Francis, J., Seiler, R. J., Wilkie, I. W., O’Boyle, D., Lumsden, M. J. and Frost A. J. (1978) - Vet. Rec. 103: 420.

Ketterer, P. J., Rogers, R. J. and Donald, B. (1981) - Aust. vet. J. 57: 61.

Lepper, A. W. D., Newton-Tabrett, D. A,, Corner, L. A., Carpenter, M. T., Scanlan, W. A.. Williams, 0. J. and Helwig, D. M. (1977) - Aust. vet. J. 53:208.

Norton, J . H., Duffield, B. J., Coward, A. J., Hielscher, R. W., and Nicholls, R. F. (1984) - Aust. Vet. J . 61:75.

Pearson, C. W., Corner, L. A. and Lepper, A. W. D. (1977) - Aust. vet. J . 53:67.

Radunz, B. L. and Lepper, A. W. D. (1984). Advances in vet. Science. 43.

Robertson, T. G. (1963) - N.Z. vet. J . 11:6. Rogers, R . J., Donald, B. A. and Schultz, K . (1980) - Aust. vet.

Roswurm, J. D. and Konyha, L. D. (1973) - Proceed. 77th Ann.

(Accepted for publication 19 April 1985)

J. 56542.

Meet. U S . Anirn. Hlth. Assoc.: 368.

Inclusion body hepatitis in a tawny frogmouth (Podargus strigoides: Caprimulgiformes)

Department of Agriculture, Veterinary Research Institute, Park Drive, Parkville, Victoria 3052

School of Veterinary Studies, Murdoch University, Murdoch, Western Australia 6150

Royal Melbourne Zoo, P.O. Box 74, Parkville, Victoria 3052

R . L. REECE

D.A. PASS

R. BUTLER*

Mare (1975) pointed out that those who are concerned with captive and free-living birds should be alert for signs that inclusion body diseases may be emerging as major threats to aviaries and to some of the rare and endangered species of birds. This communication records the case of a fledgling tawny frogmouth (Podargus strigoides; Order Ca- primulgiformes) which had focal necrotic hepatitis and haemorrhagic typhlitis. lntranuclear inclusion bodies were seen in hepatocytes and epithelial cells of the caecal mucosa, and virus particles were demonstrated in affected hepatocytes by electron-microscopy .

A 17-day-old tawny frogmouth fledgling died after being anorectic for several days. The bird was in poor condition and jaundiced. The liver was enlarged with miliary white foci throughout its substances. There was haemorrhage into the caecal lumens.

Histological examination of the liver revealed multiple small foci of necrosis. Many of the hepatocytes immediately adjacent to these areas had an enlarged nucleus with some small chromatin clumps on the periphery while the remainder of the nucleus contained uniform densely basophilic material. There was erosion and necrosis of the caecal epithelium with haemorrhage into the lumen. A few of the sloughed eipthelial cells had large basophilic intranuclear inclusion bodies.

Liver material was post-fixed in osmium tetroxide and examined by electron microscopy. Some enlarged hepatocyte nuclei showed splitting of the nucleolus, a diffuse increase in flocculent moderately electron-dense material and clusters of round donut-shaped viral particles. These particles meas- ured approximately 81 nm in diameter with an electron-dense core of 64 nm. Particles were seen only in the nuclei. As enveloped particles were not seen it was difficult to determine

Present address: 33 Dunkley Avenue, Applecross, Western Australia 6153.

whether these particles were adenoviruses or herpesviruses. The size of the particles was more typical of adenovirus (McFerran 1981), but they were similar in size to the herpesvirus identified in parrots by Randall et af (1979). The particles were too large for papovavirus to be considered.

Adenoviruses cause inclusion body hepatitis in chickens (Wells et af 1977) and a similar disease associated with adenoviruses has been reported in kestrels (Sileo et a1 1983), geese (Riddell 1984) and pigeons (Coussement et a1 1984). Intranuclear inclusion bodies in hepatocytes are sometimes a feature of herpesvirus infection in ducks (Leibovitz 197 I ) , parrots (Cho and McDonald 1980), pigeons (Boyle and Binnington 1973), falcons (Mare and Graham 1973) and owls (Burtscher and Schmacher 1966). Intranuclear inclusion bod- ies in hepatocytes have also been recorded in fledgling budgerigars infected with papovavirus (Dykstra and Bozeman 1982) and goslings infected with parvovirus (Schettler 1971).

The light microscopic appearance of large basophiolic intranuclear inclusion bodies and the size of the particles suggests that the agent in this bird was an adenovirus rather than a herpesvirus.

References Boyle, D. B. and Binnington, J . A. (1973) - Aust. vet. J . 49: 54. Burtscher, H. and Schumacher, A. (1966) - Path. Vet. 3: 506. Cho. B. R. and McDonald, T. L. (1980) - Avian Dis. 24: 268. Coussement, W., Ducatelle, R., Lemahieu, P. Froyman, R., Deu-

riese, L. and Hoorens, J. (1984) - Vlaams Diergen. Tijdsch. 53: 277.

