Surgical Amputation of a Digit and Vacuum-Assisted-Closure (V.A.C.) Management in a Case of Osteomyelitis and Wound Care in an Eastern Black Rhinoceros ( Diceros bicornis michaeli )

CT based 3D reconstruction of the forefoot's blood supply in a white rhinoceros

BACKGROUND

The white rhinoceros (Ceratotherium simum) is close to extinction, listed as "Near Threatened", with a decreasing population on the Red List of Threatened Species of the International Union for Conservation of Nature. In at least 50% of the specimens in captivity, podiatric diseases, such as osteitis, osteomyelitis, chip fractures, enthesophytes, fractures and osteoarthritis were found during necropsy. These osteal deformations cause further pathogenic alterations in the soft tissues, particularly in the digital cushion. The literature provides good description of the skeleton of the rhino's limbs, but similar for the vascular system is non-existent. In order to recognize the symptoms in an early state and for a successful surgical treatment, precise knowledge of the vascular anatomy is essential. The purpose of our study was to provide detailed anatomical description of the blood supply of the digits and that of the digital cushion.

RESULTS

The blood supply of the distal foot, digits and digital cushions were perfectly visible on the reconstructed and coloured 3D models. The deep palmar arch provided not only the blood supply to the digits but had a palmaro-distal running branch which developed a trifurcation proximal to the proximal sesamoid bones of the third digit. Two of its branches participated in the blood supply of the digits' proximal palmar surface, while the major branch supplied the digital cushion from proximal direction.

CONCLUSIONS

Our findings show a unique blood supply: the main vessels of the digital cushion stem both directly from the deep palmar arch and from the digits' own arteries. The detailed description of vessels may be useful in planning surgery of the region and also in cases where the veins of the ear are not accessible.

Phenylbutazone pharmacokinetics in southern white rhinoceros (Ceratotherium simum simum) after oral administration

Southern white rhinoceros (Ceratotherium simum simum) frequently develop painful conditions, such as traumatic injuries or osteoarthritis, necessitating the administration of pain-relieving medications. One of the preferred treatments is the nonsteroidal anti-inflammatory drug phenylbutazone because of the availability of oral formulations and the familiarity of its use in horses. For the main study, a single oral dose of phenylbutazone at 2 mg/kg was administered to healthy adult rhinoceros (n = 33) housed at six North American zoological institutions. Each rhinoceros had up to four blood samples collected under voluntary behavioural restraint at up to four predetermined time points (0, 1, 1.5, 2, 3, 4, 6, 8, 10, 24, 30 and 48 h). Drug analysis was performed by high-performance liquid chromatography. The population pharmacokinetic parameters were calculated with nonlinear mixed-effects modelling, and analysis showed a peak concentration (C_MAX ) of 3.8 µg/ml at 1.8 h and an elimination half-life of 9 h. The concentrations achieved were similar to what has been reported for horses and were within the half maximal effective concentration for horses for at least 10 h. A multi-dose trial in five rhinoceros receiving 2 mg/kg orally once daily for five days found mild accumulation at a predicted factor of 1.2. This study represents the first pharmacokinetic data of phenylbutazone in any rhinoceros species.

RETROSPECTIVE STUDY OF SURGICAL TREATMENT OF REFRACTIVE OSTEOMYELITIS AND INFECTIOUS ARTHRITIS IN THE FLIPPERS OF SEALS IN THE NETHERLANDS

Amputation surgery in pinniped rehabilitation centers is a feasible procedure when animals are presented with open fractures, osteomyelitis, and/or infectious arthritis of the flippers that appear to be refractory to medical treatment. From 2011 to 2017, the Sealcentre Pieterburen in The Netherlands admitted 3,775 seals for rehabilitation. Of these, 37 individuals presented clinical and radiologic signs of bone abnormalities indicative of osteomyelitis or infectious arthritis refractory to medical treatment. Seven cases resulted in euthanasia, and 30 cases underwent amputation surgery. The surgical procedure involved amputation of part of a flipper (24; two animals twice) or of a complete flipper (eight). All procedures were done under general anesthesia except one that was performed with local anesthesia, and all 30 animals were released. In two cases, the osteomyelitis presented with the rare Totenlade phenomenon, a sequestrum surrounded by new periosteal bone formation. The purpose of this retrospective study was to evaluate the outcome of the operative treatment of osteomyelitis and infectious arthritis in the flippers of harbor (Phoca vitulina) and grey seals (Halichoerus grypus) during this 6-yr period.

