Clinical Forms of Acquired Myasthenia Gravis in Dogs: 25 Cases (1988–1995)

The purpose of this project was to investigate the clinical forms of acquired myasthenia gravis in dogs. The medical records from 25 dogs with seropositive acquired myasthenia gravis were reviewed, and the following data were recorded for each patient: signalment, history, clinical findings; results of IV edrophonium chloride administration, repetitive nerve stimulation, and presence or absence of muscle membrane staining by immunocytochemical methods; serum acetyl-choline receptor antibody concentration; treatment; and outcome. Several clinical forms of acquired myasthenia gravis were identified. Nine of the 25 patients (36%) had no historical or clinical evidence of appendicular muscle weakness, and were designated as focal myasthenics. These dogs exhibited focal weakness in one or more of the following muscle groups: facial {3 of 9), pharyngeal (3 of 9), and laryn-geal (3 of 9). The remaining 16 dogs (64%) exhibited appendicular muscle weakness. Four of these 16 dogs had acute onset and rapid development of clinical signs, and were designated as acute fulminating myasthenics. The remaining 12 dogs were classified as generalized myasthenics. All 4 dogs with acute fulminating myasthenia gravis had megaesophagus, 2 had facial muscle weakness, and 1 had pharyngeal muscle weakness. Ten of the 12 dogs with generalized myasthenia gravis had megaesophagus, 4 had facial muscle weakness, 4 had pharyngeal muscle weakness, and 3 had laryngeal muscle weakness. Historical or clinical evidence of exercise-associated appendicular weakness was found in only 6 of the 12 (50%) dogs with generalized myasthenia gravis, and in none of the dogs with acute fulminating myasthenia gravis. Seven of the 12 dogs with generalized myasthenia gravis had weakness primarily (n = 1) or exclusively (n = 6) of the pelvic limbs. Two of the 4 dogs with acute fulminating myasthenia gravis had primarily pelvic limb weakness. Twelve of the 25 dogs (48%) died or were euthanized shortly after admission to the hospital due to aspiration pneumonia. The dogs with acute fulminating myasthenia gravis had a markedly higher 1-year mortality rate in comparison with the other 2 groups. The use of immunosuppressive therapy had a significant positive effect on patient survival, regardless of the type of myasthenia gravis. This investigation demonstrates that acquired myasthenia gravis in dogs is a disorder with a wide spectrum of clinical forms, similar to the analagous disorder in people.     

Postweaning growth of unselected Hereford and Angus cattle fed two different diets

Two unselected herds of purebred Hereford and Angus cattle were created and their progeny evaluated during a 4-yr period (1964 to 1967) for 168-d postweaning gain when they were fed either a high- or medium-energy diet. Birth weight and 200-d adjusted weaning weight also were measured and the importance of sire x diet interactions for postweaning gain examined. Year effects were significant (P less than .001) for all traits in Herefords and for postweaning gain in Angus. Postweaning gain of both breeds increased in successive years, but no trend was observed for birth and 200-d weights. Bulls were heavier than heifers (P less than .05) for all three traits in both breeds. Hereford and Angus calves receiving the high-energy diet gained more (P less than .001) than their contemporaries fed the medium-energy diet. Sire differences were significant for birth weight in Herefords and for all three traits in Angus. Sire x diet interactions were not significant for postweaning gain in either breed. Genetic correlations were calculated by two methods: the two-way ANOVA approach using sire and sire x diet interaction variance components and the one-way ANOVA approach in which gains by progeny of each sire on each diet were considered to be two distinct traits. The genetic correlations for gain in Herefords could not be estimated by either method because of negative sire variance component estimates. The genetic correlations for gain in Angus were 1.08 for the two-way ANOVA method and 1.43 +/- .64 for the one-way ANOVA method. These results indicate that sires ranked the same based on progeny performance when fed either diet.     

Factors influencing difficulty of removing pelts from lamb carcasses.

