Geriatric Vestibular Disease

Geriatric Vestibular Disease of Dogs and Cats

Geriatric vestibular disease (GVD) is characterized by an acute onset, unilateral failure of the peripheral vestibular system. The cause remains idiopathic, but causes such as neuritis (viral or immune mediated) or atrophy have been hypothesized. A recent study (DOI: 10.1111/vru.12893) by Sungjun Won and Junghee Yoon out of South Korea identified a significant size difference in the utricle, one of the parts of the bony labyrinth in the ear, in dogs with GVD compared older dogs without GVD. Necropsy evaluation has shown a reduction in the size of the peripheral CN 8 and the affected ganglion, further supporting atrophy as a cause. And yet, it is difficult to explain the recovery that most dogs and cats experience 1-6 weeks after onset of signs.

Common Clinical Signs

Animals with GVD are middle age to older dogs and cats and demonstrate peracute onset of signs, often proceeded by vomiting with no progression after 24 hours. These dogs and cats usually have very severe vestibular signs such as head tilt, nystagmus, ataxia (if ambulatory), positional strabismus and rolling/nonambulatory vestibular ataxia. IF you are able to have the animal stand you should not find paw replacement deficits, hemiparesis or obtunded mentation. If you do, the lesion localization is central and a different set of differential diagnoses should be considered.

Differential Diagnoses for Peripheral Vestibular Disease
Not accounting for history, a general list of differential diagnoses for peripheral vestibular disease would be as follows:
Degenerative: none
Anomalous: none
Metabolic: hypothyroidism
Neoplasia/nutritional: Yes (lymphoma, nerve sheath tumor)
Infectious/Inflammatory/Idiopathic: Yes (neuritis and geriatric vestibular disease)
Trauma/Toxin: Metronidazole SHOULD be central, but it may be difficult to tell in a recumbent animal. Trauma - less common in dogs and cats.
Vascular: none.

Geriatric vestibular disease is diagnosed by exclusion at this time. Although the report referenced above does provide measurements for the utricle on MRI, it is not yet a diagnostic marker for GVD. Exclude all other causes using chest x-rays, blood work including T4, brain MRI and spinal tap if needed.

Treatment?

This is a self-resolving disease. The head tilt is commonly permanent, but all other signs of vestibular disease should resolve over several weeks. Signs begin to improve 24-48 hours after onset of signs but may take up to 1 week to show improvement. Full resolution of clinical signs should be by 6 weeks. If signs wax and wane, or progressive worsen, GVD is not the proper diagnosis. Supportive care such anti-emetics. diazepam or meclizine for anti-vertigo effects, and nutritional support such as hand feeding (only when sternal!) , may be used. IV fluids may be needed for severe or prolonged nausea.

Prognosis

Don't euthanize these pets in the first 24 hours! They look miserable...but they can recover with time and supportive care. This can be very difficult for clients to witness and, because the pets are elderly, may result in a triggered response to consider euthanasia. If you can, please hang in there for a few days even if that means hospitalization. Signs may occur multiple times over the animals' life.

Thanks for reading! This TidBit Tuesday was prompted by one of you so keep those suggestions coming! If there is something you'd like to read about, chances are that someone else is also interested too.

My hours are changing the last week of August due to school starting. As always, please let me know if you cannot find an appointment time through the online scheduler.
Have a great week!

Time for a Tongue Twister!

Signalment: 12 year old MC Mixed breed dog, 45 kg
History: 1 month history of change in bark, with a 1-2 week history of difficulty eating and drinking. The owners also identified difficulty walking in the last few days and a decrease in the dog's interaction with them.
Physical Examination: Grade II/VI left heart murmur, previously noted and not progressed. The remainder of the exam was unremarkable.

Neurologic Examination

Mentation: Mildly obtunded. The pet interacted when asked, but otherwise seemed content to stare at the floor.
Cranial nerves: Decreased to absent gag reflex, tongue atrophy (see the photo above), all remaining cranial nerves were normal.
Gait: Ambulatory mild proprioceptive ataxia in all four legs
Reflexes: Normal spinal reflexes including c. trunci and perineal.
Palpation: Non painful spinal palpation however pain elicited with cervical ventroflexion
Postural reactions: absent right thoracic and right pelvic limb paw replacement test, normal left paw replacement thoracic and pelvic.

Neuroanatomic Lesion Localization?? To do this, we need to break it down and identify all of the possible anatomic localizations each neurologic deficit could be noted. Unfortunately the table does not copy to this blog very well so please email me or join our TidBit Tuesday mailing list to get all of the details.
What I did was list all of the possible locations that the affected deficit might involve and then narrowed down the lesion localization two ways:

1. Find the common denominator. In this case, the medulla. OR

2. Find the cranial nerve(s) affected and determine if the pet also has: a) abnormal mentation, b) hemiparesis ipsilateral to the affected cranial nerve or c) paw replacement deficits ipsilateral to the affected cranial nerve. If they do, it is central. If not, it is a likely a peripheral neuropathy.

Neuroanatomic Lesion Localization: Medulla, right side.

Differential Diagnoses: Neoplasia, meningoencephalitis (infectious or inflammatory)

Case Conclusion

This dog had normal CBC, serum biochemistry, UA, chest radiographs and abdominal ultrasound. Brain MRI identified a discrete contrast enhancing extra-axial mass in the right caudal fossa affecting the right side of the medulla. This finding was most consistent with a meningioma. A spinal tap was not performed due to the proximity of the mass to the cerebellomedullary cistern. Based on the working diagnosis surgical decompression, radiation therapy or supportive care were discussed with the owners and they elected supportive care.

You may recognize this case if you have been a loyal TidBit Tuesday reader. This was repeated from February 2020 because I felt like it was a good time to review cranial nerve lesion localization with a very interesting cranial nerve deficit. Thanks for reading (again)!

