Canada West Veterinary Specialists http://canadawestvets.com Quality, Compassion and Caring. Committed to Making the Critical Difference. Fri, 17 Feb 2012 17:16:15 +0000 en hourly 1 http://wordpress.org/?v= Pacemaker placement for treatment of advanced second degree heart block in a 13 yr old Lhasa Apso http://canadawestvets.com/pacemaker-placement-for-treatment-of-advanced-second-degree-heart-block-in-a-13-yr-old-lhasa-apso/ http://canadawestvets.com/pacemaker-placement-for-treatment-of-advanced-second-degree-heart-block-in-a-13-yr-old-lhasa-apso/#comments Sun, 15 Jan 2012 22:50:55 +0000 Laurence Braun http://canadawestvets.com/?p=1837 Dharma is a 13 year old female spayed Lhasa Apso referred to the Cardiology Service at Canada West Veterinary Specialists in October 2011 with a history of exercise intolerance. Dharma was diagnosed with an arrhythmia during a wellness examination by her regular veterinarian. Dharma also had an episode of acute weakness (“flopping down”) while walking, approximately two weeks prior to our evaluation. She was not on any medications at that time. A standard ECG showed the presence of second degree AV block with an average ventricular rate of 80 BPM.

An atropine test was performed that showed only partial response to atropine, indicating that structural damage to the conduction system was present. An echocardiogram showed normal cardiac morphology, dimensions and function, ruling out the absence of other significant heart diseases.

In order to more thoroughly evaluate Dharma’s heart rhythm at home, we performed a 24 hour Holter monitor recording. This study showed the presence of advanced second degree AV block with a minimum heart rate of 30 beats per minute. The picture shows a representative portion of Dharma’s Holter recording. The red arrows indicate blocked P waves. The pause associated with the two consecutive blocked P waves was greater that 3 seconds in duration.

Dharma's Holter

 

Advanced second degree AV block is likely a progressive condition that carries a high risk for the patient. Many patients affected by this conduction disorder progress to complete heart block (third-degree AV block). Implantation of an artificial permanent pacemaker is the treatment of choice. 

Pacemaker lead placement under fluoroscopy

 

Dharma was hospitalized the day prior to the procedure. The day of the procedure we placed two adhesive electrodes on her chest to be able to artificially pace her after induction of anesthesia in case her heart rate dropped.  

Dharma’s surgery went very well and our anesthesiologist, Dr Craig Mosley was pleased with her anesthesia recovery.

Lead and pacemaker

 
The pacemaker was programmed to sense Dharma’s intrinsic heart beats and start pacing when the heart rate approaches 80 beats per minute. Dharma was monitored overnight in the ICU and discharged to the care of the owners the day after the procedure. 
 
 
 
 
 
 
  
The picture shows two consecutive sinus beats followed by a blocked P wave (red arrow).
This pause in the ventricular rhythm triggers the pacemaker that starts pacing the ventricles at a heart rate of 80 BPM (blue arrows), until a sinus-initiated QRS complex is sensed by the pacemaker (black arrow).

Dharma's ECG at discharge

 

 

 

 

Sutures were removed 9 days later and a brief recheck two weeks after the surgery showed that Dharma was healing well.

Dharma at recheck

Pacemaker recipients are routinely rechecked one month after the procedure. The first week of January Dharma’s pacemaker was interrogated and re-programmed with a special computer via a radio frequency “wand” placed on the patient’s skin. Modern pacemakers collect and store data that is used to optimize the settings of the device with the intention of maximizing the patient’s quality of life and device battery duration. Dharma’s case highlights the diagnostic value of a Holter monitor recording in patients affected by conduction abnormalities.

This case reminds us that also relatively asymptomatic patients at high risk for progression of their conduction disorders are candidates for pacemaker implantation.

