Nervous System Diseases Found in Animals

List of nine major diseases of the nervous system found in animals:- 1. Concussion of Brain 2. Cerebral Apoplexy 3. Epilepsy 4. Kumri 5. Chorea 6. Sun Stroke, Heat Stroke 7. Lightening Stroke 8. Cerebral Meningitis 9. Encephalitis.

Nervous System: Disease # 1. Concussion of Brain:

It is caused by mechanical violence to cra­nium such as kicks, collisions, blows and falls. The brain matter receives a shock and is bruised or partially destroyed, and haemorrhage may oc­cur into it.

Symptoms:

Follow immediately or some­time after the injury. The animal stumbles, falls, loses consciousness, muscles are relaxed, respira­tion may be temporarily suspended, pupils are dilated, reflexes are absent, heart and pulse vary, vomiting may occur. In some cases, the animal may recover very rapidly.

In bad cases, convul­sions set in which may be followed by coma and death in a few minutes. Sometimes, the coma lasts for some time even in cases which completely recover. In some cases, the recovery may be quite complete but paralysis of a large portion of body, even hemiplegia and loss of sensation—according to the areas of brain involved—may follow.

In other cases, the animal may be subjected to epi­leptic fits etc. These symptoms may disappear if injury is temporary. Sometimes, there are wounds or fractures, there is no fever unless there are complications. When hemiplegia occurs, it affects the side opposite to that on which the head injury has been inflicted.

Treatment:

There is no effective treatment. Ensure complete rest, give soft bed and frequently turn to avoid bed sores. Head may be slightly raised, give a laxative, apply ice-packs or cold douches to head or massage to limbs. If a fracture is present which is beyond cure and in case of food animals, it is better to slaughter the animal if there is no sentimental barrier.

Nervous System: Disease # 2. Cerebral Apoplexy:

Synonym:

Cerebrovascular accident.

It is not due to injury or inflammation, not common among domestic animals but is brought about by some defects in the vessels of the brain and by increased blood pressure from work or excitement, degeneration of blood vessels, para­sitic affection, Purpura haemorrhagica, Anthrax.

Symptoms:

Just as for concussion but no injury. When haemorrhage is small, paralysis of only a local area may occur. In severe haem­orrhage, the symptoms are similar to those of concussion. When the animal survives, usually some paralysis is left.

Treatment:

Intravenous saline drip may be administered. Give stimulant with very great care. When paralysis follows as sequelae, massage the affected parts and also electric treatment.

Nervous System: Disease # 3. Epilepsy:

Synonym:

Falling sickness, chronic condi­tion in which the animal is subject to fits.

Between the fits, the animal appears quite normal and these intervals vary considerably. When the attack lasts only a short time and the convulsion is feeble, it is called an epileptic-form fit or Petit mal but when convulsions are long and pronounced, it is called Grandmal. This is seen most commonly in dogs and pigs.

Etiology:

True epilepsy is due to an in­creased excitability of cortex of brain. Sometimes, the attack may be brought on from excitement, blows, falls or fright. Common causes of epilepsy in dog and pig are forms of Reflex epilepsy, such as,

1. Distemper in dog

2. Affections of alimentary canal

3. Intestinal worms—Ascariass in dog, tape worm in dog (Irritation of nerve endings in bowel walls and toxins liberated and acting on brain are believed to be the cause of fits in these cases). Other parasites such as—Linguatula or Otodectes in dogs (by irritation).

4. Some exostoses or pressure on the brain following an accident.

5. Chronic uraemia — In a great many cases, none of these causal agents can be found to account for the fit.

Symptoms:

Come on very suddenly. Animal becomes very restless, rushes about, champs jaws, shakes head, salivates and twitches the lips. Then the respiration becomes very deep, animal sways and falls and may struggle when down. Legs become stretched out and rigid. Head is drawn back, eyeballs are staring and may roll in sockets. It may last only a few seconds or minutes, con­sciousness returns, spasms disappear and animal becomes normal but is apparently exhausted.

The slight affection may consist only of restlessness, twitching of head muscles, champing of jaws, yelping, salivating. Attacks appear at varying in­tervals. They are not usually fatal but the animal may injure himself during the attack and when the fits are severe and occur at very short inter­vals, they may cause death by exhaustion.

Treatment:

During the attack, prevent the animal from injuring himself. Remove collar, ap­ply cold water or cold sweats to head. After an attack, give sedatives. Give first a laxative or purgative and vermifuge. Change feeding. When the fits are believed to be due to some pressure on brain, operation is indicated. Luminal or Dial to be given for some time.