Dykstra, M. J. and Bozeman, L. H . (1982) - Avian Path. 11: 1 1 . Leibovitz, L. (1971) - Am. J . vet. Res. 32: 278. McFerran, J. B. (1981) - In: Comparative Diagnosis of Viral

Mare, C. J . (1975) - J . Zoo Anim. Med 6: 6. Mare, C. J. and Graham, D. L. (1973) - Infect and Immunol 8:

118. Randall, C. J., Dagless, M. D.. Jones, H. G. R. and MacDonald,

J. W. (1979) - Avian Path. 8: 229. Riddell, C. (1984) - Avian Dis. 28: 774. Schettler, C. H. (1971) - Avian Dis. 15: 809. Sileo, L., Franson, J. C., Graham, D. L., Domermuth, C. H.,

Rattner, B. A. and Pattee, D. H. (1983) - J. Wildl. Dis. 19: 244.

Wells, R. J. H., Westbury, H. A,, Harrigan, K. E., Coleman, G. D. C. and Beilharz, R. G. (1977) - Aust. Vet. J. 53: 586.

(Accepted for publication 14 March 1985)

Diseases Vol 111, Academic Press; New York: P. 101.

Therapeutic failure of levamisole in dairy goats

Tasmanian Department of Agriculture R. J . GILLHAM,* D. L. OBENDORFt

During investigations of gastro-intestinal parasitism in a dairy goat herd, it was established that the mixed parasite population consisting of Haemonchus contortus, Tricho- strongylus colubriformis and Ostertagia circumcincta failed to succumb to treatment with benzimidazole anthelmintics. The initial parasite problem related to H. contortus and standard egg reduction tests confirmed ’that this nematode was resistant to benzimidazoles. ClosantelS was used in association with a management program to control haemon- chosis in the herd. Subsequent to the successful control of Haemonchus, continual illthrift in the herd during the following autpmn and winter was shown to be due to parasitism caused principally by T. colubriformis. Morantel citrates was used in the herd; however no clinical response was evident. Egg reduction tests using morantel citrate a t 10 mg/kg bodyweight failed to demonstrate efficacy. Larval culture from goats 10 days after drenching with morantel,

‘P.0. Box 20, Huonville, Tasmania 7109 t Mt Pleasant Laboratories, P.O. Box 46 Launceston South, Tasmania 7249 *Seponver,@ SmithKline Animal Health Products, ‘ Frenchs Forest, N S W 32.5 g l l §Exhelm-E,O Pfizer Agricare Pty Ltd, Thornleigh, NSW

Australian Veterinary Journal, Vol. 62, No. 12, December, 1985 426

consisting of “90% Trichostrongylus larvae, were experi- mentally passaged through young worm-free sheep and goats at Mt Pleasant Laboratories. I n vivo studies which involved drench and slaughter investigations confirmed that the strain was resistant to benzimidazoles and morantel in both sheep and goats but susceptible to levamisole only in sheep. In experimentally infected goats, the strain was apparently “resistant” to oral administration with levamisole a t 8 mg/ kg bodyweight, in that no egg reduction occurred. I n V k O studies were carried out on infective L, larvae derived from faecal samples collected from herd goats. On 3 separate occasions, the larvae were subjected to a larval paralysis test using levamisole hydrochloride and morantel citrate as de- scribed by Martin and Le Jambre (1979). These studies demonstrated that the larval populations had an LD50 of > 1, 0.5, and 3 .3 pg/rnl to levamisole HCI and an LDSo of 16, 35 and 40 pg/ml to morantel citrate. Independent investi- gations at CSIRO McMaster Laboratories confirmed that the Trichostrongylus isolate was highy resistant to morantel but susceptible to levamisole (Waller e t a/ 1985).

The findings of these in vitro and in vivo studies suggested that the pharmacodynamics of levamisole in sheep and goats may be important in understanding these differences in the therapeutic response in the 2 species. To investigate the hypothesis, it was decided to determine the levamisole concentrations in plasma at set intervals after oral dosing with levamisole HCI. The study involved 12 Saanen-type commercial dairy goats of approximately 2 to 3 years of age towards the end of their lactation. The goats were at pasture, but received some concentrate feeding during milking. Egg counts were performed on faecal samples from individual goats in the study on the morning of day 6 and day 3 prior to anthelmintic treatment (day -6 and -3), on the day of treatment (day 0) and on day 3 , 6 , 9 and 12 after treatment. On the day 0 each goat received an oral dose of 7.1 mg/kg levamisole HCI 1 this dose rate is equivalent to 10 mV45 kg bodyweight. Blood samples were taken from the jugular vein at 0, 5 , 10, 15 , 20, 40, 80, 150 and 300 min after anthelmintic treatment. Larval paralysis tests using levamisole were con- ducted on larvae derived faecal samples collected from all goats. Larval paralysis tests were done on larval cultures of faecal samples collected on (1) days -3 and -6 (2) day 0 and (3) days 3 and 6. All paralysis tests demonstrated the larvae had an LD50 < 1 pg/ml to levamisole H C l .

