A Missense Variant in ALDH5A1 Associated with Canine Succinic Semialdehyde Dehydrogenase Deficiency (SSADHD) in the Saluki Dog

Dogs provide highly valuable models of human disease due to the similarity in phenotype presentation and the ease of genetic analysis. Seven Saluki puppies were investigated for neurological abnormalities including seizures and altered behavior. Magnetic resonance imaging showed a diffuse, marked reduction in cerebral cortical thickness, and symmetrical T2 hyperintensity in specific brain regions. Cerebral cortical atrophy with vacuolation (status spongiosus) was noted on necropsy. Genome-wide association study of 7 affected and 28 normal Salukis revealed a genome-wide significantly associated region on CFA 35. Whole-genome sequencing of three confirmed cases from three different litters revealed a homozygous missense variant within the aldehyde dehydrogenase 5 family member A1 (ALDH5A1) gene (XM_014110599.2: c.866G>A; XP_013966074.2: p.(Gly288Asp). ALDH5A1 encodes a succinic semialdehyde dehydrogenase (SSADH) enzyme critical in the gamma-aminobutyric acid neurotransmitter (GABA) metabolic pathway. Metabolic screening of affected dogs showed markedly elevated gamma-hydroxybutyric acid in serum, cerebrospinal fluid (CSF) and brain, and elevated succinate semialdehyde in urine, CSF and brain. SSADH activity in the brain of affected dogs was low. Affected Saluki dogs had striking similarities to SSADH deficiency in humans although hydroxybutyric aciduria was absent in affected dogs. ALDH5A1-related SSADH deficiency in Salukis provides a unique translational large animal model for the development of novel therapeutic strategies.

Feline cholangitis: a necropsy study of 44 cats (1986-2008)

Forty-four cats diagnosed with moderate to severe cholangitis at necropsy are described. The population comprised 0.86% of all feline necropsies performed during the 22-year study period. Liver specimens were classified as acute neutrophilic cholangitis (ANC), chronic neutrophilic cholangitis (CNC), lymphocytic cholangitis (LC) or chronic cholangitis associated with liver fluke infestation (CC) based on the World Small Animal Veterinary Association (WSAVA) classification scheme. ANC (seven) and CNC (33) comprised the majority of cases. In contrast to previous descriptions, overlap was seen in clinical findings between ANC and CNC subtypes. Results suggest that liver enzyme activity may not predict degree of inflammation. Severity of inflammation varied between liver sections in individual cats, underscoring the need to obtain biopsy samples from multiple sites. Inflammatory bowel disease (50%), pancreatitis (60%), or both (32%) commonly accompanied cholagitis. We conclude that cholangitis is not a common cause of feline mortality. Most cats that succumb to cholangitis have ANC or CNC, and concurrent disease contributes to death in many.

Clinicopathologic, histologic, and toxicologic findings in 70 cats inadvertently exposed to pet food contaminated with melamine and cyanuric acid

OBJECTIVE

To document clinicopathologic, histologic, and toxicologic findings in cats inadvertently exposed to pet food contaminated with melamine and cyanuric acid.

DESIGN

Case series.

ANIMALS

70 cats from a single cattery inadvertently fed contaminated food that was the subject of a March 2007 recall.

PROCEDURES

Clinical signs, clinicopathologic and histopathologic findings, and results of toxicologic analyses were recorded.

RESULTS

Clinical signs were identified in 43 cats and included inappetence, vomiting, polyuria, polydipsia, and lethargy. Azotemia was documented in 38 of the 68 cats for which serum biochemical analyses were performed 7 to 11 days after consumption of the contaminated food. One cat died, and 13 were euthanized. Histologic examination of kidney specimens from 13 cats revealed intratubular crystalluria, tubular necrosis with regeneration, and subcapsular perivascular inflammation characterized by perivascular fibroplasia or fibrosis and inflammation with intravascular fibrin thrombi. Toxicologic analyses revealed melamine and cyanuric acid in samples of cat food, vomitus, urine, and kidneys.

