Mycotic abortion in cattle.

Placentas and foetuses from 1107 bovine abortions were examined and a fungal infection was diagnosed in 131 instances. Fungi seen in silver impregnated sections of tissues could be placed into 3 categories designated aspergillus, phycomycete and atypical. Culture indicated that the first 2 of these categories were due to Aspergillus sp and Mortierella wolfii respectively. The infections in the atypical category are probably also due to Aspergillus sp. Gross or microscopic examination or culture of the placenta were valuable diagnostically but examination of the foetus was seldom of value as infection in most instances did not involve foetal tissues. Questionnaires indicated that many M. wolfii abortions were associated with the feeding of poorly prepared or stored grass silage. As the majority of cattle are fed hay or silage, no association could be demonstrated between Aspergillus sp abortion and these feeds. Fertility following fungal abortion was apparently unimpaired.

Multiple apparent Sarcocystis abortion in four bovine herds.

Foetuses recovered from multiple abortions in four dairy herds had multifocal nonsuppurative encephalitis, myocarditis and hepatitis. Focal placentitis was usually present. Sarcocystis-like protozoa were found in the brains of foetuses from two of the outbreaks. Apart from excess salivation in a few cows in one herd, farmers reported no clinical abnormalities prior to the abortions, and all cows remained normal after the abortions. Dogs and cats fed an affected foetus and neonatal calves from the affected herds failed to excrete protozoa in their faeces. The identity of the protozoa in the foetal brain was not confirmed.

Diagnostic studies of the fetus, placenta and maternal blood from 265 bovine abortions.

During 1981, the fetus, placenta and maternal serum were received from each of 265 bovine abortions. These specimens were examined using histopathological, histochemical, bacteriological, mycological, endocrinological, immunological, serological and virological techniques. The cause of abortion was identified in 98 (37%) cases. Of these diagnosed abortions 27 (28%) were due to infection with fungi, 17 (17%) to Salmonella spp, 11 (11%) to Campylobacter fetus and 10 (10%) to Corynebacterium pyogenes infection. Of the remaining 33 (34%) diagnosed abortions 8 were due to Leptospira sp, 5 due to protozoan (probably Sarcocystis) encephalitis and 20 due to miscellaneous bacterial infections (including Brucella abortus) and fetal deformities. Bovine virus diarrhoea virus was isolated in 5 (2%) abortions, however the significance of the isolations was not known. Infectious bovine rhinotracheitis virus and chlamydia were not identified as causal agents in any abortion. In 18 (7%) abortions no definite etiologic agent was identified despite pathological findings suggestive of infection. Fetal heart blood serology and immunoglobulin values were not reliable indicators of infectious abortion. Of the remaining 149 (56%) abortions, 17% had high maternal serum cortisol levels and twin fetuses occurred in 9%.

Phosphatic fertiliser poisoning of sheep: experimental studies.

The toxicity of serpentine phosphate and superphosphate for non-pregnant dry ewes, pregnant ewes and lactating ewes was investigated by oral dosing. An attempt was made to reproduce a natural episode of poisoning by exposing pregnant and lactating ewes to topdressed pasture. A total dose in the range of 1200 to 1800 g of serpentine phosphate was required to kill two ewes and it was concluded that natural episodes of poisoning with this material are unlikely. The toxic process was similar to that caused by superphosphate. The LD50 of superphosphate was estimated to be in the range of 5 to 6 g/kg and a dose in the range of 200 to 300 g was sufficient to kill most sheep. The apparently greater susceptibility of pregnant and lactating sheep to poisoning suggested by the study of natural outbreaks was not demonstrated in these experiments, but the numbers of experimental animals may have been too small to detect differing susceptibility. The clinical disease resembled that seen in natural episodes; anorexia, diarrhoea, progressive depression and death in a period of 5 to 8 days after the start of dosing. Sublethal doses produced a transient diarrhoea and, in two sheep, a severe wool-break. The principal biochemical changes were hyperphosphataemia and evidence of renal failure (oliguria, uraemia, azotaemia). Gross lesions were not consistently present but included abomasal ulceration and renal cortical swelling and pallor. The histopathological evidence of renal tubular obstruction by flocculant eosinophilic casts was characteristic.

