Allele frequency and likely impact of the glycogen branching enzyme deficiency gene in Quarter Horse and Paint Horse populations.

Glycogen Branching Enzyme Deficiency (GBED), a fatal condition recently identified in fetuses and neonatal foals of the Quarter Horse and Paint Horse lineages, is caused by a nonsense mutation in codon 34 of the GBE1 gene, which prevents the synthesis of a functional GBE protein and severely disrupts glycogen metabolism. The aims of this project were to determine the mutant GBE1 allele frequency in random samples from the major relevant horse breeds, as well as the frequency with which GBED is associated with abortion and early neonatal death using the tissue archives from veterinary diagnostic laboratories. The mutant GBE1 allele frequency in registered Quarter Horse, Paint Horse, and Thoroughbred populations was 0.041, 0.036, and 0.000, respectively. Approximately 2.5% of fetal and early neonatal deaths in Quarter Horse-related breeds submitted to 2 different US diagnostic laboratories were homozygous for the mutant GBE1 allele, with the majority of these being abortions. Retrospective histopathology of the homozygotes detected periodic acid Schiff's (PAS)-positive inclusions in the cardiac or skeletal muscle, which is characteristic of GBED, in 8 out of the 9 cases. Pedigree and genotype analyses supported the hypothesis that GBED is inherited as a simple recessive trait from a single founder. The frequency with which GBED is associated with abortion and neonatal mortality in Quarter Horse-related breeds makes the DNA-based test valuable in determining specific diagnoses and designing matings that avoid conception of a GBED foal.

Transplacental toxoplasmosis in a reindeer (Rangifer tarandus) fetus.

Toxoplasma gondii infection was diagnosed in a full term stillborn reindeer (Rangifer tarandus) fetus. The fetus had encephalitis and placentitis associated with T. gondii. Tissue cysts were identified histologically in sections of brain and tachyzoites were present in placenta and the myocardium. Protozoa in the brain, heart, and placenta stained positively with T. gondii antibodies, but not with Neospora caninum antibodies in an immunohistochemical test. The dam of the fetus had a 1:12,800 titer to T. gondii in the modified agglutination test employing whole tachyzoites and mercaptoethanol. This is the first confirmed report of T. gondii infection in reindeer.

Bilateral aural hyalohyphomycosis in sable antelope (Hippotragus niger).

Three juvenile sable antelope (Hippotragus niger) were diagnosed with bilateral aural hyalohyphomycosis based on histopathology. All three animals were suspected to be immunodeficient based on low IgG levels determined using the zinc sulfate turbidity test. The serum and hepatic copper levels of one animal were below the bovine reference range. Clinical signs in the three animals included bilateral ventral deviation of the pinnae with multifocal subcutaneous aural tumefaction and poor body condition. Numerous septate, nonpigmented fungal hyphae were found within the auricular cartilage, dermis, and subcutaneous granulomas. No significant fungal agents were isolated by culture, and no signs of systemic fungal dissemination were identified except for a concurrent fungal rhinitis in one animal.

Hydrocephalus associated with Neospora caninum infection in an aborted bovine fetus.

This paper describes Neospora caninum-associated hydrocephalus in an aborted Hereford bovine fetus of 7 months' gestational age. Numerous tachyzoites were observed in areas of the cerebrum with lesions of non-suppurative necrotizing encephalitis.

Reproductive effects of fenoxycarb on sheep.

Fenoxycarb (ethyl [2-(4-phenoxyphenoxy)-ethyl] carbamate) is an insect growth regulator used for long-term fire ant control. Because of its effects on insect reproduction and its potential use on pasturage consumed by food animals, a reproductive study was conducted using Rambouillet sheep. The sheep were dosed daily with a placebo or with fenoxycarb at 0.69 or 1.38 mg/kg/day, representing ten (10x) and 20 times (20x) the maximum amounts of fenoxycarb in forage or hay treated at recommended levels for fire ant control. Parameters that were measured included rates of weight gain of adults, serum clinical chemistry profiles of adults, spermatozoal morphology and motility, estrus cycling, pregnancy rates, maintenance of pregnancies to term, numbers of live births, and rates of weight gain of lambs to 28 days. There were no statistically significant (P < or = 0.05) differences between the exposed and control groups of sheep in any of these facets of the study. No clinical signs associated with exposure to fenoxycarb were observed in any animal at any time, and no exposure-related pattern of pathologic lesions or reproductive organ histology was observed. Means of hepatic fenoxycarb residues in the rams followed a statistically significant (P < or = 0.05) dose-related pattern. No fenoxycarb was detected (detection limit of 5 ppb) in any neonatal liver, despite the presence of hepatic fenoxycarb residues in the treated ewes, indicating that transplacental transport of fenoxycarb was minimal. No fenoxycarb was detected in any lamb liver at 28 days, although both the colostrum and the milk of exposed ewes were found to contain fenoxycarb at levels proportional to the treatments. Based on the lack of significant findings in this study, it is unlikely that use of fenoxycarb, according to label instructions (currently applicable to homeowner and registered agricultural usage) for fire ant control in pasturage or hay fields, will affect ruminant reproduction.

