H. De Bosschere

Cystic endometrial hyperplasia- pyometra complex in the bitch: should the two entities be disconnected?

The uteri of 26 clinically healthy bitches and 42 bitches with a clinical suspicion of pyometra were examined histologically using a computerized image analysis system. Histologic lesions were characterised mainly by thickening or atrophy of the endometrium and by varying degrees of cystic changes of the glands. These lesions were observed in most of the clinically healthy bitches as well as in all of the clinically ill animals. In most of the ill bitches a variable degree of inflammation also was found. Some bitches with clinical signs indicative for pyometra had no inflammatory reaction in the uterus. These bitches were misdiagnosed as suffering from pyometra, confirming the difficulty of diagnosing pyometra by simple clinical examination. Determination of sex hormone serum levels revealed that all dogs in both groups were either in metestrus or in anestrus. Based on the results of this study the cystic endometrial hyperplasia-pyometra complex can be divided in two entities: a cystic endometrial hyperplasia-mucometra complex and an endometritis-pyometra complex. Both entities bear many similarities with each other, except for the inflammatory reaction in the endometritis-pyometra complex. It is concluded from this study that the latter complex probably does not necessarily follow the former, but that both can arise de novo.

Scrapie case similar to Nor98 diagnosed in Belgium via active surveillance

SCRAPIE is a fatal transmissible spongiform encephalopathy (TSE) caused by prions. Other diseases caused by prions include Creutzfeldt-Jakob disease in human beings and bovine spongiform encephalopathy (BSE) in cattle. Typical features of these diseases are a long incubation period and the gradual vacuolation of brain neurons and neuropil. The pathogenesis of the diseases is believed to be due to the conversion of the normal protease-sensitive prion protein, PrPc, into a partly protease-resistant isoform, PrPSc, which accumulates progressively in the central nervous system of affected animals (Prusiner 1982, Bueler and others 1993). Several (classical) scrapie strains have been described based on lesion profiling in mice (Wood and others 1997, Ligios and others 2002). Since April 2002, all sheep older than 18 months in Belgium have been tested with a rapid test (BSE Platelia test; Bio-Rad) through the active TSE surveillance programme (Pastoret and others 2001, Roels and others 2002) (EC regulation 999/2001). The rapid test is used for the diagnosis of BSE in bovine brain tissues (Moynagh and Schimmel 1999), but is also suitable for the diagnosis of scrapie in sheep, as the monoclonal antibodies used recognise the ovine PrP (Andreoletti and others 2000). This short communication describes a case of scrapie which was similar to Nor98, an unusual case of scrapie first detected in Norway (Benestad and others 2003). Up until the end of 2003, more than 5000 sheep had been tested for scrapie, and six primary outbreaks were detected. Five of the outbreaks showed a classical scrapie lesion profile, but one sheep showed unusual features. The ewe was apparently healthy and presented for slaughter. According to the active epidemiosurveillance protocol, only part of the medulla oblongata around the region of the obex was removed. The sample repeatedly tested positive with the rapid test (Debecker and others 2000). Histopathological investigation revealed no vacuolar lesions either in the neurons or in the neuropil in the region of the obex. There was no detectable PrPSc as revealed by immunohistochemistry of the obex region and tonsils using polyclonal R524-7. The detection of scrapie-associated fibrils (SAFs) was also negative. PrPSc analysis using Western blotting (Bio Rad protocol) with antibodies 12F10 and SAF60 (Fig 1) and BAR226 and SAF60, gave a clear positive result, showing a PrPSc glycoprofile with a strong lower band at approximately 12 kDa, compared with a classical scrapie glycoprofile (Fig 1). The glycoprofile of the present case was confirmed by the National Veterinary Institute, Oslo. Under the terms of the surveillance protocol, the whole flock was culled and the brains of all the animals older than 18 months were examined, but no other animal in the flock tested positive with the rapid test. The affected sheep’s PrP genotype was A136R154Q171 homozygous; this was determined by denaturing gradient gel electrophoresis (Bossers and others 1996). The present case has unusual characteristics: only one of the 55 animals in the flock was affected; no lesions were present in the brainstem (obex) compared with the lesion profiles of classical scrapie cases (Wood and others 1997, Ligios and others 2002); there was no PrPSc immunolabelling in the area of the obex; and the PrPSc glycoprofile differed clearly from the glycoprofiles found in isolates of classical scrapie strains and the BSE strain, and was not distinguishable from the Nor98 glycoprofile. All these features corresponded very well with those reported of the unusual Nor98 strain detected in Norway (Benestad and others 1999, 2002, 2003, Bratberg and others 2003). This raises questions concerning the scrapie active epidemiosurveillance protocol because, from a diagnostic point of view, the positive results obtained with a rapid test require confirmation by standard methods such as histopathological examination and the immunohistochemical detection of PrPSc at the level of the obex. In the present case, the confirmation tests (histology, immunohistochemistry and detections of SAFs), which are officially recognised in Belgium, were all negative. Only Western blotting was positive for scrapie; thus, the diagnosis of scrapie could have been overlooked. This may be of significance for future sampling in scrapie surveillance programmes and confirmation tests.

