Meningitis, Encephalitis and Myelitis

Overview

Meningitis is an inflammation of the meninges. These form a tough, protective layer of fibrous tissue that covers the brain and spinal cord and sits just beneath the bones of the skull and vertebrae. Meningitis can occur on its own, in which case it results in pain without neurological deficits. Encephalitis is an inflammation of the brain and as such it is usually associated with neurological deficits. As this inflammation usually affects most of the brain, the resultant neurological deficits often reflect involvement of multiple areas of the brain. These deficits can be of varying severity and severe encephalitis can easily be fatal. Myelitis is an inflammation of the spinal cord. It can occur primarily on its own but it is usually combined with both meningitis and encephalitis. Causes of these three related disorders can be either infectious and non-infectious. Infectious causes can be due to viral, bacterial or … Continue reading

Magnetic Resonance Imaging (MRI)

In order to generate an image in an MRI machine, the animal is first placed in the centre of a very powerful magnetic field and then pulses of radio wave energy are directed at it. In response to these pulses of radio wave energy, each different body tissue emits a characteristic type of energy signal. A computer then uses these characteristic types of signal to produce a picture of the various tissues within the animal’s body along with their specific location. An animal must keep perfectly still during a study and so it therefore has to be anesthetized lightly.

We are fortunate to be able to use a state-of-the-art scanner at MRI Vancouver. With such a powerful magnet, potential contraindications to MRI include the presence of metal within the body, such as metal plates, gold bead implants or lead shot. Additional information on MRI is available under Neuroimaging.… Continue reading

Lumbosacral Disease

Overview

This is a general term used to describe any abnormality in the lumbosacral region. The most common cause is a straightforward disc herniation between the seventh lumbar vertebra and the sacrum (often termed L7/S1), which is the last disc in the spine. The classic clinical signs are low back pain and a reluctance to jump. Paralysis does not occur although some dogs will become a little weak on one or both rear legs. Cats also suffer occasionally from disc problems in this area. Diagnosis is best made by either a CT scan or by using an MRI. Each imaging technique has it advantages: CT is usually more readily available and less expensive and it gives better images of bone whereas MRI provides better images of soft tissues.

Figure 10-1: Cross-sectional CT scans through the lumbosacral (L7/S1) disc of two dogs with their spines in an extended position to … Continue reading

Hepatic Encephalopathy

Overview

This disorder occurs when the liver is unable to purify the blood properly. In particular, the liver serves to remove noxious substances from blood that has just passed through intestinal blood vessels. As it passes through the intestine the blood absorbs a number of potentially harmful substances along with nutrients, vitamins, and minerals. When the liver (i.e. hepatic) fails to remove these harmful substances they are liberated into the general circulation and can have a toxic effect on the brain (i.e. encephalopathy). Liver dysfunction can occur mainly as one of two types.

The first type is unique to animals and occurs where the animal is born with an abnormal blood vessel that takes blood from the intestines and delivers it directly into the general circulation without allowing it to go through the liver. This is often called a congenital shunt as the blood is shunted around the liver from … Continue reading

Head & Spinal Trauma

Overview

The most common cause of head and spinal trauma is an impact with a motor vehicle although falls, running into objects and kicks from large animals also account for a proportion of injuries. Signs are typically sudden in onset and there is usually other evidence of trauma such as abrasions or broken teeth and claws. Likewise, the animal is very likely to have suffered injuries to internal organs such as the bladder or heart after sustaining trauma severe enough to damage the skull or break the spine.

Head Trauma

Head trauma in dogs and cats is not quite as common as it is in humans, in part because animals have relatively thicker skulls that are protected by a good deal of muscle. Animals also seem much less prone than humans to subdural hematomas, which are blood clots that develop underneath the skull after trauma.

Following the emergency assessment, any … Continue reading

Fibrocartilaginous Embolism (FCE)

Overview

This condition is quite common in dogs although it is very rare in cats. It is really a type of stroke that affects the spinal cord instead of the brain. In this case the stroke is caused by small pieces of disc material that somehow get into the blood vessels supplying the spinal cord to cause a blockage. Clinical signs are therefore very sudden in onset and often cause immediate paralysis of one limb, of the rear limbs or sometimes of all four limbs. The animals may be painful initially but the pain usually resolves completely within a few hours. Diagnosis depends on ruling out other potential causes of the signs such as a fracture or disc disease. There is no treatment although physical therapy has been shown to influence recovery favorably. The completeness of the animal’s recovery depends mainly on how much of the spinal cord has … Continue reading