Methods and characteristics used in resident selection within the American College of Veterinary Ophthalmologists

A survey of Diplomates from the American College of Veterinary Ophthalmologists, which trains residents, confirms that subjective criteria are most commonly used in selecting new residents. The ophthalmologist(s) who oversee(s) the training was/were primarily responsible for resident selection. In general, Diplomates seemed to be searching for a resident who was intelligent, could communicate well, was hard working, and had good interpersonal skills. The most important part of an application was the letters of recommendation, with the most important consideration being how well the person doing the selecting knew the author of a letter. The current process of resident selection does result in a majority of residents' completing their programs and ultimately becoming Diplomates of the American College of Veterinary Ophthalmologists.     

Hypofractionated radiation therapy for the treatment of malignant melanoma and squamous cell carcinoma in dogs and cats

This study describes the experience with hypofractionated radiation therapy of squamous cell carcinoma and melanoma in dogs and cats. A total dose of 32-48 Gray (Gy) was delivered once a week in 8 Gy fractions. 34 animals in which a complete surgical excision was impossible were treated. There was no tumor detectable macroscopically in 14 patients at the beginning of radiation therapy. In 20 animals the median volume of the tumor was 9.9 cm3. The median survival times and the local tumor control of squamous cell carcinoma of the oral and nasal cavities and of the body are comparable to results which were reached with a Monday-Wednesday-Friday scheme. For the treatment of Melanoma the hypofractionated radiation therapy is first choice. There are no significant side effects. Late side effects did not occur. 88% of the owners are satisfied with this kind of treatment and would choose it again.     

Comparison of models for estimation of genetic parameters for mature weight of Hereford cattle

Genetic parameters of mature weight are needed for effective selection and genetic evaluation. Data for estimating these parameters were collected from 1963 to 1985 and consisted of 32,018 mature weight records of 4,175 Hereford cows that were in one control and three selection lines that had been selected for weaning weight, for yearling weight, or for an index combining yearling weight and muscle score for 22 yr. Several models and subsets of the data were considered. The mature weight records consisted of a maximum of three seasonal weights taken each year, at brand clipping (February and March), before breeding (May and June), and at palpation (August and September). Heritability estimates were high (0.49 to 0.86) for all models considered, which suggests that selection to change mature weight could be effective. The model that best fit the data included maternal genetic and maternal permanent environmental effects in addition to direct genetic and direct permanent environmental effects. Estimates of direct heritability with this model ranged from 0.53 to 0.79, estimates of maternal heritability ranged from 0.09 to 0.21, and estimates of the genetic correlation between direct and maternal effects ranged from -0.16 to -0.67 for subsets of the data based on time of year that mature weight was measured. For the same subsets, estimates of the proportions of variance due to direct permanent environment and maternal permanent environment ranged from 0.00 to 0.09 and 0.00 to 0.06, respectively. Using a similar model that combined all records and included an added fixed effect of season of measurement of mature weight, direct heritability, maternal heritability, genetic correlation between direct and maternal effects, proportion of variance due to direct permanent environmental effects, and proportion of variance due to maternal permanent environmental effects were estimated to be 0.69, 0.13, -0.65, 0.00, and 0.04, respectively. Mature weight is a highly heritable trait that could be included in selection programs and maternal effects should not be ignored when analyzing mature weight data.     

Canine choroidal melanoma with metastases

A 3-year-old-female, spayed Golden Retriever was examined for a unilateral retinal detachment with exophthalmos. Ultrasonographically, a mass was detected with intra- and extraocular extension. The orbit was exenterated and the dog recovered uneventfully. Histopathologic diagnosis was a primary choroidal melanoma with orbital extension, however, the behavioral and cytologic features were benign. Routine examinations postsurgically were nonremarkable. Twenty-one months after surgery the dog was euthanized for respiratory collapse with radiographic signs of metastasis. Necropsy revealed black lesions in the lung and liver. Histopathologic diagnosis was metastatic melanoma with morphology and behavior identical to the primary choroidal melanoma. This is the first definitive case of a canine choroidal melanoma with metastasis.     

Studies on the pathogenesis of chicken infectious anaemia virus infection in six-week-old SPF chickens

The pathogenesis of chicken infectious anaemia virus (CAV) infection was studied in 6-week-old and one-day-old SPF chickens inoculated intramuscularly with graded doses of Cux-1 strain (10(6)-10(2) TCID50/chicken). Viraemia, virus shedding, development of virus neutralizing (VN) antibodies and CAV distribution in the thymus were studied by virus isolation, polymerase chain reaction (PCR), immunocytochemistry (IP) and in situ hybridization until postinfection day (PID) 28. In 6-week-old chickens infected with high doses of CAV, viraemia and VN antibodies could be detected 4 PID and onward without virus shedding or contact transmission to sentinel birds. However, virus shedding and contact transmission were demonstrated in one-day-old infected chickens. In the 6-week-old groups infected with lower doses, VN antibodies developed by PID 14, transient viraemia and virus shedding were detected. The thymus cortex of all 1-day-old inoculated chickens stained with VP3-specific mAb. Cells with positive in situ hybridization signal were fewer and scattered throughout the thymus tissue of the one-day-old inoculated chickens as compared to IP-positive cells. These results suggest that early immune response induced by high doses of CAV in 6-week-old chickens curtails viral replication and prevents virus shedding.     