]]> http://canadawestvets.com/pacemaker-placement-for-treatment-of-advanced-second-degree-heart-block-in-a-13-yr-old-lhasa-apso/feed/ 0 Wobbler Syndrome http://canadawestvets.com/wobbler-syndrome/ http://canadawestvets.com/wobbler-syndrome/#comments Fri, 18 Feb 2011 00:16:53 +0000 Cintia Stela http://canadawestvets.com/?p=1585 Overview

This is a lay term used to describe a condition that is both simple and yet at the same time complex and only poorly understood. The simplest explanation is that this disorder results from a chronic compression of the spinal cord in the neck caused by multiple factors. These factors include being born with a bony canal that is slightly too narrow, together with subsequent degenerative changes like disc herniations and overgrowth of other soft tissues. These structures cause compression of the spinal cord, often at several different levels within the neck. Instability between certain vertebrae may also play a factor in this disorder. There are therefore three major factors in this disorder, namely abnormalities that the animal is born with, abnormalities that the animal develops as it ages and the effect of instability. What is only poorly understood is what role each of these three factors plays in the final disease process and also whether there is an inherited component to any of them. The disorder has many similarities with Cervical Spondylosis / Cervical spondylotic myelopathy of humans.

Figure 11-1: Myelogram of a dog with Wobbler syndrome. At one level there is severe spinal cord narrowing (arrow), which has been caused by compression of the spinal cord by ligament and joint capsule from above as well as from the disc below. Adjacent to this level there is a second level of spinal cord compression caused by a disc herniating from below (arrowhead). The spinal cord is normal and is not under compression at the disc space nearest the dog’s head (*). The relative diameters of the spinal cord at each of these three levels is indicated by the vertical black bars.

Clinical signs of Wobbler syndrome include combinations of neck pain and neurological deficits that affect all four limbs, although initially the signs are often more severe in the rear limbs. In contrast to simple extrusion of a disc in the neck, the pain associated with wobbler syndrome is usually much less severe whereas the neurological deficits are often more marked. Diagnosis is made by imaging the spinal cord using either myelography combined with a CT scan or by using an MRI. The main advantage of myelography compared to MRI is that myelography makes it easy to examine the spinal cord with the dog’s neck in different positions. The appearance of the spinal cord in different neck positions may in turn dictate the type of surgery that will be recommended.  The main advantage of MRI is that it is non-invasive and gives excellent detail of the spinal cord.

Figure 11-2: MRI of a young Great Dane with Wobbler syndrome. Note the severe spinal cord compression caused by overgrowth of the joints at the top of the spine (arrow). This dog also has a problem higher up its spine, indicated by the white area within the spinal cord (arrowhead) that probably represents fluid accumulation due to repeated, low-grade injury. This dog did very well after his spine was fused at three spaces using a modification of the distraction-fusion technique.

Two broad types of surgery are performed in wobbler syndrome. The first type of surgery is to simply remove the tissues causing compression of the spinal cord. This may be done by either a ventral decompression, where the incision is made on the underside of the dog’s neck, or a dorsal laminectomy where the incision is made on the top of the dog’s neck. The second type of surgery is to fuse the vertebrae at the affected level(s) in a position that provides more room for the spinal cord than it had before surgery. This is often called a fusion or distraction-stabilization technique and it can be performed using a number of different techniques.

In general, the two main surgical techniques, decompression and distraction-fusion, have similar success rates of between 70% to 90%. The actual rate depends both on the severity of the clinical signs and on the number of level(s) in the neck that are affected. Although there is a small risk of complications (see below), there are no other good options for dogs with obvious neurological signs because non-surgical management is usually unsuccessful in these animals. Strict rest with no running, jumping, stair climbing or off-leash activity combined with use of a chest harness may help animals with mild clinical signs of short duration or dogs that develop signs following minor trauma. Animals less than one year of age may benefit from a severe reduction in food intake but this approach has not been proven and does not help older animals.

The prognosis is generally good for dogs with wobbler syndrome that retain the ability to walk (see above). Dogs that are so weak that they cannot stand have a more guarded prognosis, as they are more prone to complications.  Complications that may occur after surgery in all dogs include post-operative deterioration in neurological status or loss of stability at a distraction site. Dogs that are unable to stand are also at particular risk of other complications such as pneumonia or gastric torsion.

