Reactivity of Equine Palmar Digital Arteries and Veins to Vasodilating Agents

Palmar digital arteries and veins removed surgically from healthy horses under general anesthesia were cut into 4 mm vascular rings, suspended in tissue baths, and attached to force displacement transducers for continuous measurement of vascular tension. In vitro vascular responses were determined for acetylcholine, acepromazine, isoxsuprine hydrochloride (isoxsuprine), prostaglandin E₂ (PGE₂), and prostaglandin I₂ (prostacyclin). After preconstriction with norepinephrine hydrochloride (norepinephrine), or prostaglandin F₂ alpha (PGF₂ alpha), the concentrations needed to produce 50% maximum relaxation (EC₅₀) and the maximum percentage of relaxation were determined for each drug.
Acetylcholine was the most potent arterial vasodilator (smallest EC₅₀ value) and PGE₂ was the least potent. Prostacyclin was the least potent venodilator (highest EC₅₀ value); there were no differences between acetylcholine, acepromazine, isoxsuprine, and PGE₂. Isoxsuprine produced greater arterial relaxation than all other agents. Isoxsuprine and acepromazine produced significantly greater venous relaxation than did acetylcholine and PGE₂. Prostacyclin produced minimal vasodilation of arteries or veins. Acepromazine and isoxsuprine relaxed the veins significantly more than the arteries. When PGF₂ alpha was used instead of norepinephrine to preconstrict the arteries and veins, the potency and effectiveness of acepromazine and isoxsuprine to produce vasodilation were significantly decreased. Results indicate that acepromazine and isoxsuprine can relax the equine digital vasculature but their effectiveness varies depending on the origin of the constriction.     

Allergy Testing for Skin Disease in the Cat In Vivo vs In Vitro Tests

Abstract— The results of in vitro and in vivo tests for 36 cats with signs suggestive of allergic skin disease were compared. The cats were presented to the dermatology section of the Department of Veterinary Medicine, University of Bristol, with a variety of skin conditions. Intradermal skin testing with flea extract alone (six cats) or combined with a panel of 40 inhalant altergens (30 cats) was employed. Serum samples were tested with a commercial IgE ELISA against flea extract and 36 inhalant allergens. A diagnosis of flea bite hypersensitivity was made in 18 cats, atopic disease in nine cats and food hypersensitivity in one cat. Intradermal skin testing gave a positive predictive value in over 85 per cent of flea allergic cases and 100 per cent of atopic cases; the IgE ELISA test demonstrated relatively low predictive values for flea allergy and atopic disease and was not considered to be a useful diagnostic test. Résumé— Les résultats de tests in vitro et in vivo faits chez 36 chats ayant des symptômes évocateurs d'une dermite allergique ont été comparés. Des tests cutanés à la seule puce (six chats) ou combinés avec un panel de pneumallergènes (30 chats) ont été utilisés. Les sérums ont été testés avec un kit commercial de dosages d'IgE spécifiques de la puce et de 36 pneumallergènes par technique EIA. Un diagnostic de dermite par hyperseensibilité aux piqùres de puce a été fait chez 18 chats, une atopie chez neuf et une hypersensibilité d'origine alimentaire chez un. Les tests cutanés avaient une valeur prédictive de 85% pour les allergies à la puce et 100% pour les cas d'atopie; les tests IgE EIA avaient une valeur prédictive assez faible et n'ont pas été considérés comme étant un test utilisable en diagnostic. Resumen En este artículo se comparan los resultados de pruebas in vivo e in vitro efectuadas en 36 gatos con cuadro clínico indicativo de alergias cutáneas. Éstos animales fueron presentados en la sección de Dermatología del departamento de medicina de la Universidad de Bristol con una variedad de condiciones cutäneas. En las pruebas de invecciones intradérmicas se utilizaron alergenos de extracto de pulga solos o combinados con un panel de 40 alergenos inhalatorios (30 gatos). También se llevaron a cabo pruebas de suero con el test comercial de IgE ELISA para el extracho de pulga y 36 de los alergenos inhalatorios. En 18 de los gatos se diagnostico hipersensitividad a las pulgas, en nueve atopía y solo uno hipersensitividad a los alimentos. Las pruebas intradérmicas produjeron una predictividad positiva en 85% de los casos de alergia a las pulgas y 100% de los casos de atopía. Sin embargo el test ELISA de IgE produjo una baja predictividad relativa en los casos de hipersensitividad a las pulgas y casos de atopía y no se consideró como un test de gran utilidad diagnóstica.     

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.     

Rostral Mandibulectomy Three Case Reports in Dogs

A rostral mandibulectomy was performed on three dogs with mandibular neopiasia. The technique involves stabilization of the mandibular rami, excision of the mandible rostral to the frenulum of the tongue, and cosmetic closure of the wound. Two patients were living 11 months postoperatively. This technique is effective in treating some malignant neoplasms of the rostral mandible.     

