Hematopoietic chimerism induces renal and skin allograft tolerance in DLA-identical dogs.

OBJECTIVE: Hematopoietic chimerism, a state where donor and recipient bone marrow cells coexist, is associated with donor-specific tolerance. Nonmyeloablative bone marrow transplantation (BMT) has been shown to induce stable mixed hematopoietic chimerism in dog leukocyte antigen (DLA)-matched dogs. The potential for inducing renal and skin allograft tolerance with nonmyeloablative BMT was investigated in DLA-identical and DLA-haploidentical dogs in this study. MATERIALS AND METHODS: Renal allografts were performed in 8 DLA-identical and 4 DLA-haploidentical dogs with nonmyeloablative conditioning (200 cGy TBI) and transient immunosuppression with cyclosporine (CSP) and mycophenolate mofetil (MMF) with (n = 8) and without (n = 4) simultaneous BMT. Skin allografts were performed in 2 DLA-identical and 4 DLA-haploidentical dogs after stopping CSP and MMF. Two DLA-identical control dogs received renal allografts without TBI, BMT, or immunosuppression with CSP and MMF. Molecular chimerism was determined with a PCR-based DNA microsatellite assay. Serum creatinine (Cr) concentration, urine specific gravity, and sequential renal biopsies were monitored to assess renal allograft function. RESULTS: Donor-type blood cells were first detected 4 weeks posttransplantation in both the myeloid and lymphoid lineages. Donor chimerism was present for at least 76 weeks in the DLA-identical dogs. Mixed chimerism was not observed in the DLA-haploidentical dogs or DLA-identical dogs that did not undergo BMT. The renal allografts were acutely rejected within 14 days in the 2 DLA-identical control dogs. There was long-term (> 5 yrs) renal allograft survival as evidenced by a normal (< 2.0 mg/dL) serum Cr concentration in both the DLA-identical and DLA-haploidentical dogs that underwent 200 cGy TBI and transient immunosuppression with CSP and MMF either with or without simultaneous BMT. Renal allograft inflammation was severe in the control dogs, mild to moderate in the DLA-haploidentical dogs, and minimal in the DLA-identical dogs. Donor-specific skin grafts were accepted in the DLA-identical dogs but rejected in the DLA-haploidentical dogs. Nonmyeloablative conditioning (200 cGy TBI) and transient immunosuppression with CSP and MMF induce renal and skin allograft tolerance in DLA-identical and permit long-term renal allograft survival in DLA-haploidentical dogs. These findings suggest it may possible to obtain long-term allograft survival in DLA-identical and -haploidentical dogs without the need for chronic immunosuppressive therapy.

Management of hard-to-heal wounds.

Some wounds do not heal normally and present the practitioner with a challenge. These can be thought of as hard-to-heal wounds. There are numerous causes of such wounds, and when they occur, the veterinarian should consider all factors associated with the wound. When diagnostic tests are indicated, they should be performed. Finally, appropriate measures should be taken to correct the underlying cause of the hard-to-heal wound.

Comparison of the role of the subcutaneous tissues in cutaneous wound healing in the dog and cat.

OBJECTIVE: To describe and compare the contribution of the subcutaneous tissues to 1st and 2nd intention cutaneous wound healing in the dog and cat. STUDY DESIGN: Experimental study. ANIMALS: Domestic shorthaired cats (n=6) and 6 beagle dogs. METHODS: Paired wounds were created on either side of the dorsal midline; the subcutaneous tissue was removed on 1 side and left intact on the other. Square, open wounds of the dorsal aspect of the thorax were observed for 21 days to monitor granulation tissue formation, wound contraction, epithelialization, and total healing (contraction+epithelialization). Breaking strength of sutured linear wounds was measured 7 days after wounding. Laser-Doppler perfusion imaging (LDPI) was used to measure cutaneous perfusion. RESULTS: First intention healing: subcutaneous tissue removal had no consistent effect on sutured wound strength at 7 days in dogs or cats. Second intention healing: removal of subcutaneous tissue reduced wound perfusion, granulation, contraction, epithelialization, and total healing. Granulation tissue formation and wound contraction were delayed to a significantly greater degree in cats than in dogs (P<.05). Two dogs (33%) had minor wound infections. CONCLUSIONS: The subcutaneous tissues make an important contribution to 2nd intention cutaneous healing. Dog and cat wounds had delayed 2nd intention healing when subcutaneous tissues were removed; wounds in dogs, but not cats, had largely recovered from this delay by 21 days. CLINICAL RELEVANCE: Extensive debridement of subcutaneous tissue may delay wound healing particularly in feline patients. A higher risk for wound infections may accompany extensive removal of subcutaneous tissues in dogs.