I hope you have a great week!

Dysautonomia in Dogs and Cats

Dysautonomia in Dogs and Cats?

Before we dive into this topic, I wanted to report the diagnosis for the case from last week's TidBit Tuesday mailer. The cat with the C6-T2 myelopathy was diagnosed with an FCE and was managed successfully over about 2 months to an almost normal return to function.

Now, on to this week's TidBit Tuesday...

Several of us worked on an interesting case together this week that tickled my memory about a disease that we, in Wisconsin, do not see very often. I thought we could all refresh together.

Dysautonomia is (typically) caused by degeneration of the autonomic, and some somatic, nerve cell bodies throughout the spinal cord and some brainstem nuclei.
Common Clinical Signs

With this disease, you may see vomiting first, followed by dysuria (enlarged bladder that is easy to express but difficult to void by the patient). One of the hallmark signs is a loss of anal tone and THIS IS SOMATIC not autonomic. We can see a mix of lower motor neuron signs with autonomic loss in this disease! Absent PLR and elevated 3rd eyelid are common findings on physical examination. From there, you may diagnose megaesophagus and ileus on radiographs.

Diagnosis

A study by Dr. Berghaus et al in 2001 identified that dysautonomia was found more often in rural areas, with access to water or farm land. Additionally, all of the published US cases have been from Missouri/southern Illinois region.

This disease is diagnosed through pharmacological testing and elimination of other etiology. In Dr. Berghaus' study, the Schirmer tear test was below 5 mm/min in 50% (20) of dogs, between 5-10 mm/min in an 10 additional dogs. There was no response to an atropine response test in many dogs, and some response in a few cases. Finally, most dogs had a rapid response to dilute pilocarpine in the eye, but not all. All of these tests are looking at the autonomic system in different areas of the body. When a reduced response to one or more of these tests is noted, taking into account the clinical history, you may wish to consider dysautonomia as a diagnosis.

Unfortunately, there is no known treatment that will reverse clinical progression. A combined immune mediated dysautonomia, and myasthenia gravis has been reported but even these cases do not appear to respond adequately to immunosuppression. The final diagnosis is obtained on necropsy.

Although we are ending on a sour note, I hope you have enjoyed this review of dysautonomia. Please let me know if you have any questions on this case, or any other neurology case.

I love helping you, help your patients with neurologic disease!

Neurologic Cat?

Where is the Lesion?

History: Sarah is a 4 year old, indoor only FS DSH. She was obtained as a kitten and had been normal, per clients, her entire life thus far. She presented to me for acute onset (same day) weakness. No known trauma, toxin ingestion or medication exposure.

Physical examination: No abnormalities, normal TPR.

Neurologic examination:
•Mentation: BAR
•Gait: Ambulatory severe left hemiparesis with proprioceptive ataxia in all four limbs
•Cranial nerves: Normal
•Postural reactions: absent left thoracic and pelvic limbs only
•Reflexes: reduced withdrawal left thoracic limb, normal all other limbs. Cutaneous trunci absent left, normal right side.
•Palpation: Non-painful

Lesion localization? I do not see evidence of intracranial disease so automatically I localize caudal to C1. Both a front and rear leg are affect, so again, we can isolate cranial to T2. So...right away you can think left C1-C5 or C6-T2 myelopathy. Which is it? Well, the reflexes were reduced to the left thoracic limb, and the reflex arc is C6-T2, so our localization must involve C6-T2.
Up is differential diagnoses building. Here is what I came up with:
D: none, this is acute
A: None, the cat is too old for congenital disease onset signs
M: none
N: Lymphoma is possible however it is rarely acute in nature
I: Meningomyelitis (infectious or inflammatory) is possible
T: No known trauma, but cannot rule it out
V: Fibrocartilagenous embolism is highly likely due to the acute onset of signs.

Did you think of something else that I missed?
Unabashed plug for the CE August 2nd here - we will look more specifically at this case and do lesion localization in greater detail. Please consider joining us from 7-8PM. Details can be found at my website.

Diagnosis: I debated about giving this away before the talk and I have decided NOT to tell you the final diagnosis this week. I will share it on next week's TidBit Tuesday (August 3rd) so stay tuned!

Hopefully you enjoyed this case review this week. Do you have a suggestion for a TidBit Tuesday topic? If so - please send me an email. I would prefer to write about something you want to read. :)

I hope you have a great week!

How is Sleep Linked to Seizures?

I had the privilege to be involved in a prospective study regarding the effects of sleep and epilepsy. This study was published this week in the Journal of Veterinary Internal Medicine (see below for a link).

Disrupted sleep is common in human patients with epilepsy. Is the same true for dogs with epilepsy?

Dr. Starr Cameron spearheaded a study at the University of Wisconsin-Madison, and enrolled dogs with confirmed or suspected epilepsy, fit them with a FitBark(TM) the dog equivalent of a FitBit(TM) and watched their sleep patterns over 12 weeks. This study was one part of a multi-part study using the FitBark(TM) technology.

So, what is the answer?

Interestingly, a statistically significant change in sleep patterns was NOT noted. These were age and breed matched dogs, too. There was a trend toward poorer sleep for dogs receiving higher doses of bromide, but it was not noted at lower doses.

What is the relationship with sleep and seizures?

In human epileptic patients, seizures beget poor sleep and poor sleep can result in an increased frequency of seizures. This wasn't shown in our dog population, but that doesn't mean that it isn't a concern for some dogs. What do we take away from this? Keep an eye on the sleep pattern of your epileptic patients and consider sleep aids if they are restless. Oh, and stay tuned for more results looking at sleep and seizures in dogs - this is a hot area of research right now. :)
Article: https://onlinelibrary.wiley.com/share/JD24HPYCTIRKYTBVSJZA?target=10.1111/jvim.16205

I hope you have a great week! Let me know if you have an epileptic patient that needs a little extra assistance - I'd love to help!

