An outbreak of sodium fluoroacetate (1080) intoxication in selenium- and copper-deficient sheep in California.

Sodium fluoroacetate is an organofluorine compound toxic to mammals, insects, and birds, currently registered for use only in livestock protection collars as a predacide in some North American states, with restricted use in California. A flock of 445 lambs and ewes in California were moved into a native pasture on a municipal refuse disposal site. Within 24 hours, 14 ewes were found dead, and the remaining sheep were moved off the site. Both ewes and lambs exhibited disoriented running, followed by apparent blindness, weakness, ataxia, coma, and death. Over the next 4 days, 63 ewes and 80 lambs died with a peak at 3 days after grazing the suspect pasture (157/445, 35% mortality). Two dead 4-month-old lambs and 2 ewes were submitted to the California Animal Health and Food Safety laboratory for necropsy. Grossly, there were bilateral diffuse pulmonary congestion and edema, hydrothorax and hydropericardium with fibrin clots, and multifocally extensive areas of epicardial petechiae, ecchymoses, and pallor. In 1 ewe, there was regional caudodorsal pulmonary hemorrhage and intraluminal tracheal clotted blood. Microscopically in all cases, there was multifocal acute myocardial degeneration and necrosis with nonsuppurative pleocellular myocarditis. Sodium fluoroacetate was detected in kidney from a lamb and a ewe at 27.5 and 12.5 parts per billion, respectively. All sheep were selenium deficient, and concurrent copper deficiency was diagnosed in 3. The pathological and toxicological findings were consistent with 1080 poisoning, possibly exacerbated by micronutrient deficiency. This outbreak raised an alert about the use of restricted products with potential lethal effect in animals in California.

Risk factors for transmission and methods for control of caprine arthritis-encephalitis virus infection.

The major route of transmission of caprine-encephalitis virus (CAEV) is through the ingestion of CAEV-infected colostrum or milk. Less efficient routes of transmission are associated with prolonged contact with infected goats and are reviewed in this article. Prevention of CAEV is based on the removal of kids from their dam at birth, and feeding the kids heat-treated colostrum and pasteurized milk until weaning. Serologic testing and segregation or culling of seropositive goats is necessary to minimize horizontal transmission of CAEV.

Cervical and thoracic vertebral malformation ("weak neck") in Colombia lambs.

The purpose of this study is to describe a developmental defect of the caudal cervical and cranial thoracic vertebrae in 11 purebred Colombia lambs. The lambs were either affected at birth, or developed the condition within the first 18 days of age. Cervicothoracic kyphosis, with a compensatory cervical lordosis and ataxia were common; 8 lambs had abnormal head posture, characterized by inability to lift the head from the ground. One lamb had rigid head and neck, and had to move the entire body to look to the left or right. Neurological signs included ataxia, tetraparesis, diminished conscious proprioception, and increased patellar and triceps reflexes. One lamb had inspiratory stridor because of compression of the trachea in the area overlying the abnormal vertebrae (cervical vertebrae 6 [C6] and 7 [C7]). Radiographic and pathological abnormalities included malalignment and malarticulation of the caudal cervical and cranial thoracic spine, rounded cranioventral margins in the bodies of vertebrae C7 and T1, wedging of the intervertebral disc spaces between C6 and T1 vertebrae, and hypoplasia of the dens. Pathological changes in the soft tissues included hypoplasia of the cervical epaxial and hypaxial musculature, with associated focal areas of myodegeneration. Mild Wallerian axonal degeneration, compatible with a mild cord compression syndrome, was found in 3 lambs in the cervicothoracic spinal cord adjacent to the vertebral anomalies. The concentrations of copper and selenium in blood, plasma, or tissues were normal in 10 of 11 lambs. All but one of the lambs in which pedigree information was provided were genetically related. Siblings born as twins to 5 of the affected lambs were normal, but both lambs from one twin pregnancy were affected. Owners reported that breeding stock had been shared among the ranches. Because of the close familial relationships of the affected lambs, the condition is suspected to have a hereditary basis.