Nervous System: Disease # 4. Kumri:

Synonym:

Weak loins, Paraplegia, Gone in the back.

Kumri is the word used in India for a condi­tion scientifically known as Paraplegia—a muscu­lar weakness in the region of the loins amounting to bilateral paralysis (partial or complete) of the musculature of the hind limbs of the horse. It is a rather serious chronic disease of horses. It occurs in various parts of India, Sri Lanka and Malayasia and particularly common to plains of India. It has a remarkably regional distribution.

In India, it is restricted to certain states such as Tamil Nadu, Assam, West Bengal, Bihar, Orissa, Uttar Pradesh, specially districts along the borders of Bihar and Orissa. In addition to being regional, the disease is strictly seasonal in its appearances. In majority of cases, make their appearance after the mon­soon.

The imported and unacclimatised animals show a much higher incidence of attack than country or stud breds. The great majority of cases are usually seen in Australian Wehlers, who ap­pear to be more susceptible. Arabs come next in order of susceptibility. The country-bred animals are said to be relatively immune but there is no doubt that cases among them do occur.

Etiology:

Within recent years, a great amount of research work has been devoted to this disease but as yet, there is little or no definite knowledge available concerning the causation of Kumri.

The theories held at the present day may be conve­niently classified as follows:

1. The disease is due to some specific mi­cro-organisms of unknown type.

2. The disease is caused by unfavourable climatic condition such as extreme cold.

3. The disease is due to some vegetable poisons (Ryegrass poison).

4. The disease is a form of filariasis.

5. The disease is a form of Schistosomiasis. The schistosomiasis theory as suggested by Prof. Malkani explains some of the features of the dis­ease. The reasons and seasons for Kumri provide just the condition for snails which act as interme­diate host in the life history of Schistosoma.

Symptoms:

This disease is characterised in a fairly advanced stage chiefly by loss of strength in the hind limbs and irregular movements arising from defective coordination between the various groups of muscles. When the animal is standing, the hind limbs are held wide apart and the fore­legs are carried backwards to bear more than their share of the body weight.

During walking, the hind feet are lifted hesitatingly and incom­pletely from the ground, the toes being dragged and gradually worn or the heels coming first in- contact with the ground with the toe tilted at each step. At a trot, the legs swing outward in an attempt to clear the ground, while the hind quar­ters show the characteristic swinging, pointing the inability to keep the loins rigid.

This irregular movements are particularly well seen when the animal turns and if the horse is made to turn rapidly, he may come to the ground. The animal has difficulty in backing, drags the toes along and may come to ground if backed quickly.

Clinically, there is evidence of pain or suffering during the course of the disease and even in most extreme cases, there is no distress, physical or mental. On manipulation of the loins, some degree of pain or discomfort may be evinced by flinching or crouch­ing. There is no wasting of muscles, no loss of sensation, no paralysis of the bladder or the rec­tum.

Treatment:

Kumri once developed is incur­able, although improvement of gait does occur up to a certain point but no farther. This is ascribable to improve muscle tone only from improved con­ditions of environment, compulsory rest etc. Prof. Malkani in his survey of the disease concluded that the disease is due to schistomiasis.

The schis­tosomes responsible for the condition resemble somewhat the Schistosoma indicans. This sugges­tion is based on autopsy findings and results of treatment adopted in a few of these findings. Treatment of the disease with Tartar emetic (a well-known specific drug) in schistosomiasis was then adopted. The results of this treatment are encouraging according to Prof. Malkani.

The re­covery from this disease will depend upon the amount of damage done to the tissues and their ability to repair. Maclister believes that there are slight but characteristic degenerated lesions in the spinal cord in cases of Kumri.

If that be so, reso­lution will depend upon whether the nerves have been destroyed or not. The treatment now sug­gested by Prof. Malkani will be indirect, confir­matory or contradictory evidence is this connec­tion.

Definite prophylactic measures as suggested by Prof. Malkani are:

1. Inspection of the fodder and grazing ground.

2. Animals should not be allowed to graze during periods when Kumri is common.

3. Attention should also be directed to the quality of drinking water. Tanks and pools being avoided.

4. Animals exposed to danger of infection should undergo a course of treatment with Anti­mony, so that parasite will be destroyed before it has a chance to do irreparable damage to the system. Moreover, Tartar emetic does not only kill adult parasites but also destroy their eggs. It would serve as the most valuable agent for com­pletely preventing further multiplication of the parasite in the affected lesion.

