First report of the use of mucosal swabs of the palatine tonsillar crypt for detection of Mycoplasma bovis in naturally infected calves.

Aims: To compare detection by real-time PCR of DNA from Mycoplasma bovis on mucosal swabs taken from the palatine tonsillar crypt and the mainstem bronchi of clinically asymptomatic calves after slaughter. Methods: We compared the sensitivity of mucosal swabs taken from two sites: the palatine tonsillar crypt and the mainstem bronchi. Paired samples were taken post-mortem at slaughter from 55 clinically well calves from an infected herd and were tested by real-time PCR for the presence of M. bovis-specific DNA. Results: Mycoplasma bovis DNA was detected in 51 palatine tonsillar crypt swabs (92.7 (95% CI = 82.4-98.0)%) and seven mainstem bronchial swabs (12.7 (95% CI = 5.3-24.5)%). All seven calves with positive mainstem bronchial swabs also had positive palatine tonsillar crypt swabs. Conclusions: When compared to mucosal swabs of the mainstem bronchi, mucosal swabs of the palatine tonsillar crypt were seven times more sensitive for the post-mortem detection of M. bovis DNA. The viability of detected M. bovis was not assessed, because any cattle carrying viable or non-viable M. bovis DNA were determined to be a potential risk to eradication. Palatine tonsillar crypt mucosa may be a useful anatomical site for real-time PCR detection of M. bovis DNA in naturally infected calves. More work is needed to define the persistence and viability of M. bovis at this anatomical site. Clinical relevance: The results of this study helped form the basis of surveillance tools used in M. bovis control and eradication efforts. Familiarity with these results may help veterinarians better communicate with their clients about the science behind the eradication efforts.

An overview of dropped hock syndrome cases in New Zealand cattle.

Case history: Data were collected from 47 outbreaks of dropped hock syndrome (DHS) that were reported by veterinarians in New Zealand to the Ministry for Primary Industries between October 2012 and August 2017. There were 181 affected dairy cows from 44 farms. Of those with records, all 86 were aged between 2-3 years-old, and 4/94 (4%) were Friesian, 56/94 (60%) were Jersey and 33/94 (35%) were Jersey/Friesian cross. Of the 47 outbreaks, 45 (96%) occurred during winter and 37 (79%) in the South Island.Clinical findings: Of 151 cases with records, hindlimb weakness (117 cows), shortened gait (112 cows) and dropped hocks (106 cows) were most commonly reported, with 110 cases being bilaterally affected. The level of diagnostic work-up and the data recorded by veterinarians for each outbreak were highly variable. Creatine kinase and aspartate aminotransferase activities were reported for 22 cases and were within normal ranges for cows with mild disease but increased in cows with severe disease. Concentrations of Cu in serum and liver were below normal for 13/22 and 9/10 cows, respectively, from six outbreaks. Of 41 cows with records for clinical outcomes, 12 had complete resolution, 18 had partial resolution, and 11 had no resolution.Pathological findings: Post-mortem data were available from 26 cases. Muscle necrosis and haemorrhage of the origin of the gastrocnemius muscle were the key gross findings. In 14 cows with records for muscle histopathology, myodegeneration and recent haemorrhage were observed, and connective tissue pathology was reported to predate muscular pathology in seven cases.Diagnosis: DHS appeared to be a degenerative rather than inflammatory condition primarily affecting the connective tissue of the hind limb, especially at the dense collagen interfaces of the gastrocnemius. Although no evidence of neuropathy was found, this cannot definitively be ruled out as a potential cause.Clinical relevance: A more standardised and systematic approach to investigating cases and recording case data is required to make robust inferences about the aetiology, risk factors, and treatment interventions for DHS.

Systemic granulomatous disease in dairy cattle during a dicyandiamide feeding trial.

