Dermatologic tumors (excluding sarcoids)

Cutaneous neoplasia represents a clinical problem with which veterinarians are commonly challenged. This article addresses equine cutaneous squamous cell carcinoma, squamous cell papilloma, melanoma, mastocytosis, and lymphosarcoma. Current concepts regarding the origin, pathogenesis, diagnosis and treatment of each neoplasm is emphasized.     

Epidemiological observations on sarcoids in a population of donkeys (Equus asinus)

An epidemiological study of equine sarcoid in a population of 4126 donkeys showed that the peak incidence of the disease was 15.2 cases per 100 animal-years and occurred in animals in their fourth year of life. The crude incidence of the disease was 0.6 cases per 100 animal-years. The disease occurred most frequently in younger, male animals during their first five years in the population. The lesions were observed most commonly in the paragenital region. Pre-entry quarantine procedures did not appear to play a significant role in the spread of the disease but there was an indication that close in-contact animals were more likely to have sarcoids than animals in the general population. This suggested that a transmissible agent might have been involved in the aetiopathogenesis or that the animals had encountered some event that had predisposed them to the disease.     

The therapy of equine sarcoid with a non-specific immunostimulator--the epidemiology and spontaneous regression of sarcoids

20 sarcoid-affected horses from a practice in the northern Jura were used in this experiment. The mean age of the 20 horses was 3.9 years at the time of the first observation of sarcoid tumors. On the average, 4.4 tumours were noted per horse. 10 of the horses were treated in a double-blind study with an unspecific immunostimulant (Baypamun P), 10 others received a placebo. One single tumour only was treated per horse. The injections were given under and around the sarcoid. In eight out of the 20 horses all tumours regressed totally or for more than 50% of their initial size. Five of these had received placebo, three the immunostimulant. Four animals showed a modest, but measurable reduction in tumour size (3 immuno-stimulant, 1 placebo) and in the remaining eight horses (4:4) no reduction or even an increase in tumour size was observed. The phenomenon of tumour regression was very probably due to spontaneous regression and horses which had been observed to develop sarcoid within the last three months had significantly more regressions than animals with older tumours (p < 0.05). The haplotype of the equine leucocyte antigens was thought to predispose 12 of the 20 horses for the sarcoid. However, the ELA-type did not measurably influence the phenomenon of tumour regression.     

Equine oocyte-cumulus morphology as affected by follicular size

From the ovaries of 256 slaughtered mares a total of 1713 follicles were isolated from which 1641 (95.8%) oocytes were recovered (6.4/mare). A total of 564 follicles and oocytes were evaluated for the degree of vascularisation of the follicle wall, the appearance of the follicular fluid and the location and morphology of the cumulus-oocyte-complex. Follicles with a diameter of >10 mm displayed more numerous, well branched and more pronounced blood vessels than the smaller ones (4-10 mm diameter) and most of them contained clear, yellowish fluid with few granulosa cells. The percentage of oocytes with compact cumuli increased significantly with an increasing diameter of the follicle, being 233%, 43.9%, 55.6% and 64.2% (P<0.01) for the follicles with diameters of 4-10, 11-15, 16-20 and 21-35 mm, respectively. The percentage of oocytes attached to the follicle wall also increased with increasing follicle size, being 48.0%, 59.6%, 81.5% and 90.1% (P<0.01), respectively. On the contrary, the percentage of oocytes floating in the follicular fluid decreased with increasing follicle diameter, from 52.0% in the smallest follicles to 9.9% in the biggest ones. A significantly greater percentage of oocytes found on the follicular wall than in the follicular fluid had a compact cumulus (56.6 versus 21.3%; P<0.01). For in vitro culture were accepted 30.4%, 54.3%, 60.7% and 77.8% (P<0.01) of oocytes from the follicles with diameters of 4-10, 11-15, 16-20 and 21-35 mm, respectively. After culture for 28-40 h in TCM 199 medium, 90 of a total of 165 (54.5%) oocytes reached the metaphase II stage of maturation.     

Equine infectious arteritis: molecular biology, epidemiology and preventative measures

After a brief historical account of the outbreak of infectious arteritis of horses which occurred in 1984 in Kentucky (United States of America), the author reports on the present state of knowledge concerning the organisation of the genome of the virus. Clinical signs of the disease are described, as well as modes and routes of transmission. Finally, currently-available vaccination procedures are discussed and their value is assessed.     

Equine dyschondroplasia (osteochondrosis)--histological findings and type VI collagen localization

Platelets are small, disc-shaped, anucleated cells formed by fragmentation of megakaryocytes in the bone marrow. They circulate in blood with a lifespan of 7 to 10 days and, together with fibrin, form hemostatic plugs at sites of vessel injury. Abnormalities of platelets, either quantitative or qualitative, may cause clinically significant bleeding with resultant morbidity and, on occasion, mortality. This review will focus on platelet disorders in neonates, defined as infants of up to 4 months of age. Special emphasis will be given to the physiology of platelet function in healthy and sick newborn infants. The review will be divided into sections as follows: role of platelets in hemostasis, platelet function in newborn infants, quantitative platelet disorders, qualitative platelet disorders, and platelet transfusion therapy.     

