Molecular characterization of Prototheca in 11 symptomatic dogs

Protothecosis is an uncommon disease caused by algae of the genus Prototheca. In dogs, the infection is usually first localized to the colon but has the propensity to later disseminate hematogenously to many other organs, with marked tropism for the eyes and central nervous system. Diagnosis is established by culture and/or evidence of Prototheca organisms in cytologic or histologic preparations. Species characterization, however, requires molecular investigations. Our laboratory set up a real-time PCR targeting portion D1/D2 of the 28S rRNA for identification of Prototheca species from both positive cultures (of rectal swabs and urine) and formalin-fixed, paraffin-embedded tissue. Prototheca bovis, P. ciferrii, and P. wickerhamii were characterized in 11 dogs with systemic or cutaneous protothecosis. Prototheca identifications were phylogenetically consistent with the new taxonomy proposed for this genus based on the mitochondrial cytochrome b gene. As a pilot study, we screened feces and rectal scrapes from 200 asymptomatic dogs, using 2 cohorts of stray and owned animals, to determine the prevalence of intestinal carriage of Prototheca spp. The Prototheca-negative results from both cohorts of healthy dogs suggest that predisposing factors related to the host probably contribute more to the acquisition of clinical disease than exposure to contaminated environments.     

IDENTIFICATION OF ARACHNOID CYSTS IN THE QUADRIGEMINAL CISTERN USING ULTRASONOGRAPHY

The ultrasonographic findings in three small breed dogs with intracranial arachnoid cysts are described. Ultrasound images were obtained via the foramen magnum, temporal window and persistent bregmatic fontanelle (when possible). In transverse, dorsal and sagittal transcranial ultrasound images there was marked dilation of the lateral ventricles and a well-defined, oval to triangular-shaped anechoic area between the caudal aspect of the occipital lobes, dorsal to the midbrain, and rostral to the cerebellum. These findings were consistent with a diagnosis of concurrent hydrocephalus and an arachnoid cyst within the quadrigeminal cistern.     

Endogenous Benzodiazepine Activity in the Peripheral and Portal Blood of Dogs With Congenital Portosystemic Shunts

Objective- The purpose of this study was to determine whether an endogenous benzodiazepine receptor ligand (EBZ) was present in the arterial and portal blood of dogs with congenital portosystemic shunts (CPSS).
Study Design- The presence or absence of an EBZ was determined by the collection of systemic and portal blood from dogs with CPSS.
Animals- Fifteen client-owned dogs with a confirmed CPSS. All dogs had historical signs compatible with hepatic encephalopathy. Eight healthy dogs were used as controls.
Methods- In all dogs, systemic blood samples were collected after they were anesthetized. Portal blood samples were collected intraoperatively. EBZ was measured by radioreceptor assay.
Results- In 10 of 15 dogs, the portal blood concentration of EBZ was significantly elevated compared with normal dogs (mean, 13.2 ±18.55 ng/mL). Five dogs had elevated systemic blood EBZ levels (mean, 8.2 ±16.08 ng/mL). Eleven of 15 dogs had a higher portal than systemic blood concentration of EBZ. In contrast, control dogs had extremely low EBZ concentrations detected in their portal blood (mean, 0.16 ±0.3 ng/mL) and systemic blood (0 ng/mL). The mean portal and systemic blood concentrations in dogs with CPSS were significantly greater than in control dogs ( P <.05).
Conclusions- Elevated blood levels of EBZ were found in dogs with CPSS. The portosystemic gradient noted in 11 dogs suggests the gastrointestinal tract as a possible source for the endogenous ligand.
Clinical Relevance- Generalized motor seizures have been reported in dogs after surgical correction of CPSS. If the presence of a CPSS results in stimulation of brain receptors for benzodiazepines, post-CPSS ligation seizures may result from a withdrawal of EBZ after ligation of the portosystemic shunt.     

TRUE DIAPHRAGMATIC HERNIA IN A CAT

A report of a cat with a true diaphragmatic hernia in which only falciform fat had herniated is pressented. The lession was misinterpreted as a pulmonary mass. Additional radiographic studies which may have been of diagnostic benefit are briefly discussed.     

Modelling the potential impact of exotic diseases on regional Australia

SUMMARY: Recent international initiatives for disease control suggest that, in the future, the consequences for trade of an exotic disease outbreak may not be as severe as estimated in the past. If zoning were to be accepted by Australia's trading partners, then the major effects may be felt at the regional rather than the national level. A study, using an integrated epidemiological/economic model, was undertaken to compare the impacts of 3 important exotic diseases (foot-and-mouth disease, classical swine fever and sheep pox) in 3 different regions of Australia. The study demonstrated that there are significant differences between the size and effect of different disease outbreaks. Regional factors influence not only the way that the disease will spread and manifest itself, but also the effects on local communities. Foot-and-mouth disease caused more economic losses than sheep pox or classical swine fever. The major determinant of differences in the effects of the diseases between regions was the nature of the regional economies. The less diversified the economy, the greater the effect of an exotic disease outbreak in relation to the size of that economy.     

Sequential opportunistic infections in two German Shepherd dogs

Two German Shepherd dogs with sequential opportunistic infections are described. The first was a 2-year-old male with cryptococcal rhinitis that spread to involve the optic nerves and brain. It was successfully treated with combination therapy utilising amphotericin B administered for 2 years, but the dog developed a disseminated Aspergillus deflectus infection 5 years later and was euthanased. The second case was a 4-year-old male that presented for a severe, deep-seated infection of the right antebrachium, with gradual extension to contiguous tissues. Neosartorya fischeri (anamorph; Aspergillus fischerianus) was isolated in pure culture and detected in histological sections. The infection was refractory to itraconazole, but resolved after amputation of the affected limb. Five months later, the dog developed a localised cutaneous lesion on the proximal pelvic limb, from which Pythium insidiosum was isolated and then visualised in tissue sections, together with a structure thought to be grass seed. This lesion was treated by wide surgical resection, although it was reported that the dog died of disseminated disease some months later. These cases provide further circumstantial evidence that young adult German Shepherd dogs have a predilection to developing invasive infections with fungi and other saprophytic pathogens.