Segmental Meningomyelitis in 2 Cats Caused by Toxoplasma gondii

Toxoplasma gondii spinal granuloma in a cat

Case summary

A 7-year-old female spayed domestic shorthair cat was presented with a history of progressive pelvic limb ataxia. A CT scan of the thoracic spine identified an extradural, left lateralised and compressive soft tissue mass at the level of T9. A decompressive hemilaminectomy at the level of T8-T10 and tissue sampling of the mass were performed. Histopathological examination revealed a parasite granuloma caused by Toxoplasma gondii infection. Postoperatively, the cat improved consistently, but mild left pelvic limb lameness remained. At 5 weeks, a recheck CT scan showed a small, enhancing soft tissue lesion in the left epidural space at T9, causing a mild left lateral compression of the spinal cord. After 9 months, the cat acutely deteriorated neurologically and was euthanased without postmortem examination.

Relevance and novel information

To our knowledge, this is the first report of a T gondii spinal granuloma in a cat. Such a granuloma should be considered as a differential in cats with evidence of an extradural soft tissue mass.

All about toxoplasmosis in cats: the last decade

Toxoplasma gondii infections are common in humans and animals worldwide. Toxoplasmosis continues to be of public health concern. Cats (domestic and wild felids) are the most important host in the epidemiology of toxoplasmosis because they are the only species that can excrete the environmentally resistant oocysts in feces. Cats can excrete millions of oocysts and a single cat can spread infection to many hosts. The present paper summarizes information on prevalence, persistence of infection, clinical signs, and diagnosis of T. gondii infections in domestic and wild cats for the past decade. Special emphasis is paid to genetic diversity of T. gondii isolates from cats. Review of literature indicates that a unique genotype (ToxoDB genotype #9 or Chinese 1) is widely prevalent in cats in China and it has been epidemiologically linked to outbreaks of clinical toxoplasmosis in pigs and deaths in humans in China; this genotype has rarely been detected in other countries. This review will be of interest to biologists, parasitologists, veterinarians, and public health workers.

Littermate cats rescued from a shelter succumbed to acute, primary toxoplasmosis associated with TOXO DB genotype #4, generally circulating in wildlife

Cats are important in the epidemiology of Toxoplasma gondii infection because they are the only hosts that can excrete the environmentally resistant oocysts in the environment. Although exposure is common (approximately 30% of cats in the USA), clinical toxoplasmosis is relatively rare. Here, we report overwhelming disseminated toxoplasmosis in two litter mate 8-week-old kittens, thought to have acquired toxoplasmosis postnatally. Five domestic shorthair kittens, approximately 2-3 weeks of age, and the queen were found in upstate New York by a rescue group in spring of 2018. The kittens and queen were placed in a foster home for approximately 4-5 weeks and then transferred to a shelter. Two kittens died unexpectedly following a short illness. Postmortem examination of the two deceased kittens revealed overwhelming toxoplasmosis and the presence of entero-epithelial stages in small intestine, suggestive of recent ingestion of infected tissues. Antibodies to T. gondii were found in the deceased kittens and the queen but not in the three asymptomatic littermate kittens. No obvious cause of immunosuppression was demonstrated. Genetic typing of T. gondii from DNA extracted from liver and lungs of both kittens revealed Toxo DB #4 genotype, commonly found in wildlife. Owners and veterinarians should be aware of dangers of feeding raw meat to cats and contact with infected cat feces. Procedures to safely handle T. gondii infected feces in hospital setting are outlined.

Clinical Toxoplasmosis in Dogs and Cats: An Update

Toxoplasmosis is caused by the globally distributed protozoan parasite Toxoplasma gondii (phylum Apicomplexa); the disease can be clinically important for almost all homeothermic animals, including birds and humans. Toxoplasmosis course involves general clinical signs, such as fever, anorexia, or dyspnea, and more specific signs with neural, respiratory, cutaneous, or ocular involvement. Because of the wide range of clinical signs, the diagnosis in domestic and pet animals can be complicated. Hence, this review aims to provide a comprehensive analysis of some scarcely discussed aspects of toxoplasmosis, such as ocular and cutaneous manifestations, congenital infections, influence of T. gondii genotype on clinical toxoplasmosis, and recent findings regarding differential diagnosis. This review could be of special interest to clinicians and researchers.

Serological prevalence of toxoplasmosis and neosporosis in dogs diagnosed with suspected meningoencephalitis in the UK

OBJECTIVES

To assess the prevalence of antibodies to Toxoplasma gondii and Neospora caninum in a population of dogs with a diagnosis of suspected inflammatory meningoencephalitis.

