Colin Penny

Cerebrospinal fluid and plasma glucose concentrations of ovine pregnancy toxaemia cases, inappetant ewes and normal ewes during late gestation

Cerebrospinal fluid (CSF) and plasma glucose concentrations of spontaneous ovine pregnancy toxaemia cases, determined within 24 h of the onset of clinical signs, were significantly lower (P < 0.01) compared to inappetant ewes and healthy ewes at a similar stage of gestation. A highly significant correlation (P < 0.001, r = 0.91) was present between the plasma and CSF glucose concentrations when the data from the three groups were combined. The data suggest that plasma glucose concentration accurately reflects CSF glucose concentration across the range of energy states in pregnant ewes and may provide support for the postulate that the neurological signs of ovine pregnancy toxaemia result from cerebral hypoglycaemia, as reflected by CSF glucose concentration. No cerebral glucose estimations were undertaken in this series.

Upper respiratory disease and encephalitis in neonatal beef calves caused by bovine herpesvirus type 1

Retrospective study of 50 dogs with status epilepticus THE medical records of 50 dogs with generalised convulsive tonic-clonic status epilepticus were compared with those of 50 dogs with different types of seizures. There were no significant differences between the mean ages and bodyweights, or the genders of the two groups. The dogs in the non-status epilepticus group were twice as likely to be idiopathically epileptic, whereas the dogs with status epilepticus were 1-57 times more likely to have secondary or reactive epilepsy. The dogs in the status epilepticus group were more likely to have high cell counts and/or protein concentrations in their cerebrospinal fluid, but they were no more likely than the nonstatus epilepticus group to have abnormalities detected by computed tomography. It is suggested that dogs with status epilepticus should be thoroughly investigated for secondary causes. PLATT, S. R. & HAAG, M. (2002) Canine status epilepticus: a retrospective study of 50 cases. Journal ofSmall Animal Practice 43, 151-153

Plasma enzymes and metabolites as potential prognostic indices of ovine pregnancy toxaemia—A preliminary study

Three ewes with naturally occurring pregnancy toxaemia and increased plasma glucose concentrations within 24 h of the onset of clinical signs, made a complete recovery following treatment with a concentrated oral rehydration solution. Four ewes in which plasma glucose concentrations fell did not recover. Ewes with elevated plasma alkaline phosphatase concentrations were slower to recover than ewes with normal plasma alkaline phosphatase concentrations. These findings suggest that plasma alkaline phosphatase concentration and change in plasma glucose concentration might offer useful prognostic indices in cases of ovine pregnancy toxaemia, and influence a decision to perform an elective caesarean operation. Further studies using a larger number of ketotic ewes are necessary before firm conclusions can be made.

Unexpected production loss caused by helminth parasites in weaned beef calves.

SHEEP farmers are generally quick to consider helminth parasitism as the cause of diarrhoea and illthrift in their lambs, because they are aware that effective helminth control using anthelmintic drugs is difficult to achieve. There is a general awareness among sheep farmers of the production-

Teladorsagia circumcincta resistance to moxidectin and multiple anthelmintic groups in ewes following use of the persistent drug before lambing

This paper describes the nematode control strategy adopted by a Scottish hill sheep farmer. It provides an example of the limited use of anthelmintic drugs, targeted towards control of the periparturient rise in faecal nematode egg output in ewes and exploitation of grazing management, resulting in limited exposure of naive sheep to infective larvae on pasture. Resistance to benzimidazole, imidazothiazole and macrocyclic lactone anthelmintics, and to a combination of a macrocyclic lactone and imidazothiazole anthelmintic drugs was diagnosed. The targeted use of a persistent anthelmintic drug to control a periparturient rise in faecal nematode egg output in ewes may be unnecessary and selects strongly for resistance when the reservoir of anthelmintic-susceptible nematodes in refugia is small at the time of treatment. However, the use of a persistent anthelmintic drug in a selective proportion of ewes can be important and probably does not select strongly for resistance when the reservoir of anthelmintic-susceptible nematodes in refugia is large at the time of treatment. The former circumstances might arise on many Scottish hill sheep farms, whereas the latter may occur on upland and lowground farms, depending on previous grazing management, anthelmintic use and winter weather conditions. These factors must be taken into account when preparing sustainable health plans for nematode parasite control in individual sheep flocks.

Characterisation of milbemycin-, avermectin-, imidazothiazole- and benzimidazole-resistant Teladorsagia circumcincta from a sheep flock.

Selection for milbemycin resistance in a population of Teladorsagia circumcincta was examined in a sheep flock in which a lack of persistence of an oral dose of 0.2 mg/kg moxidectin against T circumcincta had previously been identified. A faecal egg count reduction test also showed resistance to benzimidazole, levamisole and avermectin anthelmintic groups. Bioassays were used to compare the moxidectin-resistant T circumcincta with another previously characterised benzimidazole-, levamisole- and ivermectin-resistant (MTci5) strain that had been isolated from a sheep flock in the same region in south-east Scotland and with an anthelmintic-susceptible (MTci3) strain of T circumcincta. The mean ED50 value (the concentration of drug required to prevent 50 per cent of eggs from hatching) obtained for thiabendazole in egg hatch assays was higher in the moxidectin-resistant T circumcincta than in the ivermectin-resistant MTci5 strain. The inclusion of the cytochrome p450 inhibitor piperonyl butoxide in larval feeding inhibition assays increased the level of ivermectin resistance in vitro in the ivermectin- and moxidectin-resistant populations, but not in the ivermectin-susceptible MTci3 strain of T circumcincta.