Equine CRISP-3: primary structure and expression in the male genital tract

Although originally described in the male rodent genital tract, cysteine-rich secretory proteins (CRISPs) are expressed in a variety of mammalian tissue and cell types. The proteins of the male genital tract have been observed associated to spermatozoa and are believed to play a role in mammalian fertilization. Here we describe the identification and primary structure of the first equine member of the CRISP family. Equine CRISP-3 is transcribed and expressed in the stallion salivary gland, in the ampulla and the seminal vesicle. It displays all 16 conserved cysteine residues and shows 82% homology to human and 78% to guinea pig CRISP-2 (AA1, TPX 1) and 77% to human CRISP-3. In contrast to other mammalia, in the horse CRISP-3 is synthesized in great amounts in the accessory sexual glands, ampulla and seminal vesicle, thus allowing the isolation of equine CRISP-3 in amounts suitable for biochemical, physiological and structural studies from stallion seminal plasma.     

Organisation of the equine immunoglobulin constant heavy chain genes. II. Equine cgamma genes

The number of immunoglobulin G constant heavy chain genes (cgamma genes) varies broadly among mammalian species, reflecting structural and functional differences between expressed immunoglobulin G (IgG) isotypes and allotypes. Up to now equine IgG isotypes have been defined only at the biochemical and serological level. It is still not clear how many IgG isotypes exist in horses and whether there are any allotypes. Here, we describe the isolation and characterisation of equine cgamma genes. An equine genomic lambda phage library was screened with a human cgamma4 probe. Cross-hybridising equine cgamma sequences were cloned twice and characterised by restriction mapping with the human cgamma4 and a murine sgamma1 probe. Genomic equine DNA probes for both, cgamma genes and corresponding switch regions (sgamma), were isolated and used for a more detailed BamHI restriction analysis, comparing genomic DNA of various horses. This analysis reveals the existence of at least five, or probably six cgamma genes in the equine haploid genome. Beside the porcine system, this is the highest number of cgamma genes described for any mammalian species. Moreover, for two of these cgamma genes, BamHI restriction fragment length polymorphism became evident.     

Eastern Equine Encephalitis (EEE) antibody status in St. Thomas, Jamaica, 1975

The Escherichia coli isolated from faecal and nasal swabs from all babies present in a maternity ward were serotyped and their anbitiotic resistance patterns and fermentation characteristics with six carbohydrates were determined. These were compared with E. coli isolated from hands and clothing of attendants and samples of ward air. The results suggest that mothers may be the primary source of E. coli in the ward but the colonized babies themselves provide the main reservoir of nursery E. coli. As most of these serotypes of E. coli were found on the attendant's hands or clothing or in the air, it is difficult to assess transmission routes for E. coli, particularly as some strains appear to possess a greater inherent ability to colonize babies than others. By the use of markers other than O antigens it was possible to characterize strains to a far greater extent.     

Report of the Second Equine Leucocyte Antigen Workshop, Squaw valley, California, July 1995

The final assignment of antibody clusters for leucocyte antigens and immunoglobulins, as described in detail in Sections 3 and 4, is summarized in Table 4. Together with other mAbs developed outside of ELAW II (Table 9) this pool of reagents represent a powerful array of tools for the study of equine immunity. The Second Equine Leucocyte Antigen Workshop made considerable advances in pursuing the objectives of establishing the specificities of mAbs and achieving consensus on the nomenclature for equine leucocyte and immunoglobulin molecules. Of equal importance, several productive collaborations were fostered among the participating laboratories and observers. Overall, enormous advances have been made in the past decade since mAbs specific for equine leucocyte antigens and immunoglobulins were first reported. There remains enormous scope and need for further studies of equine leucocyte antigens and immunoglobulins, both for the purposes of comparative immunology and for the good of the horse. In the future novel techniques will be required to develop reagents for specific target antigens such as the orthologues of the CD25 or CD45 isoforms. In studies of equine immunoglobulins the functional role of the IgG isotypes must be better established, reagents for IgE must be developed, and cloning of the immunoglobulin heavy chain genes will be essential if the complexities of the IgG sub-isotypes are to be elucidated. The tasks still facing the currently small group of equine immunologists throughout the world remain formidable, and will only be tackled successfully in a spirit of collaboration.     

Equine monocyte-derived macrophage cultures and their applications for infectivity and neutralization studies of equine infectious anemia virus

Equine infectious anemia virus (EIAV) has been shown to infect cells of monocyte/macrophage lineage. These primary cells are intrinsically difficult to obtain, to purify and to culture in vitro for extended periods of time. As a result, most in vitro studies concerning this lentivirus make use of primary equine fibroblasts or transformed canine or feline cell lines. We describe methods that yield reproducibly pure cultures of equine blood monocytes from peripheral blood mononuclear cells. The in vitro differentiation of these cells into mature equine macrophage was verified using various cytochemical staining methods. The equine monocyte-derived macrophage (MDM) cultures were found to replicate cell-adapted and field strains of EIAV more efficiently than cultures of fully differentiated equine splenic macrophage. Having established reproducible and fully differentiated cultures of equine macrophage, in vitro assays of virus infectivity and serum neutralization were developed using the in vivo target cell of EIAV. These procedures, while developed for the EIAV system, should be equally useful for in vitro cultures of other macrophage-tropic pathogens of horses.