MATERIALS AND METHODS

Medical records of three referral centres were reviewed from 2008 to 2016 to identify a cohort of dogs diagnosed and treated for suspected inflammatory meningoencephalitis after testing for evidence of exposure to these pathogens.

RESULTS

In our sample of 400 dogs the prevalence for exposure (IgG>1:50) to Toxoplasma gondii was 8/201 (3∙98%). Active infection (IgG titre >1:400 or/and an IgM titre >1:64 and/or positive PCR in CSF) was suspected in 1/400 (0∙25%). The prevalence for exposure [Indirect fluorescent antibody (IFA) titre >1:50] and active infection (IFA titres ≥⃒1:400 and/or positive PCR in CSF) with Neospora caninum were 14/201 (6∙96%) and 9/400 (2∙25%), respectively.

CLINICAL SIGNIFICANCE

In view of the low prevalence of protozoan infections, the risk associated with starting immunosuppressive medication in dogs with evidence of inflammatory meningitis or encephalitis in the UK appears low.

Clinical presentation, diagnostic findings and long-term survival in large breed dogs with meningoencephalitis of unknown aetiology

Although several studies indicate that meningoencephalitis of unknown aetiology (MUA) might affect every dog breed at every age, little is known about clinical presentation, diagnostic findings and long-term survival in large breed dogs. The aim of this study was therefore to compare the clinical presentation, diagnostic findings and long-term survival between large and small/medium breed dogs diagnosed with MUA. One hundred and eleven dogs met the inclusion criteria. 28 (25 per cent) dogs were considered large breed dogs compared with 83 (75 per cent) small/medium breed dogs. Large breed dogs presented significantly more often with a decreased mentation. Age, gender, duration of clinical signs prior to diagnosis, presence of seizures or cluster seizures, variables on complete blood count and cerebrospinal fluid analysis, and all variables on MRI were not significantly different between small/medium and large breed dogs. Median survival time was 281 and 106 days for the large and small/medium breed dogs, respectively, with no significant difference in survival curves for both groups. Although considered not typically affected by MUA, 25 per cent of dogs included in this study were considered large breed dogs. Therefore, MUA should be included in the differential diagnosis for large breed dogs presenting with intracranial neurological signs. If diagnosed with MUA, large breed dogs also carried a guarded prognosis.

Distal polyneuropathy in an adult Birman cat with toxoplasmosis

Case summary

A 6-year-old female spayed Birman cat presented with a history of weight loss, stiff and short-strided gait in the pelvic limbs and reluctance to jump, progressing to non-ambulatory tetraparesis over 6 weeks. Poor body condition, dehydration and generalised muscle wastage were evident on general examination. Neurological examination revealed mildly depressed mental status, non-ambulatory flaccid tetraparesis and severely decreased proprioception and spinal reflexes in all four limbs. The neuroanatomical localisation was to the peripheral nervous system. Haematology, feline immunodeficiency virus/feline leukaemia virus serology, serum biochemistry, including creatine kinase and thyroxine, thoracic radiographs and abdominal ultrasound did not reveal significant abnormalities. Electromyography revealed fibrillation potentials and positive sharp waves in axial and appendicular muscles. Decreased motor conduction velocities and compound muscle action potential amplitudes were detected in ulnar and sciatic–tibial nerves. Residual latency was increased in the sciatic–tibial nerve. Histologically, several intramuscular nerve branches were depleted of myelinated fibres and a few showed mononuclear infiltrations. Toxoplasma gondii serology titres were compatible with active toxoplasmosis. Four days after treatment initiation with oral clindamycin the cat recovered the ability to walk. T gondii serology titres and neurological examination were normal after 11 and 16 weeks, respectively. Clindamycin was discontinued after 16 weeks. One year after presentation the cat showed mild relapse of clinical signs and seroconversion, which again resolved following treatment with clindamycin.

Relevance and novel information

To our knowledge, this is the first report of distal polyneuropathy associated with toxoplasmosis in a cat. This case suggests the inclusion of toxoplasmosis as a possible differential diagnosis for acquired polyneuropathies in cats.

Intramedullary spinal cord mass presumptively associated with leishmaniasis in a dog

CASE DESCRIPTION

A 9-year-old male Miniature Poodle was evaluated because of progressive severe right hemiparesis, right forelimb lameness, and signs of cervical pain.