Idiopathic bovine neonatal pancytopenia in a Scottish beef herd

PANCYTOPENIA, due to hypoplastic or aplastic bone marrow, has historically been uncommon in cattle. Fatal haemorrhagic pancytopenia has been reported in cattle due to the ingestion of trichloroethylene-extracted soya oil meal (TCESOM) ([Rundles 1958][1]), bracken fern ( Pteridium species) ([Hirono

Shiga toxin-producing Escherichia coli as a perennial cause of abortion in a closed flock of Suffolk ewes

of E coli and Salmonella enterica serotype Derby was isolated from the stomach contents of a lamb that had died shortly after birth. No diagnosis was made in six lambs due to bacterial overgrowth of fetal stomach content cultures (Table 1). E coli isolated from the stomach contents of an aborted and an unborn lamb, submitted during January 2003 and December 2004, respectively, were identified at the Veterinary Laboratories Agency – Weybridge as serotype O15:K. The Verocell toxicity test (Konowalchuk and others 1977) demonstrated the expression of Shiga-like toxins. The identity of genes encoding virulence factors stx1 and stx2 was confirmed by multiplex PCR. The putative diagnosis of E coli as a perennial cause of abortion is supported by its isolation in pure culture from the stomach contents of 38 per cent of the fetuses or lambs submitted for laboratory diagnosis between December 2002 and January 2005, and by the consistent failure to identify any of the major recognised causes of ovine abortion, despite routine screening for Toxoplasma gondii, Chlamydophila abortus, Salmonella species, Campylobacter species and other bacteria. The roles of S Derby and C jejuni as causes of ovine abortion within the flock are unproven, and bacterial overgrowth of cultures precluded positive diagnoses in 46 per cent of the submissions. A study of non-O157 STEC isolated from healthy cattle faeces collected from Scottish farms, identified O15 serotypes in seven of 423 samples (Jenkins and others 2002). In another study, serotype O15 was identified in only one of 384 ovine STEC strains (Blanco and others 2003), although there have been fewer studies on STEC carriage in sheep than in cattle. The O15 serotype of the STEC identified from stomach contents of aborted fetuses or lambs in January 2003 and December 2004 was similar to, or possibly the same as, that identified during January 2001. This recurrence of an unusual serotype of STEC is unlikely to be coincidental and indicates the presence of a reservoir of a potential pathogen on the farm, most likely in the intestinal tract of healthy carrier sheep (Ramachandran and others 2001). This short communication shows that STEC, which are usually considered to be non-pathogenic in their ruminant reservoir hosts (Beutin and others 1993), but of greater importance as latent zoonoses (Beutin and others 1996), can, under certain circumstances cause serious production losses in sheep. Application of the basic principles of immediately isolating aborting ewes, disposing of the abortion products, strict hygiene precautions and biosecurity were ineffective. Furthermore, whole-flock antibiotic treatment proved inefShiga toxin-producing Escherichia coli as a perennial cause of abortion in a closed flock of Suffolk ewes

Assessment of xylazine hydrochloride epidural analgesia for open castration of rams

Epidural xylazine injected at the sacrococcygeal site 40 to 150 min prior to surgery (at a dose of 0.05 to 0.10 mg/kg) provided good analgesia during scrotal skin incision in all 20 experimental rams but in only 10 rams (50%) at incision and separation of tunica vaginalis, and 6 rams (30%) during ligation of the spermatic cord. There was a significant correlation between the decrease in heart rate and the dosage of epidural xylazine. Heart rate increased significantly during incision of the tunics and spermatic cord ligation but was not significantly correlated to the clinical assessment of analgesia. There was no significant correlation between the presence of surgical analgesia and the dosage of epidural xylazine: Pelvic limb ataxia was still evident in 12 rams (60%) at 8 h after epidural xylazine injection. Epidural xylazine provided good somatic analgesia during open castration of 20 rams but visceral analgesia was unpredictable. Factors in addition to the dosage of sacrococcygeal epidural xylazine affects the degree of surgical analgesia obtained for open castration of rams.

Application of lumbosacral spinal anesthesia for ovine Caesarian surgery and for vasectomy under field conditions

A 2% lignocaine solution infused at a dose of 2 mg/kg at the lumbosacral site gave excellent analgesia in 28 vasectomy operations and in 33 of 38 (87%) Caesarian operations at a dose of 4 mg/kg. Failure of the anesthetic technique in 4 sheep (6% of all operations) was associated with poor positioning of the ewe and incorrect identification of the epidural space. One fatality was recorded and was considered to result from lignocaine overdosage and the probable pooling of blood in the splanchnic vasculature. Pelvic limb paresis persisted for 2 to 4 h post epidural injection in all ewes, but no permanent paralysis was encountered. Lumbosacral epidural anesthesia gave excellent analgesia for vasectomy, and was indicated for Caesarian surgery when a dystocia was associated with severe vaginal prolapse or the delivery of a fetal monster. Further work is needed to find an analgesic preparation which has a shorter duration than the 2% lignocaine solution.