CONCLUSIONS AND CLINICAL RELEVANCE

In cats unintentionally fed pet food contaminated with melamine and cyanuric acid, the most consistent clinical and pathologic abnormalities were associated with the urinary tract, specifically tubular necrosis and crystalluria.

A novel locus for dilated cardiomyopathy maps to canine chromosome 8

Dilated cardiomyopathy (DCM), the most common form of cardiomyopathy, often leads to heart failure and sudden death. While a substantial proportion of DCMs are inherited, mutations responsible for the majority of DCMs remain unidentified. A genome-wide linkage study was performed to identify the locus responsible for an autosomal recessive inherited form of juvenile DCM (JDCM) in Portuguese water dogs using 16 families segregating the disease. Results link the JDCM locus to canine chromosome 8 with two-point and multipoint lod scores of 10.8 and 14, respectively. The locus maps to a 3.9-Mb region, with complete syntenic homology to human chromosome 14, that contains no genes or loci known to be involved in the development of any type of cardiomyopathy. This discovery of a DCM locus with a previously unknown etiology will provide a new gene to examine in human DCM patients and a model for testing therapeutic approaches for heart failure.

A complex rearrangement in GBE1 causes both perinatal hypoglycemic collapse and late-juvenile-onset neuromuscular degeneration in glycogen storage disease type IV of Norwegian forest cats

Deficiency of glycogen branching enzyme (GBE) activity causes glycogen storage disease type IV (GSD IV), an autosomal recessive error of metabolism. Abnormal glycogen accumulates in myocytes, hepatocytes, and neurons, causing variably progressive, benign to lethal organ dysfunctions. A naturally occurring orthologue of human GSD IV was described previously in Norwegian forest cats (NFC). Here, we report that while most affected kittens die at or soon after birth, presumably due to hypoglycemia, survivors of the perinatal period appear clinically normal until onset of progressive neuromuscular degeneration at 5 months of age. Molecular investigation of affected cats revealed abnormally spliced GBE1 mRNA products and lack of GBE cross-reactive material in liver and muscle. Affected cats are homozygous for a complex rearrangement of genomic DNA in GBE1, constituted by a 334 bp insertion at the site of a 6.2 kb deletion that extends from intron 11 to intron 12 (g. IVS11+1552_IVS12-1339 del6.2kb ins334 bp), removing exon 12. An allele-specific, PCR-based test demonstrates that the rearrangement segregates with the disease in the GSD IV kindred and is not found in unrelated normal cats. Screening of 402 privately owned NFC revealed 58 carriers and 4 affected cats. The molecular characterization of feline GSD IV will enhance further studies of GSD IV pathophysiology and development of novel therapies in this unique animal model.

Fibrocartilaginous Embolic Myelopathy in Five Cats

Five cats had clinical signs, radiographic findings, and cerebrospinal fluid analyses consistent with fibrocartilaginous embolic myelopathy. All cats had an acute onset of nonpainful, asymmetrical spinal cord signs (paresis or paralysis of one or more limbs). Magnetic resonance imaging was performed in three cats. On T2-weighted images, an intramedullary lesion was revealed that was hyperintense to normal spinal cord gray matter. On T1-weighted images, the lesion was isointense. Three of the cats were euthanized, and postmortem examination confirmed myelomalacia with intralesional fibrocartilaginous emboli. Two cats survived and were clinically improved within 3 weeks.

