Scott Lindsay

A review of neosporosis and pathologic findings of Neospora caninum infection in wildlife.

Highlights • The importance of Neospora caninum-associated disease in wildlife is reviewed.• There are only 12 reports of clinical neosporosis in wildlife species to date.• The best practice guidelines to follow for reporting wildlife cases of neosporosis are presented.

Extensive production of Neospora caninum tissue cysts in a carnivorous marsupial succumbing to experimental neosporosis

Experimental infections of Sminthopsis crassicaudata, the fat-tailed dunnart, a carnivorous marsupial widely distributed throughout the arid and semi-arid zones of Australia, show that this species can act as an intermediate host for Neospora caninum. In contrast to existing models that develop relatively few N. caninum tissue cysts, dunnarts offer a new animal model in which active neosporosis is dominated by tissue cyst production. The results provide evidence for a sylvatic life cycle of N. caninum in Australia between marsupials and wild dogs. It establishes the foundation for an investigation of the impact and costs of neosporosis to wildlife.

Myelitis due to reactivated spinal toxoplasmosis in a cat

The diagnosis, management, and subsequent post-mortem confirmation of a case of suspected reactivated spinal toxoplasmosis in a 10-year-old female neutered Cornish Rex are described. While an ante-mortem diagnosis of toxoplasmosis was considered possible based on the neuroanatomical diagnosis of central nervous system (CNS) disease primarily involving spinal cord segment C6–T2 and the progressive elimination of other potential causes, Toxoplasma gondii antibody titres were consistent with previous exposure rather than active infection. A poor response to appropriate therapy did not support a diagnosis of toxoplasmosis. A post-mortem morphological diagnosis of marked segmental non-suppurative myelitis and necrosis, and an aetiological diagnosis of toxoplasmosis were made. The clinical and pathological findings are supportive of CNS inflammation due to reactivation of latent tissue T gondii cysts.

Severe systemic hypertension in a cat with pituitary-dependent hyperadrenocorticism.

A seven-year-old Burmese cat was presented with sudden onset blindness. On physical examination, the cat had bilateral retinal detachment and severe systemic hypertension. Further clinical investigations revealed pituitary-dependent hyperadrenocorticism. Antihypertensive therapy was discontinued when the hypertension resolved after bilateral adrenalectomy. Systolic blood pressure remained normal until 19 months post-operatively when systemic hypertension recurred and was attributed to chronic kidney disease. The cat was euthanased 47 months after initial presentation. A pituitary adenoma was identified at post-mortem examination. This case illustrates that systemic hypertension can occur secondary to hyperadrenocorticism in the cat.

Encrusting cystitis in a cat secondary to Corynebacterium urealyticum infection.

An 18-year-old male neutered domestic shorthair cat was presented for investigation of haematuria and lethargy. The cat had sustained a traumatic T3–L3 lesion 5 years prior resulting in upper motor neuron incontinence. On further investigation the cat was found to be hyperkalaemic, hypothermic and dehydrated. Ultrasonography of the bladder revealed a markedly hypoechoic, thickened bladder wall with an irregular, hyperechoic mucosal layer. The patient responded to symptomatic and supportive care and was discharged. Despite initial improvement, the patient returned 10 days after discharge with recurrence of haematuria and lethargy. Ultrasound-guided aspiration and culture of the material on the mucosal surface of the bladder confirmed diagnosis of UTI caused by Corynebacterium urealyticum. On post-mortem examination, gross and histopathological features were consistent with encrusting cystitis. This is the first case report of encrusting cystitis in a cat. C urealyticum, an uncommon urinary tract pathogen in small animals, should be considered in patients with predisposing conditions.

Cryptococcus neoformans var. grubii-Induced Arthritis with Encephalitic Dissemination in a Dog and Review of Published Literature.

This article describes the clinical, pathological, and immunohistochemical findings associated with Cryptococcus neoformans var. grubii in a 4-year-old female Boxer dog from Uberlândia, Minas Gerais, Southeastern Brazil. Clinically, there was a swelling at the right metatarsal region and the hock joint with enlargement of regional lymph nodes. Radiographical evaluation revealed lysis of the tarsal bone; cytology demonstrated cryptococcal intralesional organisms at the swollen joint. Despite empirical antifungals therapeutic, the animal developed neurological cryptococcosis and died spontaneously. Significant pathological alterations included arthritis, lymphadenitis, and encephalitic cryptococcomas associated with numerous intralesional narrow-necked budding encapsulated yeasts. Immunohistochemistry utilising monoclonal antibodies that label C. neoformans sp. complex capsule, characterised the yeasts as C. neoformans var. grubii. Collectively, the pathological and immunohistochemical findings of this dog indicate that the intralesional organisms observed within the articular surface of the hock joint, lymph nodes, and the brain were C. neoformans var. grubii, confirming the participation of this fungal pathogen in the development of cryptococcal arthritis. In this case, the most likely pathogenesis was percutaneous inoculation with resultant abscess-like lesion, which resulted in the draining sinus, swelling of the right hind limb with progression to the articular disease. Thereafter, the fungal pathogen probably compromised the adjacent lymph nodes with subsequent haematogenous distribution to the brain, terminating with cryptococcal arthritis, lymphadenitis, and encephalitis.