Fibrocartilagenous Emboli

First...a Case (Details have been changed for anonymity!)

I evaluated a 3 year old MI Mixed breed dog with a history of acute onset paraparesis after chasing a ball. This dog is an athlete, and he competes at an international level. After acute onset signs, the dog was seen to gradually improve motor and coordination over about 7 days.
Neurologic Examination
Mentation: BAR
Cranial nerves: Normal
Gait: Ambulatory mild right monoparesis, remainder normal
Reflexes: normal including c. trunci and perineal
Postural reactions: absent right pelvic limb only.
Palpation: Non-painful, normal cervical ROM
Neuroanatomic lesion localization? ---> see below for the answer

Differential diagnoses: FCE, Acute non-compressive disc herniation, spinal trauma.
Due to the marked improvement, diagnostic testing such as MRI was not elected. Supportive care with physical therapy, acupuncture, and limiting jumping and other highly impactful activities was recommended. The dog continued to improve and returned to normal.

What are Fibrocartilagenous Emboli (FCE)?

As the name suggests, FCE are pieces of fibrocartilage that run amok, in this case, in the spinal cord vasculature. The material is thought to be part of the nucleus pulposus which somehow gains access to the blood supply around the spinal cord. This is very different from a typical type I disc herniation! How different, you ask? Let's compare...

—-> There is a table here but it wouldn’t copy to the website. Email me for a copy of a comparison between type I, Type II, ANNPE, AHNPE and FCE if you’re interested. (Barnes@barnesveterinaryservices.com)

Neuroanatomic Lesion Localization Answer: T3-L3, right sided.

We have had some really unusual cases this week...Keep them coming! I love working through these tough cases with you and look forward to doing so again. (The not-so-tough ones are also nice...and a nice break from the tough ones!)

Let me know how I can help you, help your patients.

Audiogenic Reflex Seizures, Anyone?

As I write this, the fireworks are blazing in my neighborhood and there is a general sense of noise in the nation. How can noise relate to seizures?

What are they?

Feline audiogenic reflex seizures (FARS) start in cats late in life (> 10 years of age) and are triggered by a sound or sounds. The seizure phenotype (appearance) has a myoclonic component, but may also have absence or generalized seizures, as well.

What causes FARS?
Any noise, but usually a high frequency sound such as clinking a spoon in a tea cup triggers the seizures. Some cats will have spontaneous seizures in addition to FARS and others will purely have FARS. If you are seeing an older cat with new onset seizures, consider having the client keep a "sound diary" for a few weeks to see if there is a correlation.

Why bother identifying this...you're going to tell me to give phenobarbital!
Au contraire mon frere! A sentinel study was published in 2017 by Lowrie, et al (https://doi.org/10.1177%2F1098612X15622806) that showed a marked improvement in cats on levetiracetam in a randomized, controlled, open-label study with phenobarbital. 100% of the cats in the levetiracetam group obtained seizure control compared to 3% in the phenobarbital group. So you're correct that I typically prefer phenobarbital for feline seizures...except for FARS!

What causes FARS?

Interestingly, the majority of cats diagnosed with FARS in the published studies have had idiopathic epilepsy with a small portion showing progressive signs suggestive of active forebrain disease (neoplasia, meningoencephalitis).

That's it for today, folks! I hope you have a safe, fun week and stay cool during this hot weather!

Seizures are GOOD thing??

Brain tumors in adult dogs are relatively common. There are two primary brain tumor types in dogs: meningioma and glioma. Glial cell tumors are further divided into 3 subtypes varying from less aggressive to more aggressive in growth with rare metastasis. These tumors typically have a shorter long-term survival compared to meningiomas and are less surgically accessible. According to a recent study, dogs receiving palliative treatment have a median survival of about 1 month, compared to dogs receiving definitive treatment. Median survival for definitive treatment was almost 3 months.

This study looked at long-term survival using the new WHO classification scheme and found several interesting findings. The one that is most clinically applicable, and interesting to our pet population, is this:

Dogs with seizures as their first sign had a longer survival, regardless of histopathologic grade, than those with other neurologic signs at onset.

What does this mean? It means that, like in humans, seizures are like a warning shot, letting the rest of us know that something isn't right in the brain and we'd better take a look! If we proceed to MRI and make that diagnosis, dogs survive longer because of early onset palliative OR definitive therapy. This is yet another reason why we really should encourage clients to pursue a definitive diagnosis (i.e. brain MRI, spinal tap) even if they wouldn't consider definitive therapy such as surgery or radiation therapy. Early, aggressive, palliative medical care may actually prolong their dog's life beyond what we might get if we waited to "see what progressed".

I hope you have a good week and look forward to working with you, and your team, soon!

The full results of this study can be found at: https://onlinelibrary.wiley.com/doi/full/10.1111/jvim.16199?campaign=wolearlyview

Hepatic Encephalopathy - UPDATE

Hepatic encephalopathy is caused by changes in hepatic metabolism that result in neuronal damage or swelling. Clinical signs can include neurological, gastrointestinal or urinary due to the abnormal metabolites or the formation of stones. As a neurologist, I see these patients when they have seizures, changes in mentation or behavior, or other neurological signs.

The preferred treatment is surgical correction with slow closing of the offending vessel. As many of us know, this doesn't always correct all clinical signs and some dogs require life-long treatment despite successful surgical closure.
Life-long medical management must provide a high quality protein source, but yet remain a low protein diet to avoid excessive amino acids.

There was an interesting article published recently (https://onlinelibrary.wiley.com/doi/full/10.1111/jvim.16135?campaign=woletoc) that outlined the changes in the different types of amino acids present in the body. There are two main types of amino acids that researchers watch: branched chain amino acids (BCAA) and aromatic amino acids (AAA). In normal animals, the ratio of BCAA to AAA is 3.0 to 4.0, whereas it is 1.5 in animals with a portosystemic shunt. The study goals were to evaluate what happened with the amino acids after shunt surgery.