Technological Advances in Wound Treatment of Exotic Pets

Although most research about the use of technological advances for wound healing was performed in laboratory animals but oriented to human medicine, recent technological advances allowed its application not only to small animals but also to exotic pets. This article reviews the literature available about some of these techniques (negative wound pressure therapy, photobiomodulation [laser therapy], electrical stimulation therapy, therapeutic ultrasonography, hyperbaric oxygen therapy), and other advances in wound management (skin expanders, xenografts, and bioengineered autologous skin substitutes) in exotic pet species.

Foot pressure distribution in White Rhinoceroses (Ceratotherium simum) during walking

White rhinoceroses (Ceratotherium simum) are odd-toed ungulates that belong to the group Perissodactyla. Being second only to elephants in terms of large body mass amongst extant tetrapods, rhinoceroses make fascinating subjects for the study of how large land animals support and move themselves. Rhinoceroses often are kept in captivity for protection from ivory poachers and for educational/touristic purposes, yet a detrimental side effect of captivity can be foot disease (i.e., enthesopathies and osteoarthritis around the phalanges). Foot diseases in large mammals are multifactorial, but locomotor biomechanics (e.g., pressures routinely experienced by the feet) surely can be a contributing factor. However, due to a lack of in vivo experimental data on rhinoceros foot pressures, our knowledge of locomotor performance and its links to foot disease is limited. The overall aim of this study was to characterize peak pressures and center of pressure trajectories in white rhinoceroses during walking. We asked two major questions. First, are peak locomotor pressures the lowest around the fat pad and its lobes (as in the case of elephants)? Second, are peak locomotor pressures concentrated around the areas with the highest reported incidence of pathologies? Our results show a reduction of pressures around the fat pad and its lobes, which is potentially due to the material properties of the fat pad or a tendency to avoid or limit "heel" contact at impact. We also found an even and gradual concentration of foot pressures across all digits, which may be a by-product of the more horizontal foot roll-off during the stance phase. While our exploratory, descriptive sample precluded hypothesis testing, our study provides important new data on rhinoceros locomotion for future studies to build on, and thus impetus for improved implementation in the care of captive/managed rhinoceroses.

Etorphine-Ketamine Constant Rate Infusion for Maintenance of Anaesthesia in a Compromised White Rhinoceros (Ceratotherium simum)

A subadult white rhinoceros bull presented for oesophageal endoscopic evaluation and foreign body removal under general anaesthesia. The animal had a history of nasal and oral regurgitation of water and ingesta with weight-loss for 6 days prior to the procedure and had been diagnosed with oesophageal obstruction caused by a bailing wire. Anaesthesia was induced with intramuscular etorphine and azaperone delivered remotely by dart, followed by an intravenous bolus of ketamine. The trachea was intubated, and anaesthesia was maintained with an etorphine-ketamine constant rate infusion (CRI). The rhinoceros did not respond predictably to induction of anaesthesia and developed life-threatening systemic hypotension throughout the 90-minute procedure. A mega-vertebrate demand ventilator was successfully used to provide intermittent positive pressure ventilation when the rhinoceros developed apnoea. This case report describes the maintenance of anaesthesia of a white rhinoceros using an etorphine-ketamine CRI and the causes and management of hypotension and respiratory impairment observed in this patient.

