Postmortem diagnosis of preclinical and clinical scrapie in sheep by the detection of disease-associated PrP in their rectal mucosa

Samples of tissue from the central nervous system (cns), the lymphoreticular system (lrs) and the rectal mucosa of a large number of scrapie-exposed sheep, with and without signs of clinical disease, were examined immunohistochemically for evidence of disease-associated prion protein (PrP(d)). The rectal mucosa has received almost no attention so far in scrapie diagnosis, despite its abundant rectoanal mucosa-associated lymphoid tissue, and its accessibility. The scrapie-confirmed cases included 244 with clinical disease, of which 237 (97.1 per cent) were positive in the rectal mucosa, and 121 apparently healthy sheep, of which 104 (86 per cent) were positive in the rectal mucosa. PrP(d) was detected in 86.4 to 91.5 per cent of the other lrs tissues of the healthy sheep examined and in 77.7 per cent of their cns tissues. The stage of infection, therefore, affected the probability of a positive result in the rectal mucosa, whereas the breed, PrP genotype, age and sex had little or no independent effect. Accumulations of PrP(d) were observed in the rectal mucosa and other lrs tissues of vrq/arr sheep with preclinical and clinical scrapie, albeit with a lower frequency and magnitude than in sheep of other PrP genotypes. Western immunoblotting analyses of samples of rectal mucosa gave the characteristic PrP glycoprofile, with a sensitivity similar to that of immunohistochemistry.     

Characteristics, prevalence and aetiology of lesions of the oral mucosa in adult sheep

A total of 214 sheep with lesions of the oral mucosa were recorded at the Veterinary Laboratories Agency regional laboratories between March 15, 2002 and February 28, 2003. Using denominator data from the scrapie abattoir survey a prevalence of 0.95 per cent (95 per cent CI 0.82 to 1.10 per cent) was recorded, and using the fallen stock survey a prevalence of 1.15 per cent (95 per cent CI 0.64 to 1.91 per cent) was recorded. The lesions varied widely and included dental pad lesions in 20 per cent of cases. In total, 248 sites were affected, the commonest being the lower gum below the incisors, which was affected in 100 sheep. Most of the lesions were 1 cm or less in diameter. Ninety per cent of the 251 lesions examined histologically were erosions, ulcers, healed ulcers, focal epithelial necrosis or haemorrhages, and the changes observed indicated that trauma was the most likely primary cause.     

Prevalence, incidence, signs and treatment of clinical listeriosis in dairy cattle in England

The prevalence, incidence and clinical signs of listeriosis in dairy cattle in England were investigated by means of a postal questionnaire survey of 1500 dairy farmers. The response rate was 64.1 per cent. Overall the farm prevalence of listeriosis was 11.7 per cent, 9.3 per cent for milking cows, 5.0 per cent for replacement heifers and 1.4 per cent for dairy calves. The within-herd incidence rate per thousand animal-years was 51.4 for all cases, 39.7 for milking cows, 86.6 for replacement heifers and 73.7 for dairy calves. Most cases of clinical listeriosis were reported between December and May, and the most common signs were silage eye, followed by nervous signs. The results of the questionnaire were validated internally by re-estimating the farm prevalence by including only those cases diagnosed by a veterinarian or veterinary investigation centre; the prevalence did not change significantly. The proportion of cases which were culled or died of encephalitic listeriosis was compared with the proportion diagnosed during statutory BSE reporting. The fact that the two proportions were similar provided external validation for the results of the questionnaire.     

Neuropathological findings in cats with clinically suspect but histologically unconfirmed feline spongiform encephalopathy

Central nervous system (CNS) tissues from 192 cats with neurological signs were examined histologically, and tissues from 173 of them were later examined immunohistochemically as part of a survey to determine the prevalence of feline spongiform encephalopathy (FSE). One of the cats was from Norway and the others were from Great Britain. The most commonly recorded clinical signs were ataxia, behavioural changes and epilepsy, but none of the cats had histopathological evidence of FSE. The most common organic CNS lesions were non-suppurative encephalomyelitis in 28 per cent, neoplasia in 15 per cent and a heterogeneous group of degenerative encephalopathies in 9 per cent of the cats. A range of minor histological lesions of uncertain significance was also observed. No histological lesions were observed in the tissues of 63 (33 per cent) of the cats. Disease-specific prion protein (PrP(Sc)) was observed in only one of the 173 cats examined by immunohistochemistry.     

Parasitic otitis in sheep associated with psoroptes infestation: a clinical and epidemiological study.