In vitro penetration and absorption of chemicals into the ovine hoof.

Techniques are described for testing the ability of chemicals to penetrate through ovine hoof horn. Most chemicals tested had penetration rates of less than 0.1 mm per hour and formalin, a chemical widely used for treatment of foot rot, penetrated very poorly (less than 0.02 mm per hour). Chloramphenicol in ethanol solution gave the highest penetration rate (0.21 to 2.38 mm per hour) and other penetrative chemicals were zinc sulphate (0.06 to 0.58 mm per hour), copper sulphate (less than 0.05 to 0.38 mm per hour) and sodium azide (less than 0.05 to 0.24 mm per hour) in aqueous solution. Inclusion of sodium lauryl sulphate in treatments enhanced the penetration rates of zinc and azide approximately sixfold. Ethanol and nickel ammonium hydroxide also improved the penetration of zinc and azide, particularly through the hard horn from the abaxial wall of the claw. Absorption of zinc from solutions containing 10 per cent zinc sulphate gave hoof tissue concentrations of zinc from 0.22 to 0.88 mg zinc ions per g tissue (10 to 20 times that found in normal hoof samples) and most of this zinc was retained after the horn was washed continuously in running water for 24 hours.

White liver disease of sheep.

Outbreaks of ovine white liver disease (WLD) on 7 farms in eastern Victoria were investigated. Most occurred in late spring and mainly affected lambs 3 to 6 months old, with a morbidity of 20 to 100% and mortality of 8 to 15%. Clinically affected lambs showed illthrift, emaciation and bilateral, serous, ocular discharge. Clinical pathology showed mild anaemia, elevated serum liver enzymes (GGT, OCT, AST) and low levels of serum vitamin B12. Grossly, the livers were pale, fatty and friable; microscopically there was parenchymal fatty change, bile duct proliferation and ceroid pigmentation. Liver cobalt values were consistently low (mean 0.4 +/- 0.4 mumol/kg D.W.). Levels of cobalt in pasture from 2 properties were very low (0.34 mumol/kg D.W.) The diagnosis of white liver disease was made on the basis of clinical features, specific liver pathology and low cobalt status. Treatment trials established that cobalt injections or oral bullet administration resulted in clinical improvement, significant weight gains, and improved serum vitamin B12 levels. WLD did not recur in previously affected sheep using these treatments. However, when blocks containing cobalt were available continuously, WLD recurred 2 years after the initial outbreak.

The use of immunochemically purified anti-brucella antibody in a direct fluorescent antibody test for Brucella abortus.

Antibodies specific for Brucella abortus were purified from the serum of hyperimmunized sheep using immunochemical procedures. They were conjugated to fluorescein isothiocyanate and used in a fluorescent antibody (FA) test for B. abortus. The conjugate did not stain any heterologous bacterial or fungal species tested and background fluorescence associated with its use on smears and sections of abortion materials was particularly low. Of 239 cases of abortion examined fluorescent microscopy demonstrated B. abortus in all 12 cases in which the organism was isolated. A few areas of fluorescence typical of B. abortus were also seen in 3 cases from which the organism was not cultured. B. abortus was demonstrated in lymph nodes from 6 of 36 Brucella reactor cows by culture and 7 by the FA test. However, only very low numbers of B. abortus were isolated or seen and sampling errors would have been significant. Use of the FA test allows diagnosis of Brucellosis to be made in 2 hours, compared to 6 days by the usual cultural procedures.

Intestinal rupture in sows fed whey.

A problem of sudden deaths was investigated on a 600 sow piggery after 35 (8%) mature sows died during 10 months. Thirty four (90%) of the sows which died in the following 20 months were all fed whey and had acute severe peritonitis associated with rupture of the large or lower small intestine. No similar deaths occurred in sows, gilts or boars receiving only formulated feed pellets. It is suggested that ruptures resulted from overdistention with gas produced from whey and that the likelihood of their occurrence was directly related to the volume of whey ingested.