Further Resources

Wobbler Syndrome

Human Cervical Spondylosis / Cervical spondylotic myelopathy

]]> http://canadawestvets.com/wobbler-syndrome/feed/ 1 Vestibular Disease http://canadawestvets.com/vestibular-disease/ http://canadawestvets.com/vestibular-disease/#comments Thu, 17 Feb 2011 23:26:57 +0000 Cintia Stela http://canadawestvets.com/?p=1580 Overview

The vestibular system is the primary sense that governs balance. Just like vision depends on the eyes to convert light to electrical impulses and then requires a specialized region of the forebrain to interpret the information correctly, the vestibular system also depends on two components. These are the inner ear structures that convert information about head position into electrical impulses and then an area of the brainstem that interprets this information. An animal can have a disturbance of balance due to either a problem affecting the inner ear, such as a severe and deep-seated ear infection, or the problem could be caused by either a tumor or an infection in the vestibular center of the brainstem. The signs of vestibular disease include not only a loss of balance but also a head tilt and nystagmus. Nystagmus is a specific, involuntary eye movement where the eyes flick rapidly in one direction and then slowly drift back before repeating the movement again. Diagnosis depends first on a full neurological examination to differentiate inner ear problems (usually called peripheral vestibular disease) from brainstem disorders (usually called central vestibular disease). Depending on the examination results, the structures of the ear and brainstem may need to be imaged using either a CT scan or an MRI. In addition, a sample of CSF may also need to be taken. Treatment and prognosis will depend on the results of these tests.

Figure 9: A: CT scan of the skull of a cat with peripheral vestibular disease due to otitis media and interna (inflammation of the structures of the middle and inner ear). The right tympanic bulla (white arrowheads) is normal; it is full of air, which shows as black on the CT scan. The left tympanic bulla (white arrow) is full of either fluid or tissue and the bony wall is also thickened slightly compared to the right side. The inflammation within the left bulla has affected the structures of the inner ear (position indicated by the black arrowhead) to cause the typical clinical signs of vestibular disease. The position of the vertical and horizontal canals of the left external ear are shown by *.

B: CT scan of the skull of a dog with normal tympanic bullae but a tumor (arrowheads) within the brainstem. This is an example of an animal with central vestibular disease. The tumor shows up as whiter then the rest of the brain because it has enhanced after the administration of intravenous contrast.

The prognosis is generally good for peripheral vestibular disease but is more guarded for central vestibular disease. Complications are dependent on the specific diagnosis.

Further Resources

]]> http://canadawestvets.com/vestibular-disease/feed/ 0 Tetanus http://canadawestvets.com/tetanus/ http://canadawestvets.com/tetanus/#comments Thu, 17 Feb 2011 23:16:25 +0000 Cintia Stela http://canadawestvets.com/?p=1577 Overview

This condition is not common in dogs and cats as they are quite resistant to the tetanus toxin. As in people, animals get tetanus when a cut gets infected by a bacterium called Clostridium tetani that produces tetanus toxin. The causes the muscles of one or more limbs, and usually those of the entire body and the head, are caused to contract forcefully and continuously. The result is that the animal goes very stiff. Animals also develop a characteristic facial expression as all the muscles of the head contract as well.  The prognosis is guarded but many animals will recover with long-term, intensive care. Complications relate mainly to the risk of pneumonia or, in a few cases, that the animal becomes so stiff and rigid that it is unable to breathe on its own and requires ventilation.

Further Resources

]]> http://canadawestvets.com/tetanus/feed/ 0 Syringohydromyelia http://canadawestvets.com/syringohydromyelia/ http://canadawestvets.com/syringohydromyelia/#comments Thu, 17 Feb 2011 23:14:48 +0000 Cintia Stela http://canadawestvets.com/?p=1573 Syringohydromyelia, also known as COMS or Caudal Occipital Malformation Syndrome, is a condition where there is insufficient room for cerebrospinal fluid (CSF) to pass out of the back of the skull and down around the spinal cord. Instead of flowing gently as CSF should do normally, it seems as if the lack of space affects CSF flow in similar fashion to putting ones finger over the end of a hose and so CSF tends to jet out. This jet-effect damages delicate nervous tissue and forms cavities within the spinal cord that are the hallmark of syringohydromyelia. This condition was first described in Cavalier King Charles spaniels but has since been reported in a number of breeds. Animals are usually born with the malformation predisposing them to this condition and some develop signs within the first year of life whereas others only show signs considerably later. The main clinical sign is neck pain but some dogs show unusual behavior, scratching at the neck, weakness or disturbances of gait. Diagnosis usually depends on an MRI. Treatment usually requires surgery for the best outcome although some animals will respond to corticosteroids like Prednisone. Prognosis is often favorable; signs tend not to resolve completely with Prednisone whereas about half of all dogs treated with surgery are able to stop taking Prednisone completely.

