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.

Clinicopathological features of 11 suspected outbreaks of bovine adenovirus infection and development of a real-time quantitative PCR to detect bovine adenovirus type 10

CASE HISTORY

A retrospective study was conducted to investigate 11 outbreaks of presumptive fatal adenovirus infection diagnosed through two New Zealand diagnostic laboratories during 2014 and 2015. Outbreaks occurred in 6-12-month-old Friesian or Friesian cross cattle during autumn, winter and spring. Individual outbreaks were short in duration, with mortality rates ranging from 3/250 to 20/600 (1.2 to 3.3%).

CLINICAL AND PATHOLOGICAL FINDINGS

Clinical signs included severe diarrhoea, depression, recumbency, and death. Post-mortem examination revealed congestion and oedema of the alimentary tract and fluid to haemorrhagic intestinal contents. Histopathological lesions were characterised by congestion and haemorrhage of the alimentary tract mucosa, oedema of the submucosa, and mild interstitial inflammation in the kidneys. Large basophilic intranuclear inclusion bodies were identified in vascular endothelial cells of the alimentary tract in 11/11 cases and of the kidney in 8/9 cases.

MOLECULAR TESTING

A real-time quantitative PCR (qPCR) assay was designed to detect bovine adenovirus type 10 (BAdV-10) using hexon gene sequences available in GenBank. DNA extracted from a field case and confirmed by sequencing was used as a positive control. The qPCR had a reaction efficiency of 101% (R(2)=0.99) and the limit of detection was <10 DNA copies/reaction. The qPCR detected BAdV-10 in formalin-fixed paraffin-embedded (FFPE) tissue from 10/11 cases. DNA sequencing of PCR products from nine of these cases showed them to be identical to BAdV-10 sequences in GenBank. For the PCR-negative case, the PCR product had a hexon sequence 99% similar to bovine adenovirus Wic isolate Ma20-1, a close relative of BadV-10.

DIAGNOSIS

Bovine adenovirus type 10 was identified in FFPE tissues from cattle with histopathological evidence of adenovirus infection.

CLINICAL RELEVANCE

Bovine adenoviruses, and especially BAdV-10, should be considered in the differential diagnosis for acute enteric disease and death in young cattle. The qPCR detected BAdV-10 from FFPE tissue of cattle with suspected adenoviral infection diagnosed by histopathology. However results should be interpreted in light of clinical and pathological findings due to the possibility of adenovirus shedding by healthy cattle and the presence of pathogenic adenoviruses other than BAdV-10.

A Novel and Likely Inherited Lymphoproliferative Disease in British Shorthair Kittens

An unusual lymphoproliferative disease was identified in multiple closely related British Shorthair (BSH) kittens, suggesting an inherited predisposition to disease. Affected kittens typically developed rapidly progressive and marked generalized lymphadenopathy, moderate splenomegaly, and regenerative and likely hemolytic anemia from 6 weeks of age. Microscopic findings were suggestive of multicentric T-cell lymphoma, but additional testing revealed a polyclonal population of CD3+/CD4–/CD8– “double negative” T cells (DNT cells). This is a novel disease presentation with similarities to the human disorder autoimmune lymphoproliferative syndrome (ALPS), a rare inherited disease causing lymphoproliferation and variable manifestations of autoimmunity. The human disease is most commonly due to the presence of Fas gene mutations causing defective lymphocyte apoptosis, and further investigations of both the mode of inheritance and genetic basis for disease in affected cats are currently in progress.

Post-vaccinal distemper encephalitis in two Border Collie cross littermates

CASE HISTORY

One 4.5-month-old male Border Collie cross presented with aggression and seizures in October 2006. A 16-month-old, female, spayed Border Collie cross presented with hypersalivation and a dropped jaw and rapidly became stuporous in September 2007. The dogs were littermates and developed acute neurological signs 5 and 27 days, respectively, after vaccination with different modified live vaccines containing canine distemper virus.

HISTOPATHOLOGICAL FINDINGS

Sections of brain in both dogs showed evidence of encephalitis mainly centred on the grey matter of brainstem nuclei, where there was extensive and intense parenchymal and perivascular infiltration of histiocytes and lymphocytes. Intra-nuclear and intra-cytoplasmic inclusions typical of distemper were plentiful and there was abundant labelling for canine distemper virus using immunohistochemistry.

DIAGNOSIS

Post-vaccinal canine distemper.

CLINCIAL RELEVANCE

Post-vaccinal canine distemper has mainly been attributed to virulent vaccine virus, but it may also occur in dogs whose immunologic nature makes them susceptible to disease induced by a modified-live vaccine virus that is safe and protective for most dogs.