Histological ageing of bruises in lambs and calves.

Groups of 10-day-old calves and 5-month-old lambs were bruised 48 hours, 24 hours, 8 hours, or the instant before slaughter. By gross examination, 48-hour-old calf bruises had a characteristic red-yellow colouration, but other bruises could not be differentiated reliably. By microscopic examination, bruises of all ages could be differentiated by cellular criteria common to both species. Unlike fresh lesions, 8 hour bruises contained numerous neutrophils. Twenty-four hour old bruises contained equal numbers of macrophages and neutrophils and at 48 hours macrophages, fusiform cells and new capillaries were present in the damaged muscle. The criteria established in this study could be used to determine the ages of spontaneous bruises in abattoir carcases and so provide a basis for an investigation aimed at detection of the traumatic episode from which they result.

The distribution of dextran macromolecules in the glomeruli of normal and nephrotoxic rats.

The incorporation of intravenously injected dextran molecules (molecular weight 500,000 & 2,000,000) by the glomeruli of laboratory rats was studied by electron microscopy. In normal rats some dextran molecules were observed 12 minutes after injection in vesicles and invaginations of both endothelial and mesangial cells. Rats with nephrotoxic serum nephritis showed extensive separation of endothelial cells from the glomerular basement membrane. These subendothelial spaces contained irregular granular material, cytoplasmic extensions of mesangial cells and, in animals injected with dextran, dense accumulations of dextran molecules. There was no apparent difference in distribution of the two test samples of dextran. These findings demonstrated the involvement of both endothelial and mesangial cells in the glomerular localization of circulating material and indicated that immunologically inactive macromolecules can be incorporated into subendothelial deposits following immunological injury to the glomerulus.

Experimental autoimmune glomerulonephritis in the rat. I. Factors influencing induction.

Albino Holtzman, albino Wistar and hooded HS rats were injected fortnightly for 14 weeks with human glomerular basement membrane (GBM) emulsified in Freund's complete adjuvant. Half of the rats were pretreated with Freund's complete adjuvant and some were unilaterally nephrectomized. Anti-GBM antibody glomerulonephritis, characterized by proteinuria (greater than 100 mg/16 h) and a diffuse linear deposition of host immunoglobulin along the glomerular basement membrane, was first detected in Holtzman rats 4 weeks after treatment with GBM had begun, and had developed in 69% of these rats by 15 weeks. In contrast, none of the similarly treated Wistar or HS rats became proteinuric at any time, although a few showed weak glomerular fluorescence at the end of the experiment. Thus Holtzman rats are susceptible, and HS and Wistar rats are resistant to experimental anti-GBM antibody glomerulonephritis. Pretreatment with Freund's complete adjuvant apparently shortened the induction period of the experimental disease in the Holtzman rats whereas unilateral nephrectomy appeared to decrease their susceptibility to it.

Experimental autoimmune glomerulonephritis in the rat. II. A histopathological and fine structural study.

Human glomerular basement membrane (GBM) emulsified in Freund's complete adjuvant was injected into 16 Holtzman rats. Eleven (69%) of them subsequently developed glomerulonephritis. This disease was characterized by glomerular changes which included focal lobular hypercellularity due to localized hyperplasia of intracapillary (mesangial or endothelial) cells which often obstructed glomerular capillaries. Later, affected lobules showed necrosis of intracapillary cells, and capillary lumina were filled with homogeneous eosinophilic material. An immunoperoxidase technique revealed autologous anti-GBM antibody in all 3 layers of the GBM and in some regions it was present in greater amount in the lamina rara interna and externa than in the lamina densa. Experimental auto-immune glomerulonephritis in the rat is thus characterized morphologically by a focal proliferative glomerulonephritis which proceeds to focal glumerulosclerosis.