Bioelastic membranes for topical application of a thromboxane synthetase inhibitor for protection of skin from pressure injury: a preliminary study.

A previous study showed that topical exposure to bioelastic-thromboxane synthetase inhibitor-matrix resulted in local tissue concentrations of thromboxane synthetase inhibitor sufficient for thromboxane synthetase inhibition. The objective of this research was to use an animal model to determine if a dressing having controlled release of thromboxane synthetase inhibitor (dazmegrel) could be used to prevent tissue breakdown over pressure points, i.e., lesion at the assistive device-skin interface. The animal model studies utilized the greyhound, a dog that has thin skin, angular conformation, limited body fat and is predisposed to pressure ulcers similar to those occurring in humans. The model uses a short-limb walking cast on one pelvic limb with the severity of the dermal pressure lesions induced over the medial malleolus controlled by the amount of padding in the cast and length of time the cast is in place. The bioelastic matrix loaded with dazmegrel provided protection from shearing and pressure skin injury over the medial malleolus, as evidenced by a decrease in epidermal abrasion/ulceration as measured with planimetry. Histopathologic evaluation of the skin over the medial malleolus indicated a protective function of the bioelastic matrix as measured as lower numbers of neutrophils, lymphocytes, and decreased collagen density compared to such numbers when no bioelastic matrix was present. These studies provided evidence that bioelastic-thromboxane sythetase inhibitor- matrix helps in preventing or reducing the severity of pressure lesions, e.g., assistive device-skin interface wounds.

In vitro skin penetration of dazmegrel delivered with a bioelastic matrix.

The penetration of dazmegrel, a selective thromboxane synthetase inhibitor, through excised human and greyhound skin was measured. A bioelastic matrix was used for topical delivery. Results demonstrated that dazmegrel readily penetrated the skin. Penetration through greyhound skin was significantly greater than penetration through human skin. Penetration through greyhound skin was not significantly different between 4, 24, and 48 h of exposure for the low and intermediate doses studied.

Effects of 3 biologic dressings on healing of cutaneous wounds on the limbs of horses.

Three biologic dressings [split-thickness allogeneic skin (STS)], allogeneic peritoneum (P), and xenogenic porcine small intestinal submucosa (PSIS)] were studied to determine their effects on bacterial proliferation, inflammatory reaction, vascularization, and overall healing and to compare the effects of these dressings with the effects of a nonbiologic dressing, a nonadherent synthetic pad (NASP). A medial wound (3 cm in diameter) and 2 lateral wounds (2 cm in diameter) were created at the junction of the proximal and middle thirds of each metacarpus and metatarsus in 5 horses. Each medial wound and the proximolateral wound received an STS, P, PSIS, or NASP dressing on day 8 after wounding. The other lateral wound received an NASP dressing. Bacterial proliferation, inflammatory reaction (histologic changes), and drhessing vascularization were evaluated 6 d after application of the dressing. Percentages of contraction and epithelialization, as well as healing time, were determined when the wounds had completely epithelialized. The practical applicability of the different dressings to equine wound management was also assessed. No significant difference was detected in the parameters evaluated among the treated wounds or between the treated and control wounds. The biologic dressings had no effect on infection, inflammatory response, or healing time. Vascularization was not identified in any of the biologic dressings. The PSIS and P dressings required numerous applications over the study period. The STS dressings are more practical than PSIS and P dressings owing to ease of application and stability. Thus, these biologic dressings offer no apparent advantage over a nonbiologic dressing for treatment of small granulating wounds.

