Protothecosis in four dogs in New Zealand.

CASE HISTORIES: Medical records of four dogs diagnosed with protothecosis in New Zealand were reviewed. The dogs were aged between 4 and 9 years and three of the four dogs were female. Breeds were one Labrador, one Miniature Schnauzer and two crossbreeds. The reasons for initial veterinary evaluation were a cough and opaque appearance of the right eye (Case 1), diarrhoea (Cases 2 and 3), and cutaneous disease (Case 4). CLINICAL FINDINGS: The ocular signs were characterised by panuveitis, retinal detachment and secondary glaucoma. Gastrointestinal signs included chronic haemorrhagic diarrhoea due to colitis. Three cases had disseminated infection and developed both bilateral, blinding, ocular disease and chronic gastrointestinal disease. Cutaneous signs consisted of draining fistulae over the olecranon, multifocal cutaneous nodules, and ulceration and tracts of the foot pads. Disseminated protothecosis was confirmed by histopathology of biopsied ocular tissues in Cases 1 and 2 and by gastrointestinal biopsies in Case 3. Prototheca spp. were also identified in cytological specimens from Cases 1 and 4 and recovered by culture in Cases 2 and 4. Cutaneous protothecosis was diagnosed in Case 4 initially by cytology and histopathology of skin lesions, and Prototheca zopfii was confirmed by PCR of cultured organisms. TREATMENT AND OUTCOME: Prior to diagnosis of protothecosis, a variety of treatments were prescribed to treat the gastrointestinal and ocular signs. After diagnosis, only Cases 2 and 4 received medication aimed at treating the protothecal infection, which was itraconazole in both cases. Following the progression of clinical signs and concerns about quality of life, all four dogs were euthanised. DIAGNOSIS: Disseminated protothecosis in three dogs, cutaneous protothecosis in one dog. CLINICAL RELEVANCE: Canine protothecosis is rarely reported, despite the ubiquity of the causal algae, and the disease usually carries an extremely grave prognosis when infection is generalised. In New Zealand, protothecosis should be considered as a differential diagnosis in dogs with panuveitis, chorioretinitis or retinal detachment, colitis, or nodular, ulcerative or fistulating cutaneous lesions.

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.

Histological evaluation of the soft palate in dogs affected by brachycephalic obstructive airway syndrome.

AIMS: To histologically examine tissue obtained from the thick rostral portion of the soft palate in severely affected brachycephalic dogs, and to quantitatively compare the histological findings with a similar region in control dogs. METHODS: Nine dogs examined for treatment of brachycephalic obstructive airway syndrome (BOAS) were prospectively recruited into the study. Four mesaticephalic dogs were also recruited following euthanasia for reasons unrelated to respiratory or gastrointestinal disease. Palatine tissue was harvested using an elliptical incision extending from the junction with the hard palate to the free caudal edge, and passing axial to the tonsilar crypts. The resected portion was fixed in formalin and stained using H&E. Tissues were examined in transverse section and assessments of the palatinus muscles, interstitium, lamina propria and salivary tissue were recorded. Quantitative analysis of the proportions of palatinus muscle, salivary tissue and stroma was performed using ImageJ image analysis software. RESULTS: When compared to the control dogs, the histological findings of the clinically affected dogs showed a marked increase in acute and chronic muscle degeneration and necrosis. This was typified by swollen, hypereosinophilic fibres with centralised nuclei, myofibre atrophy, loss of cross striations and fragmented sarcoplasm. There was reduced proportions of palatinus muscle (p<0.001) and increased proportions of collagenous stroma (p=0.004) and salivary gland tissue (p=0.046) in the clinical samples, compared to control dogs. CONCLUSIONS: Increased thickness of the palate in dogs with BOAS was not due to muscle hypertrophy but was due to increased stroma within the lamina propria, and increased proportions of salivary tissue. There was also a reduction of muscle mass, especially within the paired palatinus muscles, that may have consequences for palate function. CLINCAL RELEVANCE: The results of this study enable us to start investigating the aetiology of the changes seen in brachycephalic compared to mesaticephalic dogs, which will impact timing and extent of treatment of clinical cases.