Results

Interestingly, specific BCAA and AAA did not change a lot, nor were they all outside of the reference range to start. However, the ratio of BCAA to AAA did increase (improve) but did not return back to the normal range. Clinical improvement was noted in most of the dogs, however!

What does this mean? It means that functional recovery occurs faster than biochemical recovery and functional recovery may be more "complete". This also (probably) means that we still need to dig into the amino acids a bit more to see if there are specific amino acids to be more or less worried about.

Yes, I know, this was a very academic TidBit this week and I promised they would be clinically applicable...I'm sorry! I do try to keep it clinically relevant but every now and again I must deep dive into research with you. :)

Keep those consults coming! This has been a terrific few weeks, with interesting cases. I love working with you and your staff to help patients.

Thanks for reading and have a great week!

Update on Acute Seizure Management

"Doc, The Dog is Having A Seizure!"

No one likes to hear those words (not even neurologists). You rush into the exam room and are faced with a convulsing dog on the floor. Here is your preemptive stop and think moment (yay!):

Why do we want to stop seizures, anyway?
Prolonged seizures can result in hypertension, tachycardia, acidosis and hyperthermia with secondary neuronal cell death and hypoxia. These changes negatively affect the brain and may have systemic effects as well. The goals of acute seizure management are to stop the seizure as quickly as possible thereby limiting secondary brain and extra cranial organ damage.

Give me the "Go-To", Barnes!

Look no further than your Benzodiazepine class of drugs. Benzodiazepine drugs (Diazepam, Midazolam, Lorazepam) were introduced in the 1960s for human status epilepticus. A recent human meta-analysis identified that benzodiazepines are the “best” first line IV drugs and identified the therapeutic concentration to be between 150-300 ug/ml. To date, there have not been any veterinary studies identifying which drug is ‘best’ for acute seizure management. We’ve always used benzodiazepines so we continue to do so.

• Rectal, at home care: Home care with liquid rectal diazepam is often recommended for patients at risk for cluster seizures. Compounded suppositories are not currently recommended. Rectal midazolam and lorazepam are not! We also know that chronic phenobarbital use reduced plasma concentrations of diazepam. With this knowledge we recommend dosing rectal diazepam at 1-2 mg/kg if the patient is receiving chronic phenobarbital therapy.

• Intranasal diazepam and midazolam: Intranasal diazepam, using an atomizer, resulted in detectable levels in about 2.5 minutes which makes this drug a viable alternative for at home anticonvulsant care. Midazolam was even more rapid and had a better outcome than rectal diazepam in one study of epileptic dogs so it is currently my drug of choice for at home (or non-IV) care.

All the "cool kids" are using levetiracetam. Should I?

Well, maybe yes, maybe no. Levetiracetam is still considered a new anticonvulsant drug, however its use has been documented in veterinary medicine since 2004. It is considered a relatively safe drug, with few reported side effects. This drug is typically used as an add-on or alternative to intravenous benzodiazepine therapy for acute seizure management at doses ranging from 30-60 mg/kg IV. Adding diazepam and levetiracetam together resulted in improved seizure control in epileptic cats so this is currently my recommended way to give IV levetiracetam. (Unless diazepam is contra-indicated such as with hepatic failure.)
Rectal levetiracetam may be on the horizon according to one study in 2014. However the first sampling time was 10 minutes therefore it is unclear if this drug will be useful in acute seizure management.

Is Propofol Still Used?

Yes, but there isn't any new information. We all like shiny, new things, but propofol does have a place in acute seizure management. There are a small number of published studies addressing this use in veterinary medicine. This drug is only recommended for intravenous use. Care must be exercised when using propofol due to its respiratory suppressive effects. Occasionally, intubation may be required if apnea is encountered during bolus therapy. Propofol withdrawal may result in distal limb twitching which may be difficult to distinguish from seizure activity. Extended exposure in cats to propofol may result in Heinz body anemia therefore a CBC analysis is recommended every 24 hours during constant rate infusion of propofol with cats.

Have a topic suggestion for TidBit Tuesdays? Please reach out!

Need a consult?
Email: barnes@barnesveterinaryservices.com
Telephone: 608-597-0077
website: www.barnesveterinaryservices.com

Happy Father's Day to all of you lucky Dads! Hope you have a safe, relaxing day.

When Should You Start Anticonvulsant Drugs (and Why)?

Following the recommendations of the International Veterinary Epilepsy Task Force I suggest starting anticonvulsive drugs if a patient meets one or more of the following criteria:

• Two or more seizures within 6 months

• History of status epilepticus (one seizure longer than 5 min)

• History of cluster seizures (cluster seizures meet the definition in the first point above)

• Post ictal signs are severe (ex: aggression) or lasting longer than 24 hours.

• Seizure frequency or duration is progressing in the last 3 interictal periods. (ex: 12 months apart, then 8 months then 6 months)

Medications are selected based on the metabolic status of the patient, seizure pattern and client constraints (administration frequency, cost, bias). Phenobarbital and bromide are considered first line treatments by the IVETF and are recommended for most forms of seizures in dogs. Phenobarbital could be considered a first line drug for cats as well (Bromide is a big NO-NO for cats). The level of evidence available to make these recommendations is, at the time of writing, more complete than for the other anticonvulsant drugs. I use the following table to as a guide for starting or changing anticonvulsant drugs; hopefully you find it useful also. Remember that these are guidelines and many animals need manipulation of their seizure control life-long.

Table 1: Indications and limitations of phenobarbital, bromide, levetiracetam, zonisamide and gabapentin as first line anticonvulsant therapy.