Cutaneous wound healing in the cat: a macroscopic description and comparison with cutaneous wound healing in the dog.

OBJECTIVE: To describe the macroscopic features of first and second intention cutaneous wound healing in the cat and compare with the dog. STUDY DESIGN: Experimental study. ANIMALS: Domestic shorthaired cats (6) and beagle dogs (6). METHODS: Square, open cutaneous wounds created on the dorsal aspect of the thorax were evaluated for 21 days for temporal and spatial development of granulation tissue, wound contraction, epithelialization, and total healing. To evaluate first intention healing, breaking strength of sutured linear cutaneous wounds was measured at 7 days post-wounding. Laser-Doppler perfusion imaging was used to measure cutaneous perfusion. RESULTS: First intention healing: sutured wounds in cats were only half as strong as those in dogs at day 7 (0.406 versus 0.818 kg breaking strength). Second intention healing: cats produced significantly less granulation tissue than dogs, with a peripheral, rather than central distribution. Wound epithelialization and total wound healing (total reduction in open wound area from contraction and epithelialization) were greater for dogs than for cats over 21 days. Wound contraction on day 7 was greater for dogs, but not on day 14 or 21. Cutaneous perfusion was initially greater for dogs than for cats, but no differences were detected after day 7. CONCLUSIONS: Significant, previously unreported differences in cutaneous wound healing exist between cats and dogs. In general, cutaneous wounds in cats are slower to heal. Cats and dogs also appear to use different mechanisms of second intention healing. In cats wounds close mainly by contraction of the wound edges, whereas in dogs wounds close more from central pull, and epithelialization. CLINICAL RELEVANCE: Surgeons should view the cat as a unique species, which presents its own special challenges in wound healing, and should take this into account when planning treatment of feline wounds, either by primary closure, or by second intention healing.

The effect of topical tripeptide-copper complex on healing of ischemic open wounds.

OBJECTIVE: To evaluate the effects of topical glycyl-L-histidyl-L-lysine tripeptide-copper complex (TCC; Iamin 2% Gel; Procyte Corporation, Redmond, WA) on healing in ischemic open wounds. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Twenty-four adult male Sprague-Dawley rats. METHODS: Rats were divided into 3 groups: topical TCC, topical TCC vehicle (hydroxypropyl-methylcellulose), and no treatment (control). Six-mm-diameter, full-thickness wounds were created within an ischemic bipedicle skin flap on the dorsum of each rat. Each day, for 13 days, wound margins were traced, and the TCC and TCC vehicle groups were treated topically. Tracings were scanned, and wound perimeter and area were calculated. On days 6, 10, and 13, selected wounds were biopsied and analyzed for tumor necrosis factor alpha (TNF-alpha) and matrix metalloproteinases (MMP) 2 and 9. RESULTS: A significant decrease in wound area was seen in the TCC group, but not the vehicle group, when compared with the control group on days 3 to 5, 6 to 9, and 11 to 13 and when TCC was compared with TCC vehicle on days 3 and 9. On day 13, initial wound area had decreased by 64.5% in the TCC group, 45.6% in the vehicle group, and 28.2% in the control group. On days 6, 10, and 13, TCC-treated wounds contained significantly lower concentrations of TNF-alpha and MMP-2 and MMP-9 than control wounds. CONCLUSION: Topical TCC resulted in accelerated wound healing in ischemic open wounds. CLINICAL RELEVANCE: Topical TCC is an effective stimulant of healing of ischemic open wounds in rats and may have an application for the treatment of chronic wounds in other species. Clinical evaluation of topical TCC is warranted.

Nasal and facial reconstruction in a dog following severe trauma.

