Australian Veterinary Journal

Objective To investigate the distribution and incidence of chytridiomycosis in eastern Australian frogs and to examine the effects of temperature on this disease.

Design A pathological survey and a transmission experiment were conducted.

Procedure Diagnostic pathology examinations were performed on free‐living and captive, ill and dead amphibians collected opportunistically from eastern Australia between October 1993 and December 2000. We conducted a transmission experiment in the laboratory to investigate the effects of temperature: eight great barred frogs (Mixophyes fasciolatus) exposed to zoospores of Batrachochytrium dendrobatidis and six unexposed frogs were housed individually in each of three rooms held at 17°C, 23°C and 27°C.

Results Chytridiomycosis was the cause of death or morbidity for 133 (55.2%) of 241 free‐living amphibians and for 66 (58.4%) of 113 captive amphibians. This disease occurred in 34 amphibian species, was widespread around the eastern seaboard of Australia and affected amphibians in a variety of habitats at high and low altitudes on or between the Great Dividing Range and the coast. The incidence of chytridiomycosis was higher in winter, with 53% of wild frogs from Queensland and New South Wales dying in July and August. Other diseases were much less common and were detected mostly in spring and summer. In experimental infections, lower temperatures enhanced the pathogenicity of B dendrobatidis in M fasciolatus. All 16 frogs exposed to B dendrobatidis at 17°C and 23°C died, whereas 4 of 8 frogs exposed at 27°C survived. However, the time until death for the frogs that died at 27°C was shorter than at the lower temperatures. Infections in survivors were eliminated by 98 days.

Conclusion Chytridiomycosis is a major cause of mortality in free‐living and captive amphibians in Australia and mortality rate increases at lower temperatures.

SUMMARY An in vitro cellular assay for bovine tuberculosis has recently been developed. This assay detects gamma‐interferon released in response to specific antigen in a whole blood culture system. The bio‐assay previously described for the detection of bovine gamma‐interferon (IFN‐γ) has now been replaced with a sandwich enzyme immunoassay (EIA) which utilises two monoclonal antibodies to bovine IFN‐γ. The EIA detects less than 25pg/ml of recombinant bovine IFN‐γ and is specific for biologically active bovine IFN‐γ; and does not detect bovine alpha or beta interferon. IFN‐γ from sheep, goat and buffalo, but not from pig, deer or man, are also recognised by the EIA. The bovine IFN‐γ EIA when used in conjunction with the whole blood culture system has resulted in a simple, rapid and sensitive in vitro assay for specific cell mediated immune responsiveness to M. bovis infection in cattle.

Objective To compare the effects of surgical and latex banding methods of castration in 14‐ and 9‐month‐old bulls.

Design Two randomised, controlled experiments.

Procedure In Experiment 1, following administration of local anaesthetic, 14‐month‐old bulls were castrated by either surgical or banding methods, or left entire. Behavioural, plasma cortisol, plasma haptoglobin and bodyweight responses were recorded. A group of steers from the same mob was used as an additional comparison for bodyweight data. In Experiment 2, following administration of local anaesthetic, 9‐month‐old bulls were castrated by either surgical or banding methods and cortisol, haptoglobin and bodyweight responses were recorded. Entire bulls from the same group were used as an additional comparison for bodyweight data.

Results In Experiment 1, surgical castrates exhibited more leg stamping and tail swishing than banded or entire animals in the hours after castration. Surgical castrates in both experiments also showed an increase in plasma haptoglobin, which resolved after 4 days. Plasma cortisol was generally not affected by castration. Surgical castrates grew more slowly than entire bulls, but faster than banded animals, in the 56 days after treatment. In Experiment 1, after 56 days, the bodyweights of surgical and banded castrates were not different from the bodyweights of the steers. Fourteen‐month‐old banded cattle developed persistent wounds above the latex band which remained for several weeks after scrotal dehiscence, but this did not occur in the 9‐month‐old animals.

Conclusion The banding procedure produced fewer acute effects, but a greater suppression of growth than surgical castration and induced prolonged wound formation in the older age group, suggesting that this procedure may not be as suitable for yearling cattle.

Objective  To determine the pain responses of lambs to mulesing, and the effectiveness of potential analgesic treatments.

Procedures  Merino lambs (n = 64) were allocated at 5 weeks of age to eight treatment groups: 1) sham mules; 2) conventional mules; 3) topical anaesthetic, incorporating lignocaine, bupivicaine, adrenaline and cetrimide, applied immediately after mulesing; 4) flunixin + topical anaesthetic, with flunixin administered 2.5 mg/kg s.c. 90 min before mulesing; 5) carprofen + topical anaesthetic, with carprofen administered 4 mg/kg s.c. 90 min before mulesing; 6) carprofen, administered as above; 7) flunixin, administered as above; and 8) carprofen + flunixin, administered as above. Plasma cortisol was measured at 0, 0.5, 6, 12 and 24 h relative to mulesing. Animal behaviour, including posture, was recorded for 12 h after mulesing.