PhenobarbitalBromideLevetiracetamZonisamideGabapentinIndication (Dog)Generalized tonic, clonic seizuresFocal or cluster seizuresReactive seizuresGeneralized seizuresInfrequent statusIndication (cat)Generalized, focalnot recommendedReactive seizures, orofacial seizuresLimited data. Consider for generalized?Very little data. Consider as last choice.limitationsAnimals with hepatic disease should not use this drug.Give with care for dogs with renal failure, or renal tubular acidosis (or with zonisamide)Chronic administration may result in honeymoon effectDo not use in cats or dogs with known sulfa hypersensitivity, or liver diseaseNone known

Whew, it's hot out here! I hope you are staying cool, safe and enjoying this blast into summer.

My summer 2021 hours have started! Please email me if you have a case to discuss, cannot find a time on the scheduler for a consult, or just like to chat about all things neurology. :)

I look forward to working with you, and your clients and staff, soon!

Tetanus and Dogs

What is tetanus?

Tetanus is caused by the Clostridium tetani bacteria which produces a neurotoxin that causes muscle contractions. This bacterium is found commonly in soil and is ubiquitous throughout the world. After the bacterium is injected into an anaerobic environment it produces the toxin. The toxin targets inter neurons in the spinal cord, inhibiting their function.

Diagnosis?

A diagnosis is made by observation of classic clinical signs such as limb rigidity, muscle retraction on the face or periocular. Detection of the C. tetani bacterium in the wounds through culture can provide a definitive diagnosis, if obtained.

Treatment?

Wound debridement followed by appropriate antibiotics (penicillin or metronidazole) will result in recovery for the majority of dogs and cats. For severe cases, respiratory assistance with a ventilator, sedation to avoid painful sustained muscle contractions and 24-hour nursing care may be needed.

Seasonality?

An interesting article came across my view recently that identified a spike in tetanus cases in the winter months (December-February) in England. This was surprising because more cases are reported in warm, humid climate than cold ones. The authors didn't provided substantial reasoning for the odd seasonality but suggested it may be related to the exposure by walking in wet muddy environments. Here is the link to the article if you'd like to read more: https://doi.org/10.1111/vec.13068

I hope you have a wonderful, productive, safe week and I look forward to working with you soon. Thanks for reading!

Isoxasoline Flea Treatment and Seizures

Recently published data (2020) suggests that adverse events (AE) - the new word for side effects - are higher than reported by the manufactures of isoxazoline flea treatments. Specifically, researchers looked at Bravecto (fluralane), Nexgard (afoxolaner) and Simparica (Sarolaner) in both the US and Europe.

What did they find?

This is a TidBit Tuesday-style abbreviated summary. For the full report see the link at the bottom. There is a lot of data in this report!

• The survey (called Project Jake Survey) had 2751 respondents. It was compared to the data requested of the FDA and the EMA (European Medicines Agency).

• Almost 69% gave Bravecto, 26% gave Nexgard and a small 5% gave Simparica.

• Overall, 66.6% of dogs had a reaction to treatment

• Of the 911 dogs getting Bravecto, 791 had an AE (86.8%)

• Of the 342 dogs getting Nexgard, 235 had an AE (68.7%)

• Of the 72 receiving Simparica, 44 had an AE (61.1%)
  

What about seizures??

Death and seizures were a focus for this report, however other side effects are certainly noted and were reported. I will focus on seizures.

FDA report: Overall, 5.34% of dogs experienced seizures

• 20% of dogs receiving Simparica

• 2.8% of dogs receiving Bravecto

• 6.9% of dogs receiving Nexgard

EMA report: Over all 30.3% of dogs experienced seizures (!!)

• 60.2% of dogs receiving Simparica

• 18.7% of dogs receiving Bravecto

• 46.69% of dogs receiving Nexgard

Project Jake Survey:

• 4.5% of dogs receiving Simparica

• 14.8% of dogs receiving Bravecto

• 12% of dogs receiving Nexgard
  
  

Why are the numbers SO MUCH higher in the EMA?

Perhaps it is related to genetics in the dog population, better reporting habits, or reporting by vets vs owners (or vice versa). That question wasn't answered in the report. The take home message for me was that Simparica is blowing things out of the park with seizures but that the other two still have a substantial group of dogs with seizures as an AE.
Critically, this report did NOT state if the dogs had ever had seizures prior to administration of the drugs. They did state that at least some of the dogs had novel seizures after administration of one of these drugs...but alas we don't know the details on this.

When do the majority of Adverse Events occur?

Within the first 24 hours. These are supposed to be insect specific GABA mediated chloride channel blockers that are distributed around the body in the first 24 hours so it isn't surprising that this is the highest spike of possible toxicity to the dog. Also, AE were reported as a small spike between 8-14 days.

So, what is the take away?

• Any of the drugs in this report (Bravecto, Simparica or Nexgard) can have seizures as a side effect. Are they a cause of seizures? I'd say probably yes, for at least some of the dogs. Perhaps they lowered the threshold in prone animals too?

• It looks like Simparica may have a higher incidence of seizures

• If a dog has a FIRST seizure (within 24 hours or at 8-14 days) after using an isoxazoline drug, discontinue use and try a different class or different drug in this class.

Link: https://onlinelibrary.wiley.com/doi/epdf/10.1002/vms3.285. Publication date 2020. This was a very interesting read and eye opening for me.

Keep those consults coming! The more we work together, the more we learn from each other.

This TidBit Tuesday grew from a recent spike in questions about flea/tick medications from some of YOU...so, thank you!

I look forward to working with you and your staff, soon!

NSAIDs vs. Prednisone...What Do I Do??

Case 1: A 4 year old Dachshund with 3 day history of back pain. On neurologic examination you find spinal pain at TL junction with reduced paw replacement in both pelvic limbs, normal reflexes and normal gait analysis. Neuroanatomic lesion localization (NALL): T3-L3 myelopathy
What would you rank for a differential diagnoses list?
I'd consider IVDH, meningomyelitis, discospondylitis and neoplasia.