Scrotal hydrocele secondary to ascites in 28 bulls.

Twenty-eight of 104 mature bulls in a herd were examined to determine the cause of scrotal enlargement. Ascites was determined as the source of a transudate that accumulated in and expanded the scrotal vaginal cavity to induce a scrotal hydrocele. In our experience, scrotal hydrocele in mature bulls usually is caused by the accumulation of fluids in the scrotal vaginal cavity without evidence of local inflammation or traumatic lesions. In the bulls reported here, ascites was associated with intestinal edema that was tentatively attributed to a hypersensitivity reaction to gastrointestinal nematodes. Ascites in mature bulls with scrotal hydrocele in which primary lesions of the scrotum and scrotal contents are not detected should induce practitioners to perform additional diagnostic procedures to determine the cause of the fluid.

Estimation of genotype distributions and posterior genotype probabilities for beta-mannosidosis in Salers cattle.

beta-Mannosidosis is a lethal lysosomal storage disease inherited as an autosomal recessive in man, cattle and goats. Laboratory assay data of plasma beta-mannosidase activity represent a mixture of homozygous normal and carrier genotype distributions in a proportion determined by genotype frequency. A maximum likelihood approach employing data transformations for each genotype distribution and assuming a diallelic model of inheritance is described. Estimates of the transformation and genotype distribution parameters, gene frequency, genotype fitness and carrier probability were obtained simultaneously from a sample of 2,812 observations on U.S. purebred Salers cattle with enzyme activity, age, gender, month of pregnancy, month of testing, and parents identified. Transformations to normality were not required, estimated gene and carrier genotype frequencies of 0.074 and 0.148 were high, and the estimated relative fitness of heterozygotes was 1.36. The apparent overdominance in fitness may be due to a nonrandom sampling of progeny genotypes within families. The mean of plasma enzyme activity was higher for males than females, higher in winter months, lower in summer months and decreased with increased age. Estimates of carrier probabilities indicate that the test is most effective when animals are sampled as calves, although effectiveness of the plasma assay was less for males than females. Test effectiveness was enhanced through averaging repeated assays of enzyme activity on each animal. Our approach contributes to medical diagnostics in several ways. Rather than assume underlying normality for the distributions comprising the mixture, we estimate transformations to normality for each genotype distribution simultaneously with all other model parameters. This process also excludes potential biases due to data preadjustment for systematic effects. We also provide a method for partitioning phenotypic variation within each genotypic distribution which allows an assessment of the value of repeat measurements of the predictive variable for genotype assignment.

Protozoal abortion in a herd of cattle concurrently infected with Hammondia pardalis.

Protozoal infection was diagnosed as the cause of abortion in a large drylot dairy herd located in northeastern Mexico. Diagnosis was made on the basis of finding encephalitis, myocarditis, protozoal cysts, and protozoal tachyzoites in aborted fetuses. The blended ration fed to the cows had been contaminated by the feces of a large resident population of feral domestic cats that used components of the blended ration for den sites (stored hay) or as a latrine (grain). The cows that aborted contained tissue phases of a protozoan infective for domestic cats. The morphologic features of the oocyst and biologic features of the protozoan were identical to those of Hammondia pardalis.

Bovine plasma beta-mannosidase activity and its potential use for beta-mannosidosis carrier detection.