Parasitic otitis associated with psoroptes infestation was diagnosed in a small pedigree flock of sheep with aural haematomas, abscessation and cauliflower ears. Thirteen of the 15 lambs were affected but the clinical signs were mild; small, discrete, crusty lesions on the inner aspect of the ear at the junction of its anterior and posterior borders were typical. Nine of the 20 adults were affected but the lesions were more severe. Eighteen of the 64 members of the breed society who responded to a telephone survey reported sheep with similar clinical signs in their flocks. The proportion of animals affected ranged from 1 to 60 per cent with a median value of 16 per cent.     

A census of the prevalence of vaginal prolapse in sheep flocks in the Borders region of Scotland

A postal census of vaginal prolapse in sheep flocks in the Borders region of Scotland yielded 540 replies from 963 owners (56 per cent). There were 262,250 ewes in 976 flocks and 2573 vaginal prolapses were reported. Analysis of the data revealed that 390 (40 per cent) of the flocks had no vaginal prolapses and in 237 (24.3 per cent) the reported prevalence was between 0.1 per cent and 1.0 per cent. Only 63 (6.5 per cent) of flocks had a greater than 5 per cent prevalence of vaginal prolapses. The greatest number of prolapses occurred in an upland flock of greyface ewes mated with Suffolk tups with 50 cases among 700 ewes (7.1 per cent) and the highest prevalence was in an upland Scottish blackface flock of ewes bred with Suffolk tups with 15.2 per cent (35 cases among 230 ewes). There were marked breed differences; very few hill breeds were affected and most cases occurred in greyface ewes mated with Suffolk tups.     

Abattoir survey of acquired reproductive abnormalities in ewes.

Abnormalities of the reproductive tract of female sheep were studied by examining 9970 reproductive tracts from cull ewes and 23,536 tracts from nulliparous sheep (prime lambs) over a period of 12 months in abattoirs in south-west England. Overall, 3.37 per cent of the tracts were pregnant (8.11 per cent of cull ewes, and 1.36 per cent of nulliparous sheep), with a peak incidence between September and December. A total of 655 ewes (6.57 per cent) and 459 nulliparous sheep (1.95 per cent) had acquired abnormalities of the reproductive tract. Within these totals, abnormalities of the ovaries accounted for 3.51 per cent (for the ewes) and 10.68 per cent (for the nulliparous sheep) of all the abnormalities, and abnormalities of the ovarian bursa and uterine tube accounted for 42.1 per cent (for the ewes) and 5.23 per cent (for the nulliparous sheep). In addition, uterine lesions (hydrometra and metritis) accounted for 9.92 per cent (for the ewes) and 13.51 per cent (for the nulliparous sheep); lesions of the cervix and vagina (total of 1.44 per cent) and Cysticercus tenuicollis cysts associated with the reproductive tract (total of 3.05 per cent) were less common. Among the ewes the most common ovarian lesions were ovulation tags, and follicular cysts were the most common in nulliparous animals. Lesions such as bursitis, parametritis and abscesses of the reproductive tract were much more common in cull ewes than in nulliparous sheep, probably having arisen from peripartum infections. Hydrosalpinx and hydrometra, in which the intraluminal fluid was clear, were present at relatively high incidence in nulliparous animals, but not in cull ewes. The proportion of tracts containing macerated fetal remnants (2.14 per cent of all abnormalities in cull ewes) was lower than expected. It was considered that the functional significance of many of the lesions, such as ovulation tags and C tenuicollis cysts, was likely to be low, although in some cases of the latter calcification of the cyst had occluded the uterine tubes. Other lesions, notably hydrosalpinx, bursitis and metritis were likely to have made the affected animals sterile. The acquired abnormalities were therefore more significant in terms of individual animal infertility than as a major cause of infertility in flocks.     

A novel nigrostriatal dopaminergic disorder in sheep affected by Tribulus terrestris staggers

An investigation was carried out into the pathogenesis of a unique locomotory disorder of sheep. Thirty sheep which had exhibited clinical signs for more than 15 months were examined for the presence of muscle atrophy, limb paresis, and spontaneous rotational behaviour. A single large dose of levodopa was administered to 12 normal and 12 affected sheep, and the drug-related effects of sedation and excitation were monitored continuously for three hours. The striatum was removed from eight normal and eight affected sheep and assayed for dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC). The findings of asymmetrical atrophy of pelvic limb extensor muscles, asymmetrical paresis of the limbs, a left:right dominance ratio of 50:50, spontaneous rotational behaviour, decreased response to levodopa loading, and decreased levels of DA (19 per cent reduction) and DOPAC (30 per cent reduction) in the striatum of affected sheep, were interpreted as indicative of a primary nigrostriatal dopaminergic disorder. It is suggested that a striatal presynaptic receptor malfunction has occurred.     