Results  The conventional mules lambs exhibited large increases in plasma cortisol, reduced lying and increased standing with a hunched back compared with sham mules animals. Topical anaesthetic reduced the cortisol peak to mulesing and hunched standing, and increased lying compared with the conventional mules treatment, but generally did not result in values equivalent to sham mules animals. Carprofen, flunixin, and carprofen + flunixin treatments did not reduce the cortisol response to mulesing but substantially ameliorated some changes in behavioural postures. Flunixin + topical anaesthetic reduced the cortisol peak following mulesing and substantially ameliorated most changes in behavioural postures. Carprofen + topical anaesthetic abolished the cortisol peak following mulesing and substantially ameliorated most changes in behavioural postures. All mulesed animals lost weight in the week after mulesing regardless of analgesic administration, but there were no significant differences in growth rate between any of the eight treatments over the 3 weeks after mulesing.

Conclusions  Analgesics can moderate the pain response of lambs to mulesing. The welfare outcome for lambs of mulesing could be improved by use of a combination of local anaesthetic and long acting non‐steroidal anti‐inflammatory drug.

SUMMARY: A simple device for collecting saliva (mainly parotid) from sheep is described. The collection of saliva, and the assay of “free” cortisol in saliva appears to offer certain advantages over the collection of blood, and the assay of serum cortisol, for the assessment of stress in sheep. With a little experience, it is easier to collect saliva than take blood samples when sheep are passing through a race. The “free” cortisol can be measured directly in saliva, whereas in serum, it is first necessary to separate “free” from protein‐bound cortisol. Basal levels of “free” cortisol of less than 10 nmol/1 were recorded in saliva and blood plasma or serum in unstressed sheep which had previous experience of being handled in a race, Significant increases in salivary cortisol and “free” and total (“free” plus protein‐bound) cortisol in serum were found in sheep following adrenal stimulation with synacthen, or after 30 min of stressful transport. This indicates that the salivary cortisol technique is applicable to studies of stress in sheep, and should also be useful for other ruminants.

Objectives  To define the prevalence of Bartonella spp., Rickettsia felis, Mycoplasma haemofelis, ‘Candidatus Mycoplasma haemominutum’ (Mhm) and ‘Candidatus Mycoplasma turicensis’ (Mtc) in cats and their fleas in eastern Australia.

Design and procedure  Conventional PCR assays that detect Bartonella spp., M. haemofelis, Mhm, Mtc, Rickettsia spp., Ehrlichia spp., Anaplasma spp. and Neorickettsia spp. were performed on DNA extracted from blood and fleas collected from 111 cats. Cat sera were assayed by ELISA for IgG of Bartonella spp.

Results  DNA of M. haemofelis, Mtc and Mhm was amplified from 1 (0.9%), 1 (0.9%) and 17 cats (15.3%), respectively. Only DNA of Mhm was amplified from the 62 of 111 pooled flea samples (flea sets; 55.9%). Overall, the prevalence rates for Bartonella spp. DNA in the cats and the flea sets was 16.2% (18 cats) and 28.8% (32 flea sets), respectively. Bartonella spp. IgG was detected in 42 cats (37.8%), of which 11 (26.2%) were positive for Bartonella spp. DNA in their blood. R. felis DNA was amplified from 22 flea sets (19.8%), but not from cats. Overall, DNA of one or more of the organisms was amplified from 27% (30) of cats and 67.6% (75) of the flea sets.

Conclusions  This is the first Australian study to determine the prevalence of R. felis and B. clarridgeiae in both fleas and the cats from which they were collected. Flea‐associated infectious agents are common in cats and fleas in eastern Australia and support the recommendation that stringent flea control be maintained on cats.

Objective To determine if dogs and cats with renal failure, or other severe non‐cardiac disease, and no antemortem evidence of cardiac disease on basic clinical evaluation, have elevated levels of cardiac troponin I (cTnI).

Design Cross‐sectional study using 56 dogs and 14 cats with primary non‐cardiac disease (39 dogs with azotaemic renal failure, 14 cats with azotaemic renal failure, 17 dogs with non‐cardiac systemic disease); 7/25 dogs and 6/14 cats had murmurs detected on physical examination. Serum or heparinised plasma was collected and analysed for cTnI.

Results Cardiac troponin I concentrations were elevated above reference intervals in 70% of dogs and 70% of cats with azotaemic renal failure and in 70% of dogs with a variety of systemic non‐cardiac diseases. Cardiac troponin I concentrations did not correlate with the degree of azotaemia, presence of murmurs, hypertension or type of non‐cardiac illness.

Conclusions Cardiac troponin I concentration is often elevated in dogs and cats with azotaemic renal failure and in dogs with other systemic non‐cardiac illness, suggesting that these conditions often result in clinically inapparent myocardial injury or possibly altered elimination of cTnI.