Successful reconstruction of the nasomaxillary region requires closure of oronasal communication and maintenance of a patent upper airway. A dog with traumatic amputation of the nasomaxillary region was presented for reconstructive surgery. Staged surgical procedures were performed with the goal of closing the oronasal fistula, reapposing facial tissues, forming a granulation bed in each nasal passage, and harvesting and placing mucosal grafts in the nasal passages. A novel technique for developing a granulation tissue bed for mucosal grafts using silicone rubber tubing was employed. The end result of the reconstructive surgeries was a relatively cosmetic appearance with patent nasal openings.

Effects of bandage configuration on paw pad pressure in dogs: a preliminary study.

Seven bandage configurations were placed on the right forepaw of six English pointer dogs to evaluate the effects that configurations have on reducing pad pressure. The "clam shell" configuration resulted in less pressure being applied to all palmar pad surfaces. For the major weight-bearing pad, a basic paw bandage with an intermediate compressible foam sponge that had a hole under the major weight-bearing pad, combined with a metal splint paw cup under the sponge, resulted in a significantly lower pressure recording than for other bandage configurations. Digital pads 3 and 5 had the greatest pressure in a basic bandage configuration. Based on pressures on these pads, a basic paw bandage with an intermediate compressible foam sponge under the major weight-bearing pad, with or without a metal splint paw cup under the sponge, helped elevate the digits to relieve pressure on them. Placing a foam sponge pad, with or without a splint paw cup under the palmar paw surface, also provided less pressure on these pads.

The effect of a porcine-derived small intestinal submucosa product on wounds with exposed bone in dogs.

OBJECTIVE: To determine the effect of a porcine-derived small intestinal submucosa product (PSIS) on healing time, epithelialization, angiogenesis, contraction, and inflammation of wounds with exposed bone on the distal aspect of the limbs of dogs. STUDY DESIGN: Prospective, controlled, experimental study. ANIMAL POPULATION: 10 young adult, purpose-bred, male Beagles. METHODS: Small wounds with exposed bone were created on the lateral aspect of metatarsal V and the medial aspect of metatarsal II on both hindlimbs. Three sheets of PSIS were sutured into the wounds of the treated limb, and the other limb served as a control. On day 10, punch biopsies of the medial metatarsal wounds were collected and were evaluated microscopically after routine hematoxylin and eosin and phosphotungstic acid hematoxylin (PTAH) staining. The lateral metatarsal wounds were evaluated by planimetry and laser Doppler perfusion imaging on days 7, 14, and 21. Time until complete wound healing was also recorded. The level of significance was set at P < or =.05 for all statistical analyses. RESULTS: Laser Doppler perfusion measurements were significantly higher in control wounds on day 7, but no differences were noted on days 14 and 21. No significant differences in planimetric values, histopathologic appearance, or time until complete wound healing were noted among treated and control groups. CONCLUSIONS: No objective differences in healing were noted between control wounds and wounds treated with PSIS. CLINICAL RELEVANCE: There appears to be no contraindication to the use of PSIS on clean wounds with exposed bone on the distal limbs of dogs. However, our objective data provides no evidence that this product affects epithelialization, contraction, or time to complete healing in wounds with exposed bone.

Advances in wound healing in small animal practice: current status and lines of development.