Oral Papillomas Associated With Felis catus Papillomavirus Type 1 in 2 Domestic Cats

Multiple small sessile raised lesions were detected on the ventral surface of the tongue in two 13-year-old domestic cats. The lesions were incidental in both cats. Lesions from both cats appeared histologically as well-demarcated foci of markedly thickened folded epithelium that formed keratin-filled shallow cuplike structures. Large keratinocytes that contained a swollen nucleus surrounded by a clear cytoplasmic halo (koilocytes) were common, suggesting a diagnosis of a papillomavirus-induced papillomas, and papillomavirus antigen was demonstrated by immunohistochemistry. The papillomas exhibited diffuse intense cytoplasmic and nuclear immunoreactivity against cyclin-dependent kinase inhibitor 2A protein (also known as p16 or INK4a protein). Felis catus papillomavirus type 1 DNA sequences were amplified from both papillomas. The papillomas resolved in 1 cat within 3 months of diagnosis, while the papillomas were still visible 4 months after diagnosis in the other cat. This is the first evidence that these papillomas are caused by F. catus papillomavirus type 1.

Listeria monocytogenes infection of the alimentary tract (enteric listeriosis) of sheep in New Zealand

A retrospective study of the microscopical lesions of nine cases of enteric listeriosis of sheep was conducted. Lesions were present variably in the abomasum and the small and large intestines. The inflammation was multifocal to extensive, mainly neutrophilic and involved the lamina propria, muscularis mucosa and superficial submucosa, with intense focus on the muscularis mucosa. The mesenteric lymph nodes were also affected and, in some sheep, the liver. Large numbers of gram-positive rods were demonstrated within areas of inflammation in the gastrointestinal tract and mesenteric lymph nodes and Listeria spp. were identified immunohistochemically in these lesions. Ultrastructurally, bacteria were found free within the cytoplasm of myofibres of the muscularis mucosa.

Leptospirosis associated with serovarshardjoandpomonain red deer calves (Census elaphus)

Four red deer calves (Cervus elaphus) died with severe nephritis apparently associated with infection by Leptospira interrogans serovar pomona. The sera of 12 in-contact red deer calves were examined for leptospiral agglutinins and nine showed titres to pomona consistent with recent infection. Two also showed titres of 1:100 to serovar hardjo. The urine of five of these in-contact calves was examined periodically over a period of nine months. All were initially leptospiruric, four being infected with pomona and one with hardjo. In four animals leptospiruria could only be detected for up to six months, but one animal infected with pomona was leptospiruric for at least eight months. The apparent source of infection was from infected cattle, and it is suggested that deer are unlikely to act as maintenance hosts for serovar pomona.

An outbreak of rickets in Corriedale sheep: Evidence for a genetic aetiology

CASE HISTORY

A skeletal disease characterised by lameness, limb deformities and reduced growth rate occurred over two successive years in lambs born on a commercial sheep farm in Marlborough. A genetic aetiology was considered likely following exclusion of other known causes of rickets and because of the progressive nature of the disease, even after affected animals were transferred to another property.

CLINICAL FINDINGS

Affected lambs appeared normal at birth but developed clinical signs during the first 2 months of life. The most severely affected animals either died or were euthanised within the first year of life, but some survived to breeding age. Serum biochemistry revealed hypocalcaemia, hypophosphataemia and increased concentrations of 1,25 dihydroxyvitamin D. The mean serum 25 hydroxyvitamin D concentration was similar to that of control lambs.

PATHOLOGICAL FINDINGS

Gross lesions included enlarged costochondral junctions, bilateral irregularity of articular surfaces on humeral heads due to collapse of subchondral bone, thickened cortices in long bones and irregular thickening of physeal cartilages. Microscopically, tongues of hypertrophic chondrocytes extended from physes into metaphyseal regions; metaphyseal trabeculae were thick, disorganised and often lined by wide osteoid seams. Osteoclastic activity was excessive both in cortical and trabecular bone.

DIAGNOSIS

Inherited rickets in Corriedale sheep. CLINICAL RELEVANCE AND CONCLUSIONS: This disease is likely to be present in several Corriedale sheep flocks in New Zealand and may have been misdiagnosed as arthritis or other diseases causing lameness and/or poor growth. A defect in end-organ responsiveness to 1,25 dihydroxyvitamin D is the likely mechanism. This disease of sheep may be a useful model for studying vitamin D metabolism and the treatment of inherited forms of rickets in human beings.

Recurrent localised cutaneous parapoxvirus infection in three cats

CASE HISTORY

Three cats were presented with single proliferative lesions affecting one foot, which failed to heal after medical treatment, and recurred despite surgical resection.

PATHOLOGICAL FINDINGS

Histologically, the lesions were proliferative and papillary. There was marked acanthosis, rete peg formation, and compact orthokeratosis, with large numbers of bacteria in the orthokeratotic scale. Some biopsies had multifocal keratinocyte swelling of the stratum granulosum, and amphophilic intracytoplasmic inclusions were present in some of the swollen cells. The dermis consisted of a light fibrous stroma with marked capillary proliferation. Parapoxviruses were detected in the lesions of all cats by electron microscopic examination. PCR analysis detected orf virus (contagious ecthyma virus) in two cats, and orf virus was cultured from one cat.

DIAGNOSIS

Parapoxvirus infection in cats.

CLINICAL RELEVANCE

Parapoxvirus infection should be considered as a differential diagnosis when dealing with proliferative, non-healing lesions on the feet of cats, especially cats in rural areas. The recovery of orf virus from a cat with typical poxvirus lesions extends the range of species affected by this virus.