Apparent gossypol-induced toxicosis in adult dairy goats.

Consumption of a cotton-seed meal-based mineral supplement (cattle label) and a concentrate dairy mix (goat label) resulted in gossypol toxicosis in 3 adult dairy goats. The primary clinical signs were limb swelling and stiffness, ventral abdominal edema, and anorexia. All does died within a few days of the onset of illness. Necropsy revealed generalized subcutaneous edema, acute centrilobular necrosis of the liver, and myocardial fibrosis, consistent with a diagnosis of gossypol toxicosis. It was estimated that the does had consumed from 348 to 414 mg of free gossypol/d for at least 3 months. Apparent gossypol toxicosis in goats consuming this amount of free gossypol indicates that goats may be more susceptible than cattle to this substance.

Delayed seroconversion following naturally acquired caprine arthritis-encephalitis virus infection in goats.

One hundred eight milking goats from a dairy that had been using a modified caprine arthritis-encephalitis virus (CAEV) eradication program were tested for CAEV antibodies by serologic methods and for proviral CAEV DNA by use of polymerase chain reaction (PCR) technology. All goats were free of clinical symptoms of CAEV infection. Twenty-seven of the 108 goats were considered seropositive, on the basis of ELISA results. Proviral CAEV DNA was detected, using PCR techniques, in mononuclear leukocytes in blood samples obtained from 25 of the these 27 seropositive goats. Twenty of the 81 seronegative goats also had positive PCR test results. Ten of these goats seroconverted by 8 months later, and virus was readily isolated from mononuclear leukocytes in venous blood samples after the goats had seroconverted. Virus was also isolated from mononuclear leukocytes in blood samples collected from 4 of 11 goats that were seronegative, but had positive PCR test results. These results indicated that seroconversion can be delayed for many months following natural infection with CAEV. Delayed seroconversion appears to be a feature of CAEV infection, which may have direct implications for CAEV eradication programs and epidemiologic studies that rely on serologic methods to detect infected goats.

Accidental superphosphate fertilizer poisoning in pregnant ewes.

Consumption of superphosphate fertilizer by 200 pregnant ewes resulted in signs of toxicosis in 41 ewes, 14 of which died. Predominant clinical signs were marked teeth grinding, voluminous diarrhea, CNS depression, apparent blindness, and a stiff-legged atactic gait. Biochemical abnormalities were hypocalcemia, hypoglycemia, and a high anion gap. The primary toxic principal in superphosphate fertilizers is the fluorine contaminant; however, calcium pyrophosphate and calcium orthophosphate also contribute to toxicosis, which results in acute proximal renal tubular necrosis. Voluntary consumption of superphosphate fertilizer in well-fed livestock is not expected, and was believed to be related to the lack of availability of salt.

Cohort study of natural transmission and two methods for control of caprine arthritis-encephalitis virus infection in goats on a California dairy.

A prospective observational cohort study of 361 dairy goat kids was conducted to compare 2 methods of controlling caprine arthritis-encephalitis virus infection under commercial dairy conditions. To compare effectiveness of feeding kids pasteurized milk vs serologic testing and segregation in addition to pasteurized milk feeding, goats were monitored up to the age of 30 months by use of monthly agar gel immunodiffusion testing. Survival analysis methods were used to determine whether age at seroconversion differed between the 2 groups. Significantly lower rates of seroconversion were observed in the segregated group (P < 0.001), compared with the nonsegregated group. Of 193 goats in the pasteurized milk-only group, 146 (75.6%) seroconverted within the 30-month study period, whereas infection was detected in 39 (23.2%) of 168 goats in the test/segregated group. Nonsegregated goats were 3.37 times more likely to seroconvert by 24 months of age, and 70.3% of seroconversions by 24 months of age could be attributed to nonsegregation. For age-specific intervals beyond 180 days of age, 70 to 100% of seroconversions could be attributed to lack of segregation. Cohort life tables for age at seroconversion were reported for each group. Type of colostrum fed, sex, and weaning group (season) were not significantly associated with age at seroconversion. Saanen goats had lower age-specific risk of seroconversion in the nonsegregated group alone and overall. Non-Saanen goats wee 1.5 times more likely to seroconvert than were Saanen goats, when adjusted for a possible confounding effect of weaning group. Results indicate that pasteurized milk feeding and routine test and segregation would be a substantially more effective means of control of the disease in dairy goat herds than would pasteurized milk feeding alone.

