Localized cutaneous infection with Francisella tularensis resembling ulceroglandular tularemia in a cat.

A chronically draining subcutaneous mass was removed from the ventral cervical region of a 6-year-old spayed female Domestic Shorthair cat. The histopathologic diagnosis was severe locally extensive pyogranulomatous and necrotizing cellulitis. Bacterial culture yielded Francisella tularensis subsp. tularensis as the causative agent. Immunohistochemical evaluation of sections for F. tularensis was negative. One year later, the cat was euthanized because of progressive lethargy found to be due to hypertrophic cardiomyopathy with pulmonary thromboembolism. No evidence of cutaneous or systemic infection by F. tularensis was found at necropsy. This case appears to be a localized form of tularemia resembling the ulceroglandular form of tularemia in humans and suggests that bacterial culture may be more sensitive than immunohistochemistry in detecting organisms in cases of localized F. tularensis infection.     

Diagnosis and treatment of equine polysaccharide storage myopathy

Equine polysaccharide storage myopathy (EPSM) is a recently recognized metabolic condition with a high incidence in many breeds of horses and ponies. Clinical signs are extremely variable, but all can be related to underlying skeletal muscle dysfunction. Therapy employing a high-fat, high-fiber, low-starch, low-sugar diet and as much exercise as possible has proven to be extremely successful in control of this disorder. EPSM is progressive, and early detection and institution of therapy are vital.     

Dermal intravascular leiomyosarcoma in a cat

A 10-year-old female spayed domestic shorthaired cat presented with a subcutaneous tumor between the first and second phalanges of the left hind foot. Six months after excision, a similar tumor occurred on the medial aspect of the third phalanx of the same limb. Histologically, both tumors consisted of solid masses of spindle and round cells, many of which grew within endothelial-lined vessels. Tumor cells stained positively for smooth muscle actin and vimentin, but were negative for cytokeratin, S-100, desmin, synaptophysin, factor VIII-related antigen, and neuron-specific enolase. The diagnosis was dermal intravascular leiomyosarcoma.     

Intraarticular Hyaluronic Acid Supplementation in the Horse: The Role of Molecular Weight

Osteoarthritis (OA) is a primary cause of lameness and loss of use in the equine industry. Treatment of affected joints is aimed at reducing synovial inflammation, halting the inflammatory cascade within the joint, minimizing articular cartilage breakdown, and reducing pain. Treatments of affected joints commonly used by equine practitioners include intraarticular hyaluronic acid (HA). Consideration of the average molecular weight (MW) and concentration of the HA product may dictate what product is selected. The purpose of this review is to briefly summarize for the practitioner the scientific data available evaluating the significance of hyaluronic acid molecular weight with regard to efficacy and duration of action in horses when administered intraarticularly. In summary, the beneficial effects of HA supplementation are attributable to the anti-inflammatory effects, improvement in viscoelastic properties of the synovial fluid, and interaction with the synovial membrane affecting pain transmission and joint metabolism. As this review shows, the importance of HA molecular weight with regard to efficacy of treating synovial inflammation and osteoarthritis has not been clearly demonstrated, and results are conflicting. Until there is a full understanding of the mechanism of action of HA within the joint, the veterinarian's choice of HA products will continue to be based on clinical preference. Additional studies directly comparing products of different HA average molecular weights and formulations in a controlled in vivo setting are needed to assess the importance of HA molecular weight in treating joint disease.     

Relationship between tree canopy height and the production of pasture species in a silvopastoral system based on alder trees

Silvopastoral systems in New Zealand that incorporate trees planted to control soil erosion on hills largely rely on the productivity of the pastoral system for financial returns. The effect on pasture productivity of increasing the tree canopy height by pruning Italian gray alder (Alnus cordata) was investigated by measuring the response of light, soil moisture, soil temperature, pasture production of major pasture species, and grazing behaviour of sheep. A split-plot design with four replicates was used. The main plot treatments were three levels of shade (81, 23, and 12% of available photosynthetic photon flux (PPF)), created by pruning 11 year old alder grown at the same density. The sub-plot treatments were four pasture mixes: perennial ryegrass (Lolium perenne), Yorkshire fog (Holcus lanatus), and cocksfoot (Dactylis glomerata), each sown with white clover (Trifolium repens), and cocksfoot sown with lotus (Lotus pedunculatus). Soil temperature was highest under light shade. Total herbage yield at 50 mm stubble height from October to May under heavy and medium shade was 60 and 80%, respectively, of the total herbage harvested under light shade. Cocksfoot had the greatest herbage yield, either with lotus or white clover. The tillering of perennial ryegrass was suppressed by shade more than for the other grass species making ryegrass unsuitable for use in this silvopastoral system. More sheep grazed in the light shade than in the heavy shade, but there was no difference in sheep preference for cocksfoot or Yorkshire fog. Lotus was grazed more frequently than white clover. Pruning of alder to increase canopy height has the potential to improve the productivity of the understorey pasture and its acceptability to sheep.     

Malignant transformation of a giant congenital pigmented nevus (hamartoma) in a dog

A male Golden Retriever was born with a large area of abnormal skin and hair on the distal pelvic limb. A tumour arose from the proximal margin of this area at 5 years of age. Histopathological examination of the abnormal area of skin revealed an area in which follicles were surrounded by nodular accumulations of densely packed round to spindle-shaped cells with fine granular intracytoplasmic melanin. Similar cells were present within the subcutaneous fat, and clusters of densely pigmented melanocytes were scattered within the basal epidermis, follicular epithelium, and dermis. A diagnosis of giant congenital pigmented nevus (hamartoma) was made. The tumour from the proximal end of this area was composed of densely packed, moderately pleomorphic, poorly differentiated and pigmented, spindle-shaped to epithelioid melanocytes, and was diagnosed as malignant melanoma. Metastasis of the malignant melanoma to the stifle and inguinal regions occurred within 6 months. To date, the authors are unaware of prior reports of a canine giant congenital pigmented nevus (hamartoma) with transformation to a malignant melanoma.     

Ubiquitin expression in muscle from horses with polysaccharide storage myopathy

Serial sections of formalin-fixed, paraffin-embedded muscle biopsy specimens from 28 Quarter Horse, Paint, and draft-related breeds, aged 0.5-23 years, were treated with periodic acid-Schiff (PAS) stain for glycogen and were immunostained to detect ubiquitin expression. On the basis of findings in PAS-stained sections, a diagnosis of equine polysaccharide storage myopathy (EPSSM) was made in 22 horses aged 2-23 years (mean, 9.4 years); samples from 6 horses aged 0.5-15 years (mean, 7.3 years) had a normal PAS staining pattern, with no relevant lesions. Ubiquitin expression was detected in all but a 2-year-old EPSSM-affected horse and was not detected in the non-EPSSM-affected horses. Ubiquitin expression was greater than the degree of PAS-positive, amylase-resistant material, and ubiquitin was detected in aggregates of amylase-sensitive glycogen as well as in aggregates of amylase-resistant material. Results suggest that glycogen aggregates develop and are ubiquitinated prior to development of amylase-resistant inclusions. Ubiquitin immunostaining may be most useful for confirming the diagnosis of EPSSM in horses with only amylase-sensitive glycogen aggregates and in horses with early amylase-resistant inclusions. However, ubiquitin immunostaining is no more sensitive than is PAS staining for diagnosis of EPSSM.