Abstract In the past 5 years advances in the management of wounds in dogs and cats have included the development of materials and techniques used to enhance the healing of both open and closed wounds. New topical and locally injected medications as well as new bandaging materials have been evaluated. The use of omental flaps to enhance wound healing has been found to be promising. Ultrasonography has been found useful in assessing wound tissues to guide treatment. Because tension is a major factor in dealing with wound closure, skin expanders, skin stretchers, presutures and adjustable horizontal mattress sutures have been described as means of overcoming tension. Recently completed research projects at the Scott-Ritchey Research Center studied the woundhealing effects of fibrin sealants, topical bovine collagen, omega-3 fatty acid-enriched diets and magnetic field therapy. Projects underway are evaluating the healing effects of a new biological tissue adhesive, a macrophage stimulant and a thromboxane synthestase inhibitor. Parameters for evaluating wound healing have included histopathology, tensiometry, planimetry, laser Doppler image scanning, biochemistry and immunohistochemistry. Resumen En los últimos 5 años, algunos de los avances en la curación de heridas en perros y gatos ha incluido el desarrollo de materiales y técnicas utilizados para mejorar la curación tanto de heridas cerradas como abiertas. Se han evaluado nuevas medicaciones tópicas y sistémicas asi como nuevos marteriales de vendaje. El us0 de injertos omentales para estimular la curación de heridas ha mostrado resultados prometedores. La ecografia es un método éutil en la valoración de los tejidos lesionados para guiar el tratamiento. Debido a que la tensión es un factor importante en el caso de cerramiento de heridas, se describen como métodos de evitar la tensión productos como expansores cutáneos, estiradores cutáneos, presuturas y suturas cutáneas horizontales acolchonadas ajustables. Algunos proyectos de investigación recientemente finalizados en el Centro de Investigación Scott-Ritchey estudiaron los efectos sobre la curación de heridas de selladores de fibrina, colágeno tópico bovino, dietas enriquecidas con ácido graso omega-3 y terapia de campo magnético. Otros proyectos en realización están evaluando los efectos curativos de un nuevo adhesivo tisular biológico, un estimulante de macrófagos y un inhibidor de la tromboxano-sintetasa. Los parámetros para evaluar la curación de herida han incluido la histopatología, la tensiometría, la planimetría, el scanner por imágen doppler laser, bioquímica e inmunohistoquímica. [Swaim, S.F. Advances in wound healing in small animal practice: current status and lines of development (Avances en la curcion de heridas en pequeños animales: estado actual y lineas de desarrollo). Veterinary Dermatology 1997; 8: 249-257] Zusammenfassung In den letzten 5 Jahren wurden Fortschritte in der Wundversorgung bei Hund und Katze unter anderem durch die Entwicklung von Materialien und Techniken erzielt, die zur besseren Heilung von offenen und geschlossenen Wunden verwendet werden. Neue lokale und systemische Medikamente sowie neue Verbandsmaterialien wurden untersucht. Die Verwendung von Omentumlappen zur Verbesserung der Wundheilung scheint vielversprechend zu sein. Ultraschalluntersuchungen waren von Nutzen, um Wundgewebe zu beurteilen und die Behandlung zu lenken. Spannung ist ein wesentlicher Faktor im Wundverschluss, Hautexpander, Hautdehner, vorbereitende Nähte und regulierbare, horizontale Matratzennähte wurden zur Überwindung der Wundspannung beschrieben. Kürzlich fertiggestellte Forschungsprojekte am Scott-Ritchie Research Center erforschten die Effekte von Fibrindichtungsmitteln, lokalem bovinen Kollagen, Futtermitteln mit Omega-3 Fettsäurenzusatz und Magnetfeldtherapie. Gegenwärtige Forschungsprojekte bewerten die Heilungseffekte eines neuen, biologischen Gewebehaftmittels, eines Makrophagenstimulans und eines Thromboxansynthetasehemmers. Parameter zur Bewertung der Wundheilung waren Histopathologie, Tensiometrie, Planimetrie, Laser Doppler, physiologische Chemie und Immunhistochemie. [Swaim, S.F. Advances in wound healing in small animal practice: current status and lines of development (Fortschritte bei der Wundheilung in der Kleintierpraxis: Derzeitiger Stand und Entwicklung). Veterinary Dermatology 1997; 8: 249-257] Résumé Durant les 5 dernières années, le progrés dans le traitement des plaies chez les chiens et les chats ont inclus le développement de matériaux et de techniques utilisés pour augmenter la cicatrisation des plaies ouvertes et fermées. De nouvelles médications topiques et systémiques ainsi que de nouveaux matériaux de bandages ont étéévalués. L'utilisation de lambeaux d'éplipon s'est révélée prometteuse dans l'amélioration de la cicatrisation des plaies. L'ultrasonographie s'est montrée utile dans le traitement de guidance de l'évaluation des plaies tissulaires. La tension étant un facteur major lors de la fermeture de plaies, expansseurs cutanés, étireurs cutanés et surjets de matelassier ajustables ont tous été décrits comme moyens permettant de vaincre la tension. Récemment des projets de recherche achevés au Scott-Ritchey Research Center ont étudiés les effets des joints de fibrine, du collagène bovin topique, des régimes enrichis en acides gras omega-3 et de la thérapies de champs magnétiques sur la cicatrisation des plaies. Les projets mis en route sont l'évaluation des effets sur la cicatrisation d'un nouvel adhésif tissulaire biologique, d'un stimulant de macrophages et d'un nouvel inhibiteur de la thromboxane synthase. Les paramètres intervenant dans l'évaluation de la cicatrisation des plaies ont inclus l'histopathologie, la tensiométrie, la planimétrie, le laser Doppler, l'imagerie, la biochimie et l'immunohistochimie. [Swaim, S.F. Advances in wound healing in small animal practice: current status and lines of development (Progres de la cicatrisation en pratique des petits animaux: etat actuel et lignes de developpement). Veterinary Dermatology 1997; 8: 249-257].