Plasma beta-mannosidase activities were determined for Salers cattle from 8 herds as an evaluation of this method for detection of beta-mannosidosis heterozygotes. Several biological factors, such as age, gender, herd, and risk of being a beta-mannosidosis carrier, were considered in this study. The mean enzyme activity for obligate heterozygotes (n = 8) was 55 U/ml (range = 43-65 U/ml), which was 59% of the mean enzyme activity for cattle that were low risk for being a carrier. These data indicate that bovine beta-mannosidosis is characterized by a gene dosage effect. The analytical and biological variation of plasma beta-mannosidase activity that was observed necessitates limiting the test to adult fullblood/purebred Salers cattle within a herd. Plasma beta-mannosidase analysis provides important information for intraherd selection of Salers cattle that are heterozygous for beta-mannosidosis.

Neuropathology of bovine beta-mannosidosis.

beta-Mannosidosis, an inherited defect of glycoprotein catabolism previously identified in goats and humans, has been recently diagnosed in Salers cattle. This disorder is associated with deficiency of lysosomal beta-mannosidase and accumulation of oligosaccharides. Analysis of bovine beta-mannosidosis neuropathology was initiated to determine whether independently arising gene defects in cattle and goats result in expression of similar lesions. Brain, spinal cord, and selected peripheral nerves from seven affected newborn Salers calves and three normal newborn calves were available for gross, light microscopic, and electron microscopic analysis. Gross examination revealed hydrocephalus of variable severity and myelin deficiency in the cerebral hemispheres, cerebellum, and brainstem. Microscopic examination revealed cytoplasmic vacuolation, myelin deficiency, and axonal spheroids of similar type and distribution to that reported in affected goats. Cytoplasmic vacuolation resulting from lysosomal storage showed consistent variation among cell types. Myelin deficits were more severe in the cerebral hemispheres and cerebellum than in the spinal cord. Axonal spheroids occurred in the cerebrum, brainstem, cerebellum, and trigeminal nerve endings. The presence of similar lesions in bovine and caprine beta-mannosidosis supports a direct relationship with the gene defect.

Thyroid structure and function in bovine beta-mannosidosis.

In bovine beta-mannosidosis, the thyroid in the affected newborn shows marked cytoplasmic vacuolation. There is an associated reduction in the serum concentrations of thyroxine and tri-iodothyronine.

Beta-mannosidosis in twelve Salers calves.

A diagnosis of beta-mannosidosis, a lysosomal storage disease caused by a deficiency of beta-mannosidase, was made in 12 purebred Salers calves. Affected neonatal calves were unable to rise and had intention tremors, hidebound skin, slightly domed calvaria, slight prognathism, and narrow palpebral fissures. Postmortem findings included variable dilatation of the lateral cerebral ventricles, marked pallor and paucity of white matter of the cerebrum and cerebellum, and mild to marked bilateral renomegaly. Microscopic lesions consisted of clear, intracytoplasmic vacuoles, which were especially prominent in neurons, thyroid follicular cells, proximal renal tubular epithelium, and reticuloendothelial cells. By ultrastructural examination, the intracytoplasmic vacuoles were identified as membrane-bound lysosomes distended by lucent material. The serum of affected calves was profoundly deficient in beta-mannosidase. Oligosaccharides, principally a trisaccharide with a terminal hexose in the beta-anomeric configuration, accumulated in tissues of affected calves. The percentage (37.2) of affected calves from groups of siblings, the approximately equal sex ratio, and the phenotypic normalcy of the parents of affected calves are compatible with an autosomal recessive mode of inheritance typical of other glycoproteinoses.

Bovine abortion and death associated with consumption of aflatoxin-contaminated peanuts.

Approximately 12% of a herd of 68 crossbred cows aborted third-trimester fetuses after consuming moldy peanuts for 4 days. Further investigation revealed that less than 20% of the herd had access to this supplemental feed. Results of serum biochemical analysis indicated liver damage in the affected cows. All of these cows died within 8 days of aborting. The peanuts contained 77 micrograms aflatoxin B1/g, as determined by liquid chromatography. Tissues were submitted from 1 cow, and liver contained 5 ng aflatoxin B1/g. Results of other laboratory tests were negative for common toxins and abortifacients.

Treatment of giardiasis in adult Greyhounds, using ipronidazole-medicated water.

Two of 3 adult Greyhounds with clinical signs of giardiasis were treated by the addition of ipronidazole hydrochloride to their water supply (126 mg/L) for 7 days. Within 15 hours, the dogs had improved clinically, and large numbers of degenerating Giardia cysts were passed. After 54 hours, cyst shedding had ceased. The nontreated control dog continued to shed Giardia cysts. During an additional 7 days, the dogs were treated with ipronidazole-medicated water (378 mg/L) and remained clinically normal.