Plasma samples were analysed for levamisole using high performance liquid chromatography (Marriner e t a/ 1980). The concentrations were of the free base. The results of plasma levamisole concentrations in the goats versus time after oral treatment are presented in Figure 1 . Plasma levamisole levels in sheep are presented in the same figure for comparison (Bogan e t a1 1982).

I s0 a0 * Time (min)

Figure 1 . Mean plasma concentration curves of levamisole after oral administration to goats at 7.1 rnglkg ( 0 ) and sheep at 7.5 mglkg ( 0 ) (sheep data after Bogan et a/ 1982) . ___. . .______~ plasma ,- Levamisole (pgIml)

(Nilverm Oral@ drench, ICI Australia Ltd, Melbourne, Victoria. 32g I I

Australian Veterinary Journal, Vol. 62, No. 12, December, 1985

The results presented in this study demonstrate that the blood profiles of levamisole in goats are different to those in sheep and are in agreement with comparable studies of Kettle e t a/ (1983). The figure illustrates that peak blood levels in goats occur very soon after oral drenching (between 5 and 15 min), falling rapidly to < 0.2 pg/ml after 120 min.

No egg reduction was demonstrated in any of the goats under study. The mean pre-treatment ova counts were 350, 425 and 385 eggs per gram (epg) for days -6, -3 and 0 and 440, 360, 503 and 573 epg for day 3, 6 , 9 and 12 respectively. The composition of larval cultures remained similar both before and after treatment, with 90% Trichostrongylus and 10% Ostertagia spp L3 larvae.

Concerns regarding the efficacy of anthelmintics currently used in goats were initially discussed by Hall et a/ (1981) and Kettle et af (1983). These workers concluded that the pharmacodynamics of anthelmintics may vary for different host species and that it is necessary to evaluate anthelmintic dose rates for sheep and goats independently. although our results are restricted to dairy goats on a specific dietary regime using levamisole HCI, other studies suggest that the metabolism of levamisole and benzimidazoles differ markedly between sheep and goats (Galtier e t a/ 1981; Kettle e t a/ 1983). These studies pose some interesting questions in relation to the therapeutic effectiveness of registered anthel- mintics given orally to goats. Kelly and Hall (1979) suggested that nematode resistance in goats to benzimidazoles was probably related to dose rates having been used that were only partially effective. Kettle e t a/ (1983) investigating the metabolism of anthelmintics in sheep and goats stated that dosing goats with levamisole a t the sheep dose rates (8 mg/ kg) results in underdosing whilst oxfendazole was also more rapidly eliminated by goats than by sheep.

Levamisole is thought to act as a cholinergic blocking agent a t the ganglion level, causing the nematodes to become paralysed and subsequently removed from the gastro-intes- tinal tract by the normal movements of the gut (Pritchard, e t a1 1980). The extent and duration of paralysis following treatment may be relevant to efficacy. Reduced efficacy may result from the low plasma concentrations and short duration of peak blood levels.

In this study, levamisole given orally to goats failed to control a susceptible population of T. colubriformis. The plasma profiles of levamisole in goats show that the drug is cleared very rapidly and consequently has little anthelmintic effect on the resident trichostrongyle population. This is supported by the absence of faecal egg reduction after levamisole treatment. Since the anthelmintic was not effective at removing nematodes, levamisole was exerting no selection pressure on the parasites and may explain the absence of resistance in this population.

The authors would like to thank Mr C. Wilshire, ICI Research Department, Ascot Vale, Victoria for performing the analytical studies on the goat bloods for levamisole; Messrs J. Nicholls, L. Butt, G. Graves for assisting with the sequential bleedings and the owners of the Arve Valley Goat Farm for allowing us to conduct this on-farm experiment.

References Bogan, J. A . , Marriner. S. E . , Galbraith, E . A. (1982)-Res. Ver.

Galtier, P . , Escoula, L . , Camguilham, R . and Alvineries, M.,

Hall, C. A., Ritchie, L . and McDonell, P . A., (1981)--Res. Ver.

Kelly, J. D. and Hall, C . A . , (1979). Av. Pharrn. ther. 16: 89 Kettle, P . R., Vlassoff, A. , Reid, T. C. and Norton, C. T. (1983)-

Marriner, S . E. Galbraith, E . A . and Bogan, J . A, , (1980)-Analysr

Martin, P. J. and Le Jambre, L. F. (1979)-Vet. Sci. Comm. 3:

Prichard, R . K . , Hall, C . A., Kelly, J . D . , Martin, I . C. A. and

Waller, P. J., Dobson, R. J., Obendorf, D . L . , Gillham, R . .I.,-

(Accepted for publication 8 M a y 1985)

421

Sci32: 124.

(1981)-Ann. Rech. Vet. 12: 109

Sci. 31: 116

N . Z . vet. J . 31: 139.

105: 993

159

Donald, A . D . , (1980). Aust. ver. J . 56: 239

Vet. Parasi.-in press.