Diagnosis and treatment of coenuriasis (gid) in sheep

A procedure for the clinical investigation and surgical treatment of cases of coenuriasis in sheep was assessed. The results were based on a series of 62 cases of coenuriasis, of which 58 per cent did not have any palpable skull softening. A useful correlation between the neurological signs and the location of cysts was demonstrated, enabling accurate localisation of cysts in 68 per cent of cases. The surgical technique for the removal of cysts gave a success rate of 74 per cent among the 42 cases selected for surgery, as judged by the complete removal of the cyst and recovery of neurological functions.     

Treatment and control of sheep scab (Psoroptes ovis) with ivermectin under field conditions in South Africa.

Four trials including 11,266 sheep were conducted in South Africa to evaluate the efficacy of the systemic parasiticide ivermectin against field outbreaks of sheep scab (Psoroptes ovis) when two doses of approximately 200 micrograms/kg were administered subcutaneously seven days apart (days 0 and 7). As sheep scab is a notifiable disease in South Africa, it was not possible to include an untreated control group. The prevalence of clinically affected animals in the four treated flocks varied from 0.4 per cent to 99 per cent before the two treatments. After the treatments, there were no signs of active clinical infection in any of the sheep between days 28 and 30, or at subsequent examinations. P ovis mites were recovered from scrapings from 114 of 127 indicator sheep before the treatment but no mites were recovered from them between days 28 and 30 or 42 and 58 after the treatments.     

Prevalence of clinical signs of disease in Danish finisher pigs

Between December 1999 and February 2001, two visits, eight weeks apart, were made to 90 herds of Danish finisher pigs. The prevalence of clinical signs was recorded by three veterinary technicians from the Danish Bacon and Meat Council according to a standardised procedure; they had been trained and their observations were monitored and validated before and during the study. A total of 154,347 finisher pigs were examined and 22,136 clinical signs were recorded. Vices accounted for 43 per cent of the signs. The highest mean prevalence was observed for ear necrosis (4.44 per cent), followed by respiratory signs (2.17 per cent), lameness (1.92 per cent), other skin diseases (1.73 per cent), tail bites (1.26 per cent), umbilical hernia (0.78 per cent), flank bites (0.52 per cent), diarrhoea (0.27 per cent), respiratory distress (0.12 per cent), atrophic rhinitis (0.10 per cent), recumbency (0.09 per cent) and central nervous disease (0.05 per cent). The prevalence of atrophic rhinitis was higher in conventional herds than in specific pathogen-free herds. The prevalence of clinical signs of atrophic rhinitis was higher among finishers weighing 51 to 75 kg than among finishers weighing up to 50 kg, and the prevalence of respiratory signs was higher among finishers weighing 51 to 75 kg then among finishers weighing 76 to 100 kg.     

Pithomycotoxicosis (facial eczema) in ruminants in the Azores, Portugal

Outbreaks of pithomycotoxicosis (facial eczema), a hepatogenous photosensitisation caused by the mycotoxin sporidesmin, have affected ruminants in the Azores Islands of Portugal after warm, humid periods during late summer and autumn. Twenty-two outbreaks were recorded in cattle between 1999 and 2001, affecting 11.4 per cent of the animals in the affected herds, and in 2000 there was an outbreak in one sheep flock in which more than 20 per cent of the sheep died. The clinical signs included decreases in milk production, weight loss, photosensitisation and its sequelae, including death. The animals had high activities of gamma glutamyltransferase in their serum, and icterus and severe liver disease, including biliary hyperplasia and fibrosis, were found postmortem. The characteristic spores of the toxigenic saprophytic fungus Pithomyces chartarum were found on grass; all 381 isolates of the fungus were toxigenic for sporidesmin by elisa, and the results were confirmed by high-performance liquid chromatography analysis. Cattle from farms at greatest risk of pithomycotoxicosis were protected by supplementing their concentrate feed with zinc oxide, or using a slow-release intraruminal zinc bolus.     

Role of thiamine status in sulphur induced polioencephalomalacia in sheep.