Canine Intracranial Primary Neoplasia: 173 Cases (1986–2003)

This study investigates the clinical and pathologic findings associated with 173 primary brain tumors in our hospital population of dogs that presented between the years 1986 and 2002. Of the 173 primary brain tumors, 78 (45%) were meningiomas, 29 (17%) were astrocytomas, 25 (14%) were oligodendrogliomas, 12 (7%) were choroid plexus tumors, and 7 (4%) were primary central nervous system lymphomas. Smaller numbers of glioblastomas (n = 5), primitive neuroectodermal tumors (n = 5), histiocytic sarcomas (n = 5), vascular hamartomas (n = 4), and unclassified gliomas (n = 3) were identified. One dog had both a meningioma and an astrocytoma. Most tumors were located within the telencephalon, and seizures were the most common clinical presenting complaint. Of 168 tumors for which a location in the brain was recorded at postmortem examination, 79 were found to involve more than 1 brain division. Other neoplasms unrelated to the primary brain tumor were identified on postmortem examination in 39 dogs (23%). Intrathoracic and intraabdominal neoplasms were present at necropsy in 13 and 24 cases, respectively. Based on the results of this study, thoracic radiographs and abdominal ultrasonography may be indicated to look for extracranial neoplasia prior to advanced imaging of the brain or intracranial surgery.

Prevalence of diseases of the spinal cord of cats

A retrospective review of records of 205 cats with histologically confirmed disease of the spinal cord was performed to identify the prevalence of disease in this nonrandomly selected population of cats. Clinical records were reviewed, and age, duration of neurologic illness, and clinical and histopathologic findings in cats with spinal cord disease were abstracted. Disease processes were classified into 7 categories and 23 groups. The most common diseases affecting the spinal cord of cats were feline infectious peritonitis (FIP), lymphosarcoma (LSA), and neoplasia of the vertebral column secondarily affecting the spinal cord. Information on age, onset and duration of clinical signs, and lesion localization at the postmortem examination in cats belonging to the 7 categories of disease were analyzed to create a practical list of differential diagnoses. Cats were also subcategorized into 3 groups based on their age at death. FIP was the most common disease of cats younger than 2 years of age. LSA and vertebral column neoplasia were the most common diseases affecting cats between 2 and 8 years of age. Vertebral column neoplasia was the most common disease affecting cats older than 8 years of age. Results of this histopathologic study showed that FIP and LSA were the most common disease processes affecting the spinal cord of cats. However, at least 21 other groups of diseases and their relative prevalence were identified.

Magnetic resonance imaging features of feline intracranial neoplasia: retrospective analysis of 46 cats

The purpose of this retrospective study was to determine the magnetic resonance imaging (MRI) characteristics of feline brain tumors and to determine whether these characteristics can be used to accurately predict the histologic diagnosis. MRI scans of 46 cats with histologically confirmed brain tumors were reviewed, including 33 meningiomas, 6 lymphomas, 4 gliomas, 2 olfactory neuroblastomas, and 1 pituitary tumor. MRI features including axial origin, shape, location, signal intensity, contrast enhancement, peritumoral edema, and mass effect were reviewed and characterized for each tumor type. Tumor shape, axial origin, contrast enhancement, and degree of peritumoral edema aided in the identification of tumor type. Meningiomas were always extra-axial and were most often ovoid with marked contrast enhancement and mild peritumoral edema. Gliomas were always intra-axial with ring enhancement and generally caused more peritumoral edema than other tumors. The brain tumor was detected on MRI in 45 (98%) cats. Two blinded independent reviewers correctly identified 82% of all of the tumor types on the basis of MRI appearance alone. Thus, MRI is an excellent diagnostic tool for the detection of brain tumors in cats, and it provides important information to aid in the diagnosis of tumor type.

Feline intracranial neoplasia: retrospective review of 160 cases (1985-2001)