Heterosis retained in advanced generations of crosses among Angus and Hereford cattle

Data from 1,909 purebred, F1, backcross and F2 and F3 inter se combinations of Angus and Hereford were used to estimate average individual, maternal and grandmaternal genetic effects, individual and maternal heterosis, dominance and epistatic genetic effects. Models for evaluating heterosis and epistatic or recombination effects were discussed. Average individual effects indicate that Angus, compared with Hereford, had calves that were born earlier, had lighter birth weights, lower pre- and postweaning gains and lower pregnancy rates. Angus also produced lighter weight carcasses with more fat cover and marbling. Maternal effects of Angus were in the direction of reduced birth weight, greater calving ease, higher preweaning but lower postweaning growth rate and increased fatness when contrasted with Hereford. There was a tendency for opposite direction of maternal and grandmaternal effects for traits influenced by preweaning maternal environment. When additive X additive effects were ignored, total heterosis was significant for earlier day born, heavier birth weight, preweaning and postweaning gain, and heavier and fatter carcasses. Heterosis retained in F3 inter se vs F1 generation crosses indicated that net epistatic effects were relatively negligible for date of calving, birth weight, weaning gain and fat cover. There was a greater reduction of heterosis effects than expected from dominance alone for survival, pregnancy and marbling score. Loss of heterosis in F3 was less than expected for postweaning gain, carcass weight and rib eye area. Except for survival, pregnancy and marbling, these deviations from dominance expectations, or lack of them, are favorable for F3 composite populations.     

Biological characteristics for assessing low phosphorus intake in growing swine

A total of 195 swine from 18 to 35 kg were used to evaluate various biological responses of growing swine fed low P diets at different Ca:P ratios. Three replicates of a randomized complete-block design in a 3 X 3 factorial arrangement of treatments were used. Total dietary P levels of .12, .31 and .50% were fed in 1:1, 1.5:1 or 3:1 Ca:P ratios. Diets were formulated using corn starch, dextrin and soy protein concentrate, with monosodium phosphate and limestone used to supply appropriate dietary treatment levels of Ca and P. Gain and feed performance were generally influenced by both Ca:P ratio and dietary P level. Serum inorganic P decreased linearly as Ca:P ratio widened and increased linearly as dietary P increased. Serum Ca concentrations responded inversely to serum inorganic P in response to both Ca:P ratio and dietary P level. Serum alkaline phosphatase was not affected by Ca:P ratio, but declined quadratically with increasing dietary P level. Bone bending moment was influenced by both dietary P level and Ca:P ratio. Bone component weights (ash, organic matrix), percentage bone ash and net accretion of bone ash and organic component weights were not influenced by Ca:P ratio but increased linearly as dietary P level increased. These results suggest that bone component weights, net ash accretion and percentage bone ash were more sensitive criteria than bone bending moment or serum alkaline phosphatase, which in turn were more sensitive than serum inorganic P, Ca, Mg and growth performance characteristics in response to dietary P level.     

The use of monoclonal antibodies in an enzyme immunospot assay to detect isotype-specific antibody-secreting cells in pigs and chickens

Monoclonal antibodies directed against porcine immunoglobulin isotypes G, G1, G2, M, and A and against chicken immunoglobulin isotopes G, M, and A were tested in an antigen-specific spot-forming cell (SFC) assay based on the principle of the enzyme immunoassay. The SFC assay was used to quantitate ovalbumin (OA)-specific antibody-secreting cells (ASC) in pigs that had been primed and boosted with OA. The SFC assay was also used to quantitate trinitrophenyl (TNP)-specific ASC in chickens that had been primed with TNP-conjugated keyhole lympet haemocyanin (TNP-KLH). Although, the classical plaque-forming cell (PFC) assay cannot reliably detect isotope-specific ASC in pigs and chickens, it can detect these cells in mice. Therefore, we compared the OA- and TNP-specific SFC assays with PFC assays that were specific for these antigens in mice. The study demonstrated that the SFC assay is superior to the PFC assay in detecting both OA-specific ASC and TNP-specific ASC. The frequencies of OA-specific and TNP-specific SFC detected in mice were of the same order of magnitude as those detected in pigs and chickens. We concluded that the SFC assay is the better method for quantitating ASC in pigs, chickens, and probably all domestic animals for which isotype-specific monoclonal antibodies are available.