Biochemical and histopathological evaluation of changes in sled dog paw skin associated with physical stress and cold temperatures.

Abstract Twenty-six Alaskan sled dogs were used to study the biochemical and histopathological changes which occur when dog paws are exposed to cold temperatures and physical stress. They were separated into a running group of 20 dogs and a control group of six non-running dogs. Over 2 1/2 days, the running group ran in their natural environment for 170 miles and environmental parameters were recorded. Following the run, an 8-mm díameter skin biopsy specimen was taken from the lateral aspect of the right fore and hind paws of the running and non-running dogs. The skin was evaluated for histopathological changes and the présence of 2, 3-dinor thromboxane B2 (2, 3-dinor TxB2 ). No significant histopathological changes were noted in any of the biopsy specimens. Based on measured elevation of 2, 3-dinor TxB2 , the forepaws experienced more physical stress than the hind paws. Wet snow at higher environmental temperatures caused more paw stress than hard crusted snow at lower environmental temperatures. Resumen Se emplearon veintiséis perros trineo de Alaska para estudiar las alteraciones bioquimicas e histopatológicas ocurridas durante la exposición de las patas a las bajas temperaturas y al estrés fisico. Se dividieron entre un grupo de 20 perros corredores y un grupo control de seis perros no corredores. Durante dos días y medio el grupo de corredores corrió en su ambiente natural 170 millas. Durante la carrera se tomó una biopsia por punch de 8 mm del aspecto lateral de la pata derecha delantera y trasera de los perros corredores y no corredores. Se evaluaron las alteraciones histopatológicas cutáneas y la presencia de tromboxano B2 2, 3-dinor (2, 3-dinor TxB2 ). No se observaron alteraciones histopatológicas significativas en ninguna de las muestras de biopsia. Según la elevación detectada en 2.3-dinor TxB2 , las patas delanteras sufrieron un estrés fisico mayor que las traseras. La nieve húmeda en temperaturas ambientales elevadas causó un estrés mayor que la nieve dura en temperaturas ambientales más bajas. [Bradley, D.M., Swaim, S.F., Vaughn, D.M., Powers, R.D., McGuire, J.A., Reinhart, G.A., Burr, J., Swenson, R.A. Biochemical and histopathological evaluation of changes in sled dog paw skin associated with physical stress and cold temperatures. (Estudio bioquimico e histopatologico de las alteraciones en las patas de perros de trineo asociadas al estrés fisico y por las bajas temperaturas). Veterinary Dermatology 1996; 7: 203-208.] Résumé Vingt six chiens de traineau de l'Alaska fürent utilisés dans une étude évaluant les modifications biochimiques et histologiques survenant lorsque les pattes sont exposées à des températures froides et des stress physiques. lls fürent divisés en un groupe de vingt chiens de course et un groupe de six chiens ne courant pas. Après deux jours et demi, le groupe de