Molecular Diagnosis of Felis catus Gammaherpesvirus 1 (FcaGHV1) Infection in Cats of Known Retrovirus Status with and without Lymphoma

The pathogenicity of Felis catus gammaherpesvirus 1 (FcaGHV1), a common infection of domestic cats, is unknown. To explore an association between FcaGHV1 detection and feline lymphoma, a retrospective, cross-sectional, disease-association study was conducted. The infection status of all cats for feline immunodeficiency virus and feline leukaemia virus was determined. Neither a molecular diagnosis of FcaGHV1 nor whole-blood FcaGHV1 load was related to outcome in 122 lymphoma cases compared with 71 controls matched for age and sex. Molecular analysis of lymphoma-derived DNA paired with autologous uninvolved tissue did not suggest restriction of FcaGHV1 DNA to tumour tissue. FcaGHV1 DNA detection was associated with significantly shorter survival in lymphoma cases, an observation that could not be adequately explained by treatment differences. In addition, regressive feline leukaemia virus infection was identified as a risk factor for lymphoma. A history of fighting or roaming was identified as a novel epidemiological risk factor for FcaGHV1 detection, lending support to intercat aggression as a potential route of transmission. Studies investigating the cellular location and expression of FcaGHV1 are indicated to assist in ruling out a lymphomagenic role for this virus. Prospective investigation of FcaGHV1 DNA detection as a prognostic marker in feline lymphoma is warranted.

ACUTE LYMPHOBLASTIC LEUKEMIA IN A PYGMY HIPPOPOTAMUS (HEXAPROTODON LIBERIENSIS)

Abstract:  A captive, 31-yr-old, intact male pygmy hippopotamus presented with nonspecific signs of weight loss, inappetence, diarrhea, and lethargy. After 5 wk of diagnostic investigation and symptomatic treatment, an acute leukemic process with concurrent polycystic kidney disease was suspected. The animals condition continued to deteriorate prompting euthanasia. Necropsy, histopathologic, and immunohistochemical examination confirmed acute T-cell lymphoblastic leukemia and polycystic kidneys. Acute T-cell lymphoblastic leukemia has not previously been documented in this species; however, polycystic kidney disease has been reported. This case report adds to the increasing number of pygmy hippopotamuses diagnosed with polycystic kidney disease and describes acute T-cell lymphoblastic leukemia, a previously unreported disease of this species.

A Novel Hepadnavirus Identified in an Immunocompromised Domestic Cat in Australia

High-throughput transcriptome sequencing allows for the unbiased detection of viruses in host tissues. The application of this technique to immunosuppressed animals facilitates the detection of viruses that might otherwise be excluded or contained in immunocompetent individuals. To identify potential viral pathogens infecting domestic cats we performed high-throughput transcriptome sequencing of tissues from cats infected with feline immunodeficiency virus (FIV). A novel member of the Hepadnaviridae, tentatively named domestic cat hepadnavirus, was discovered in a lymphoma sample and its complete 3187 bp genome characterized. Phylogenetic analysis placed the domestic cat hepadnavirus as a divergent member of mammalian orthohepadnaviruses that exhibits no close relationship to any other virus. DNA extracted from whole blood from pet cats was positive for the novel hepadnavirus by PCR in 6 of 60 (10%) FIV-infected cats and 2 of 63 (3.2%) FIV-uninfected cats. The higher prevalence of hepadnavirus viraemia detected in FIV-infected cats mirrors that seen in human immunodeficiency virus-infected humans coinfected with hepatitis B virus. In summary, we report the first hepadnavirus infection in a carnivore and the first in a companion animal. The natural history, epidemiology and pathogenic potential of domestic cat hepadnavirus merits additional investigation.

Severe Subacute Necrotizing Encephalopathy (Leigh-like Syndrome) in American Staffordshire Bull Terrier Dogs

Seventeen American Staffordshire bull terrier puppies, 6-8 weeks of age, from seven closely related litters, presented with rapidly progressive central vestibular neurological signs. Previously reported hereditary ataxias in the breed, including l-2 hydroxyglutaric aciduria and cerebellar cortical degeneration, as well as thiamine deficiency, were excluded. Elevated lactate levels and lactate:pyruvate ratios gave supporting evidence of a defect of the respiratory chain or Leigh-like syndrome. Histopathology in all cases showed a bilaterally symmetrical necrotizing encephalopathy, with malacia of the neuropil centred on the vestibular and olivary nuclei of the brainstem. This is the first documentation of a heritable rapidly progressive lethal necrotizing encephalopathy consistent with Leigh-like syndrome, in American Staffordshire bull terrier dogs.