Ataxia and paralysis in cats in Australia associated with exposure to an imported gamma-irradiated commercial dry pet food

Between June 2008 and March 2009, 87 cats in Australia developed symmetrical hindlimb ataxia, paraparesis, tetraparesis, paraplegia or tetraplegia in association with eating an imported, irradiated dry pet food. This communication reports the clinical signs and outcomes of those cats.     

Acquired arachnoid cyst in a cat

A 5-year-old Birman cat presented with paraparesis associated with a fracture of the third thoracic vertebra and was managed conservatively. Voluntary function was regained over the next 6 months, but the cat was referred 4 years after the trauma because of recurrence of hindlimb paresis and ataxia. Magnetic resonance imaging (MRI) showed a spinal arachnoid cyst at the level of the fourth thoracic vertebra, which was treated surgically by dorsal laminectomy and durectomy, and hindlimb function subsequently recovered. The cat re-presented 4 years later for recurrent hindlimb paresis. Myelography and computed tomography–myelography (CT-M) showed dorsolateral pooling of cerebrospinal fluid (CSF) at the previous laminectomy site. The neurological signs after the second surgery improved, but not as much as after the first surgery and the cat remained ataxic with moderate paresis. Seven months later repeat CT-M revealed an atrophic spinal cord, but negligible pooling of CSF at the previous site of the arachnoid cyst. The cat could walk, but was being treated for self-induced trauma of the left hindlimb that was thought to be related to paraesthesia. The neurological signs gradually deteriorated over 3 months and the cat was euthanased.     

Investigation of Johne's disease in Tasmanian fallow deer (Dama dama)

In 2012 when many sheep flocks in northern‐central Tasmania were experiencing a high prevalence of ovine Johne's disease, 34 wild adult fallow deer shot on or near infected properties were negative to microscopic Mptb lesions of the ileo‐caecal valve, terminal ileum and ileo‐caecal lymph nodes. This study demonstrated 95% confidence of detecting Johne's disease in this fallow deer population if ≥10% of animals were shedding Mycobacterium avium subsp. paratuberculosis in their faeces, or if ≥21% of animals were sub‐clinically infected.     

Acute cortisol responses of calves to four methods of dehorning by amputation

Objective To measure the plasma cortisol response in calves dehorned by four different methods (scoop, guillotine shears, saw, embryotomy wire) for 9 h after dehorning.
Design A physiological study with controls.
Procedure Horn amputation was carried out on calves restrained manually in a race.
Results The four methods of dehorning provoked similarly increased cortisol responses which lasted for 6 h. During the first hour after dehorning the plasma cortisol concentrations were similar to those following ACTH injection. The overall cortisol response to control handling was about 30% of the responses to dehorning.
Conclusions The similarity of the cortisol responses produced by the four methods of dehorning suggests that the distress experienced by calves following dehorning by amputation is similar regardless of method used.     

Antimicrobial Resistance in Some Gram‐Negative Bacteria Isolated from the Bovine Ejaculate

The bacterial load and degree of antibiotic resistance present in untreated and antibiotic‐treated semen samples were investigated in five bulls standing at a cattle‐breeding centre. Bacterial load was determined by colony counts from semen samples cultured on brain heart infusion and nutrient agar plates. Antibiotic resistance in these bacteria was assessed by measuring the diameter of bacterial growth inhibition zones around discs containing different concentrations of antibiotics. Representative antibiotic‐resistant bacterial isolates were selected for identification. Untreated semen contained few culturable bacteria, and all were completely sensitive to gentamycin, spectinomycin and lincomycin: six of the isolates showed some resistance to tylosin. In semen to which antibiotics had been added as part of the routine production process, two isolates were sensitive to all of the antibiotics tested, and the remainder were resistant to all. Resistant Gram‐negative isolates that were identified included Pseudomonas and Stenotrophomonas spp. both in the class Gammaproteobacteria and a Sphingomonas sp. which is in the class Alphaproteobacteria.     

The effects of antigenic competition on the efficacy of multivalent footrot vaccines

SUMMARY A multivalent footrot vaccine has been developed, containing pilus antigens produced in recombinant Pseudomonas aeruginosa and representing all nine serogroups of Dichelobacter (Bacteroides) nodosus commonly recognised in the field. The responses of sheep to the multivalent vaccine have been compared with those to monovalent vaccines representing only a single serogroup. Antigenie competition between serogroups occurred in sheep immunised with the multivalent formulation, but high levels of protection were still achieved. The study showed that in multivalent footrot vaccines, antigenic competition is predominantly due to the presence of a family of immunologically-related pilus antigens rather than to interference by extraneous proteins.     

Anthelmintic resistance in Australian sheep nematode populations

SUMMARY The resistance status of gastro–intestinal nematodes to anthelmintics was evaluated on 881 sheep farms throughout Australia during 1991–92. Resistance was shown to be widespread. Overall, 85% of farms had sheep infected with nematodes resistant to benzimidazole, 65% to levamisole and 34% to combination (benzimidazole + levamisole) products. Resistance to ivermectin was not detcted. On only 9% of farms did all anthelmintic groups reduce egg counts by greater than or equal to 95%. The culture of faeces from untreated sheep showed Telodorsagia circumcincta, Trichostrongylus spp, Chabertia ovina and Haemonchus contortus to be the principal species. The nature and prevalence of resistance was not significantly correlated with stocking rate. However, resistance to combination products was almost twice as prevalent on farms in areas with an average annual rainfall of greater than 500 mm.     

Conversion of Cortisone to Cortisol and Prostaglandin F2α Production by the Reproductive Tract of Cows at the Late Luteal Stage In Vivo

Previous in vitro studies demonstrated that bovine endometrium has the capacity to convert inactive cortisone to biologically active cortisol (Cr) and that Cr inhibits cytokine‐stimulated prostaglandin F_2α (PGF) production. This study was carried out to test the hypothesis that bovine reproductive tract has the capacity to convert cortisone to Cr in vivo and to evaluate the effects of intravaginal application of exogenous cortisone on uterine PGF secretion during the late luteal stage. The temporal relationships between PGF and Cr levels in uterine plasma were also determined. Catheters were inserted into jugular vein (JV), uterine vein (UV), vena cava caudalis (VCC) and aorta abdominalis (AA) of six cows on Day 15 of the oestrous cycle (ovulation = Day 0) for frequent blood collection. On Day 16, the cows were divided randomly into two groups and infused intravaginally with vaseline gel (10 ml; control; n = 3) or cortisone dissolved in vaseline gel (100 mg; n = 3). Blood samples were collected at ?2, ?1, ?0.5, 0, 0.5, 1, 1.5, 2, 3, 4, 5 and 6 h after treatments (0 h). Intravaginal application of cortisone increased plasma concentrations of Cr between 0.5 and 1.5 h in UV, at 0.5 h in VCC, at 1 h in JV and at 1.5 h in AA. The plasma concentrations of PGF in UV and of PGF metabolite in JV were greater at 0.5 and 1 h in the cortisone‐treated animals than in control animals. The levels of PGF in UV blood plasma decreased after Cr reached its highest levels. The overall findings suggest that the female reproductive tract has the capacity to convert cortisone to Cr in vivo. Based on the temporal changes of PGF and Cr levels in the uterine plasma, a biphasic response in PGF secretion was found to be associated to the Cr increase induced by the cortisone treatment at the late luteal stage in non‐pregnant cows.