Risk factors associated with the incidence of seroconversion to caprine arthritis-encephalitis virus in goats on California dairies.

Incidence of seroconversion to caprine arthritis-encephalitis virus (CAEV) was determined for 1,194 goats on 11 dairies, using 2 repeated annual herd tests for CAEV. Current life table methods were used to compare age-specific incidence of seroconversion for pasteurized milk-raised and unpasteurized milk-raised goats. Logistic regression models were used to determine the risk factors associated with CAEV seroconversion, and to estimate odds ratios for seroconversion for various factor levels. Goats raised by unpasteurized milk-feeding methods were 2.5 to 6.7 times more likely to seroconvert than were goats raised by pasteurized milk-feeding methods, depending on the method of comparison. Similarly, 61.6 to 85.0% of seroconversions in yearling goats possibly were attributable to unpasteurized milk feeding. Among yearling goats, CAEV seroconversion was associated with feeding method, breed, and source of goat (herd of origin) when the effect of dairy was considered. In addition to the 6.7 times greater risk of seroconversion for unpasteurized milk-raised goats, yearling goats of the Saanen and Toggenburg breeds were 2.2 and 3.3 times, respectively, more likely to seroconvert than were Alpine yearling goats. Yearling goats purchased from another source were less likely to seroconvert than were yearlings raised on the dairy where they were studied. Among goats > 1 year old, age was associated with risk of seroconversion. Goats that were 3 years old or were > or = 4 years old were 1.7 and 3.2 times, respectively, more likely to seroconvert than were 2-year-old goats, when adjusted for effect of dairy. The effects of dairy were significant (P < or = 0.001) in yearling and older goats.

Risk factors associated with caprine arthritis-encephalitis virus infection in goats on California dairies.

Log-linear methodology was used to examine relations among caprine arthritis-encephalitis virus (CAEV) seroreactivity and host/management factors in a cross-sectional study of 2,826 goats on 13 California dairies. The CAEV serologic status was associated with age and feeding method (pasteurized/unpasteurized milk), but not with breed. Data from a prevalence survey of 321 goats from 2 additional dairies demonstrated very good fit of the selected log-linear model (P = 1.00), indicating that the model was very appropriate to describe the relations. Odds of seropositivity and odds ratios were generated by use of a logit model derived from the log-linear model. Goats raised by the unpasteurized feeding method were estimated to have been 3.3 times more likely to be CAEV-seropositive than goats fed by the pasteurized method, when adjusted for the effects of age. Goats aged 2, 3, 4, and 5 or greater years were estimated to have been 1.7, 2.6, 4.5, and 5.7 times, respectively, more likely to be CAEV-seropositive than were yearling goats when ratios were adjusted for pasteurization status. Breed, gender, and herd of origin were not associated with CAEV seroreactivity when the effects of other factors were considered. Estimated odds of CAEV seroreactivity and the associated odds ratios for combinations of factor levels are reported. In this study, the magnitude and direction of the associations among CAEV serologic status, age, and pasteurized feeding methods were demonstrated.

Abomasal dilatation and emptying defect in a flock of Suffolk ewes.