Nervous System: Disease # 5. Chorea:

This disease is one in which certain muscles of the body are affected with chronic spasms as distinguished from the corresponding disease in human medicine. The twitchings persist during sleep and are purposeless. The disease is most common in dogs and has only been occasionally observed in pigs and horses, rarely cattle.

In dogs, it almost invariably follows and complicates an attack of Distemper. Sometimes, the distemper is so slight that the disease is overlooked and chorea may not develop for a period up to 3 months after an attack of distemper has passed off.

Symptoms:

Consist of chronic spasms and twitchings of various groups of muscles. Con­sciousness is not affected, the muscular twitchings are often confined to certain muscles, lips, muscles of mastication, sometimes the limbs — fore or hind, occasionally the body. Affecting the limbs, the twitchings may be so severe that the animal is unable to put the foot on ground.

Course:

Only occasionally mild cases re­cover. If the twitchings are localised, light and infrequent and the condition is good, the animal may recover. In other cases, the animal remains affected throughout life while in many other cases, the twitchings become more severe and generalized and become associated with paralysis. The spasms bring about exhaustion and wasting fol­lowed by death. Occasionally, a limb becomes ulcerated by frequent growing.

Treatment:

On same line as prevention of fits. Keep the animal quiet and comfortable. Feed well and keep the bowels open. Give sedatives to relieve twitchings.

Nervous System: Disease # 6. Sun Stroke, Heat Stroke:

This is noted in very hot weather and spe­cially when the atmosphere is moist and if ani­mals are at work. This particularly applies to heat stroke and the effects are due to overheating of the C.N.S. followed by paralysis of vasomotor and respiratory centre. Horses which do not sweat are more susceptible. It may occur also at night time. Sun stroke on the other hand results from the action of the direct rays of the sun falling upon cranium. Heat stroke may occur in animals during transport even in covered trucks or rail­way wagons.

Symptoms:

Appear specially when the ani­mal is working. There is rapidly progressive de­bility, gait becomes stumbling, animal is de­pressed and soon collapses and becomes coma­tose, or convulsions may occur. The heart beat becomes very weak and may show palpitation.

Temperature rises up to 108° F (42.4°C) in heat stroke but normal in sun stroke though some­times it may be high. Death or recovery may take place very rapidly; if even the affection is pro­longed, it may be complicated by pulmonary con­gestion or pneumonia.

Lesions:

The blood fails to clot and vessels of nervous system are engorged with blood. The liver and kidneys are degenerated, congestion of the lungs and brain is intense.

Treatment:

The chief indication is to reduce the temperature of the body by rapid cooling. Apply cold packs to the head and enemas of cold water. Jugular venisection is indicated in conges­tion of lungs. Put animal in a shade and free circulation of air is desirable. Intravenous injec­tion of 1,000 ml to 1,500 ml of 10% saline solution is indicated. Those that would not eat were given a second intravenous injection after an hour and a third two hours later. Sprinkling of cold water over the body will act upon the dilated peripheral vessels.

Nervous System: Disease # 7. Lightning Stroke:

Lightning occurs in two forms — diffuse or sheet lightning and linear lightning or fork. It shoots from cloud to earth or earth to cloud or from cloud to cloud. The light­ning follows the lines of greatest conductivity. It is more frequent in summer and during rains. The lightning is more common in certain places, such as iron and stone areas.

Trees are most commonly struck and the incidents are more fre­quent in rural areas than in cities. If animals are sheltering under a tree or standing in contact with wire fencing, they are liable to be struck. Light­ning has an explosive character in passing through the body, it follows vessels, bones and nerves.

Death occurs:

(a) as a result of inhibition of nerve centres, thus bringing about respiratory arrest while the heart still continues to beat, or

(b) the heart is also inhibited with the respiratory centres.

Symptoms:

Apart from discoverable lesions, symptoms are mainly associated with damage to the nervous system and they vary in extent and degree. Frequently, the animal is killed at once. In other cases, the extent of the symptoms vary from coma or paralysis of local muscles to paresis or complete paralysis. Sometimes an animal falls to the ground, remains comatose for a varying pe­riod, then rises apparently unhurt; toxic spasms may be noted. Common sequelae are — Paralysis which may be local or general, temporary or permanent and blindness.

In investigation of cases of lightning stroke, the following sources are necessary:

(a) The evidence of appearance of lightning in the neighbourhood, such as effect on trees etc., position of the animal etc.