Forty-eight Suffolk x white-faced ram and wether lambs approximately 5, 7, or 9 mo of age were slaughtered to evaluate the effects of age and gender on difficulty of pelt removal, pelt damage, and leg damage. A commercial belt-type pelt puller and a scale that recorded force required to remove the pelt from the thickest part of the legs was used as lambs hung suspended from their front legs. Rams required more force (P less than .05) to remove the pelt than wethers, and the difference between genders became larger as age increased. Neither pelt damage due to grain crack nor leg damage judged by amount of fell and fat removed by the pelt puller changed with age. Rams possessed thicker pelts (P less than .05) than wethers; this plus a greater amount of collagen crosslinking in ram skins could be responsible for the slightly smaller amount of grain crack observed in ram pelts. Factors involved in difficulty of pelt removal in ram lambs included age, splenius weight, and overall maturity. Difficulty of pelt removal in wether lambs was best predicted by including age and splenius weight in the model. These data tend to support packers' common practice of discounting rams over 5 mo of age because rams develop masculine characteristics and become harder to dress with increasing age.     

Reference serum biochemical values for emus and ostriches.

Reference serum biochemical values were determined in blood samples from 15 male, 18 female, and 4 unsexed emus (Dromaius novaehollandiae) 1 to 48 months old. Serum biochemical values also were obtained for 19 male, 26 female, and 4 unsexed ostriches (Struthio camelus) 1 to 60 months old. Parametric (mean +/- 2 SD) and non-parametric (fifth to 95th percentile) reference ranges and linear trends as influenced by age were determined for enzyme activities and concentrations of glucose, inorganic phosphate, BUN, uric acid, creatinine, triglyceride, cholesterol, total protein, and albumin. Species differences for all analytes, except cholesterol and inorganic phosphate concentrations, were detected. Creatine kinase values in ostriches were higher than those in emus. There were no linear relationships between age and analyte values in emus, and sex did not significantly (P < 0.05) affect the values in emus. Analyte values in ostriches tended to increase with age, but cholesterol, creatine kinase, inorganic phosphate, and alkaline phosphatase concentrations decreased with age. Glucose, triglyceride, gamma-glutamyltransferase, and cholinesterase concentrations in ostriches were not linearly associated with age. Age had a greater effect on the analyte values of female ostriches than it did on male ostriches. Concentrations generally increased with age in female ostriches, except for cholesterol, cholinesterase, inorganic phosphate, and alkaline phosphatase concentrations, which decreased with age.     

Isolation and characterisation of bacteria from pyothorax (empyaemia) in cats

Samples from 19 cases of feline empyaemia were examined. All cases had no prior treatment and specimens were collected by thoracocentesis after preparation of the skin as for aseptic surgery. Of the 87 bacterial strains isolated, 70 (80.5%) were anaerobes and 17 (19.5%) were facultative anaerobes. Fourteen cases contained mixtures of anaerobes and facultative anaerobes, and five contained anaerobes only. Bacteroides was the most commonly isolated genus (42.5% of all isolates). Clostridium villosum (16.1%) was the most frequently isolated bacterial species followed by Peptostreptococcus anaerobius and Pasteurella multocida (each 12.6%). The most commonly isolated anaerobic species was Clostridium villosum sp.nov. (20% of anaerobic isolates and 16.1% of all isolates) and Pasteurella multocida was the most commonly isolated facultatively anaerobic species (64.7% of facultative isolates and 12.6% of all isolates).     