Estrogen-α and progesterone receptor expression in cystic endometrial hyperplasia and pyometra in the bitch

Estrogen-alpha receptor (ER) and progesterone receptor (PR) were examined immunohistochemically in uteri of normal bitches, in uteri of bitches with cystic endometrial hyperplasia-mucometra (CEH-M) and in uteri of bitches with endometritis-pyometra (E-P), under exogenous progesterone treatment. In the CEH-M group, the ER- and PR-scores of all uterine cell types were higher than the ER- and PR-scores of normal uteri, although these differences were not always statistically significant. The ER-scores of E-P group were significantly lower than the ER-scores of the normal uteri and CEH-M group. The PR-scores of the E-P group tended to be higher than the PR-scores of the normal uteri, except for the surface epithelium, although these differences were not statistically significant. Exogenous progesterone treated bitches with CEH-M or E-P showed reduced ER- and PR-scores in the different uterine cell types, compared with the corresponding nontreated CEH-M or E-P group. The differences in ER and PR expression between CEH-M and E-P suggest different factors in the pathogenesis of both entities. Although, these changes in ER and PR expression do not seem to be directly involved in the pathogenesis of CEH-M and E-P. It is suggested that for CEH-M and progestin induced CEH-M a hormone dependent pathway is responsible. For P, the trigger may be bacterial infection.

An outbreak of histomoniasis in free-range layer hens

Histomonas meleagridis was held primarily responsible for an outbreak of 6% increased mortality and 11%decreased egg production between weeks 57 and 72 in a flock of free-range layer hens, concurrently infected withBvachyspira-like bacteria. This case can be considered an example of ancient diseases re-emerging in alternativehousing systems that are promoted because of animal welfare considerations, but that at the same time allowrapid spread of pathogens in birds for which only few curative drugs are registered. Therefore, new housingmethods should be introduced gradually to gain experience with them.

Changes in sex hormone receptors during administration of progesterone to prevent estrus in the bitch.

The development of lesions and the changes in sex hormone receptors were studied in the uteri of bitches under progesterone treatment. Twelve weeks after the onset of treatment, there was atrophy of the endometrium and increased thickness of the myometrium, without cystic dilatation of endometrial glands. This was accompanied by a dramatic reduction in estrogen-alpha and progesterone receptors in all cell types of the uterine wall. By 24 weeks after the onset of treatment, however, the endometrium was thickened due to the development of cysts of endometrial glands, while the myometrium thickness had returned to normal. The estrogen-alpha and progesterone receptors in most cell types of the uterine wall were again within the normal range. These results clarify and reconcile some apparent contradictions in the literature. They show that sex hormone receptors in most cell types of the uterine wall, especially endometrial gland cells and stromal cells, escape progestin (down) regulation after prolonged exogenous administration of progesterone.