CASE HISTORY: Mature, in-calf, non-lactating, Friesian or Friesian-cross cows were fed dicyandiamide (DCD) at daily doses of 0.15 g/kg (Group 1; n=31), 0.45 g/kg (Group 2; n=21) and 0.75 g/kg (Group 3; n=12), as part of a safety trial, which also included a control group (n=15). Daily health observations were carried out on each cow until Day 86 of the study. On Day 28 one cow from Group 3 was observed with signs of disease, and subsequently disease was noted in other cows. CLINICAL FINDINGS: Clinical signs in the first case included depression, pyrexia (40.9°C), salivation and dehydration, in addition to progressive weight loss, followed by death on Day 32. Other cows from all treatment groups developed clinical signs of disease resulting in euthanasia of seven animals. Disease occurred in 10/12 (83%) cows in Group 3, 11/21 (52%) cows in Group 2, and 7/31 (23%) cows in Group 1. Clinical signs were variable and included dermatitis and pruritus of the head and neck, petechial haemorrhages, pyrexia, weight loss, thrombocytopenia, neutropenia, and regenerative anaemia. PATHOLOGICAL FINDINGS: Gross findings included generalised lymphadenopathy, subcutaneous oedema, petechiation of mucosal and serosal surfaces, and gastrointestinal haemorrhage. Histologically, multiple organs and tissues contained inflammatory foci characterised by infiltrates of lymphocytes, plasma cells, macrophages and occasionally prominent multinucleated giant cells and eosinophils. DIAGNOSIS: Multisystemic granulomatous and haemorrhagic syndrome resembling cell-mediated hypersensitivity, associated with DCD ingestion. CLINICAL RELEVANCE: This is the first report of toxicity in cattle associated with ingestion of DCD. The proportion of affected cows increased with increasing dose of DCD, but not all cattle in the high dose group developed disease, therefore additional factors may determine whether or not an individual cow will develop DCD-associated disease.

Systemic granulomatous and haemorrhagic syndrome in New Zealand dairy cattle.

CASE HISTORY: Cases were obtained through passive surveillance reporting by veterinary pathologists, via the Ministry for Primary Industries Exotic Pest and Disease Hotline. They included ill or dead cows that had evidence of frank haemorrhage, petechial haemorrhages on mucous membranes, wasting or dermatitis of unknown cause, and were reported between 2009-2014. Affected cows (n=16) were from nine seasonally calving dairy farms, aged ≥3 years, and were predominantly in their mid-to-late non-lactating period. A brassica crop was identified in 15/16 cases as part of the current or recent ration. CLINICAL FINDINGS: Eight cows were found dead or died within 2 days of first signs. In eight cases death or euthanasia took place up to 3 weeks after signs were first observed. Cattle clinically examined prior to death (n=11) were generally inappetant, and recumbent or reluctant to move. Five cases had pale mucous membranes, three had petechiae and two were jaundiced. Rectal temperature was normal to sub-normal in eight cases. Evidence of melena or fresh blood at the anus or mouth was found in five cases. In three cases, alopecia and skin thickening was present, predominantly affecting the head and neck. PATHOLOGICAL FINDINGS: Petechiation of mucosal and internal serosal membranes, myocardium, subcutis and skeletal muscle was found in 10 cases. Frank haemorrhage was present in six cases, including haematomas of the subcutis, skeletal musculature, mesentery or omentum, and lumenal haemorrhage of the abomasum and/or intestine. In five cases pale nodules within myocardium and/or kidney, liver or spleen were present. Histopathologically, these were confirmed as granulomatous inflammatory lesions, which were also present within a wide range of tissues. Granulomatous foci typically comprised aggregates of macrophages, lymphocytes, plasma cells, prominent multinucleated giant cells and eosinophils. DIAGNOSIS: Idiopathic multisystemic granulomatous and haemorrhagic disease, occurring sporadically in dairy cattle, in the absence of feeds or feed additives previously associated with comparable syndromes. CLINICAL RELEVANCE: This is the first description of a novel systemic granulomatous and haemorrhagic syndrome seen in adult dairy cattle most often in their non-lactating period. The presentation can mimic important exotic disease differentials in New Zealand including anthrax, haemorrhagic septicaemia (associated with selected Pasteurella multocida strains) or infection with bovine viral diarrhoea virus type 2.

First report and histological features of Chlamydia pecorum encephalitis in calves in New Zealand.