Case 2: A 1.5 year old FS Cavalier King Charles spaniel. On neurologic examination you find moderate cervical spinal pain with reduced paw replacement in the left pelvic limb and marked phantom scratching at the neck when lightly stimulated.
NALL: C1-C5 myelopathy
What differential diagnoses would you consider for this case? I would suspect syringohydromyelia first, followed by less likely meningomyelitis and IVDH.

Case 3: A 2 year old MC Labrador with lumbar pain, a normal neurologic examination and fever of 102.0F.
NALL: Lumbar pain (You cannot have a NALL without neurologic deficits!)
What is your differential diagnoses list for this patient? I'd consider discospondylitis, type II disc herniation, and some non-neurologic causes such as musculoskeletal injury or joint infection. Rarely we see referred pain from prostatic disease (cysts, neoplasia, prostatitis).

We know we need anti-inflammatory medication for pain management, right? Which one?

Case 1: The risk is low for infectious disease in this patient. For confirmed IVDH, neither prednisone or an NSAID has been shown to be superiors for pain control. Without a confirmed diagnosis, we must treat for the top 1-2 differential diagnoses, right? I typically start with NSAID therapy for these patients and if they are unable to proceed with MRI/spinal tap to obtain a definitive diagnosis and clinical signs of pain persist, I switch to prednisone after an appropriate washout period. Is it wrong to start steroids? No. The side effects of GI upset, ulceration and mild immune suppression make them less desirable when treating IVDH but they are not contraindicated.

Case 2: This case has a high likelihood of Syringohydromyelia (SHM) based on the breed and clinical signs. SHM has a high amount of neuropathic pain, which can be mediated by COX-2. Therefore, NSAIDs that target COX-2 may provide some relief. That said, steroids mediate sympathetic pain, decrease substance P expression and decrease expression of lots of inflammatory mediators and may decrease CSF production to boot. Therefore, with a low infection likelihood in this pet and high likelihood of SHM, prednisone is my drug of choice over NSAIDs. If you haven't confirmed the diagnosis, however, it is worth a discussion about the possibility of worsening clinical signs and the side effects of steroids prior to starting the drug.

Case 3: This dog has a high risk of infectious disease based on breed, age and clinical signs. Therefore, in addition to taking radiographs to try to find this dog's discospondylitis (!!), I would NOT use prednisone in this patient. NSAIDs provide wonderful bone penetration and excellent periosteal block of COX-2 mediated pain and would be my drug class of choice.

Steroids, especially prednisone, are not evil and they have a time and a place in neurology. (Understatement of the year😂 ) However, they have a greater chance of adverse clinical adverse effects than NSAIDs therefore they are not needed for every patient with spinal pain. Develop a differential diagnoses list that fits your patient before deciding between NSAIDs and prednisone. Still not sure? Call/email me to discuss your case, or set up a neuro consult!

Heads up - I will be on vacation May 29-June 5th and will have limited telephone and email access. I will respond to emails as I am able but will not be as prompt as usual. Please plan to schedule consults around this window as well. Thanks for your understanding, and support of my small business. I look forward to working with you soon!

The Neurology Checklist

The Checklist

Odds are high that you have probably heard about surgical or operative checklists and, perhaps, some of you employ them in your clinic. This week I wanted to revisit this idea because a recent article reminded me of the benefit of checklist so I thought I'd share it with you!

How Does it Work?

You and your team devise a list of important things to remember for a given procedure and create a checklist. This list then hangs in your OR, or outside of a lab, or wherever it will be used. Ten years ago I read a book called The Checklist Manifesto (https://www.amazon.com/Checklist-Manifesto-How-Things-Right/dp/0312430000). One of the simplest ways to save a life is to know the name of your anesthetist and lead surgeon. Yep, that's it. Instead of bumbling around and saying "hey you...anesthesia..." you can address them by their name and shorten communication time in a crisis. Perhaps you work very closely with your staff everyday and it seems inconceivable that you wouldn't know someone's name! However for new staff members, or in large clinics, this may not be the case.

What is the evidence?

A study published in the Journal of Veterinary Surgery this month identified that surgical times were significantly shorter (p= .005) , antibiotic administration (when appropriate) was given as intended more often (p=.01), and fewer dogs had an unplanned return to the OR (p=.006) when a perioperative checklist was employed. (Reference below.) It takes less than 1 minute to run through the checklist and it may change the course of you or your patient's day!

What is the Take Home Message?

If you don't already have one, consider making a checklist for any procedure in which patient care could be compromised if something was forgotten. This doesn't need to apply ONLY to surgical situations! I make an effort to know the name of my assistant during each and every neurologic examination for this exact reason. I don't expect a crisis during a neurologic examination but everyone feels more committed to the team when we ARE a team! (And I like to be friendly, too!) I also had a checklist hanging in the neurology room when I was at UW and at VCA Aurora to remind trainees of the parts of the neurologic examination.

Neuro Checklist:
Mentation
Cranial nerves
Gait assessment
Postural reactions
Reflexes
Palpation
Ask about a seizure history.

Having this list in your work space ensures that you don't accidentally forget to perform part of the neurologic examination and yet, it isn't so overwhelming that you hesitate to read it. (A checklist MUST be short or people hate to do them!)

I hope you enjoyed this not-fully-totally-neurology-related TidBit Tuesday. Please let me know if you have any comments, questions, or requests for topics. Have a great week and keep those consults coming!