The effects of excess dietary sulphur were studied in sheep supplemented and unsupplemented with thiamine. The diets contained either 0.19 per cent sulphur (LS) or 0.63 per cent sulphur (HS) in combinations with 14 mg kg-1 thiamine (LB1) or 243 mg kg-1 thiamine (HB1). A total of 56 two-month-old lambs were used. Groups consisting of nine, nine, 22 and 16 lambs were fed LS-LB1, LS-HB1, HS-LB1 and HS-HB1 diets, respectively for 14 weeks. Out of 22 lambs fed the HS-LB1 diet, seven lambs developed neurological signs between the third and eighth week of the trial. Two of these lambs died, three that were in extremis were euthanased, and two recovered completely. All clinically affected animals had extensive malacic lesions in the cerebral cortex, midbrain and brainstem. None of the lambs from the LS groups or HS-HB1 group developed clinical signs. Several clinically normal lambs from the HS-LB1 group had necrotic lesions in their brains at gross and microscopic examination. Supplementation with dietary thiamine prevented development of clinical signs, but did not totally prevent development of microscopic brain lesions. Brain thiamine concentration, transketolase activity and thiamine pyrophosphate (TPP) effect were not different (P greater than 0.05) among groups. There was a strong effect (P less than 0.0001) of dietary thiamine supplementation on blood thiamine concentration and TPP effect. Blood thiamine concentration was higher whereas TPP effect was lower in the thiamine supplemented sheep. Blood and tissue thiamine concentrations in sheep exposed to high dietary sulphur did not indicate either systemic or local thiamine deficiency per se. Increased TPP effect in sheep fed the HS-LB1 diet indicated mild to moderate metabolic thiamine deficiency. Thiamine inadequacy may be an effect of an increased requirement for thiamine in animals exposed to excess dietary sulphur.     

Evaluation of a direct ELISA for the serodiagnosis of Oestrus ovis infections in sheep.

Oestrosis is a parasitic disease of sheep and goats caused by the nasal bot fly Oestrus ovis. In the United Kingdom the economic losses as a result of infestation can be considered negligible, but the differentiation of O ovis cases from more serious diseases such as listeriosis, gid and sheep scab is of considerable importance. Currently, diagnosis of oestrosis relies on the subjective observation of clinical signs or the demonstration of larvae postmortem. This paper assesses the effectiveness of a direct enzyme-linked immunosorbent assay (ELISA) using a crude somatic antigen from first-stage larvae (L1) in the serodiagnosis of oestrosis. The system has been validated with sera from both endemic and non-endemic areas and the results correlated with the clinical data found postmortem. The sensitivity and specificity of the assay were 97.4 per cent and 97.6 per cent, respectively, using a cut-off point based on 35 per cent binding of a reference positive control serum.     

Feline osteoarthritis: a prospective study of 28 cases

OBJECTIVES: To identify a cohort of cats with clinical osteoarthritis and to report on the clinical signs, the frequency of joints affected and the possible aetiopathogenesis within this population. METHODS: Inclusion criteria for this prospective study were presence of historical evidence and/or clinical signs of osteoarthritis, together with radiographic evidence of osteoarthritis. Patients showed clinical improvement within four weeks of analgesic administration and were free from other disease processes, which might explain the clinical signs and/or their response to analgesia. RESULTS: Twenty-eight cases were included in the cohort. The elbow (45 per cent) and the hip (38 per cent) were the most frequently affected joints. Seventy-one per cent of cases had primary/idiopathic aetiology. Alterations in both the ability to jump (71 per cent) and the height (67 per cent) of jump (lifestyle changes) were the most frequent signs of disease. Sixty-one per cent of owners felt that their pet had made a marked improvement following administration of an analgesic/anti-inflammatory drug. There were statistically significant improvements in the ability to jump (P < 0.001), the height of jump (P < 0.001), lameness (P = 0.03), stiff gait (P = 0.04) and the activity level (P = 0.02) when compared with the start and the end of the study period. CLINICAL SIGNIFICANCE: Osteoarthritis is a clinical problem in cats, but overt lameness is not the most common clinical feature.     

Fever of unknown origin in the horse: a review of 63 cases

Fever of unknown origin (FUO) is a syndrome characterised by prolonged, unexplained fever associated with non-specific signs of illness such as lethargy, inappetence and weight loss. This paper reviews the details of 63 horses affected by FUO. The cause was found to be infection in 43 per cent of the cases, neoplasia in 22 per cent, immune-mediated diseases in 6.5 per cent and miscellaneous diseases in 19 per cent; the cause remained undiagnosed in 9.5 per cent.     