Lesions in the brains of three cattle resembling the lesions of enterotoxaemia in lambs

CASE HISTORY

A 3-month-old female Angus calf was found dead, and two adult Friesian dairy cows died soon after developing nervous signs.

PATHOLOGICAL FINDINGS

Grossly, bilateral and mostly symmetrical areas of haemorrhage were evident that mainly involved areas of grey matter in the brainstem from the level of the caudal colliculi to the thalamus and, in one, the internal capsule and caudate nucleus. In the occipital and caudal parietal cortex, there was extensive oedema of white matter. Histologically, in addition to haemorrhage, there was protein-rich oedema around arterioles and venules in the cerebrum, hippocampus, internal capsule, thalamus, midbrain, dorsal medulla, and central cerebellar and cerebellar folial white matter. The calf 's brain had bilateral and symmetrical oedema and necrosis affecting several brainstem nuclei and the occipital grey matter overlying areas of oedema of the corona radiata.

DIAGNOSIS

Although the cause was not established, the perivascular lesions resembled those produced in calves by the intravenous administration of epsilon toxin.

CLINICAL RELEVANCE

It is possible that epsilon toxin-induced enterotoxaemia occurs naturally in cattle, and where bilateral haemorrhage is recognised in the brains of cattle, small intestinal contents should be collected for analysis of epsilon toxin.

The histological lesions of Trichophyton mentagrophytes var erinacei infection in dogs

A retrospective study of the histological features of four cases of canine Trichophyton mentagrophytes var erinacei infection is reported. In all four dogs the initial lesions affected the dorsal muzzle and in two dogs the lesions spread to more distant sites on the body. Clinically, the lesions were characterized by scaling, crusting and hair loss. Histologically, the main lesions were characterized by acanthosis, epidermal, ostial and infundibular hyperkeratosis, serocellular crusting, mural folliculitis and furunculosis. Fungal hyphae were usually sparse and often difficult to see in haematoxylin and eosin stained sections. When visible they were seen in the epidermal, ostial and infundibular scale and, less frequently, within hair shafts.

Equine basal cell tumors: 6 cases (1985-1999)

Basal cell tumors are rare benign tumors in horses. Over a 15-year period, 6 horses were diagnosed with basal cell tumors. The tumors were well-circumscribed. freely moveable, firm, raised papules, nodules, or masses that ranged from 0.6 to 5 cm in diameter. Five of the 6 tumors were ulcerated. Based on gross appearance, the tumors were diagnosed as sarcoids, and 1 was diagnosed as a melanoma. The range of age of affected horses was 6-26 years. The tumors were identified clinically 1 week to 3 years before excision. In 4 horses for which information was available, complete surgical excision was curative with no recurrence 4 months to 2 years after removal.

Suspected actinobacillosis manifested by facial enlargement in a heifer

Actinobacillosis was the suspected cause of severe, bilateral facial enlargement of 8 months' duration in a 2.5-year-old Holstein heifer. Serum protein electrophoresis revealed a polyclonal gammopathy. Necropsy findings indicated that facial swelling was caused by fibrosis between the skin and underlying bone. Lesions were characterized microscopically by scattered pyogranulomas containing eosinophilic, club-like colonies surrounding gram-negative bacterial rods. The lesion was compatible with diagnosis of actinobacillosis. It is unusual for severe bilateral facial enlargement to be associated with actinobacillosis.

Cryptosporidiosis in a feline leukemia virus-positive cat

A 4-year-old FeLV-positive cat with a 1-year history of intermittent diarrhea and subsequent anorexia, depression, and weight loss had enteric cryptosporidiosis at necropsy. Cryptosporidium sp is an important cause of gastroenteritis and diarrhea in various species, including human beings with acquired immunodeficiency syndrome. A major determinant of the severity of the disease caused by Cryptosporidium sp is the immunologic status of the affected animal. Cryptosporidiosis should be included in the differential diagnosis of protracted diarrhea in FeLV-positive cats. Because cryptosporidiosis now is recognized as a zoonosis, cats with this disease should be considered a potential source of human infection.

Haemolytic disease associated withLeptospira Interrogansserovarpomonain red deer calves (Cervus elaphus)

Three red deer calves (Cervus elaphus) died with a haemolytic disease associated with infection by Leptospira interrogans serovar pomona. Infection within the herd was more prevalent than disease. Sera from 16 herd mates were tested by the microscopic agglutination test (MAT) and 12 had leptospiral titres, the majority to serovar pomona. A few calves had titres to balcunica and hardjo. Urine was obtained for culture from six of these calves and serovar pomona was isolated from five with titres to pomona, and hardjo from one with a titre to hardjo but not pomona. A fourth calf died with severe nephritis but a diagnosis of leptospirosis was not confirmed in this case.

Photosensitive dermatitis in two Collie working dogs

Two Collie working dogs were examined because of the sudden appearance of a skin condition. Both dogs were depressed and anorectic with an acute exudative dermatitis confined to areas of non-pigmented skin. Antibacterial treatment was instituted initially followed by long-term use of a sun-protective cream. A diagnosis of photosensitive dermatitis was made but the cause of the photosensitivity was not determined.