Effect of dihydrostreptomycin or oxytetracycline on reproductive capacity of bulls.

Young beef bulls (n = 27) were used in a trial to study the effect of dihydrostreptomycin sulfate (DHS) or oxytetracycline (OTC) hydrochloride on spermatogenesis, epididymal sperm maturation, and freezability of sperm. Nine of the bulls were given a 22 mg/kg dose of DHS twice, 12 hours between doses. Nine other bulls were treated with OTC--1 dose of 26.4 mg/kg of body weight, and then 6 more doses each of 17.6 mg/kg, ca 12 hours between doses. The remaining 9 bulls were nontreated controls. The treatment regimens with the 2 antibiotics were without effect on spermatogenesis. These treatments also were without effect on seminal pH, ejaculate volume, percentage of motile spermatozoa, rate of spermatozoal motility, or concentration of spermatozoa in ejaculates harvested on day 3 or 7 of the study (day 0 = 1st day of treatment). There was a treatment-by-day effect on spermatozoal concentration; the number of sperm per milliliter was markedly increased on day 3 for OTC-treated bulls. The increased spermatozoal concentration in the OTC-treated group was associated with an influence of the antibiotic on ejaculation. All bulls given this antibiotic ejaculated without palpable penile engorgement or erection on day 3. On day 7 the rate of spermatozoal motility was increased in the 2 treatment groups compared with the rate in the control bulls. Also on day 7, the percentage of motile spermatozoa was greater in the OTC-treated bulls than in the control or DHS-treated bulls.(ABSTRACT TRUNCATED AT 250 WORDS)

Catastrophic death losses in a dairy herd attributed to type D botulism.

Clostridium botulinum type D intoxication was diagnosed as the cause of death of 42 of 67 lactating cows in a southeast Texas dairy herd over an 11-day period. By necessity, the diagnosis was based on clinicopathologic findings, as the toxin could not, by standard laboratory tests, be demonstrated in affected cattle. The predominant clinical findings were hindlimb weakness/ataxia rapidly progressing to persistent recumbency. Affected cattle were alert until just before death, which occurred without notable agonal movements or respirations after 6 to 72 hours' recumbency. Abnormal laboratory findings included neutrophilic leukocytosis (all affected cattle), proteinuria (most affected cattle), slight elevations of serum aspartate transaminase and low serum inorganic phosphorus (some affected cattle), and patchy areas of hyperemia/congestion of the mucosa in the small intestine (postmortem examination of 3 affected cattle). This report confirms the findings of others with regard to the difficulty of demonstrating the causative toxin in C botulinum type D-intoxicated cattle and presents available information on the clinicopathologic features of this intoxication that may aid in the differentiation of this condition from other causes of down cows.

Serum progesterone concentration in pyometritic and normal postpartum dairy cows.

Two studies were conducted to evaluate the concentration of serum progesterone in pyometritic cows and relate it to palpation of ovarian structures per rectum . In Trial 1, serum samples from 34 pyometritic cows were assayed for progesterone. Mean serum progesterone concentrations were 6.8 +/- 0.7 ng/ml. In Trial 2, each of 54 pyometritic cows was paired with a control cow on the basis of days post partum (18-50 days). Mean concentration of progesterone was 9.7 +/- 1.0 ng/ml for the pyometritic cows and 5.7 +/- 0.8 ng/ml in control cows (P<0.005). Progesterone concentration was greater (P<0.005) in both groups of cows with palpable corpora lutea (CLs). Ninety-six percent of the pyometritic cows had palpable CLs compared to 57% of the control group. Comparing serum progesterone only in cows with a palpable CL, the mean concentration was still greater (P<0.005) in the pyometritic group (10.6 +/- 1.0 ng/ml) than the control group (6.6 +/- 1.0 ng/ml). Compatability of rectal palpation findings and concentrations of serum progesterone were 92.6% for the pyometritic group and 72.2% for the control group. Progesterone concentration increased (P<0.05) by increased days post partum in Trial 2 (n=54) but not in Trial 1 (n=23). In both Trials 1 and 2, uterine size due to pyometra increased (P<0.05) with increased days post partum. No other associations were found.