Bovine Neurological Diseases
History, clinical and laboratory differentiation of the common
Bovine Neurological Diseases:
Many conditions may give similar clinical neurological symptoms; however with a thorough central nervous system examination, each disease has certain peculiarities which may help to reach a clinical diagnosis.
You should be able to recognize the normal and abnormal reactions which may result from damage to one or more of the twelve cranial nerves.
Most diseases may exhibit ataxia, weakness, excitement, prostration, opisthotonos, coma, and convulsions, recumbence and death.
Hind limb ataxia, weakness and paralysis are typical of many bovine diseases. ****** Constant straining with or without rectal prolapse is a red flag and Rabies should be suspected.
The Most important diseases:
o Lead poisoning
o Thrombo-embolic meningoencephalitis (TEM),
o polioencephalomalacia (PEM)
o Space occupying lesions: Coenurosis, brain abscess
o Organophosphorous poisoning
o Hepatic encephalopathy
Clinical signs: In acute cases, the animals are generally found dead. Signs may
include excitability, twitching, ear flicking, aggressiveness, abnormal gait,
vocalization, convulsions, and frothing at the mouth. Their body temperature
begins to rise and their heart beats louder and faster. Death generally occurs
within one hour of the onset of symptoms.
In the nervous form, affected cattle excessively lick and chew or grind their teeth. The cattle may also walk aimlessly and appear blind and become recumbent.
General signs include fever (last 2-4 days), anorexia, depression, excessive salivation. Neurological signs include constant or sporadic walking or circling.
Head tilt opposite of the direction of circling. Dropped jaw and or facial anesthesia, drooped ear, a tendency to circle to the side with the lesion, paresis or paralysis of the tongue, the tongue may protrude from the side of the mouth.
Polioencephalomalacia (Polio) PEM
Acute onset of ataxia, tremors, blindness, opisthotonos, convulsions, and recumbency
Trombotic meningoncephalitis TME H. somni infection
Fever, depression, ataxia, and recumbency. opisthotonus, nystagmus, blindness, hyperesthesia, and convulsions may also be noted.
Infection with H. somni can result in fibrinopurulent bronchopneumonia, myocarditis and encephalitis.
Lead Poisoning Bloat, tenesmus with diarrhea or constipation, hyperesthesia, muscle twitching, rapid spastic twitching of the eyelids, ataxia and weakness. Signs progress to aggression, convulsions, blindness, wandering, head pressing, opisthotonos, bellowing, and eventual death.
Bovine progressive paralytic rabies (BPR)
Hind limb ataxia, aggressive behavior, prostration, tenesmus, yawning knuckling of the fetlocks and ascending hind leg paralysis that progress to prostration, hypoaesthesia and death.
Note: when only spinal cord disease is present (Spinal cord or paralytic form), virus and Negri bodies may not be found in the brain (only the spinal cord).
Therefore, early euthanasia is not advised.
A tendency to remain in sternal recumbence with the head turned to the flank, but skin sensation remained. Loss tongue tone and poor tongue retraction.
Note: History is very very important.
Progressive muscular rigidity. The clinical signs include initial stiffness in movement, which progresses over a 24 hours period to spasticity, mouth
foaming due to inability to swallow, “erected ears”, trismus (“lockjaw”), ventrolateral strabismus and dilated pupils in advanced cases. Eventual lateral recumbency and muscular rigidity occur and finally respiratory paralysis and death.
Affected cattle stand with an arched back and a wide-based stance. Affected cattle become anxious, apprehensive and over-reactive to sudden movements and loud noises. There is marked incoordination of the hind legs. Cows have difficulty encountering obstacles such as steps, ramps and narrow
gateways. When confined in stocks, stimulation often provokes violent kicking and bellowing.
Some neurological tests related to damage to one or more of the twelve cranial nerves.
1. The facial nerve function can be evaluated by placing a quinine sulfate solution on the dorsum of the tongue and observing the presence or absence of salivation. Normally, salivation ceases; however in listeriosis,
rabies and TEM, drooling of saliva continues.
2. Visual impairment can be easily determined by eliciting a blink as the hand is brought toward the eyes. In,. The administration of ophthalmic atropine ointment will dilate the pupil and restore sight if the cause is the pupillary closure that causes apparent blindness as in TEM.
3. A swallowing reflex can be elicited by pulling out the tongue and releasing it.
4. Limbs and head are very resistant to passive flexion. Tetanus
5. A menace response that results in rapid flashing of 3rd eyelid and retraction of the eye.