course avait parcouru 170 miles dans son environnement naturel, dont les paramètres fürent enregistrés. Après la course, des biopsies de 8 mm de díamètre fürent prises sur les faces latérales des pattes antérieure et postérieure droites des chiens d'attelage et de ceux qui étaient restés au repos. L'évaluation de l'état cutané s'est faite sur les modifications histologiques et la présence de 2, 3-dinor thromboxane B2 (2, 3-dinor TxB2 ). Aucune modification histologique significative n'a été notée dans aucune des biopsies réalisées. Jugé sur l'élévation du 2, 3 TxB2 , les pattes antérieures subissent un stress physique supérieur aux pattes postérieures. La neige humide à temperatures plus élevées cause plus d'agression que la neige dure et crouteuse à des températures plus basses. [Bradley, D.M., Swaim, S.F., Vaughn, D.M., Powers, R.D., McGuire, J.A., Reinhart, G.A., Burr, J., Swenson, R.A. Biochemical and histopathological evaluation of changes in sled dog paw skin associated with physical stress and cold temperatures. (Evaluation des modifications biochimiques et histologiques induites par les stress physiques et le froid au niveau de la peau des pattes de chiens de traineau). Veterinary Dermatology 1996; 7: 203-208.] Zusammenfassung Sechsundzwanzig Alaska-Schlittenhunde wurde für eine Studie über biochemische und histopathologische Veränderungen herangezogen, die an den Pfotenballen auftreten, wenn sie kalten Temperaturen und physischem Streß ausgesetzt sind. Die Hunde wurden in eine Renngruppe von 20 Hunden und eine Kontrollgruppe von sechs Nicht-Rennhunden eingeteilt. Über einen Zeitraum von zweieinhalb Tagen rannte die Renngruppe in lhrer natürlichen Umgebung 170 Mellen, wobei die Umgebungsparamenter aufgezeichnet wurden. Nach dem Rennen wurden Biopsien mit einem Durchmesser von 8 mm von der Lateralseite der rechten Vorder-und Hinterpfote bei den Renn-und Nichtrennhunden entnommen. Die Haut wurde auf histopathologische Veränderungen und die Anwesenheit von 2, 3-dinor-Thromboxan BA (2, 3-dinor TxB2 ) untersucht. Es wurden keine signifikanten histopathologischen Veränderungen bei einer der Biopsien festgestellt. Auf der Basis der gemessenen Erhöhung von 2, 3-dinor TxB2 erfuhren die Vorderpfoten mehr physischen Streß als die Hinterpfoten. Nasser Schnee und höhere Umgebungstemperaturen verursachten mehr Pfotenstreß als harter, verkrusteter Schnee bei niedrigeren Umgebungstemperaturen. [Bradley, D.M., Swaim, S.F., Vaughn, D.M., Powers, R.D., McGuire, J.A., Reinhart, G.A., Burr, J., Swenson, R.A. Biochemical and histopathological evaluation of changes in sled dog paw skin associated with physical stress and cold temperatures (Biochemische und histopathologische Untersuchung von Hautveränderungen an den Pfoten von Schlittenhunden in Verbindung mit physischem Streß und Kälte). Veterinary Dermatology 1996; 7: 203-208.].

Evaluation of Effects of Dietary n-6 to n-3 Fatty Acid Ratios on Leukotriene B Synthesis in Dog Skin and Neutrophils.