Particle size reduction during initial mastication of forages by dairy cattle

Four experiments were conducted with dairy cattle to determine the effects of initial feed particle size and moisture content on particle size of ingested masticates. Three mature Holstein cows were used in either latin square or Youden square designs. Samples of masticated and ingested boli were collected at the cardiac opening through a ruminal fistula between 0 and 5, 5 and 10 and 10 and 15 min after meal initiation. In Exp. 1, masticate log mean particle sizes (LMPS) (ln microns, log normal distribution) were 3.50, 3.53 and 3.50 for corn silage, fine-chopped alfalfa haylage and coarse-chopped alfalfa haylage, respectively. In Exp. 2, boli LMPS for ground, chopped and long alfalfa hay were 3.11, 3.76 and 4.09, respectively. Boli LMPS in Exp. 3 for ground, chopped and long timothy hay were 2.93, 3.12 and 3.03, respectively. Exp. 4 compared the effect of addition of water to produce 30%, 47%, 64% and 82% DM in chopped alfalfa hay. Boli LMPS were 3.66, 3.56, 3.64 and 3.68 for the respective alfalfa hay DM contents. Feed LMPS was not reduced during mastication in Exp. 4, nor were there differences in LMPS due to time after feeding. Boli LMPS was affected by feed particle size of alfalfa hay, but there was no effect of feed particle size on masticate particle size in timothy hay. The magnitude of particle size reduction during mastication appears to be dependent on forage type and is not dependent totally on initial feed particle size and DM content of forages.     

Cauda equina syndrome in the dog: Radiographic evaluation

Dogs with clinical signs typical of cauda equina syndrome require careful evaluation to determine the cause of the disease as this strongly influences choice of treatment. Possible aetiologies include congenital or developmental, inflammatory, traumatic, neoplastic, and degenerative lesions that may involve vertebrae, vertebral joints, intervertebral discs, spinal cord, spinal nerves, or meninges. It must be determined whether clinical signs are due to musculoskeletal or neurological disease before performing special radiographic procedures. Non-contrast radiography permits false-positive diagnosis of obvious degenerative changes involving the L-S disc that may be without clinical signs or permits a false-negative diagnosis due to the failure to appreciate soft tissue lesions not seen radiographically. Special radiographic techniques are recommended and include: (1) stress radiography, (2) discography, and (3) epidural myelography. Evaluation of the results of these studies assists in determining the cause of the cauda equina syndrome and the type of therapy required.     

Colonization characteristics of Campylobacter jejuni in chick ceca

We report our findings on several parameters influencing cecal colonization of chickens by Campylobacter jejuni. Thirty-five colony-forming units (CFU) of a composite culture of C. jejuni colonized the ceca of one-half of the newly hatched chicks challenged by oral gavage. A challenge dose of 3500 CFU/chick consistently colonized the ceca of all chicks challenged. Challenge doses of approximately 10(5) CFU of C. jejuni per chick resulted in consistent cecal colonization, regardless of whether the birds were challenged 1, 2, or 3 days post-hatch. Four isolates showed consistently strong cecal colonization abilities, whereas two isolates colonized the ceca in only 20 of 122 chicks when given levels of 10(5) CFU per chick. One of these poorly colonizing isolates was repeatedly transferred by fecal-oral passage through chicks; subsequently, this isolate was able to consistently colonize chicks. Competitive exclusion (CE) microflora did not diminish the colonization rates for C. jejuni. Birds treated with five different CE cultures were colonized at a rate of 81 of 84 chicks; control chicks were similarly consistently colonized (45 of 46 chicks).     

Haematological and biochemical values in horses naturally infected with Strongylus vulgaris

The concentrations of serum proteins (beta 1, beta 2, gamma, alpha 1, alpha 2 globulins and albumin) and absolute numbers of eosinophils, neutrophils and lymphocytes were examined in 64 naturally infected horses and ponies in which the number of larvae of Strongylus vulgaris in the cranial mesenteric artery and the severity of the lesion of verminous arteritis could be determined. The horses were grouped according to the number of larvae found and the severity of the arteritis. The results demonstrated that, although some significant deviation from a random distribution occurred in certain of the values (chi 2 test), there was considerable individual variation in the values obtained for individual animals within groups and overlap of the range of values between groups. Also the number of larvae present in the artery did not necessarily accurately reflect the severity of the arterial lesion. Thus, the parameters examined could not be used reliably to estimate the intensity of infection with S vulgaris in an individual animal.