Canine dilated cardiomyopathy: a retrospective study of signalment, presentation and clinical findings in 369 cases

O bjective : To review the clinical and diagnostic findings and survival of dilated cardiomyopathy from a large population of dogs in England.
M ethods : A retrospective study of the case records of dogs with dilated cardiomyopathy collected between January 1993 and May 2006.
R esults : There were 369 dogs with dilated cardiomyopathy of which all were pure-bred dogs except for four. The most commonly affected breeds were dobermanns and boxers. Over 95 per cent of dogs weighed more than 15 kg and 73 per cent were male. The median duration of signs before referral was three weeks with 65 per cent presenting in stage 3 heart failure. The most common signs were breathlessness (67 per cent) and coughing (64 per cent). The majority of dogs (89 per cent) had an arrhythmia at presentation and 74 per cent of dogs had radiographic signs of pulmonary oedema or pleural effusion. The median survival time was 19 weeks.
C linical S ignificance : Dilated cardiomyopathy occurs primarily in medium to large breed pure-bred dogs, and males are more frequently affected than females. The duration of clinical signs before referral is often short and the survival times are poor. Greater awareness of affected breeds, clinical signs and diagnostic findings may help in early recognition of this disease which often has a short clinical phase.     

Respiratory and cardiac arrest under general anaesthesia: treatment by acupuncture of the nasal philtrum

The philtrum point VG 26 (Jen Chung) was needled in 69 cases of respiratory depression or apnoea in dogs and cats during induction or maintenance of general anaesthesia. Respiration was restored to normal or near normal rates within 10 to 30 seconds of insertion of the needle in all the cases. In seven cases of anaesthetic apnoea with concurrent cardiac arrest and absence of vital signs, the revival rate was 43 per cent. Those which recovered required four to 10 minutes of acupuncture stimulation. In eight cases of collapse due to other causes, the revival rate was 25 per cent. The cases included five sheep in shock following liver biopsy, two cases of haemorrhagic shock (dog, cat) and one terminal collapse in chronic congestive heart failure (dog).     

Emergence of suspected type D botulism in ruminants in England and Wales (2001 to 2009), associated with exposure to broiler litter

Scanning surveillance by the Veterinary Laboratories Agency revealed the emergence of suspected botulism in ruminants in 2003, presented as flaccid paralysis. From 2003 to 2009, 168 cattle and 19 sheep incidents were recorded, with mortality between 5 and 80 per cent. All sheep incidents and 95 per cent of cattle incidents had proximity to broiler litter. From July 2006, the gut contents collected from 74 affected cattle and 10 affected sheep were tested for Clostridium botulinum toxins using mice bioassays and for organisms by culture. Type D toxin was identified in 32 per cent of cattle and 18 per cent of sheep samples. C botulinum type D organisms were identified in 40 per cent of cattle and 30 per cent of sheep samples, but broth from one sample reacted with C and D antisera. Type C botulism has previously been reported more commonly than type D in the UK and has been associated with the use of poultry litter as fertiliser, bedding or feed. The almost exclusive association with C botulinum type D toxins or organisms in the gut contents in this survey suggests a change in the source or epidemiology of botulism in the UK. The source of C botulinum type D was uncertain. Broilers may carry C botulinum type D in their gut flora subclinically. The emergence of a new type D strain, or changes in broiler husbandry and nutrition, medication and other enteric infections may have affected colonisation with C botulinum. Further investigation of poultry and farm environments for sources of type D awaits the development of tests for C botulinum toxins that do not require the use of mice.     

Impact of footrot vaccination and antibiotic therapy on footrot and contagious ovine digital dermatitis

Footrot and contagious ovine digital dermatitis (CODD) are common causes of foot disease of sheep in the UK. The study reported here is a split flock randomised treatment trial undertaken on a group of 748 fattening lambs on a UK sheep farm affected by CODD and footrot. The sheep were randomly assigned to one of two treatment protocols. In protocol A, all sheep were given two doses of footrot vaccine (Footvax, MSD), plus targeted antibiotic therapy (long-acting amoxicillin, Betamox LA, Norbrook Pharmaceuticals) to sheep with foot lesions likely to be associated with a bacterial infection. In protocol B, the sheep only received targeted antibiotic therapy. Sheep were re-examined and foot lesions recorded five and nine weeks later. New infection rates in the footrot vaccinated group were lower compared with the vaccinated group for both CODD (18.2 per cent compared with 26.4 per cent, P=0.014) and footrot (12.55 per cent compared with 27.5 per cent, P<0.001). Recovery rates were unaffected for CODD (80.46 per cent compared with 70.97 per cent, P=0.14) but higher for footrot (92.09 per cent compared with 81.54 per cent, P=0.005) in sheep which received the vaccine. On this farm, a footrot vaccine efficacy of 62 per cent was identified against footrot and 32 per cent against CODD infection. An association between a sheep having footrot at visit 1 and subsequently acquiring CODD was identified (odds ratio [OR] 3.83, 95 per cent CI 2.61 to 5.62, P<0.001). These results suggest a role for infection with Dichelobacter nodosus in the aetiopathogenesis of CODD on this farm.