Lumbar hemilaminectomy for treatment of diskospondylitis in an aardvark (Orycteropus afer)

CASE DESCRIPTION A 17-year-old sexually intact male aardvark (Orycteropus afer) was evaluated because of hind limb proprioception deficits and ataxia. CLINICAL FINDINGS Results of examination and CT suggested a diagnosis of intervertebral disk disease and diskospondylitis at the L2-3 intervertebral space. Magnetic resonance imaging of the vertebral column also indicated intervertebral disk rupture with spinal cord compression and inflammation of the adjacent epaxial musculature TREATMENT AND OUTCOME Hemilaminectomy was performed according to the technique described for dogs. Anatomic variations encountered intraoperatively limited the ability to completely remove the affected disk material; however, adequate decompression of the spinal cord was achieved. Microbial culture and susceptibility testing of surgical biopsy specimens yielded a multidrug-resistant Enterococcus faecalis that was treated with a 10-week course of linezolid. Intensive postoperative care required constant rate infusions for adequate sedation, analgesia, and antimicrobial treatment. Dehiscence of the surgical site occurred 3 weeks after surgery and was treated with negative pressure wound therapy. Physical rehabilitation initiated 5 days after surgery progressed from passive range of motion to the use of an underwater treadmill. Despite initial improvement, acute deterioration occurred 5.5 months after surgery. Repeated CT revealed progression of diskospondylitis, which prompted euthanasia. CLINICAL RELEVANCE Postoperative hind limb paresis and paralysis in this species presented considerable challenges for care and rehabilitation. Patient demeanor, size, and anatomy required development of custom mechanical devices. Despite the inability to eliminate the multidrug-resistant bacterial osteomyelitis that resulted in the death of this aardvark, information gained may benefit treatment of subsequent patients.

Pedicle digital pad transfer and negative pressure wound therapy for reconstruction of the weight-bearing surface after complete digital loss in a dog

A young Labrador Retriever was presented for treatment of severe distal hindlimb necrosis caused by bandage ischemia. During digit amputation at the metatarsophalangeal joints, the third and fourth digital pads were salvaged and transferred to the metatarsal stump to create a weight-bearing surface. Negative pressure wound therapy (NPWT) was utilized for flap immobilization and to promote granulation tissue in the remaining wound defect. Sturdy adherence of the digital pads was achieved after only four days. The skin defect healed completely by second intention and the stump was epithelialized with a thin pad after three months. At the nine month follow-up examination, the stump had a thick hyperkeratinized pad. The dog walked and ran without any apparent signs of discomfort and compensated for the loss of limb length by extending the stifle and tarsocrural joints.

Despite a challenging wound in a difficult anatomical location, digital pad flap transfer and NPWT proved successful in restoring long-term ambulation in an active large breed dog.

Current concepts in negative pressure wound therapy

Negative pressure wound therapy (NPWT) is becoming recognized in veterinary medicine as a viable option for the management of complex wounds. NPWT has many advantages over traditional wound care and results in quicker and improved wound healing in many instances. This article discusses the art and science of NPWT, as well as the many current indications, complications, advantages and disadvantages, and future directions of NPWT in small animal veterinary medicine. This therapy will likely have a growing role in veterinary medical practice for complicated wound management and other usages in coming years.

Radiographic protocol and normal anatomy of the hind feet in the white rhinoceros (Ceratotherium simum)

Foot pathology is a common and important health concern in captive rhinoceroses worldwide, but osteopathologies are rarely diagnosed, partly because of a lack of radiographic protocols. Here, we aimed to develop the first radiographic protocol for rhinoceros feet and describe the radiographic anatomy of the white rhinoceros (Ceratotherium simum) hind foot (pes). Computed tomographic images were obtained of nine cadaver pedes from seven different white rhinoceroses and assessed for pathology. A single foot deemed free of pathology was radiographed using a range of different projections and exposures to determine the best protocol. 3D models were produced from the CT images and were displayed with the real radiographs to describe the normal radiographic anatomy of the white rhinoceros pes. An optimal radiographic projection was determined for each bone in the rhinoceros pes focusing on highlighting areas where pathology has been previously described. The projections deemed to be most useful were D60Pr-PlDiO (digit III), D45Pr45M-PlDiLO (digit II), and D40Pr35L-PlDiLO (digit IV). The primary beam was centered 5-7 cm proximal to the cuticle on the digit of interest. Articular surfaces, ridges, grooves, tubercles, processes and fossae were identified. The radiographic protocol we have developed along with the normal radiographic anatomy we have described will allow for more accessible and effective diagnosis of white rhinoceros foot osteopathologies.