Further Resources

ACVIM Proceedings Through VIN Require Login; For Veterinarians

]]> http://canadawestvets.com/syringohydromyelia/feed/ 0 Strokes / Brain Infarcts http://canadawestvets.com/strokes-brain-infarcts/ http://canadawestvets.com/strokes-brain-infarcts/#comments Thu, 17 Feb 2011 23:11:50 +0000 Cintia Stela http://canadawestvets.com/?p=1570 Brain infarcts, or strokes as they are more commonly known, occur in dogs as well as in people. Just like in people, strokes tends to occur in older individuals and those with risk factors such as high blood pressure, Cushing’s disease, adrenal tumors called phaeochromocytomas, kidney disease and some types of heart disease. They also occur in animals with bleeding disorders, such as immune-mediated thrombocytopenia (IMTP). Strokes are classically sudden in onset and do not usually progress for more than 24 hours before stabilizing or improving. One common site is the cerebellum and these cases are often mistaken as idiopathic geriatric vestibular syndrome. Diagnosis can be confirmed only by an MRI. There is no treatment other than giving the animals time, good nursing care and physical therapy. The prognosis depends to some extent on the part of the brain involved but is more dependent on the size of the stroke. In general dogs have a better prognosis than people after stroke, mainly because dogs can still be functional pets despite serious brain injury; most dogs that are going to recover show significant improvement within 7-10 days.

Further Resources

ACVIM Proceedings Through VIN Require Login; For Veterinarians

]]> http://canadawestvets.com/strokes-brain-infarcts/feed/ 0 Seizures http://canadawestvets.com/seizures/ http://canadawestvets.com/seizures/#comments Thu, 17 Feb 2011 21:22:21 +0000 Cintia Stela http://canadawestvets.com/?p=1565 Overview

Seizures are common in dogs and also occur occasionally in cats as well. A seizure is a neurological episode that is sudden in onset, repeatable in nature and that usually involves some disturbance in consciousness along with uncontrolled movements and unintended visceral functions such as urination. Seizures have a wide variety of causes, which can include birth defects such as hydrocephalus, metabolic defects like liver dysfunction, brain tumors, brain infections such as encephalitis, or a brain abscess, toxins such as lead and vascular disorders such as strokes and high blood pressure. Perhaps the best-known cause of seizures in dogs is idiopathic epilepsy, which is probably caused by either a genetic mutation, a microscopic brain malformation or possibly a birth injury. Epilepsy in dogs usually causes seizures to start between one and five years of age. If a dog starts to have seizures before one year of age then the cause is usually not epilepsy but rather some other disorder such as liver dysfunction. If an animal starts to have seizures after 5 years of age then it is also less likely to be due to epilepsy. After 7 years of age there is a much greater chance that the seizures are caused by another disorder such as a tumor or vascular disease. Some conditions like encephalitis can occur at any age.

Treatment of seizure disorders is dependent on first making an accurate diagnosis. For example, treatment of a liver disorder such as portosystemic shunt, or an encephalitis due to a tick-borne disease, is unlikely to be successful using phenobarbitone and will require more specific management. Diagnosis of the specific cause of a seizure disorder depends on taking a good history and then performing a good physical and neurological examination. This is followed by blood tests, which should always include assessment of liver function using a bile acids test. If these are normal then the next step is to image the brain using a CT scan or an MRI. These imaging techniques should detect structural diseases that alter the normal anatomy of the brain, such as a tumor or a stroke.   If imaging is normal or if the diagnosis is still unclear then imaging is followed by a spinal tap in order to obtain cerebrospinal fluid (CSF) for microscopic analysis. CSF analysis should detect inflammatory diseases that may have no effect on anatomy but that cause an influx of white blood cells into the brain.

Figure 8: MRIs from a dog with idiopathic epilepsy to show the amazing resolution obtained. The tongue (*) can be seen clearly in the dog’s mouth and its brain (arrowheads) is shown in exquisite detail. A: This image shows the spinal fluid that surrounds and circulates through the brain as dark in color. B: This image show the spinal fluid as white and it also display the different types of brain tissue more clearly. This difference is seen most clearly in the cerebellum, shown by the arrow.

