Cytopathological and histopathological diagnosis of canine splenic disorders

Objectives To determine (1) the common types of canine splenic disorders, and the breeds affected, that are diagnosed by cytopathological and histopathological examination in Sydney, Australia and (2) the accuracy of cytopathological examination compared with histopathological examination for the diagnosis of canine splenic disorders. Design 69 cytopathological and 51 histopathological diagnoses of canine splenic disorders presented to the Veterinary Pathology Diagnostic Services, The University of Sydney during 2006 and 2007 were tabulated and analysed; 17 cases examined both cytopathologically and histopathologically during 2001–07 were also analysed. Results The most common cytopathological diagnoses were benign disorders of growth, vascular disturbances and necrosis (29%), followed by no abnormalities detectable (28%), malignant neoplasms (20%), equivocal diagnoses (20%) and inflammatory disorders (3%). The most common breeds were Kelpie crosses and mixed breeds. The most common histopathological diagnoses were benign disorders of growth, vascular disturbances and necrosis (49%), followed by malignant neoplasms (43%) and inflammatory disorders (8%). The most common breeds were German Shepherd Dogs, Boxers and Maltese Terriers. Cytopathological and histopathological diagnoses were in complete agreement in 59% of cases, partial agreement in 29% and disagreement in 12%. Conclusion Benign disorders of growth, vascular disturbances and necrosis were the most commonly diagnosed canine splenic disorders, both cytopathologically and histopathologically. Kelpie crosses presented most frequently for cytopathological examination. German Shepherd Dogs were the most common breed diagnosed histopathologically with haemangiosarcoma. Although cytopathological and histopathological splenic examinations are complementary for diagnosis, this study has shown a high correlation for complete and partial agreement between the two.     

Indirect infection of cattle with contagious bovine pleuropneumonia.

Hay infected with Mycoplasma mycoides sub-species mycoides (M mycoides) was fed to six animals on three occasions. Five animals developed complement-fixing antibody in their sera and gave a positive reaction to the comparative intradermal allergic test. No animal died from contagious bovine pleuropneumonia (CBPP) but when they were killed, three had unequivocal lesions of the disease. M mycoides was isolated from the animals with these lesions but not from the others. CBPP was transmitted to two animals put in contact with those animals showing disease, and M mycoides was recovered from lesions in both animals. It is suggested that when unexplained outbreaks of CBPP occur, the possibility of indirect transmission should be considered.     

Suspected acute myopathy of pigs

Following sudden exposure to extreme cold, a group of 15-week-old pigs exhibited strange nervous signs which included arching the back, a high stepping gait, violent tremors of the whole body and screaming. The animals lowered themselves and once sitting, the tremors and screaming stopped. But if forced to rise, these signs recurred. When the pigs returned to a warmer environment, they rapidly recovered. An acute clinical myopathy caused by a marginal vitamin E deficiency was suspected. Other stress-induced factors, such as circulatory collapse caused by movement from a warm to a cold environment, were also thought to have contributed towards the myopathy.     

Evaluation of auditory evoked potentials to predict depth of anaesthesia during fentanyl/fluanisone−midazolam anaesthesia in rats

Objectives To assess a method for monitoring depth of anaesthesia using components of middle latency auditory evoked potential (AEP) waveforms during anaesthesia with fentanyl/fluanisone and midazolam. Study design Prospective observational study. Animals Five female Wistar rats weighing between 210 and 250 g. Methods Implanted electrodes were used to record AEPs in animals receiving five doses of anaesthetic. Recordings were made at 5 minutes post‐injection (deep anaesthesia; no pedal withdrawal response, PWR) and then at 25 minutes (light anaesthesia; strong PWR). Responses showed five characteristic peaks occurring at 11, 14, 23, 42 and 68 ms that were measured for latency of occurrence and peak amplitude. Results Auditory evoked potential peaks P14, N23 and P42 were increased significantly in latency with successive anaesthetic injections [avg. F(1,4) = 12.53, p < 0.001; avg. F(1,4) = 10.6, p < 0.001; avg. F(1,4) = 3.9, p = 0.02, respectively]. Peak N23 showed a significant reduction in latency during the 20 minute recovery period following both the first and second anaesthetic injections (t(3) = 7.52, p = 0.005; t(4) = 5.17, p = 0.007, respectively). Peak P42 occurred significantly earlier 20 minutes following the second anaesthetic injection (t(4) = 4.75, p = 0.009). The mean overall depth of anaesthesia assessed using PWR scores was significantly correlated with the mean latency of peak N23, such that as the strength of PWR increased, N23 occurred significantly earlier (r = ?0.99, p = 0.01). The amplitude difference between peaks N23 and P42 increased after the second and third drug administrations [avg. F(1,4) = 10.65, p = 0.031 and avg. F(1,4) = 11.24, p = 0.028, respectively]. Conclusion The characteristics of these peaks, and in particular latency of peak N23, may provide a useful tool for assessing depth of anaesthesia produced by this, and possibly other anaesthetic agents.     