Rhinoceros feet step out of a rule-of-thumb: a wildlife imaging pioneering approach of synchronized computed tomography-digital radiography

Currently, radiography is the only imaging technique used to diagnose bone pathology in wild animals situated under “field conditions”. Nevertheless, while chronic foot disease in captive mega-herbivores is widely reported, foot radiographic imaging is confronted with scarcity of studies. Numerous hindrances lead to such limited numbers and it became very clear that the traditional perspective on bone imaging in domestic animals based on extensive studies and elaborated statistical evaluations cannot be extrapolated to their non-domestic relatives. For these reasons, the authors initiated a multi-modality imaging study and established a pioneering approach of synchronized computed tomography (CT) and digital radiography (DR), based on X-ray projections derived from three-dimensional CT reconstructed images. Whereas this approach can be applied in any clinical field, as a case of outstanding importance and great concern for zoological institutions, we selected foot bone pathologies in captive rhinoceroses to demonstrate the manifold applications of the method. Several advances were achieved, endowing the wildlife clinician with all-important tools: prototype DR exposure protocols and a modus operandi for foot positioning, advancing both traditional projections and, for the first-time, species-related radiographic views; assessment of radiographic diagnostic value for the whole foot and, in premiere, for each autopodial bone; together with additional insights into radiographic appearance of bone anatomy and pathology with a unique, simultaneous CT-DR correlation. Based on its main advantages in availing a wide range of keystone data in wildlife imaging from a limited number of examined subjects and combining advantages of CT as the golden standard method for bone diseases' diagnostic with DR's clinical feasibility under field conditions, synchronized CT-DR presents a new perspective on wildlife's health management. With this we hope to provide veterinary clinicians with concrete imaging techniques and substantial diagnostic tools, which facilitate straightforward attainment and interpretation of field radiography images taken worldwide.

Osteopathology in the feet of rhinoceroses: lesion type and distribution

An estimated 1,170 white (Ceratotherium simum), black (Diceros bicornis), greater one-horned (Rhinoceros unicornis), and Sumatran (Dicerorhinus sumatrensis) rhinoceroses are kept in captivity worldwide, where they are a popular public attraction and serve important roles in education and conservation. Rhinoceroses in captivity are reportedly affected by a variety of foot conditions, including abscesses, nail cracking, and pododermatitis, but there are few studies reporting associated bony pathology in these species. This study aimed to describe osteopathology in rhinoceros feet and identify normal and abnormal osteologic features of rhinoceros feet. The metacarpal-tarsal and phalangeal bones from 81 feet (67 skeletal specimens and 14 cadaveric feet), derived from 27 rhinoceroses of various species, were evaluated in the study (1 black, 11 white, 2 greater one-horned, 3 Javan, 9 Sumatran, and 1 unknown). Bones were examined visually (skeletal specimens) or by computed tomography (cadaver specimens) for evidence of bony lesions. Of the 27 rhinoceroses examined, 22 showed some degree of bone pathology in at least one limb. Six broad categories of pathologic change were identified, with numbers in parentheses representing numbers of rhinoceroses with lesions in at least one limb/number of rhinoceroses examined: enthesopathy (20/27), osteoarthritis (15/27), pathologic bone remodeling (12/27), osteitis-osteomyelitis (3/27), fracture (3/8), and subluxation (3/8). The frequency of pathologic changes in fore- and hind limbs was not significantly different. Most (91%) enthesopathies were observed on the proximal phalanges of the digits, and osteoarthritis was most common in the distal interphalangeal joints of the medial and lateral digits (32 and 26%, respectively). In addition to the pathology described, all examined rhinoceroses also had multiple small surface lucencies in the distal limb bones as an apparently normal anatomic feature. This study is an important first step in identifying both normal and pathologic features of rhinoceros feet and hopefully will thereby contribute to the improved knowledge and care of these species.

Negative pressure wound therapy: experience in 45 dogs

OBJECTIVE

To report experience with negative pressure wound therapy (NPWT) in 45 consecutive dogs admitted with extensive cutaneous wounds and to determine if NPWT is feasible in veterinary hospital practice.

STUDY DESIGN

Prospective descriptive study.

ANIMALS

Dogs (n = 45).