CASE HISTORY: Between September and October 2013, 40 of 150 crossbred Friesian dairy calves on a farm in the Manawatu region of New Zealand developed neurological signs when between 1 and 3 months of age. Calves were grazed in multiple mobs and calves from each mob were affected. A variable response was observed to initial treatment with thiamine, fluoroquinolone antibiotics and non-steroidal anti-inflammatory drugs. CLINICAL AND PATHOLOGICAL FINDINGS: Affected calves exhibited a range of neurological signs that included generalised depression, hind limb ataxia with a stiff gait, and knuckling of the fetlocks. In advanced cases, calves became recumbent with opisthotonous. Over a 4-week period, 13 calves died or were subject to euthanasia and a thorough necropsy was performed on three of these calves. Necropsy findings included fibrinous peritonitis, pleuritis and pericarditis, with no gross abnormalities visible in the brain or joints. Histology of the brain was possible in seven of the affected calves, with lesions ranging from lymphocytic and histiocytic vasculitis and meningoencephalitis, to extensive thrombosis and neutrophilic inflammation. Immunohistochemistry using an anti-chlamydial lipopolysaccharide antibody revealed positive immuno-staining in all seven cases, with no brain samples exhibiting immunostaining for Histophilus somni. DNA was extracted from a sample of fresh brain from one case and chlamydial DNA sequences were amplified by PCR and found to be identical to Chlamydia pecorum. PCR was also performed on formalin-fixed brain tissue from three of the other cases, but no chlamydial DNA was amplified. DIAGNOSIS: Chlamydia pecorum meningoencephalomyelitis (sporadic bovine encephalomyelitis). CLINICAL RELEVANCE: This is the first time that C. pecorum has been confirmed as a cause of clinical disease in New Zealand. Practitioners should be aware of this disease as a differential in calves with neurological signs, and submit samples of formalin-fixed brain as well as fresh brain to enable confirmation of suspected cases using PCR analysis. Furthermore, these cases illustrate that the histological lesions in the brains of calves with C. pecorum are more variable than previously reported, and pathologists should be aware that histological features may overlap with those traditionally ascribed to other organisms, such as H. somni.

Investigation of an outbreak of craniofacial deformity in yellow-eyed penguin (Megadyptes antipodes) chicks.

AIM: To investigate an outbreak of severe craniofacial deformity in yellow-eyed penguin (Megadyptes antipodes, hoiho) chicks at a single breeding site on the Otago Peninsula in the South Island of New Zealand. METHODS: Morbidity and mortality of yellow-eyed penguins breeding on the coastal regions of Otago was monitored from November 2008 to March 2009. Dead chicks and unhatched eggs were recovered and examined. Between October and December 2008 32 eggs were recorded at 17 nests in the Okia Reserve. Eleven chicks survived to about 90 days of age, of which eight were found to have moderate to severe craniofacial deformity. The six most severe chicks were subject to euthanasia and examined in detail at necropsy, and the remaining two affected chicks were released to the wild after a period of care in a rehabilitation centre. Post-mortem samples were analysed for inorganic and organic toxins. RESULTS: The six deformed chicks all had severe shortening of the mandible and maxilla by 20-50 mm. The rostral and caudal regions of the skull were approximately 40 and 80% of normal length, respectively. Other, more variable lesions included cross bill deformity, malformed bill keratin, microphthalmia with misshapen scleral ossicles and oral soft tissue excess thought to be secondary to bony malformations. During the same year, mild sporadic bill deformities were also reported in 10 unrelated chicks from >167 chicks at other breeding sites on the southern Otago coast. Concentrations of organic toxins and heavy metals in body tissues from affected chicks were apparently similar to those in unaffected chicks on other beaches. CONCLUSIONS: No cause of this outbreak of craniofacial deformity could be established although the high prevalence at a single site suggests that it was due to an unidentified local teratogen.

Adenoviral infection in a collection of juvenile inland bearded dragons (Pogona vitticeps).

CASE REPORT: Juvenile inland bearded dragons (Pogona vitticeps) from a breeding collection in south-east Queensland were presented at age 6-10 weeks with neurological signs, poor growth and occasional deaths. Histopathological examination revealed that six of eight lizards had multifocal non-suppurative hepatitis associated with 5-10 µm diameter, smudgy, basophilic, hyaline intranuclear inclusion bodies that marginated the nuclear chromatin. These histological lesions were considered consistent with adenoviral hepatitis. Infection with adenovirus was confirmed positive in one of the eight dragons by PCR for adenoviral DNA. DNA was extracted from formalin-fixed paraffin-embedded pooled tissues of the juvenile inland bearded dragons and tested using a nested-PCR protocol with primers specific for identification of adenovirus. Sequencing of the one PCR-positive dragon showed 95% nucleotide sequence alignment with agamid atadenovirus 1. Further investigation involved testing the breeding population, including the parents of the affected juveniles. Blood and cloacal samples were collected from the adult population, DNA was extracted and tested by PCR for adenovirus. There was a high percentage of positive results from the samples collected from the breeding population. CONCLUSION: This is the first reported group outbreak of adenoviral disease in bearded dragons in Australia.

Primary bone tumors in birds: a review and description of two new cases.

Primary bone tumors are only occasionally reported in avian species. This paper presents the cases of an osteosarcoma in a 6-yr-old free-range chicken and a chondrosarcoma in a 3-yr-old barred Plymouth Rock chicken. The well-differentiated, moderately productive osteoblastic osteosarcoma arose from the synsacral vertebrae and had metastasized to the liver. The chondrosarcoma was well differentiated and firmly attached to the left side of the keel. There was no evidence of metastasis.