Reference: Thieman Mankin, KM, Jeffery ND, Kerwin SC. The impact of a surgical checklist on surgical outcomes in an academic institution. https://doi.org/10.1111/vsu.13629

Back Pain + Fever

The 2 year old MC Poodle with Back Pain

It is Friday afternoon, and you are about to evaluate a 2 year old Poodle with a recent onset history of reluctance to walk. Upon examination, you find back pain at TL junction and a fever or 104 F. The dog stands there, hunched, but has a normal neurologic exam (self high-five!) and normal remaining physical exam so.... now what?

When I hear this story, my first thought is of discospondylitis. (My second thought is steroid responsive meningitis-arteritis (SRMA), one of the many forms of inflammatory non-infectious meningitis. Let's talk about this another day.)

EtiologyBacterial or fungal infection of the vertebral end plates. Commonly Staphylococci, with other causes including Streptococcus, E. coli, and less commonly B. canis. B. canis is zoonotic and can cause abortion in humans so exercise caution when managing a dog with discospondylitis.

Hematogenous is the most common source, with less common direct transmission (bite wound, grass awn).

Fungal infection with aspergillus or coccidiomycosis (SW USA) most common fungal isolates. Rarely blastomycosis.

SignalmentYoung to middle aged dogs, rarely cats.
Large breed male dogs are more often affected (male: female ratio 2:1).

Clinical signsAcute pain, often with fever, anorexia and other signs of systemic illness. Signs of a myelopathy may develop if empyema occurs, or vertebral subluxation/fracture due to loss of bone integrity. <-- EEK!

Diagnostic testsSpinal radiographs may lag 3 weeks behind onset of clinical signs; however, they are an easy diagnostic test with high yield for many cases. If unrewarding and the index of suspicion is high, spinal CT and then MRI provides increasing better detection rates in early disease.
Or, you can treat the pet for suspected discospondylitis for 2-3 weeks and re-radiograph to confirm the diagnosis.

Treatment optionsAntibacterial or antifungal treatment based on blood, urine or disc cultures. If cultures are negative (approximately 30% of cases have no growth), broad spectrum bone penetrating antibiotics are recommended until radiographic resolution is obtained (maybe 9+ months). These include cephalexin, enrofloxacin and sulfa antibiotics. Pain management and exercise restriction in the early stage of disease is important.

PrognosisFavorable with appropriate treatment.

You're doing great!! I really enjoy helping you, help your patients, live their best lives with neurologic disease. Not sure what to do with a case? You can email or telephone with case questions or schedule a consult online at a time that works for you. (Vets and vet staff only, please!)

Idiopathic Facial Nerve Paralysis

Idiopathic Facial Nerve Paralysis

I thought we'd continue our theme from last week about peripheral neuropathies and talk about a neuropathy that we all (I think) see fairly regularly: Idiopathic facial nerve paralysis.

What is it?
Idiopathic facial nerve paralysis (IFNP) happens for, ahem, unknown reasons. There is some type of synaptic block that, as of now, has an unknown cause. The facial nerve is a motor nerve that starts in the medulla (brainstem), courses through the skull and bulla on it's way to the face. Other causes of facial nerve paralysis such as hypothyroidism, neoplasia, otitis media, polyps, and rarely neuritis. Remember: you must localize the lesion to the peripheral CN 7 to include IFNP on your list of differential diagnoses!

What does it look like?
The facial nerve innervates the muscles of facial expression in dogs and cats as well as providing innervation to the lacrimal eye glands. Clinical signs are typically unilateral and, result in an inability to move the eyelids (inability to blink), inability to move the lips (dogs may accidentally chew on their lips), lack of ear movement (especially noticeable in cats), and a dry, red eye with possible ocular ulceration.

Clinical Course
Signs are typically acute in nature with rapid progression to full clinical manifestation. Spontaneous resolution occurs in 3-6 weeks. Yay!

Management
Supportive care, such as eye lubricant, and ensuring lip injury is minimized by limiting chewing toys/bones, is the mainstay treatment. Antibiotics, steroids, NSAIDs and other medications do not improve the recovery time!

It's short and sweet this week. Please let me know if you have a specific topic of interest! Have a great week, and keep those consults coming.

Consults are available Monday-Saturday at various times. Check out www.barnesveterinaryservices.com (press the schedule button in the upper right corner) to schedule. Note: Only veterinarians or veterinary staff may schedule a consult.

Hypothyroidism and Neuropathies

Etiology: The peripheral nerve is the most common target in the neurologic system for hypothyroidism. What causes a peripheral neuropathy due to hypothyroidism? I'm glad you asked....

1) accumulation of mucinous deposits resulting in nerve entrapment
2) demyelination secondary to Schwann cell defect
3) vascular nerve damage secondary to hypothyroid induced dysfunction of BBB
4) disruption of axonal transport

Signalment:

• Typically older dogs, however congenital disease does (rarely) happen. NOTE: dogs are not always overweight, heat-seeking or have flaky-hair coats with peripheral neuropathy signs.
  
  

Clinical signs:

• A polyneuropathy is most common. This results in paresis without ataxia and reduced to absent peripheral spinal reflexes. Signs may be initially mild.

• Cranial nerve deficits such as facial nerve paralysis (VII), vestibular dysfunction (VIII), or laryngeal paralysis (X).

• Hypothyroidism may also cause a myopathy and/or megaesophagus.

Diagnostic tests:

• T4 is a good first step. If abnormal, a full panel is recommended.

Treatment options:

• You guessed it...supplementation!

Prognosis:

• The neuropathy is likely to improve a little or a lot, after several months with therapy if the axonal degeneration is not too severe.

• Cranial nerve deficits may persist even with appropriate treatment.

Frequency:

• Common in older dogs! (And recently seen in one cat with vestibular signs. This job always keeps me on my toes, that's for sure!)

This is Neurology Month for the WVMA. If you haven't seen already, there are 4 virtual talks available to WVMA members, and non-members, for CE credit. I do not receive any payment for promoting this but, I am one of the speakers!