METHODS

Collected data were organized into 6 categories: patient data, wound data, NPWT data, adjunctive treatments, complications, and final outcome.

RESULTS

Wounds (53 in 45 dogs) were largely traumatic in origin, and distributed fairly evenly to the trunk, proximal and distal aspects of the limbs. Most wounds (34 dogs, 76%) had no granulation tissue and were treated a mean of 4.2 days after wounding, whereas 11 dogs had granulating wounds that were initially treated a mean of 87 days after wounding. Median NPWT use was 3 days with a mean hospitalization of 7.8 days. Most wounds (33; 62%) were closed surgically after NPWT and were healed by 14 days. The other 18 wounds healed (mean, 21 days) by second intention after hospital discharge. Overall, 96% of the wounds healed; 2 dogs died before definitive closure could be attempted.

CONCLUSION

NPWT is applicable to a wide variety of canine wounds, is well tolerated, allows for several days between dressing changes, and can used to optimize the wound bed for surgical closure or second intention healing.

One small step for rhinos, one giant leap for wildlife management--imaging diagnosis of bone pathology in distal limb

Chronic foot disease poses a threat to the general health, represents a tremendous clinical challenge, and often is a reason for euthanasia in captive megaherbivores, among them the elephant and rhinoceros. Nevertheless, apart from the elephant, foot pathology is handled as being confined only to soft tissues whereas bone pathology is often overlooked. As a case in point, the authors selected the second largest mammal on land, the rhinoceros. We performed a computed tomographic (CT) study using the highest resolution available in veterinary world, followed by digital radiography of eight distal limbs from two white and one Indian rhinoceroses. Our study demonstrated that bone pathology in rhinoceroses’ foot is present and in large numbers, yet none of these were diagnosed ante mortem. Even when the animals were euthanized due to foot problems, the decision was based on soft tissue pathology rather than orthopedic reasons. Even more worrying is the fact that the largest number of osteopathologies was present in one of the white rhinoceroses that showed no discernable related clinical signs. This study describes for the first time the existence of bone pathology in white rhinoceros foot, in addition to the two previously described rhinoceros species - Indian and black rhinoceroses. Furthermore, the chronic foot disease reported for the Indian rhinoceros in our study was not restricted to soft tissue structures as was presumed ante mortem but included severe bone pathology. New evidence suggesting that osteopathology in rhinoceroses’ distal limb is more widespread than it was thought before could force us to rethink of radiographic diagnosis in captive megaherbivores as routine examination incorporated into their health management. The anticipated improvements in radiologic examinations in megaherbivores will increase the effectiveness of their management and husbandry and open the way for improved animal welfare and better wildlife conservation.

Effects of negative pressure wound therapy on healing of free full-thickness skin grafts in dogs

OBJECTIVE

To compare healing of free, full-thickness, meshed skin grafts under negative pressure wound therapy (NPWT) with bolster dressings in dogs.

STUDY DESIGN

Randomized, controlled experimental study, paired design.

ANIMALS

Dogs (n = 5) METHODS: Full-thickness skin wounds (4 cm × 1.5 cm) were created bilaterally on the antebrachia of 5 dogs (n = 10). Excised skin was grafted to the contralateral limb. Grafts were randomized to NPWT or bolster dressings (control; CON). NPWT was applied continuously for 7 days. Grafts were evaluated on Days 2, 4, 7, 10, 14, and 17, biopsied on days 0, 4, 7, and 14, and had microbial culture on Day 7. Outcome variables were: time to first appearance of granulation tissue, percent graft necrosis, and percent open mesh. Significance was set at P < .05. Histologic findings, culture results, and graft appearance were reported.

RESULTS

Granulation tissue appeared earlier in the NPWT grafts compared with CON grafts. Percent graft necrosis and remaining open mesh area were both greater in CON grafts compared with NPWT grafts at most time points. Histologic results showed no significant difference in all variables measured, and all cultures were negative.

CONCLUSIONS

Variables of graft acceptance were superior when NPWT was used in the first week post-grafting. Fibroplasia was enhanced, open meshes closed more rapidly and less graft necrosis occurred with NPWT application. More preclinical studies are required to evaluate histologic differences.