Canine storage disease characterized by hereditary progressive neurogenic muscular atrophy: breeding experiments and clinical manifestation

Progressive neurogenic muscular atrophy due to storage of a compound lipid in the lower motor neurons was diagnosed in 3 English Pointers that were littermates. Using 2 clinically normal littermates of these 3 affected dogs and 2 clinically normal dogs of the 2nd litter from the parents of the original 3 affected dogs as the initial breeding stock, a breeding experiment was performed, resulting in a breeding line of 26 dogs, 4 of which had the disease and 6 of which died before 3 months of age. Results indicated that the disease may have an autosomal recessive mode of inheritance. The clinical manifestation and electrophysiologic findings indicated lower motor neuron involvement in the affected dogs produced by breeding consistent with findings in the original 3 affected dogs. Upper motor neurons or the sensory system was not involved. The disease appeared to be distinct from other canine storage diseases previously reported.     

MAGNETIC RESONANCE IMAGING IN THE DIAGNOSIS OF CANINE INFLAMMATORY MYOPATHIES IN THREE DOGS

In humans affected with inflammatory myopathies, regions of altered signal intensity are found on magnetic resonance (MR) images of affected muscles. Although electromyography (EMG) is more practical for muscle disease evaluation, and a muscle biopsy is the only manner in which a definitive diagnosis can be made, MR imaging has proven useful if a specific anatomic localization is difficult to achieve. Three dogs with focal inflammatory myopathy diagnosed with the assistance of MR imaging are discussed and the findings are compared with those found in humans. MR images of the affected muscles in each dog were characterized by diffuse and poorly marginated abnormal signal on T1- and T2-weighted images. Marked enhancement was noted in these muscles after contrast medium administration. An inflammatory myopathy was confirmed histologically in all three dogs. A good association existed between the MR images and muscle inflammation identified histopathologically. MR imaging may be a useful adjunctive procedure for canine inflammatory myopathies.     

Distal denervating disease: a degenerative neuropathy of the distal motor axon in dogs

A group of ten dogs affected by an apparently identical denervating disease, is described. There was no breed or age predisposition but females were preferentially affected (70%). The rate of onset of signs was variable from a week to greater than 1 month. Quadriparesis was present to varying severities and in two dogs the head and neck could not be supported. Mastication, swallowing, respiration and bladder function were unimpaired. Pain sensation was normal, tone was usually decreased and the local limb reflexes depressed or absent. Muscle atrophy was often prominent. All cases bar one recovered but another dog was also destroyed. Electrophysiology revealed diffuse spontaneous activity in the muscles and the motor nerve conduction velocities were at the lower end of or just below the normal range. The evoked muscle potentials were reduced in amplitude. Sensory nerve potentials were normal. The pathology showed a degeneration of the distal intramuscular axons with collateral axonal sprouting. The muscle changes were typical of neurogenic atrophy. The disease has been called distal denervating disease (DDD) until the precise aetiology can be determined.     

Repeated transplacental transmission of Neospora caninum in dogs

Four litters of German Shorthaired Pointers from one owner developed a toxoplasmosis-like illness. According to the records, 29 of 39 dogs had hind limb paralysis. Six dogs from 2 litters were necropsied and had generalized encephalomyelitis. Tachyzoites and tissue cysts of Neospora caninum were found in the brain and spinal cord of each dog. Lesions were found in the eyes, extraocular muscles, or both in all of the dogs, and N caninum was detected microscopically in the eyes (retina and choroid in 1 dog), extraocular muscles, or both in 5 of the 6 dogs. Ocular lesions consisted of focal retinitis, choroiditis, mild nonspecific iridocyclitis, and myositis of extraocular muscles. Organisms stained with anti-N caninum serum, but not with anti-Toxoplasma gondii serum in an immunohistochemical test, except in 1 dog. In one dog, aged thick-walled N caninum tissue cysts reacted mildly with anti-T gondii serum.     

A survey of gundog lameness and injuries in Great Britain in the shooting seasons 2005/2006 and 2006/2007.

The aim of this paper was to record the types of injuries and causes of lameness exhibited by dogs involved in game shooting. The study investigated gundogs that worked in the seasons 2005/2006 and 2006/2007. Information was acquired by owner questionnaires. The dogs were classified as working in the beating line, as peg dogs or as picking up dogs. A further group comprised Setters and Pointers that worked the grouse moors. A secondary objective was to assess the incidence of injuries that were treated by owners without seeking the assistance of their veterinarian, and to identify those that may have been underestimated. Depending on whether a dog was injured or went lame, and, if so, the nature of the injury, was correlated with the number of days worked, where it worked, its breed and the type of work it did. A mildly positive association between the Spaniel breed group and injuries was seen in 2005/2006 but not in 2006/2007. However, the relationship between the type of work and injuries was very significant for both seasons with dogs working in the beating line being at greatest risk and Setters and Pointers having the least number of injuries. The dogs in the beating line were also at a significantly greater risk of injury in both years when the type of injury was investigated. Fifty-three percent of all injuries were deemed to be sufficiently minor, that veterinary attention was not sought. However, those dogs with proximal thoracic limb lameness may have been under-investigated. There was a highly significant association between tail injuries and undocked Springer and Cocker Spaniels.     

A progressive axonopathy of Boxer dogs affecting the central and peripheral nervous systems

Five Boxer dogs with a new neurological disease are described. There is a progressive ataxia and weakness, initially in the hind-legs but later involving forelegs. The onset of signs is usually around 6 months of age although an older dog was affected. Proprioceptive function, muscle tone and tendon reflexes are diminished or absent while pedal reflexes and pain sensation are preserved. Muscle atrophy is minimal. The peripheral nerves are depleted in myelinated fibres. Nerve roots and, to a lesser extent, peripheral nerves show demyelination/remyelination changes and in the cervical ventral roots in particular, regenerative clusters are present. Forelimb muscles show evidence of re-innervation. In the CNS numerous swollen axons are present. The dorsolateral and ventral columns of the spinal cord are affected throughout their length. In the brain a number of nuclei and tracts, particularly in the lower brain stem, are affected and the superior olives are severely involved. The cerebral cortex and subcortical white matter appear normal. Various portions of the auditory and optic pathways are affected pathologically as are a number of cranial nerves. The axonal swellings contain a number of organelles including smooth endoplasmic reticulum, disordered neurofilaments, vesicles and mitochondria. The disease may be specific to Boxer dogs and may be inherited.     

Myokymia and neuromyotonia in 37 Jack Russell terriers

The clinical and clinicopathological characteristics, treatment and outcome of vermicular muscle contractions (myokymia) and generalized muscle stiffness (neuromyotonia) in 37 Jack Russell terriers were evaluated retrospectively. Thirty dogs were affected by both disorders, whereas seven were presented with myokymia and never developed neuromyotonia. Clinical signs started at the mean age of 8 months. Except for signs of myokymia and neuromyotonia, clinical and neurological examination was normal in all dogs. Thirty dogs demonstrated typical signs of hereditary ataxia.Changes in serum chemistry included increased creatine kinase, aspartate aminotransferase and alanine aminotransferase concentrations. Electromyographic abnormalities, especially in muscles showing macroscopically visible myokymia, consisted of semirhythmic bursts of doublet, triplet, or multiplet discharges of a single motor unit. The amplitudes varied between 80 μV and 1 mV and occurred with an interburst frequency between 10 and 40 Hz and an intraburst frequency between 150 and 280 Hz.Most dogs were treated with a sodium channel blocker with variable results. Seven dogs died (most likely because of hyperthermia) or were euthanased during a neuromyotonic attack; 15 dogs were euthanased due to worsening of clinical signs, or lack of or no long-lasting effect of medication, and three were euthanased for unknown or unrelated reasons. Nine dogs were lost to follow-up and three were still alive 5–10.5 years after the start of clinical signs. In conclusion, young Jack Russell terriers with myokymia and neuromyotonia should undergo a complete blood and electrophysiological examination. Long-term prognosis is not favourable.     

Muscular dystrophy in dogs: does the crossing of breeds influence disease phenotype?

Golden Retriever (GR) muscular dystrophy is an inherited degenerative muscle disease that provides an excellent model for Duchenne muscular dystrophy in humans. This study defined the histopathologic lesions, including the distribution of type I and II muscle fibers (FTI and FTII), in 12 dystrophic and 3 nondystrophic dogs between 7 and 15 months of age. The authors were interested in studying the influence on disease phenotype from crossing the base GR breed with Yellow Labrador Retrievers. The dystrophic dogs were divided according to breed: GRs and Golden Labrador Retrievers (GLRs). On hematoxylin and eosin staining, histopathologic lesions were more severe in GRs than GLRs. Six of eight GR muscles (75%) had a severe lesion grade (grade 3). In contrast, seven GLR muscles (87.5%) had mild lesions (grade 2), and only one had severe lesions (grade 3). Changes in fiber-type distribution were more pronounced in GRs versus GLRs. FTI:FTII ratio inversion was observed in three dystrophic GRs but only one GLR. The mean diameter of FTI and FTII was smaller in GRs and GLRs than in nondystrophic dogs (P < .01). The FTI of five GR muscles (62.5%) were larger than those of GLRs, whereas only one GLR muscle was larger (P < .05). The differential was less pronounced for FTII, with four GR muscles being larger and three GLR being larger. Observations indicate that crossing the base GR breed with Labrador Retrievers lessened the severity of the GR muscular dystrophy phenotype.     

MAGNETIC RESONANCE IMAGING CONTRAST ENHANCEMENT OF EXTRA‐OCULAR MUSCLES IN DOGS WITH NO CLINICAL EVIDENCE OF ORBITAL DISEASE

Enhancement of extra‐ocular muscles has been reported in cases of orbital pathology in both veterinary and medical magnetic resonance imaging. We have also observed this finding in the absence of orbital disease. The purpose of this retrospective study was to describe extra‐ocular muscle contrast enhancement characteristics in a group of dogs with no known orbital disease. Magnetic resonance images (MRI) from dogs with no clinical evidence of orbital disease and a reportedly normal MRI study were retrieved and reviewed. Contrast enhancement percentages of the medial, lateral, ventral, and dorsal rectus muscles were calculated based on signal‐to‐noise ratios that were in turn determined from hand‐traced regions of interest in precontrast, immediate postcontrast and 10‐min postcontrast scans. Comparison measurements were made in the pterygoid muscle. Contrast enhancement of the extra‐ocular muscles was observed in all patients (median contrast enhancement percentage 45.0%) and was greater than that of pterygoid muscle (median contrast enhancement percentage 22.7%). Enhancement of the extra‐ocular muscles persisted 10 min after contrast administration (median contrast enhancement percentage 43.4%). Findings indicated that MRI contrast enhancement of extra‐ocular muscles is likely normal in dogs.     

A retrospective study of clinical signs and epidemiology of chronic valve disease in a group of 207 Dachshunds in Poland

Background

Chronic mitral valve disease is frequently seen in the Dachshund. Dachshunds (n=207) made up 11.73% of the dogs admitted to the Cardiology Service at the Small Animal Clinic, Warsaw University of Life Sciences, Poland (first visits only).

Results

Of these, 35 dogs had no clinically detectable heart disease while 172 had chronic valve disease with the mitral valve affected most often (130 dogs), both mitral and tricuspid valves infrequently (39 dogs) and rarely the tricuspid valve (3 dogs). Males were affected more frequently than females and the average age of dogs with chronic valve disease was 11.9 years for females and 11.3 years for males. A majority of the diseased Dachshunds were classified as ISACHC 2 (79), followed by ISACHC 1 (60). Most frequent clinical signs noted by owners included coughing, exercise intolerance, dyspnea and tachypnea. Heart murmurs were generally louder with increased disease severity; however there were 20 dogs in the ISACHC 1 group with no audible heart murmurs. The most frequent electrocardiographic abnormalities included an increased P wave and QRS complex duration, increased R wave amplitude and tachycardia. With increased disease severity, echocardiography revealed an increase in heart size. A higher ISACHC class was related to increased heart size (based on echocardiography) and increased percentage of patients exhibiting enlargement of both left atrium and left ventricle (based on radiography).

Conclusions

The Dachshund is often affected by chronic mitral valvular disease with a late onset of associated clinical signs and few cardiac complications.     

A novel mutation of the CLCN1 gene associated with myotonia hereditaria in an Australian cattle dog

BACKGROUND: Heritable myotonia is a genetic muscle disorder characterized by slow relaxation of skeletal muscles. The main clinical signs are skeletal muscle stiffness, especially after vigorous contraction, and muscle hypertrophy. Muscle stiffness may be enhanced by inactivity, and often is relieved by exercise. Myotonia can be inherited in an autosomal dominant or recessive manner (Thomsen- or Becker-type myotonia, respectively). In mice, goats, Miniature Schnauzer dogs, and most affected humans, the disorder is caused by mutations in CLCN1, which encodes the skeletal muscle voltage-gated chloride channel, Cl1C-1. HYPOTHESIS: We hypothesized that an Australian Cattle Dog with generalized muscle stiffness and hypertrophy examined at the Ontario Veterinary College would have a mutation in the CLCN1 gene. ANIMALS: A pure-bred Australian Cattle Dog from Ontario, Canada, was used. METHODS: Based on clinical signs and electromyographic test results, a diagnosis of myotonia hereditaria was made, and a muscle biopsy was collected for genetic analysis. RESULTS: Sequence data obtained from the affected dog confirmed that it was homozygous for a single base insertion in the CLCN1 coding sequence. This mutation would result in a truncated ClC-1 protein being expressed, which, based on molecular evidence from other studies, would result in functionally compromised chloride conduction in the skeletal muscles of the animal. CONCLUSIONS AND CLINICAL IMPORTANCE: To the authors' knowledge, this report describes the Ist case of myotonia in an Australian Cattle Dog and represents the 1st non-Schnauzer canine myotonia to be genetically characterized. In addition, we developed a polymerase chain reaction-based genetic screen to detect heterozygotes with this mutation in the at-large Australian Cattle Dog population.     

Analysis of muscle elements, water, and total lipids from healthy dogs and Labrador retrievers with hereditary muscular dystrophy

Skeletal muscles from healthy dogs and Labrador Retrievers with hereditary muscular dystrophy were examined morphologically and histochemically and were analyzed biochemically for Na+, K+, Ca2+, Mg2+, Zn2+, Cu2+, Cl-, total muscle water, and total neutral lipid content. Flame atomic absorption spectrophotometer was used for elemental quantitation of hydrochloric acid tissue extracts. Muscle samples from dystrophic dogs contained substantially increased concentrations of Na+, Ca2+, Zn2+, Cu2+, and Cl-, and a considerable reduction in the content of K+ and Mg2+ compared with samples from healthy dogs. Total muscle water and total fat content was higher in muscles from dystrophic dogs. Most muscle samples from dystrophic dogs had a type-2 fiber deficiency and an increase in number of fibers with internalized nuclei.     

Muscle disorders and rehabilitation in canine athletes.

Muscle disorders associated with physical exertion in human athletes include delayed-onset muscle soreness, muscle strain, muscle tears, rhabdomyolysis, and acute and chronic compartment syndromes. Given that the structure of muscle is similar among different species, it is reasonable to expect that dogs experience the same phenomena. This article focuses on several of the muscle disorders of bird dogs, namely, coccygeal muscle injury and infraspinatus muscle contracture, and on those of dogs involved in tracking-obedience-protection training, namely, fibrotic myopathy, with an additional discussion of muscle strain. For injury prevention, one important area that can be adapted to canine athletes is the incorporation of warm-up and cool-down into the training program.     

Inherited myopathy of great Danes

A hereditary, non-inflammatory myopathy occurring in young great Danes with distinctive histological features in muscle biopsy specimens is reviewed. Onset of clinical signs is usually before one year of age and both sexes are affected. Clinical signs are characterised by exercise intolerance, muscle wasting, and an exercise-induced tremor. Although most affected dogs have a severe form of the disease, occasional dogs may have a less pronounced form and survive into adulthood with an acceptable quality of life. Litters containing affected puppies are born to clinically unaffected parents, and an autosomal recessive pattern of inheritance is likely. All recorded cases have had fawn or brindle coat coloration. Elevated serum creatinine kinase concentrations and spontaneous electrical activity in skeletal muscles are frequently found. While originally reported (Targett and others 1994) as a central core myopathy in this breed, the histochemical characteristics of the distinct cytoarchitectural structures differ from those of the well-characterised central core myopathy in human beings. In fact, these structures differ from any known myopathy in human beings and likely represents a unique non-inflammatory myopathy affecting dogs. Until this myopathy is characterised further, the name inherited myopathy in great Danes is suggested.     

Linear arrector pili muscle hamartoma on the tail of a sphynx cat

Arrector pili muscle (APM) hamartoma is reported in humans and dogs. We describe a linear APM hamartoma in a sphynx cat. The lesion was characterized by multiple nodules distributed linearly along the tail, made of randomly arranged hypertrophic smooth muscles, the size of which tended to wax-and-wane during a one year follow-up.     

Muscle Contractures in the Limbs of Dogs and Cats

Muscle contractures causing varying degrees of lameness commonly occur from skeletal muscle fibrosis, the result of injury such as that caused by circulatory insufficiency, infection, autoimmune reaction, or trauma. Quadriceps contracture, whether congenital or acquired, is treated by sectioning the cordlike fibrotic muscle group by "Z" plasty, resulting in lengthening it enough to allow the knee to assume a normal standing angle. Adhesion of the muscle group to a large femoral callus (muscle tie down) may occur and require additional surgical correction. Infraspinatus contracture results in a typical foreleg deformity and change in gait. Surgical repair by tenotomy is usually followed by rapid return to normal. Gracilis contracture, though common in racing greyhounds, is not commonly reported in pet dogs. Surgical excision of the entire affected muscle mass is curative.     

COCCYGEAL VERTEBRAL CHONDROSARCOMA IN A SAINT BERNARD DOG: A CASE REPORT

A 6-year-old male Saint Bernard dog was examined because of a firm nonpainful tail-base mass. Radiographs revealed an expansile heterogeneous bony mass of the sixth coccygeal vertebra. The tail was amputated. The histologic diagnosis was coccygeal vertebral chondrosarcoma. Chondrosarcomas account for ten to eleven percent of all skeletal tumors and occur commonly in the flat bones in large-breed dogs. Radiographically chondrosarcomas appear predominantly osteolytic but may contain mottled mineralized densities. In the dog described here the radiographic signs were typical of a malignant cartilaginous tumor: cortical destruction, mottled mineralized densities, ill-defined margins, and continued but relatively slow growth. However, there was no periosteal reaction and the chondrosarcoma was at an unusual site.     

Dysphagia in Bouviers associated with muscular dystrophy; evaluation of 24 cases

Twenty-four Bouviers with dysphagia were examined between October 1986 and October 1988. The type of dysphagia was characterised by the results from the clinical examination, the videofluorographic examination and the electromyographic recordings from the oral, pharyngeal, and esophageal muscles. Electromyography indicated neurogenic as well as myogenic causes of dysphagia. Tissues from 10 dogs were available for histopathologic examination. In nine dogs there was a progressive muscular degeneration of the pharyngeal and/or esophageal muscles, resembling muscular dystrophy. In two of these dogs the same abnormalities were also noticed in the masseter and temporalis muscles and in the intrinsic laryngeal muscles. In one dog small areas with hyalin degeneration and fragmentation of muscle fibres were found in the cricopharyngeal muscle. No abnormalities in nerve tissue were found. Muscular dystrophy is a hereditary disease. The mode of transmission in these Bouviers is not yet known.     

Chronic thallium intoxication in five German pointers of one litter

The difficulty of diagnosis and therapy of chronic thallium intoxication is described in five German Pointers with the same skin disease. The detection of thallium in cases of skin lesions like the cutaneous erythema with oedema and crusts or in chronic cases with multifocal alopecia is difficult. The first diagnostic information was gathered in this case from the high thallium level in the urine. The thallium concentration in the hair is subject to great variations, even in physiologic conditions. The trichogramme showed in this case pathognomonic changes like adhesion of the hair follicles. Differential diagnosis for this symmetric alopezia without pruritus are hormonal disturbances or, in puppies, the generalized form of demodicosis. The five affected dogs were treated with Fe III-Hexacyanoferrat. The clinical appearance of the skin improved slowly during a period of 1-2 months.