Résumé- Les effets d'alimentations supplémentées avec des ratios croissants decides gras polyinsaturés n - 6/n - 3 sur la synthèse de leucotriènes B dans la peau du chien et les neutrophiles sont présentés. Trente chien Beagles ont reçu pendant 2 mois avec une alimentation ayant un ratio n -6/n -3 de 28:1. Des aliments expérimentaux contenant des ratios de 5:1, 10:1, 25:1, 50:1 et 100:1 (six chiens par groupe) ont été administrés ensuite pendant 12 semaines. A la fin des deux mois d'alimentation témoin et au bout de 6 et 12 semaines d'alimentation expérimentale, les concentrations de LTB4 et LTB5 dans la peau et les neutrophiles ont été déterminées. Les neutrophiles de chiens ayant mangé des aliments de ratio 5:1 et 10:1 ont synthétisé 30-33 pourcent moins de LTB4 (P <0,05) et 370-500 pourcent plus de LTB5 (P <0,05) à 6 et 12 semaines, mais le relargage d'anions superoxide était inchangé. La peau des chiens stimulée par un lipopolysaccharide a synthétisé 48 à 62 pourcent moins de LTB4 (P < 0,05) et 48 à 79 pourcent moins de LTB5 (P <0,05) à 12 semaines. [Vaughan, D. M., Reinhart, G. A., Swaim, S. F., Lauten, S. D., Garner, C. A., Boudreaux, M. K., Spano, J. S., Hoffman, C. E., Conner, B. Evaluation of effects of dietary n -6 to n - 3 fatty acid ratios on leukotriéne B synthesis in dog skin and neutrophils. (Evaluation de l'effet du ratio d'acides gras n - 6/n - 3 dans l'alimentation sur la synthèse de leucotriènes B dans la peau du chien et les neutrophiles). Resumen- Evaluamos los efectos producidos por el aumento en la proportion de ácidos grasos poli-insatu-rados n-6 a n-3 en la dieta sobre la sintesis de leucotrienos B en la piel del perro y en los neutrófilos. Se administró durante dos meses una dieta con una proporión 28:1 de ácidos grasos n-6 a n-3 a un grupo de treinta Beagles. Se administraron dietas experimentales con proporciones de 5:1, 10:1, 25:1, 50:1 y 100:1 durante 12 semanas (seis perros por grupo). Se cuantificaron los niveles de leucotrienos B4 y B5 en la piel y en los neutrófilos al final de los dos meses de dieta control y a las 6 y 12 semanas de la dieta-tratamiento. Los neutrófilos de perros con dietas 5:1 y 10:1 sintetizaron 30 a 33% menos leucotrieno B4 (P < 0.05) y 370 a 500% más leucotrieno B5 (P <0.05) a las 6 y 12 semanas pero no alteraron la liberación de aniones superóxido durante la espiracion. La piel de perro estimulada con lipopolisacáridos sintetizó de 48 a 62% menos leucotrieno B4 (P < 0.05) y 48 a 79% más leucotrieno B5 (P < 0.05) a las 12 semanas. [Evaluation of effects of dietary n-6 to n-3 fatty acid ratios on leukotriene B synthesis in dog skin and neutrophils (Effecto de la proporción de ácidos grasos n-6 a n-3 en la dieta sobre la sintesis de leucotrienos B en la piel del perro y en los neutrófilos). Abstract- The effects of diets supplemented with increasing ratios of n-6 to n-3 polyunsaturated fatty acids on leukotriene B synthesis in dog skin and neutrophils were evaluated. Thirty Beagles were conditioned for 2 months on a diet with an n-6 to n-3 fatty acid ratio of 28:1. Experimental diets, containing n-6 to n-3 ratios of 5:1, 10:1, 25:1, 50:1 and 100:1 (six dogs/group), were fed for 12 weeks. At the end of the 2 month control diet period, and again at 6 and 12 weeks of treatment feeding, leukotriene B4 and leukotriene B5 were quantitated in skin and neutrophils. Neutrophils from dogs fed the 5:1 and 10:1 diets synthesized 30-33 per cent less leukotriene B4 (P < 0.05) and 370-500 per cent greater leukotriene B5 (P < 0.05) at 6 and 12 weeks, but had no change in the release of superoxide anions during respiratory burst. Lipopolysaccharide-stimu-lated dog skin synthesized 48-62 per cent less leukotriene B4 (P < 0.05) and 48-79 per cent more leukotriene B5 (P <0.05) at 12 weeks.