The main anticonvulsant drugs used to treat seizures in dogs are phenobarbitone and potassium bromide. Diazepam (Valium) may be used intravenously or administered into the rectum in order to stop a dog from having multiple seizures (often called a cluster of seizures). Diazepam is not useful for long-term control as it persists in the body for less than an hour. If phenobarbitone and potassium bromide are not successful in controlling the seizures then other, more expensive anticonvulsants may be employed such as Keppra, felbamate and zonisamide.

Seizures in cats may be due to epilepsy but are more commonly caused by other disorders such as encephalitis or vascular disease. Seizures are diagnosed and treated in the same way as they are in dogs although potassium bromide can cause feline asthma and so is not usually recommended unless other therapies have been unsuccessful.

The prognosis is good for most dogs and cats with epilepsy. About 80% of animals with epilepsy can be controlled using anticonvulsants although it is unusual for the seizures to stop completely. In most the seizures usually decrease in frequency and severity so that they are much more manageable but most animals will require lifelong treatment. The prognosis for animals that have seizures caused by conditions other than epilepsy will depend on the condition itself. The most common complications with epilepsy are either poor overall seizure control or sporadic clusters of seizures that occur in otherwise well-controlled animals.

Further Resources

]]> http://canadawestvets.com/seizures/feed/ 0 Radiation Therapy http://canadawestvets.com/radiation-therapy/ http://canadawestvets.com/radiation-therapy/#comments Thu, 17 Feb 2011 21:03:35 +0000 Cintia Stela http://canadawestvets.com/?p=1559 Radiation therapy is one of the three main treatment options for various types of cancer, the other two being surgery and then chemotherapy. Radiation is offered at two centres locally, Seattle and Pullman, which are both in Washington State. Radiation works mainly by damaging the DNA of tumor cells but unfortunately it does also damage normal tissue as well. Therefore side effects can occur, particularly if the animal’s eyes, ears or nose are in the radiation field. Ideally, any owner considering radiation therapy for their pet should have a consultation with a radiation therapist. See the links below for additional information

Further Resources

]]> http://canadawestvets.com/radiation-therapy/feed/ 0 Rabies http://canadawestvets.com/rabies/ http://canadawestvets.com/rabies/#comments Thu, 17 Feb 2011 20:53:08 +0000 Cintia Stela http://canadawestvets.com/?p=1555 Overview

This is a very rare disease in British Columbia but rabies is endemic (meaning it occurs regularly) in British Columbia in bats.  It also occurred in two skunks in Vancouver’s Stanley Park in 2004. Therefore, any animal that catches a bat and any animal (or person) that is bitten by a bat or is exposed to a bat while sleeping, should seek medical attention immediately. Any animal (regardless of whether or not it has been vaccinated) that develops acute neurological disease after exposure to bats should be considered a rabies suspect until proven otherwise. Rabies causes a uniformly fatal encephalitis and this is the only type of encephalitis that can be transmitted easily from animals to people.

Further Resources

]]> http://canadawestvets.com/rabies/feed/ 0 Physical Therapy http://canadawestvets.com/physical-therapy/ http://canadawestvets.com/physical-therapy/#comments Thu, 17 Feb 2011 20:50:31 +0000 Cintia Stela http://canadawestvets.com/?p=1536 Overview

Rehabilitation after an injury or from any serious neurologic disease is enhanced considerably by the appropriate use of physical therapy techniques. For example, animals that have been paralyzed in their rear legs have to regain the strength that has been lost during their bout of paralysis and then retrain their joint position sense (called proprioception) before they can walk and balance normally. Animals that have had diseases that affect the brain also often have to learn how to balance or walk again. Physical therapy is especially important for animals that can not move themselves at all, such as to even change sides, as these animals are at great risk of complications like pneumonia. Our physical therapy service can help your pet to recover from its illness. In some cases we will recommend that you work with other centres in the lower mainland that offer hydrotherapy, such as the SPAW.

Figure 21: Dalmatian suffering from severe weakness in all four limbs caused by Wobbler syndrome. This Neoprene sling and cart made of PVC pipe supports his weight and allows him to recover the ability to walk without falling and injuring himself.

[See post to watch Flash video]

Movie 21-1: This is a video of a Dachshund that suffered a disc extrusion and is still not yet walking normally. Putting the dog in a shallow bath of warm water is a good way to provide support and allow exercise without injury. However, no matter how shallow the water, the dog must be supervised AT ALL TIMES.

Further Resources

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