The purpose of this study was to determine the frequency of different tumor types within a large cohort of cats with intracranial neoplasia and to attempt to correlate signalment, tumor size and location, and survival time for each tumor. Medical records of 160 cats with confirmed intracranial neoplasia evaluated between 1985 and 2001 were reviewed. Parameters evaluated included age, sex, breed, FeLV/FIV status, clinical signs, duration of signs, number of tumors, tumor location(s), imaging results, treatment, survival times, and histopathologic diagnosis. Most of the cats were older (11.3 +/- 3.8 years). Primary tumors accounted for 70.6% of cases. Metastasis and direct extension of secondary tumors accounted for only 5.6 and 3.8% of cases, respectively. Twelve cats (7.5%) had 2 or more discrete tumors of the same type, whereas 16 cats (10.0%) had 2 different types of intracranial tumors. The most common tumor types were meningioma (n = 93, 58.1%), lymphoma (n = 23, 14.4%), pituitary tumors (n = 14, 8.8%), and gliomas (n = 12, 7.5%). The most common neurological signs were altered consciousness (n = 42, 26.2%), circling (n = 36, 22.5%), and seizures (n = 36, 22.5%). Cats without specific neurological signs were common (n = 34, 21.2%). The tumor was considered an incidental finding in 30 (18.8%) cats. In addition to expected relationships (eg, meninges and meningioma, pituitary and pituitary tumors), we found that lesion location was predictive of tumor type with diffuse cerebral or brainstem involvement predictive of lymphoma and third ventricle involvement predictive of meningioma.

Clinical differentiation of acute necrotizing from chronic nonsuppurative pancreatitis in cats: 63 cases (1996-2001)

OBJECTIVE

To characterize clinical, clinicopathologic, radiographic, and ultrasonographic findings in cats with histologically confirmed acute necrotizing pancreatitis (ANP) or chronic nonsuppurative pancreatitis (CP) and identify features that may be useful in the antemortem differentiation of these disorders.

DESIGN

Retrospective study.

ANIMALS

63 cats with histologically confirmed ANP (n = 30) or CP (33).

PROCEDURE

Medical records were reviewed for signalment, clinical signs, concurrent diseases, clinicopathologic findings, and results of radiography and ultrasonography.

RESULTS

Cats in both groups had similar nonspecific clinical signs, physical examination findings, and radiographic and ultrasonographic abnormalities. Abdominal ultrasonographic abnormalities, including hypoechoic pancreas, hyperechoic mesentery, and abdominal effusion, were found in cats in both groups and, therefore, were not specific for ANP. Cats with CP were significantly more likely to have concurrent diseases than were cats with ANP (100 and 83%, respectively). Clinicopathologic abnormalities were similar between groups; however, serum alanine aminotransferase and alkaline phosphatase activities were significantly higher in cats with CP.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that ANP and CP in cats cannot be distinguished from each other solely on the basis of history, physical examination findings, results of clinicopathologic testing, radiographic abnormalities, or ultrasonographic abnormalities.

Association between diabetes mellitus, hypothyroidism or hyperadrenocorticism, and atherosclerosis in dogs

The objective of this study was to determine whether dogs with atherosclerosis are more likely to have concurrent diabetes mellitus, hypothyroidism, or hyperadrenocorticism than dogs that do not have atherosclerosis. A retrospective mortality prevalence case-control study was performed. The study group included 30 dogs with histopathological evidence of atherosclerosis. The control group included 142 dogs with results of a complete postmortem examination, a final postmortem examination diagnosis of neoplasia, and no histopathological evidence of atherosclerosis. Control dogs were frequency matched for age and year in which the postmortem examination was performed. Proportionate changes in the prevalence of diabetes mellitus, hypothyroidism, and hyperadrenocorticism were calculated by exact prevalence odds ratios (POR), 95% confidence intervals (95% CI), and P values. Multiple logistic regression analysis was used to examine the combined effects of prevalence determinants while controlling for age and year of postmortem examination. Dogs with atherosclerosis were over 53 times more likely to have concurrent diabetes mellitus than dogs without atherosclerosis (POR = 53.6; 95% CI, 4.6-627.5; P = .002) and over 51 times more likely to have concurrent hypothyroidism than dogs without atherosclerosis (POR = 51.1; 95% CI, 14.5-180.1; P < .001). Dogs with atherosclerosis were not found to be more likely to have concurrent hyperadrenocorticism than dogs that did not have atherosclerosis (POR = 1.8; 95% CI, 0.2-17.6; P = .59). Diabetes mellitus and hypothyroidism, but not hyperadrenocorticism, are more prevalent in dogs with atherosclerosis compared to dogs without atherosclerosis on postmortem examination.