found. The urine cortisohcreatinine ratio is a sensitive screening test for the detection of hyperadrenocorticism in dogs. As with other pituitary-adrenal function tests, however, the urine cortisohcreatinine ratio cannot be used to diagnose hyperadrenocorticism in dogs that have moderate to severe nonadrenal disease.