Lecture 12: brain abscess, Tetanus, Botulism, Otitis, ect

What is the prognosis for a brain abscess?

- very poor without surgical drainage and long term abx

What are the clinical signs of a brain abscess caused by?

- compression rather than the inflammation

What are brain abscess like?

- vital signs normal, slow onset

- poor prognosis without drainage

- tx with abx and drainage

- dehorning/sinusitis/inner ear infections, nasal foreign bodies are risk factors

- Trueperella pyogenes

What are pituitary abscess in cattle, is relatively rare abscess of the pituitary. How does it occur?

- often caused by trueperella pyogenes

- bacteria makes its way to the pituitary due to hematogenous spread

- rete mirabile near pituitary

What are clinical signs seen with a pituitary abscess?

- acute, but progressive rapidly over a 7-10 day period

- common neuro signs

- bradycardia

- ataxia + wide based stance

- asymmetric CN deficits

- eventually recumbency, coma and death

What can lead to brain abscesses?

- plant foreign bodies

What is tetanus?

- sporadic and progressive muscular rigidity due to a Clostridium tetani neurotoxin (Gram + rod)

What is the pathophysiology of tetaus?

- Clostridium tetani found in soil and feces

- enters during castration, parturition, tail docking

- incubation period 2wk and 1 month

- tetanospasmin binds to nerves & transported to CNS

- travels to spinal cord, crosses synaptic cleft to presynaptic inhibitory interneurons•

- inhibits release of glycine and GABA from Renshaw cell

- results in disinhibition of gamma motor neurons and hypertonia and muscular spasms

What are clinical signs of tetanus?

- initially stiff, "airplane ears", sawhorse stance, hypertonia, retracted lips, trismus ("lockjaw")

- lateral recumbency & muscular rigidity that becomes worse with auditory, ocular, or tactile stimuli

- eventual respiratory paralysis and death

What does tetanolysin do?

- promotes the spread by increasing local tissue necrosis

How do you diagnose tetanus?

- limbs + head resistant to passive flexion

- there is no reliable tests dead or alive

How can you treat tetanus?

- eliminate toxin --> removing existing + future toxin (debride)

- tetanus antitoxins: binds free tetanus toxin only

- tetanus toxoid (give at distance site from antitoxin)

- abx --> prevent against aspiration pneumonia

- muscular relaxation --> midazolam or diazepam

- TLC --> good footing + fluids + nutrition

How can you control and prevent tetanus?

vaccine - not routine in cattle, should be in sheep and goats

What is the prognosis of tetanus like?

mortality up to 80%

When might you consider rumenostomy for treatment of tetanus?

- only temporary

- for bloat, enteral feeding and watering

What are sources of rumen fluid?

- cannulated cow

- animal at slaughter

- oral collection

How do you want to enteral feed a cow?

- use rumen contents ASAP

- can be stored short term but decrease microbial viability

What is botulism?

- progressive muscular hypotonia (relaxation) start from pelvic limbs to front limbs in cattle

- has not effect on peripheral sensory nerves of CNS

- caused by Clostridium botulinum

- fatal if not treated

Where can the botulinum toxin be found? For how long?

- ID toxin in serum, GI or food

- toxin will be present in serum in 6 days

How can you diagnose botulism?

- not many

- previous mouse assay

- slow test

How can you treat botulism in cattle?

- antitoxin is effective if given early

- TLC and supportive care (bedding, nutrition, NSAIDs)

What is the incubation period of botulism like?

- 1- 7 days, but often 24-48 hours

What are the common clinical signs of botulism?

- flaccid tongue

- no blinking

- cranial nerve deficits

What is a SNARE protein, how does botulism impact it?

- aid in fusion of vesicles of neurotransmitters

- botulism toxin cleaves it and prevents fusion

What is the common cause of otitis media in cattle?

- mycoplasma bovis --> source is thought to be contaminated milk/colostrum

How do you diagnose otitis media in cattle?

- radiographs show opacification of the tympanic bulla

How do you treat otitis media in cattle?

- abx --> florfenicol or tulathromycin

- +/- myringotomy or TBO

What is lead poisoning like in cattle?

- Dz of

- clinical signs

- cause

a. diffuse cerebral dz

b causes aggression, convulsions, central blindness, wandering, head pressing, opisthotonos, odontoprisis, bellowing, and eventual death

c. often from batteries in farm animals

How do you diagnose lead poisoning in cattle?

- CBC = basophilic stippling and nucleated RBC

- history, envo, lead levels

How do you treat lead poisoning in cattle?

- Ca EDTA, D-Penicillamine,or succime treatment

- thiamine

- Mg sulfate laxative

What is the prognosis for lead poisoning?

- fair with aggressive and early Tx

How does locoweed cause neurologic effects?

- swainsonine toxin causes storage disease of the neuron by inhibiting a-mannosidase

- chronic exposure = irreversible

- acute exposure = if removed can be reversible

How can organophosphates cause neuro issues?

- inhibit the recycling of inhibitory acetylcholinesterase

- dx based on levels of acetylcholinesterase in blood

- tx often not successful --> eliminate underlying condition and limit excretion ideal

What can be a differential for rear end weakness and flaccid paralysis?

- organophosphate toxicity

What species is the poster child for salt poisoning?

- pigs

What is salt poisoning like?

- too much salt or too little water (far from water or frozen water)

- leads to aggressiveness then recumbency to coma

How do you diagnose salt poisoning?

- serum and CSF Na markedly elevated

- brain edema and cerebrocortical necrosis

How do you treat salt poisoning?

- slowly decrease sodium level so cells do not burst = challenging

- give water infrequently or calculate IV admin of slightly less osmolar fluids

What is vitamin A deficiency characterized by?

- central blindness

Vitamin A deficiency in cattle:

- cause

- leads to

- common when feeding drought raised forage like corn stalks to preg cows --> low levels of carotene

- abnormal bone development constrictus optic nerve --> central blindness (come are reversible)

- Hydrocephalus

What are the clinical signs of Vitamin A deficiency?

- reduced feed intake and growth

- rough hair coat

- blindness

- night blindness

- edema

- diarrhea

- seizures

- decreased reproductive and growth performances

A 4 month old calf got stuck in a tree. He was found recumbent and "angry". Based on this blood work what could have happened and how can you treat this?

- hypernatremia due to water deprivation due to Na being over 160 mEq/L

- slowly rehydrate --> water intake 0.5% of body weight/hour