(b) Any evidence of the burning of the skin of the dead animal. It is stated that an irregular characteristic line of superficial singeing of the hair is nearly always present; commencing at the tip of one of the ears, it runs down the neck, often in jugular groove to one of the forelimbs and so to earth, marked in its course merely by a superficial singeing of the hairs.

There may be found a simi­lar line communicating in the region of croup, again gaining the ground by way of one of the limbs. Bloody foam may be seen at the mouth and nostrils. Sometimes bones are fractured and joints dislocated. It is advisable to exclude Anthrax and examination of blood film should be made.

Treatment:

When effect is slight, no treat­ment is required. Burns and wounds may be treated surgically. In coma, give artificial respira­tion and hypodermic injection of stimulants may be given.

Nervous System: Disease # 8. Cerebral Meningitis:

May be pachy menin­gitis or leptomeningitis. Pachy meningitis is the inflammation of the duramater—the outer cover­ing. Leptomeningitis is the inflammation of the piamater. Leptomeningitis is more common. Piamater is also very vascular. It may be accom­panied by spinal meningitis.

Etiology:

Bacteria or some forms of infec­tion. The meningitis may be primary but may often be secondary. It is noted in Strangles, T. B., Joint-ill, Distemper etc.

Infection may enter from injury, wounds of inflammatory regions of structure in the neighbourhood of cranium, catarrh of air sinuses or pharynx, inflammation of eye or middle ear and animal parasites.

Symptoms:

When the disease is diffused, there are often symptoms of excitement at first. The animal may walk over or blunder over ob­jects standing in its way, knock itself against wall. It sometimes moves in circle, may carry the head to one side, often staggers and may take up ab­normal postures. Convulsions are sometimes seen.

In place of or following increased excitability, the animal may be very dull, often staggers and is not inclined to move. Respiration may become deep and irregular. In acute cases, there is increased sensitivity and warmth over cranium. Other symptoms shown are squinting or rotary move­ment of eyeball, unequal dilatation of pupils, de­fective papillary reflex.

Spasms of various muscles of head and neck or even limbs and later paraly­sis of certain muscles or regions. In addition, there is tendency to constipation and loss of appe­tite. Temperature is only raised in acute form. Death may occur in a few days. It is always serious and very often fatal. Course is variable.

Complication which may arise include:

1. Foreign body pneumonia;

2. Pyaemia— Common sequelae—paralysis or paresis.

Morbid Anatomy:

The brain lesions vary widely. Haemorrhage and congestion of the meninges and Choroid plexus are the most con­stant changes. In purulent types, one may find suppurative areas on the cortex. Often the Cerebro spinal fluid is increased and may be tinged yel­low or red.

Diagnosis:

Depends on the increased or decreased excitability. Paralysis or spasms due to derangement of cranial nerves. Disturbances in pupil and painful condition of Cranium. The di­agnosis may be confirmed by the examination of cerebro spinal fluid (CSF).

It may can be collected from cisterna magna or the lumbo sacral space. A special spinal needle containing a stillete should be used. A lumbar puncture is preferred in an ambulatory patient and should be done under local anesthesia. In case of meningitis, cells may be present in large numbers, protein and bacteria.

Treatment:

Keep animal in a quiet dark place and protect from injury. Keep bedding soft. Give light diet as in fever. The infection is usually bacterial and parenteral treatment with antibiot­ics is necessary. The parenteral treatment with antibiotic should be determined by a drug sensi­tivity test but the prognosis is unfavourable if the animal does not respond to treatment in 3 to 5 days. Of all the antibiotics, Chloramphenicol is the drug of choice in the treatment of meningitis because of its diffusibility into the spinal fluid.

Nervous System: Disease # 9. Encephalitis:

Synonym:

Acute Encephalitis, Non-suppura­tive Encephalitis.

The disease is characterised by motor irrita­tion and paralytic symptoms.

Etiology:

It may be due to infections or intoxications. In the horse, it may develop in Influenza or contagious pneumonia.

Symptoms:

General symptoms are usually absent, such animals may eat and drink normally, and the temperature and pulse are normal. There may be tetanic spasms of the muscles of the neck and limbs and paralysis and rolling of the eye ball. Usually, paralysis is observed in one side of the body.

The differential diagnosis between men­ingitis and encephalitis is confirmed by the physi­cal condition of the animal. In meningitis, paresis or paralysis may be marked but this tends to be general in character but in encephalitis, conscious­ness is deranged and often by a one-sided paraly­sis (hemiplegia).

Treatment:

There is no treatment and prog­nosis is unfavourable.