Regulation of Plant Germplasm Imported into the United States1

The importation of plant germplasm into the United States involves the risk that certain plant species may carry plant pests hazardous to US agriculture. On the basis of a pest risk analysis, plants or plant parts of a plant species from a particular country are assigned an entry status which constitutes the least drastic quarantine action necessary to exclude hazardous pests that could be imported with this germplasm. Quarantine procedures necessary for entry range from foreign site field inspections (preclearance) or visual inspection at a port of entry (low-risk seeds) for low-risk plant material to testing high-risk introductions for hazardous pests in quarantine facilities (prohibited). The recent revision of Quarantine 37 for the importation of nursery stock reflects changes in the assignment of certain plant genera to either a more or less restrictive entry status on the basis of risk assessments for quarantine pests of the particular genus. Pest risk analyses on certain seeds and also vegetative propagations of grasses, legumes, conifers, and certain fruits and nuts are now underway to determine if future changes in US quarantine laws are necessary to protect US agriculture.     

Disposition of sulfonamides in food-producing animals: pharmacokinetics of sulfamerazine in cattle

The disposition of sulfamerazine in the plasma and urine of cattle was determined following single intravenous and oral doses. The averaged and the individual animal data were described by a two-compartment pharmacokinetic model. The drug was eliminated with a biological half-life of 6.2 h, primarily by renal excretion of unchanged sulfamerazine and metabolism to acetylsulfamerazine. Sulfamerazine (in solution) was absorbed with a half-life 6.7 h and with relative completeness (68%) following oral administration.     

Disposition of sulphonamides in food-producing animals: disposition of sulphathiazole in tissues, urine, and plasma of cattle following intravenous administration

Plasma, urine and tissue concentrations of sulphathiazole were determined at various times following intravenous administration to fifteen cattle. The averaged plasma and urine data were consistent with a two-compartment pharmacokinetic model with a half-life of elimination of 1.3 h and a total volume of distribution of 0.41 l/kg body weight. Sulphathiazole was eliminated by excretion of unchanged drug into urine (48%) and by formation of acetylated and polar metabolites. The averaged data obtained from eight selected tissue sites were consistent with the two-compartment pharmacokinetic model presented and confirmed that residues of sulphathiazole in edible tissue can be predicted from serum and urine concentrations of the drug.     

Production, behaviour and fertility of Merino wethers, hemi-castrates with reduced testicular parenchyma and induced cryptorchids

Greasy wool production, body weight, behaviour and fertility of male, fine wool Merino sheep were studied from 10 to 21 months of age to assess their suitability for wool production. The males were either castrated (wethers), or were hemi-castrated with a vasectomy and reduction (either partially or in full) of the parenchyma of the retained testicle, or the testicles pushed up into the ingulnal canal and the scrotum shortened (induced cryptorchids). There were significant differences among all groups in body weight, with increases being associated with the larger amounts of testicular tissue present. Fertility was low in the induced cryptorchids at 19 months of age. The hemi-castrates with reduced testicular parenchyma were infertile. The hemi-castrates with reduced testicular parenchyma had significantly heavier greasy fleece weights than the wethers and induced cryptorchids, which had similar fleece weights. The wether group suffered a higher prevalence of posthitis in spring and autumn than the hemi-castrate or induced cryptorchid groups. Those hemi-castrates with the largest amount of testicular parenchyma retained and the induced cryptorchids exhibited masculine behaviour patterns and had an increased incidence of fly strike to the head. The principle of hemi-castration and reduction of the testicular parenchyma is shown to be applicable in wool producing flocks with the potential to increase greasy wool production while minimising the management and marketing limitations previously associated with induced cryptorchids.     

Sutured End-to-End and Stapled Side-to-Side Jejunal Anastomoses in the Horse

Hand sutured end-to-end (EE) and stapled side-to-side (SS) small intestinal anastomoses were performed in 10 healthy adult horses. In five SS anastomoses, staple lines on the blind ends of the jejunum were inverted (SSI) and in five they were not (SSNI). Five EE anastomoses were sutured with polydioxanone and five were sutured with polyglyconate. All horses were euthanatized on day 30. Intra-abdominal adhesions were graded (0-4), and stomal areas were calculated from contrast radiographs made with the bowel distended. Histopathology scores for the anastomoses were based on the degree of inflammation (0-3), fibrosis (0-3), and alignment and healing of intestinal layers (0-3). Mean surgery times +/- standard deviations for EE, SSI, and SSNI techniques were 33.9 +/- 5.4, 36.2 +/- 5.6, and 29.6 +/- 5.9 minutes, respectively. Mean and median stomal areas were 9.4 +/- 5.5 and 8.9 cm2 for EE anastomoses and 17.2 +/- 16.5 and 12.1 cm2 for SS anastomoses. Intra-abdominal adhesions developed in three horses, one of which had clinical signs of colic. Mean histopathology scores for EE and SS anastomoses were 4.8 +/- 2.0 (median = 5) and 4.4 +/- 1.8 (median = 4), respectively. There were no statistically significant differences in surgery times, intra-abdominal adhesion scores, stomal areas, or histopathology scores between small intestinal EE and SS anastomoses in these horses.