Idiopathic lymphoplasmacytic rhinitis in dogs: 37 cases (1997-2002)

OBJECTIVE: To determine clinical signs and rhinoscopic, computed tomographic, and histologic abnormalities in dogs with idiopathic lymphoplasmacytic rhinitis. DESIGN: Retrospective case series. ANIMALS: 37 dogs. PROCEDURE: Clinical information was obtained from medical records. Nasal computed tomographic images and histologic slides of biopsy specimens were reviewed. RESULTS: Dogs ranged from 1.5 to 14 years old (mean, 8 years); most (28) were large-breed dogs. Nasal discharge was unilateral in 11 of 26 (42%) dogs and bilateral in 15 of 26 (58%) dogs. In dogs with unilateral disease, duration of clinical signs ranged from 1.5 to 36 months (mean, 8.25 months; median, 2 months), and in dogs with bilateral disease, duration of signs ranged from 1.25 to 30 months (mean, 6.5 months; median, 4 months). Computed tomography (n = 33) most often revealed fluid accumulation (27/33 [82%]), turbinate destruction (23/33 [70%]), and frontal sinus opacification (14/33 [42%]). Rhinoscopy (n = 37) commonly demonstrated increased mucus and epithelial inflammation; turbinate destruction was detected in 8 of 37 (22%) dogs. Bilateral biopsy specimens from all 37 dogs were examined. Four dogs had only unilateral inflammatory changes. The remaining 33 dogs had bilateral lesions; in 20, lesions were more severe on 1 side than the other. CONCLUSIONS AND CLINICAL RELEVANCE: Findings suggest that idiopathic lymphoplasmacytic rhinitis is a key contributor to chronic nasal disease in dogs and may be more common than previously believed. In addition, findings suggest that idiopathic lymphoplasmacytic rhinitis is most often a bilateral disease, even among dogs with unilateral nasal discharge.     

Lesions in sheep following administration of a vaccine of a Freund's complete adjuvant nature used in the control of ovine paratuberculosis

CASE HISTORIES: Occurrences of adverse reactions in seven sheep flocks in Australia following vaccination against paratuberculosis where veterinary attention was requested are reviewed. All cases occurred within the 3-year period following commencement of use of a vaccine of a Freund's complete adjuvant nature, at a time when approximately six million doses of vaccine had been administered. CLINICAL FINDINGS: In the first case, 26/58 (45%) Merino sheep vaccinated as adults had palpable tissue reactions at or near the site of vaccination; enlarged prescapular lymph nodes were palpated in 17 (29%), and nine (16%) sheep had both palpable lesions at the site of vaccination and enlarged prescapular lymph nodes. The reactions included caseous nodules up to 5.5 cm in diameter. In the other cases, fistulating or granulomatous wounds were occasionally found at the recommended site of injection behind the ear, and myiasis was rare. Occurrences of inappropriate choice of injection site were recorded, including injection into the axilla of two Merino rams, and lesions in the tissues of the maxilla and nose of almost 50% of 350 Border Leicester lambs. Four outbreaks of progressive paralysis due to injection into cervical musculature were reported, described as "OJD staggers" by producers. DIAGNOSIS: Granulomatous cellulitis and lymphadenitis associated with oil droplets typical of "oil granulomata". Injection of vaccine into the dorsal cervical area resulted in progressive paralysis due to myonecrosis and suspected granulomatous leptomeningitis. CLINICAL RELEVANCE AND CONCLUSIONS: Although lesions at and near the site of injection are common, adverse reactions to vaccination were rare and included mortality from cervical spinal injection, production losses from injection in the maxilla or axilla or if myiasis resulted, and potential marketing losses if animals or carcasses are discounted as a result of the lesions. Risk factors for adverse reactions included inadequate restraint of sheep, breed of sheep, experience of the operator, poor injection technique, and inappropriate placement of vaccine. Increasing attention to the proper restraint of animals, restricting vaccination to the recommended site behind the ear, careful placement of the vaccine into subcutaneous tissue to avoid drainage of vaccine material into tissues such as the spinal cord, and post-vaccination supervision to address welfare concerns should adverse reactions occur are recommended.     

Efficacy of a killed vaccine for the control of paratuberculosis in Australian sheep flocks

A field trial was undertaken from 1999 until 2004 to determine the efficacy of a killed M. a. paratuberculosis vaccine, Gudair, for the control of ovine Johne's disease (OJD) in merino sheep run under Australian pastoral conditions. On each of three farms experiencing significant OJD losses (5-15% per annum), 200 merino lambs (age 1-4 months) were vaccinated, and 200 lambs were left unvaccinated. Animal assessments and sample collections were conducted twice yearly until 4 or 5 years of age. The impact of vaccination on mortality rate, faecal shedding of M. a. paratuberculosis (by pooled and individual faecal culture), liveweight, wool productivity, vaccine injection site lesions and cellular (BOVIGAM) and humoral (PARACHEK) immunity was examined. Vaccination stimulated cell-mediated and humoral immune responses, reduced mortalities due to OJD by 90% and delayed faecal shedding for the first year post-vaccination. Thereafter, the prevalence of shedders among vaccinates was reduced by 90%. The numbers of M. a. paratuberculosis excreted by the vaccinated groups were also reduced by at least 90% at most sampling times. However, high levels of excretion by vaccinates occurred on some occasions, and although only 7 of 600 vaccinates died from OJD, all 7 had multibacillary lesions. Thus there remains a risk that some vaccinated sheep will transfer the disease. Small reductions in liveweight were found in vaccinated lambs in the first year, but there was little effect on wool production. Vaccine injection site lesions were detected in almost 50% of sheep after 2 months, and these persisted for at least 4 years in 20-25% of vaccinates. Data from this trial enabled the registration of Gudair in Australia in 2002 and underpins the pivotal role of vaccination in the current management of OJD.