Seizures in Dogs and Cats: A Practical Emergency Approach

A dog arrives actively convulsing. A cat has repeated seizures before reaching the clinic. In both situations, the priority is not to establish the final underlying diagnosis immediately, it is to stabilize the patient, stop ongoing seizure activity, and identify immediately treatable abnormalities. 

Start with Triage, Then Stop the Seizure 

As with any emergency presentation, assess stability and vital parameters immediately. Determine whether the patient is actively having focal or generalized seizures and look for secondary effects of prolonged seizure activity. 

If the animal is actively seizuring, seizure control takes priority. Benzodiazepines are the first-line anticonvulsants, with diazepam and midazolam being the principal options. 

Ideally, these drugs are administered intravenously. However, treatment should not be unnecessarily delayed when venous access is difficult. Intranasal or per rectum administration can provide alternative routes, depending on the drug. 

Midazolam may be particularly useful when rapid alternative administration is required. It can be given intravenously, intranasally, or intramuscularly, while owners can also be trained to administer intranasal midazolam at home. Diazepam can be administered intravenously or per rectum, although the latter may not consistently reach therapeutic levels^[1],[2]. 

What If the Seizure Continues? 

If seizures recur after benzodiazepine administration, escalation of anticonvulsant therapy may be required. 

Phenobarbital is a second-line option and can be administered intravenously for loading. However, its potential to induce anesthesia means that patient vitals, oxygenation, and ventilation require close monitoring. It is contraindicated in patients with liver or respiratory disease because of the risk of sedation and respiratory depression^[2]. 

Levetiracetam provides another second-line option. A loading dose can be administered intravenously or orally, although oral administration should only be used when the patient can swallow. It may form part of a multimodal protocol alongside benzodiazepines and phenobarbital^[3],[4]. 

For refractory seizures, third-line options include ketamine, dexmedetomidine, and propofol. Propofol requires particularly intensive monitoring, with close attention to vital parameters, oxygenation, and ventilation; animals receiving it should be intubated. 

Do Not Miss a Treatable Metabolic Trigger 

Stopping the seizure is only one part of emergency management. Metabolic abnormalities can themselves produce seizure activity and need to be identified and corrected. 

Point-of-care assessment can rapidly identify abnormalities such as hypoglycemia and electrolyte disturbances. Other immediately relevant measurements may include packed cell volume, total proteins, lactate, venous blood gas parameters, and blood pressure. 

For example, hypoglycemia is identified at a blood glucose concentration below 3.3 mmol/L. Dextrose supplementation may be required, followed by repeat glucose measurement 20–30 minutes later. If glucose remains low or low-normal, a constant-rate infusion may be necessary^[5]. 

Other potentially seizure-associated abnormalities include severe uremia, hypocalcemia, hepatic encephalopathy, severe anemia, hyperthermia, and marked hypertension. Treating these abnormalities is integral to controlling seizure activity rather than simply managing the visible convulsions. 

Monitoring Does Not Stop When the Seizure Stops 

Patients presenting with seizures should remain under active observation. Keeping the patient in a visible kennel allows subtle recurrent activity or changes in mentation to be detected. Cameras can supplement direct observation, and some hospitals use bells attached to collars to alert staff to movements suggestive of seizure activity. 

For patients presenting with cluster seizures or status epilepticus, continued anticonvulsant therapy and hospitalization are recommended, with at least 24 hours of monitoring suggested to ensure seizure activity has stopped^[2]. 

Clinical Bottom Line 

Emergency seizure management requires three priorities: Stop ongoing seizure activity, identify and treat immediately reversible abnormalities, and continue close monitoring for recurrence or complications. The anticonvulsant pathway should be escalated according to response, while metabolic and systemic abnormalities are addressed concurrently rather than after seizure control.

References:

1. Probst CW, Thomas WB, Moyers TD, Martin T, Cox S. Evaluation of plasma diazepam and nordiazepam concentrations following administration of diazepam intravenously or via suppository per rectum in dogs. American journal of veterinary research. 2013 Apr 1;74(4):611-5. https://www.researchgate.net/profile/Sherry-Cox/publication/236082694
2. Munguia GG, Brooks AC, Thomovsky SA, Thomovsky EJ, Rincon A, Johnson PA. Emergency approach to acute seizures in dogs and cats. Veterinary Sciences. 2024 Jun 17;11(6):277. https://www.mdpi.com/2306-7381/11/6/277
3. Hardy BT, Patterson EE, Cloyd JM, Hardy RM, Leppik IE. Double-masked, placebo-controlled study of intravenous levetiracetam for the treatment of status epilepticus and acute repetitive seizures in dogs. Journal of veterinary internal medicine. 2012 Mar;26(2):334-40. https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/j.1939-1676.2011.00868.x
4. Cagnotti G, Odore R, Bertone I, Corona C, Dappiano E, Gardini G, Iulini B, