Breed Specific Necrotizing Encephalitis in Dogs

 

Necrotizing encephalitis is inflammation of the brain with concurrent necrosis (death) of brain tissue. It is seen only in a few breeds of dogs, including pugs, Yorkshire terriers, and Maltese. It is also occasionally seen in chihuahuas and shi-tzus. Symptoms vary in different breeds.

 

Symptoms and Types

 

Symptoms depend on the area of the brain that is affected, but may include:

 

• Abnormal behavior
• Seizures
• Circling
• Blindness

 

Causes

 

The exact cause for this condition is unknown.

 

Diagnosis

 

You will need to give your veterinarian a detailed medical history, including a background of the symptoms, time of onset, and the frequency of the symptoms present. After taking a history, your veterinarian will examine your dog in detail. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis. The laboratory tests are usually within normal ranges. Radiographic studies, including magnetic resonance imaging (MRI) and a computed tomography scan (CT-scan) also typically give non-specific results.

 

 

A more conclusive diagnosis may be made using a sample taken from the cerebrospinal fluid (CSF), the protective and nourishing fluid that circulate around the brain and spinal cord. The sample will be sent to laboratory for a further evaluation. The results of the CSF testing may reveal an increase in the leukocytes (white blood cells or WBCs) count, an abnormal condition referred to as pleocytosis. The laboratory tests may also indicate inflammation, infection, or the possible presence of a tumor. However, a brain biopsy (taking a small sample of brain tissue for analysis) is the only way to conclusively determine the cause for the brain disturbance.

 

Neuroaxonal Dystrophy in Dogs

 

The term abiotrophy is used to denote loss of function due to degeneration of cells or tissues without known reasons. Neuroaxonal dystrophy is a group of inherited abiotrophies affecting different parts of brain in dogs. Rottweilers, collies, German shepherds, chihuahuas, and boxers are some of the breeds known to be predisposed to this inherited disorder of the brain.

 

Symptoms and Types

 

The symptoms depend on the part of brain being affected.

 

• Uncoordinated movements
• Abnormal placement of limbs while walking
• Strength in limbs is usually normal in affected patients
• Mild tremor of head and neck
• Other nervous symptoms

 

Causes

 

• No known cause – idiopathic
• Inherited factors

 

Diagnosis

 

You will need to give a thorough history of your dog’s health, including background history and a descriptions of the onset of symptoms. After taking a complete history, your veterinarian will conduct a complete physical examination. Laboratory tests include a complete blood count (CBC), biochemistry profile, and urinalysis. The results of these routine laboratory tests are usually within normal ranges. Diagnosis of neuroaxonal dystrophy is usually accomplished by differential diagnosis. That is, by excluding other diseases and conditions until the correct cause for the condition is settled upon. A concrete diagnosis is usually made during postmortem of affected patients.

 

Idiopathic Polyradiculoneuritis in Dogs

 

Acute canine idiopathic polyradiculoneuritis (ACIP) is a creeping paralysis due to acute inflammation of the nerves. This disease is often seen in dogs that live in North America as well as in those areas where raccoons are present but overall incidence is quite low. Any breed is at risk, but dogs that regularly come into contact with raccoons are at increased risk, such as hunting dogs and dogs that live in rural or wooded areas.

 

Symptoms presented by ACIP are also classified under a condition referred to as coonhound paralysis. Diagnosis with this disease does not necessarily involve an encounter with a raccoon.

 

Symptom and Types

 

• Symptoms usually appear 7-14 days after contact with raccoon
• Stiff gait
• Generalized slow reflexes
• Low muscle tone
• Weakened vocal ability
• Labored breathing
• Decrease in muscle bulk
• Facial muscle weakness
• Muscular weakness in all four limbs which may progresses to paralysis in all limbs
• Pain
• Oversensitivity to pain stimuli

 

Causes

 

Besides the known connection that has been made with affected dogs coming into contact with raccoon saliva, the exact cause of ACIP is still unknown. Viral or bacterial infections are suspected to be responsible, and because of the correlation with the nervous system and neural pathways, an autoimmune link is being researched. It is thought that white blood cells may be attacking the nerves.

 

Diagnosis

 

Your veterinarian will take a detailed background medical history from you before making the full physical evaluation. You will need to provide a thorough history of your dog’s health, onset of symptoms, and possible incidents that might have preceded this condition, such as whether your dog has had recent contact with a raccoon.

 

As part of a standard physical examination, routine laboratory tests will include a complete blood count, biochemistry profile and urinalysis. Usually the results of all these tests are found to be within normal ranges. More specific tests will also be done, including specific testing for determination of abnormalities of electric activity in peripheral nerves, and an analysis of the spinal fluid, which will require a spinal tap, and the brain fluid (cerebrospinal fluid, or CSF), to look for specific infections that may be causing the paralysis.

 

 

Ataxia, Vestibular Disease in Dogs

 

Ataxia is a condition relating to a sensory dysfunction that produces loss of coordination of the limbs, head, and/or trunk. There are three clinical types of ataxia: sensory (proprioceptive), vestibular, and cerebellar. All three types produce changes in limb coordination, but vestibular and cerebellar ataxia also produce changes in head and neck movement.

 

Sensory (proprioceptive) ataxia occurs when the spinal cord is slowly compressed. A typical outward symptom of sensory ataxia is misplacing the feet, accompanied by a progressive weakness as the disease advances. Sensory ataxia can occur with spinal cord, brain stem (the lower part of the brain near the neck), and cerebral locations of lesions.

 

The vestibulocochlear nerve carries information concerning balance from the inner ear to the brain. Damage to the vestibulocochlear nerve can cause changes in head and neck position, as the affected animal may feel a false sense of movement, or may be having problems with hearing. Outward symptoms include leaning, tipping, falling, or even rolling over. Central vestibular signs usually have changing types of eye movements, sensory deficits, weakness in the legs (all or one sided), multiple cranial nerve signs, and drowsiness, stupor, or coma. Peripheral vestibular signs do not include changes in mental status, vertical eye movements, sensory deficits, or weakness in the legs.

 

Cerebellar ataxia is reflected in uncoordinated motor activity of the limbs, head and neck, taking large steps, stepping oddly, head tremors, body tremors and swaying of the torso. There is an inadequacy in the performance of motor activity and in strength preservation.

 

Symptoms and Types

 

• Weakness of the limbs
  • May affect one, two, or all of the limbs
  • May affect only the hind legs, or the legs on one side of the body
• Tilting head to one side
• Trouble hearing – non-responsive to being called to at normal voice pitch
• Stumbling, tipping over, swaying
• Excessive drowsiness or stupor
• Changes in behavior
• Abnormal eye movements – may be due to false feeling of movement, vertigo
• Lack of appetite due to nausea (symptom of motion sickness from loss of internal equilibrium [balance])

 

Causes

 

• Neurologic
  • Cerebellar
  • Degenerative:
    • Abiotrophy (prematurely the cerebellum loses function)
  • Anomalous:
    • Underdevelopment secondary to perinatal infection with panleukopenia virus in cats
    • A cyst located near fourth ventricle
  • Cancer
  • Inflammatory, unknown causes, immune-mediated
  • Toxic
• Vestibular – central nervous system (CNS)
  • Inflammatory, unknown causes, immune-mediated
  • Toxic
• Vestibular—Peripheral nervous system
  • Infectious:
  • Diseases of unknown cause
  • Metabolic
  • Cancer
  • Traumatic
• Spinal Cord
  • Degeneration of the nerve roots and spinal cords
  • Vascular:
    • Loss of blood to nervous system due to blockage of blood vessels by a blood clot
  • Anomalous:
    • Spinal cord and vertebral malformation
    • spinal cyst
  • Cancer
  • Infectious
  • Traumatic
• Metabolic
  • Anemia
  • Electrolyte disturbances – low potassium and low blood sugar

 

Diagnosis

 

You will need to give your veterinarian a thorough history of your dog’s health, onset of symptoms, and possible incidents that might have preceded this condition. Your veterinarian will order standard tests, including a blood chemical profile, a complete blood count, a urinalysis and an electrolyte panel.

 

Imaging is crucial for determining whether the disease is localized to the peripheral vestibular system, the spinal cord, or the cerebellum. Computed tomography (CT), magnetic resonance imaging (MRI), myelography and spinal X-rays can all be useful diagnostic tools for non-invasive internal examinations. Chest and abdominal X-rays are also important for determining if cancer or systemic infection is present. An abdominal ultrasound should be done to check liver, kidney, adrenal or pancreatic functions.

 

If the source of the disease is suspected to be in the nervous system, a sample of cerebrospinal fluid (CSF) will be taken for laboratory analysis.

 

 

Amitraz Toxicosis in Dogs 

 

Amitraz toxicosis (or poisoning) occurs when a dog is overexposed to the pharmaceutical drug Amitraz (formamidine acaricide), which is commonly used in dog collars and in topical solutions for the prevention and eradication of ticks and to control demodex mite infections.

 

Toxic levels of this drug will affect the dog’s nervous, endocrine/metabolic, and gastrointestinal systems. Amitraz topical solutions usually contain 19.9 percent of the pharmaceutical in 10.6 ml bottles, while impregnated collars contain 9 percent of it in a 25-inch, 27.5 gram collar.

 

Symptoms and Types

 

The symptoms of Amitraz toxicosis develop acutely after the overexposure occurs — usually within two to six hours after the incidence. The most common symptoms include:

 

• Vomiting
• Diarrhea
• Lethargy
• Weakness
• Staggering
• Disorientation
• Hypothermia
• Abdominal pain
• Light or severe depression

 

In severe cases where the correct treatment is not administered, Amitraz toxicosis may result in a comatose state or death.

 

Causes

 

Amitraz toxicosis can be caused in a number of ways. The most common cause of the condition is when a dog chews or ingests its own tick collar. It may also occur if an inadequately diluted Amitraz-containing solution is topically applied on the dog’s skin, or if the dog ingests the undiluted solution directly. If a diluted solution is topically applied in the proper way, Amitraz toxicosis occurs quite rarely.

 

Elderly, sick, diabetic or debilitated dogs and toy breeds are particularly vulnerable to this condition. Curious puppies are probably the most frequently affected victims.

 

Diagnosis

 

If there has been a recent incidence of access or exposure to an Amitraz-containing solution or tick collar and your dog is displaying any of the symptoms of an overdose, your veterinarian will base the diagnosis on a physical exam.

 

An abdominal X-ray will typically show that there is a collar buckle in the gastrointestinal tract. The results of an exam may reveal traces of Amitraz on the hair or in the gastrointestinal contents, and a biochemical and urine analysis will often reveal hyperglycaemia (high blood sugar).

 

Additionally, these tests may reveal an elevated level of liver enzymes when Amitraz toxicosis has occurred, although only rarely.

 

 

 

Clostridium botulinum in Dogs

 

Botulism is a rare but serious paralytic disease in dogs, related to ingestion of raw meat and dead animals. Typically, symptoms within a few hours to six days after eating spoiled animal meat that is infected with the Clostridium botulinum type C preformed neurotoxin. This neurotoxin causes spreading weakness, starting in the back legs and ascending to the trunk, front legs and neck. Paralysis of all four limbs is the next symptom.

 

Dogs generally are resistant to the more severe effects of Clostridium botulinum type C. Mildly affected dogs recover over a period of several days with supportive treatment. However, dogs with difficulties breathing will require intensive care monitoring. In severe cases, paralysis can affect the ability to breath killing the affected animal.

 

Symptoms and Types

 

• Sudden spreading weakness starting in hind legs and ascending to the trunk, front legs and neck
• Severe weakness of all four legs or paralysis of all four limbs (which usually occurs within 12 to 24 hours of onset)

 

Causes

 

• Clostridium botulinum type C preformed neurotoxin, eaten in dead animal carcasses, or in uncooked or spoiled foods

 

Diagnosis

 

You will need to give your veterinarian a thorough history of your dog’s health, onset of symptoms, and possible incidents that might have preceded this condition, such as contact with spoiled meat or dead animals.

 

Your veterinarian will perform a full physical exam of your dog, with standard tests including a chemical blood profile, complete blood count and urinalysis. Blood will also be taken to test for the botulinum toxin in the serum. Likewise, your veterinarian may take a stool sample or vomit to test for the the toxin. X-rays of your dog’s chest may be taken to check the health of the lungs and upper digestive tract, as this toxin can cause paralysis of the respiratory muscles.

 

 

Idiopathic Vestibular Disease in Dogs

 

Observing a dog tilting its head frequently is an indication that the dog feels imbalanced. The medical description of head tilt involves tilting of the head to either side of the body, away from its orientation with the trunk and limbs. The dog may appear to be trying to prevent itself from falling, or struggling to retain a balanced posture.

 

A common cause of head tilting in dogs are disorders of the vestibular system, a sensory system located in the inner ear which provides information needed to hold the body in an upright position and move about confidently. In essence, the vestibular system “tells the body where it is in relation to earth — whether it is upright, up-side-down, moving, being still, etc.

 

Head tilting may also occur from time to time in elderly dogs, and may not need medical treatment, but it is always best to have the condition checked for a more serious underlying condition.

 

Symptoms and Types

 

• Abnormal head posture
• Head tilt to either side
• Stumbling, lack of coordination (ataxia)
• Constantly falling over
• Eye movements erratic, apparent inability to focus
• Circling (turning in circles)
• Nausea, vomiting

 

Causes

 

Although the underlying cause for vestibular disease is unknown, the following factors may contribute to the condition:

 

• Ear injury
• Brain disease
• Metabolic diseases
• Neoplasia (abnormal tissue growth)
• Nutritional deficiencies (e.g., thiamine deficiency)
• Toxicity (e.g., use of toxic antibiotics in the ear)
• Upper respiratory tract infection
• Inflammation of the central and inner ear canal due to bacterial, parasitic, or other type of infection

 

 

Diagnosis

 

Your veterinarian will perform a complete standard physical exam, including a blood chemical profile, a complete blood count, a urinalysis and an electrolyte panel, and you will need to give a thorough background history of your dog’s health leading up to the onset of symptoms. The results of the blood tests are usually normal, though changes may be present depending on whether there is an existing disease, such as an infection. Further tests will be required to diagnose underlying systemic diseases like thyroid problems, and infections.

 

Nutritional status will be evaluated, and you will need to recount your dog’s normal diet, along with supplements or additional foods you may feed to your dog. Thiamine deficiency, for example, can result from over consumption of raw meats and fish.

 

To determine if an ear infection is present, your veterinarian will thoroughly examine the ear canal and will take a sample of the material present within the ear canal for further testing. Visual diagnostic tools, X-rays, computed tomography (CT), and magnetic resonance imaging (MRI) may be required to confirm a middle ear disease. Another important test used to diagnose this disease is a cerebrospinal fluid (CSF) analysis. (CSF is a clear, watery liquid that surrounds and protects the brain and spinal cord.) The results of a CSF analysis is useful in the diagnosis of inflammation and/or infection within brain. A bone biopsy may also be performed is an advanced test to confirm the involvement of the bone due to tumor or infection.

 

Bacterial Meningitis and other Nervous System Infections in Dogs

 

Much like in humans, the system of membranes which envelops the dog’s central nervous system is called the meninges. If this system becomes inflamed, it is referred to as meningitis. Meningoencephalitis, meanwhile, is the inflammation of the meninges and brain, and meningomyelitis is the inflammation of the meninges and spinal cord.

 

Inflammation of meninges commonly leads to secondary inflammation of the brain and/or spinal cord, resulting in various neurological complications. Long-term inflammation can also obstruct the flow of cerebrospinal fluid (CSF) — the protective and nourishing fluid that circulates around the brain and spinal cord — which leads to accumulation of CSF in the brain and thus severe complications such as seizures and paresis.

 

Symptoms and Types

 

Neurological symptoms often associated with meningitis, meningoencephalitis, and meningomyelitis such as impaired movement, altered mental state, and seizures, may be profound and progressive. Other symptoms generally seen in dogs suffering from one of these conditions include:

 

• Depression
• Shock
• Low blood pressure
• Fever
• Vomiting
• Abnormal increase in sensitivity to various stimuli (hyperesthesia)

 

Causes

 

The most common cause of meningitis is a bacterial infection in the brain and/or spinal cord originating from elsewhere in the body. Meningoencephalitis, meanwhile, is usually due to infections of the ears, eyes, or nasal cavity. And meningomyelitis generally proceeds following diskospondylitis and osteomyelitis. In puppies and dogs with compromised immune system, such infections commonly reach the brain and spinal cord via the blood.

 

Diagnosis

 

You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms. The veterinarian will then conduct a complete physical examination and several laboratory tests — such as complete blood count (CBC), blood culture biochemistry profile, and urinalysis — to help identify and isolate the type of infection.

 

Biochemistry profile, for example, may indicate liver and kidney involvement, while blood testing may reveal an increased number of white blood cells, which is evidence of an ongoing infection. Urinalysis may also reveal pus and bacteria in the dog’s urine, an indication of urinary tract infections.

 

Other tools often used to identify the infectious agent involved include magnetic resonance imaging (MRI), abdominal ultrasounds, thoracic and abdominal X-rays, and samples from the skin, eyes, nasal discharge, and sputum.

 

One of the most important diagnostic tests, however, is CSF (or cerebrospinal fluid) analysis. A sample of your dog’s CSF will be collected and sent to a laboratory for culturing and further evaluation.

 

 

Meningoencephalomyelitis in Dogs

 

Eosinophilic meningoencephalomyelitis is a condition that causes the inflammation of the brain, spinal cord, and their membranes due to abnormally high numbers of eosinophils, a type of white blood cell, in the cerebrospinal fluid (CSF). Often, the increase of eosinophils is in response to a parasite infection, tumor or allergic reaction in the dog.

 

Although dogs of any age may succumb to eosinophilic meningoencephalomyelitis, Golden retrievers seem to be predisposed to the condition.

 

Symptoms and Types

 

Symptoms vary in location and severity, but are often related to the nervous system such as circling, loss of memory, seizures and blindness.

 

Causes

 

It is common for the underlying cause to the eosinophilic meningoencephalomyelitis to be idiopathic (or unknown) in nature. Other typical factors associated with this disease include:<

 

• Allergies (also common)
• Tumors
• Parasite infections
• Fungal infections
• Vaccinations

 

Diagnosis

 

You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms. The veterinarian will then conduct a complete physical examination and several laboratory tests — such as complete blood count (CBC), blood culture biochemistry profile, and urinalysis — to help identify and isolate the cause of inflammation.

 

Blood testing may reveal abnormally high number of eiosinophils in the blood. Biochemistry profiling, for example, may show abnormal liver enzyme activity, indicating parasitic infections. And magnetic resonance imaging (MRI) may reveal tumorous lesions in the dog’s brain or spinal cord.

 

 

One of the most important diagnostic tests, however, is CSF (or cerebrospinal fluid) analysis. A sample of your dog’s CSF will be collected and sent to a laboratory for culturing and further evaluation. In case of idiopathic or allergic causes, abnormally high numbers of eiosinophils are seen in the CSF. Tumors, meanwhile, are generally associated with an abnormally low number of white blood cells along with a small number of eiosinophils in the CSF.

 

Myelomalacia in Dogs

 

“Myelomalacia” or “hematomyelia” is an acute, progressive, and ischemic (due to impaired blood supply) necrosis of the spinal cord after injuring the spinal cord. The premature death (necrosis) of the spinal cord cells first appears at the site of the injury but progresses forward and backward from the point of injury over time.

 

Dogs and cats of any age or breed can succumb to this condition.

 

Symptoms and Types

 

• Paralysis of hind limbs
• Numbness to pain in areas lower than the injury
• Loss of tone and reflexes in hind limbs due to softening of spinal cord (malacia)
• Hyperthermia
• Dilated anus

 

Causes

 

• Type 1 disk disease
• Spinal injury

 

Diagnosis

 

You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms, to your veterinarian. The questions may specifically pertain to accidents or injuries that may have befallen your dog. He or she will then conduct a complete physical examination, as well as a biochemistry profile, urinalysis, and complete blood count (CBC) — the results of which may be normal initially, but which may deteriorate as injuries to vital organ worsen.

 

Spinal X-rays and Magnetic Resonance Imaging (MRI) are other valuable tools for evaluation of structural and functional aspects of spinal cord. These tests may show evidence of herniated disks and vertebral fractures. Your veterinarian will also take cerebrospinal fluid (which protects and nourishes the brain and spinal cord) and will send the sample to laboratory for further evaluation.