Have a great week, and keep those consults coming. Consults are available Monday-Saturday at variable times so please reach out if I can help you with a case.

Large Breed Dogs and Disc Herniation

A little background...

Dogs greater than 10 kg experience type 2 disc herniation more frequently than type 1 disc herniation. (Refresher: Type 1 = acute extrusion of the center of the disc; Type 2 = bulge of outer ring of the disc into the spinal canal.) An estimated 10-30% of the time large breed dogs have type 1, depending on the study.

How is a type 1 disc herniation different for a large breed dog?

The answer is rather obvious, but glossed over frequently. They are bigger! That means nursing care is harder, surgery takes longer and is more extensive, and as a result there can be a greater expense for some of our larger dogs.

Does the prognosis change for a medium to large breed dog?

Yes. Dr. Woelfel from NCSU recently published data from a cohort of dogs > 10 kg that had both acute disc herniation and extensive spinal cord hemorrhage.

(Spinal cord hemorrhage occurs infrequently for large and small breed dogs and was shown in a few studies to have a minimal effect on prognosis as a stand alone feature. Meaning, the prognosis was still mostly based on the presence or absence of deep pain and didn't depend on spinal cord hemorrhage identified on advanced imaging.)

Okay, back to big dogs with disc herniation and spinal cord hemorrhage. The NCSU study reported a worse prognosis, and a higher complication rate, compared to overall data for small breed and chondrodystrophic dogs.

The details in summary:

• No deep pain before surgery, recovery about 38% (general population: 50%)

• Deep pain present before surgery, recovery rate about 77% (general population:90-95%)

• Complication rate was about 24% (general population: 10-15%)

Post Operative Complications Noted in the Referenced Study

• Decubital ulcers

• Pneumonia

• Self-mutilation

• Fever of unknown origin

• MDR UTI

• Sudden death

• Progressive myelomalacia

What is the take home message?

When talking with an owner of a medium to large breed dog with acute onset paraplegia, I suggest emphasizing the need for intense at-home nursing care, possible complications (along with the higher incidence) and a realistic prognosis if the dog is diagnosed with a disc herniation on advanced imaging. Remember that other differential diagnoses can cause acute onset paraplegia! Please do not interpret this paragraph as a call for euthanasia for large breed dogs with acute paraplegia. A 38% recovery rate is not zero! But a honest, open, vet-to-client discussion is the best way to achieve an informed decision for the client.

Not sure if you are interpreting the neurologic examination appropriately? Not sure if you are doing the neurologic examination properly? Please reach out! I am happy to work with you to help guide your clients in a compassionate and informed way.

Happy Easter to those that celebrated last weekend. We welcomed spring with big smiles around my house this weekend!

Reference: Woelfel, CW, Robertson, JB, Mariani, CL, Muñana, KR, Early, PJ, Olby, NJ. Outcomes and prognostic indicators in 59 paraplegic medium to large breed dogs with extensive epidural hemorrhage secondary to thoracolumbar disc extrusion. Veterinary Surgery. 2021; 50: 527– 536. https://doi.org/10.1111/vsu.13592

Important Questions to Ask When Evaluating a Seizure Patient

Do you know the most important questions to ask a client when evaluating a seizure patient?

Careful questioning of the owner is required to determine if the episodes described ARE seizures. Syncope, vestibular signs, neck pain, and movement disorders (think Scottie cramp) have episodic presentations with similarities to seizures. Nothing is fool proof, even an EEG, but here are some tips to get you going in the right direction.

Describe the event, please!

• Clinical appearance, including a description of any autonomic signs is critical. Videos can be priceless!
  

• Level of mentation can be confusing and difficult to determine (especially for those pesky night time seizures) so don't spend too much time grilling an owner on this one.

• How long do the events are lasting. This question is subject to tremendous bias, but if the owner says "all day" I start wondering about other non-seizure events.

How often have the events occurred?

Okay sorry, I need to harp on this one. My pet peeve is hearing "about once a month" as an answer! This is an easy one and something we should encourage ALL clients with seizure pets to do: Keep a calendar! Tell owners to write it down, put it in a spreadsheet, mark it on their phone, keep a list - the choices are as varied as the seizures they record! You will NEED this to be in place to help you direct treatment. The single biggest reason to change treatment is that the seizures do not meet the seizure goals for epileptic pets.

Your second goal here is to uncover information about possible cluster seizures. If the animal has 2 or more seizures in 24 hours that is defined as cluster seizures. Cluster seizures need at home cluster seizure management (another topic in a different TidBit Tuesday, I might add). Furthermore, some drugs work better for dogs with cluster seizures than those with single seizures. I personally believe that bromide is a terrific option for cluster seizures and will readily use it for patients with this type of pattern.

How long is each seizure?

This question is utilized to learn about status epilepticus. Any seizure longer than 3-5 minutes (people argue about what is the correct time) is considered status. Status warrants emergency management with injectable solutions (intranasal, intravenous, other). Untreated status can set an animal up for systemic side effects as well as increase the risk of permanent brain damage.

What does the animal do after the event is finished?

Your goal here is to evaluate the post ictal phase so that you can decide if a change in treatment is needed. Based on the rules outlined by the International Veterinary Epilepsy Task Force, severe post ictal changes (such as aggression) warrant treatment even if the other parameters for treatment haven't been met. I also use this question to determine how the owner is feeling about the event. Answers such as "he was fine" or "he paced and paced and seemed really upset" give me a window into how they feel about as much as how the dog did. Helping owners cope with seizures is also part of our job.

Are you working with a seizure patient and need some backup? Please reach out, I'd love to help. It is my job to help you care for your patients with seizures more confidently. We can do it!

Also, a super big thank you to those of you that have contributed head tremor cases to the database!! If you're not sure what I'm talking about please email me or check out last week's TidBit Tuesday mailer for more details.

Stay safe, stay healthy and keep those consults coming!