Abomasal dilatation and emptying defect was identified in 14 of 130 Suffolk sheep from a single flock in northern California. Abomasal dilatation and emptying defect was diagnosed in 13 of the sheep between November 1986 and April 1987. All affected sheep were ewes and in all, the condition developed during the lambing season. Clinical signs consisted of chronic anorexia and weight loss. Laboratory data from affected ewes reflected concurrent disease and was not helpful in diagnosis of the disease. Necropsy of 13 affected ewes revealed a distended, ingesta-filled abomasum in all of them. The brain stem of 6 ewes was examined, and lesions suggestive of scrapie were not observed. Pedigree analysis determined that in this flock, abomasal dilatation and emptying defect development was independent of sire. A relationship between the age of affected ewes and the disease was not found. Treatment was unsuccessful in 13 ewes, but 1 recovered after treatment with metoclopramide.

Risk factors associated with mastitis in dairy goats.

Prevalence of intramammary infection in healthy goats was determined from 4,662 composite udder samples taken over a 9-month period. For each doe, a colostral sample and 2 milk samples were collected. Breed, age, number of days not lactating before kidding, number of lactation days, and kidding date were recorded. Coagulase-negative Staphylococcus spp were isolated from 17.5% of does, Staphylococcus aureus from 3.1%, Mycoplasma spp from 1.2%, Streptococcus spp from 0.3%, and gram-negative bacteria from 2.0%. Gram-negative organisms were associated with intermittent infections, whereas coagulase-negative staphylococci were associated with persistent infections. Intramammary infection was related to breed, number of days not lactating, and number of lactation days, as determined by log-linear analysis. Does of the Nubian breed, does with nonlactating periods of greater than 60 days, and does in the first and last third of a standard 305-day lactation appeared to be at higher risk for intramammary infection.

Serologic prevalence of caprine arthritis-encephalitis virus in California goat dairies.

Fifty-three percent of goats in 13 California goat dairies had antibodies to caprine arthritis-encephalitis virus (CAEV), as determined by agar-gel immunodiffusion. Those goat dairies that reared kids on pasteurized milk had a lower seroprevalence than those that did not. Age, rearing kids on unpasteurized milk, and the presence of large joints were associated with antibodies to CAEV. Breed was associated with seroreactivity, but the association was confounded by other factors. Sex was not associated with antibodies to CAEV. The relationship between age and antibodies to CAEV was observed for goats reared on pasteurized or unpasteurized milk, which indicated that continued horizontal (contact) transmission may be important on these dairies and limited the effect of a pasteurized rearing program on control of CAEV infection.

Caprine encephalomyelomalacia.

Six cases of encephalomyelomalacia in dairy goats 3 1/2 to four months of age are described. Neurologic signs had an abrupt onset and passed rapidly from ataxia to paralysis. All goats were killed after six to ten days and had spinal cord and brain stem lesions--always more extensive and severe in the cord. The bilaterally symmetrical necrotic lesions were restricted to the ventral and intermediate gray substance in the cord and to certain brain stem nuclei. The spinal cord enlargements were affected especially.

Milkborne outbreak of Mycoplasma mycoides subspecies mycoides infection in a commercial goat dairy.

A commercial goat dairy comprised of about 300 lactating does suddenly began to have a problem with polyarthritis in the kids and clinical mastitis in the does. The problem began 3 to 4 weeks following the introduction of 27 lactating does from a herd with a history of mastitis caused by Mycoplasma mycoides subsp mycoides (Mmm). Over 2 kidding seasons (about 12 months), approximately 170 kids and 70 does died or were euthanatized. Affected kids were 2 to 8 weeks old, had multiple warm swollen joints, body temperature of 40.8 to 41.5 C, marked weight loss, and pneumonia. All were lame and some experienced so much discomfort that they were unable to get up. The predominant necropsy finding was severe fibrinopurulent polyarthritis, but fibrinous pleuritis, fibrinous pericarditis, interstitial pneumonia, and bronchopneumonia also were found in some kids. Culturing of affected joints and of bulk tank milk yielded large numbers of Mmm. The outbreak was terminated by feeding heat-treated colostrum (56 C for 1 hr) and pasteurized milk to kids. Milk from the does was cultured repeatedly; by this procedure, the does shedding Mmm in the milk were identified and culled.