CLINICAL FINDINGS

A low body condition score (2/9) and popliteal lymphadenopathy were detected. Results of a CBC, serum biochemical analyses, urinalysis, cytologic examination of bone marrow and popliteal lymph node aspirates, and serum ELISA were consistent with systemic leishmaniasis. Magnetic resonance imaging of the cervical spinal cord revealed an intramedullary mass extending from the caudal aspect of the C5 vertebral body to the C5-6 intervertebral disk space with a contrast medium-enhanced pattern that had 3 zones (central contrast medium-enhanced core, intermediate isointense zone, and peripheral contrast medium-enhanced ring). Surgical biopsy of the mass was performed by means of a right C5-6 dorsal hemilaminectomy. Results of PCR assays for detection of Leishmania DNA in CSF and tissue biopsy samples were positive.

TREATMENT AND OUTCOME

Treatment for systemic leishmaniasis was initiated. Two months later, body condition, neurologic signs, and gait of the dog had substantially improved; the dog had mild right forelimb paresis at that time. Results of follow-up MRI indicated resolution of the cervical spinal cord lesion. Four months after diagnosis, the dog's neurologic condition was stable.

CLINICAL RELEVANCE

To the authors' knowledge, this report is the first in which clinical findings, clinicopathologic data, and MRI characteristics of an intramedullary inflammatory spinal cord lesion presumptively attributable to leishmaniasis in a dog have been reported, and the first report of CNS leishmaniasis in a dog with MRI resolution and a successful clinical response to treatment.

Clinical, imaging, and pathologic characteristics of Gurltia paralysans myelopathy in domestic cats from Chile

Gurltia paralysans is a rare metastrongylid nematode of domestic cats that is found mainly in the veins of the spinal cord subarachnoid space and parenchyma. Endemic regions for G. paralysans mainly include Chile and Argentina. The ante mortem diagnosis of gurltiosis is difficult and based primarily on neurological signs, epidemiological factors, and the exclusion of other causes of feline myelopathies. The purpose of this retrospective case series was to describe clinical, imaging, and pathologic characteristics in nine domestic cats naturally infected with G. paralysans. Imaging tests included radiography, myelography, computed tomographic myelography (myelo-CT), and magnetic resonance imaging (MRI). Neurological signs included paraparesis, paraplegia, pelvic limb ataxia and proprioceptive deficits, pelvic limb tremors, lumbosacral hyperesthesia, and tail trembling or atony. Complete blood count findings included a decrease in the mean corpuscular hemoglobin concentration value in eight cats. Eosinophilia in peripheral blood was observed in three cats, and thrombocytopenia was observed in three cats. Cerebrospinal fluid analysis revealed mononuclear pleocytosis in five cases. Myelo-CT showed diffuse enlargement of the spinal cord at the midthoracic, lumbar, and sacral regions in all cats. Magnetic resonance image findings in the thoracic and lumbar region demonstrated multiple small nodular areas of T2 hyperintensity in the periphery of the spinal cord parenchyma. Localized intraparenchymal areas of increased T2 intensity were also observed in the thoracolumbar spinal cord and lumbosacral conus medullaris. In conclusion, G. paralysans should be considered as a differential diagnosis for domestic cats in endemic regions that have this combination of clinical and imaging characteristics.

CNS disease in the cat: current knowledge of infectious causes

PRACTICAL RELEVANCE

Neurological disease is a relatively common reason for referral, constituting approximately 10% of the feline referral caseload. Nearly one-third to one-half of these cases may be infectious in origin. As such, an awareness of infectious diseases causing central nervous system (CNS) signs in cats, and their clinical diagnosis and management, is relevant to anyone dealing with cats on a regular basis.

GLOBAL IMPORTANCE

Some conditions (eg, rabies) are more common in certain countries than others. Conditions such as feline infectious peritonitis (FIP) and toxoplasmosis are of global significance.

PATIENT GROUP

Many infectious diseases may affect any feline population. Some, such as FIP, are more common in pedigree households, whereas others such as toxoplasmosis, feline immunodeficiency virus (FIV) or feline leukaemia virus (FeLV) infections, are more likely to affect a single cat with an outdoor lifestyle.

EQUIPMENT

All patients benefit from thorough history taking and clinical, neurological and ophthalmic examinations, which all require minimal equipment. Infectious diseases may often be diagnosed on blood samples; however, definitive diagnosis may require more extensive investigation involving cerebrospinal fluid analysis or advanced imaging necessitating access to computed tomography or magnetic resonance imaging.

EVIDENCE BASE

The information in this review, which summarises current knowledge of infectious diseases affecting the CNS, is collated from publications on the infectious diseases comprising previous research papers, review articles, case series, case reports and textbooks, supplemented by the clinical experience of the authors.