Bile duct hamartoma in a calf.

liver was pale but of normal size, with three large protruding cysts each 8 to 10 cm x 4 to 5 cm filled with watery yellowish fluid. Samples were taken for histological and bacteriological examination. The histological sample of the liver was taken in grossly normal looking tissue. Histologically, perivasculitis and infiltration of inflammatory cells were found in several organs. The liver section

Persistent vitelline vein in a foal.

A three-day-old foal died from intestinal strangulation due to a remnant of vitelline vein which extended between the umbilicus and the portal vein. The strangulating vein was identified on the basis of its morphological and histological structure. This finding, which is the first reported case of a persistent vitelline vein in a horse, is discussed in relation to the normal development and involution of the vitelline circulation.

Hepatic lipidosis in a captive North American porcupine (Erethizon dorsatum).

The liver plays a vital role in the lipid metabolism of the body (Kelly, 1993). Fatty change, or steatosis, is a condition characterized by an abnormal accumulation of triglycerides within the cellular cytoplasm that usually occurs in the liver (Maclachlan and Cullen, 1995). Severe, diffuse hepatic lipidosis requires some time to develop and implies mild cellular injury as a result of nutritional and metabolic imbalance, rather than toxic or anoxic primary injury (Kelly, 1993). In general, the liver is enlarged and yellow coloured, and floats when placed in formalin (Kelly, 1993; Maclachlan and Cullen, 1995). However, the hepatic function is not necessarily abnormal, and the liver can return to normal structure if the metabolic alteration is corrected in time. Although the pathogenesis of this disturbance is not completely understood, some believe that any deficit in energy intake can lead to an intense mobilization of free fatty acids from fat deposits to make up for general energy demands in affected animals. Several physiological and pathological circumstances in different animal species can cause the development of severe fatty change in the liver, with or without clinical disease (Laber-Laird et al., 1987; Kelly, 1993). This is to the authors’ knowledge the first description of hepatic lipidosis in a captive porcupine (Erethizon dorsatum).

The use of epostane in an attempt to reproduce cystic endometrial hyperplasia in the bitch

The aetiology and pathogenesis of spontaneous cystic endometrial hyperplasia (CEH) in the bitch is not yet completely understood. Recent research based on the expression of uterine sex hormone receptors in spontaneous cases of CEH suggested that a temporary progesterone deficiency during late oestrus-early metoestrus may be responsible for the onset of CEH development. In the present study a temporary progesterone deficiency during late oestrus–early metoestrus was experimentally created using an inhibitor of progesterone synthesis, epostane. At day 49 of metoestrus, there was a significant reduction in the size of the uterine wall, mainly due to endometrial atrophy, and there was also a significant increase in the mucus-filled uterine lumen in the bitches that had been treated with epostane compared to the control bitches. No significant differences in the expression of sex hormone receptors was observed between the two groups. As no CEH developed in the epostane-treated bitches, an additional oestrogenic stimulus may be required to stimulate endometrial proliferation. Therefore, it is suggested that deficient luteinization of the corpus luteum may be the trigger in the pathogenesis of CEH, as the secretion of varying amounts of sex steroids depends on the degree of luteinization.

The use of a Daphnia magna bioassay for rapid screening of acute intoxications with insecticides in dogs and cats.

Sudden death due to acute insecticide intoxications occurs frequently in dogs and cats. The absence of characteristic lesions at autopsy often renders post-mortem diagnosis dependent on the analysis of samples taken from the carcase at autopsy. In the present study, a bioassay utilizing Daphnia magna was proposed and tested as a rapid screening method for acute intoxications in dogs and cats. The bioassay was shown to be highly sensitive for detecting carbamate and organophosphate insecticides in the stomach contents. Generally, the mean survival time of the waterfleas in the control group was 5.17 h (SD = 1.24) and in the intoxicated group 1.32 h (SD = 1.49), during a 6 h observation period. If a cut-off is set at 4 h, this Daphnia bioassay gave 5.5% false negative results and 18.2% false positive results, using the results of toxicological analyses as a gold standard.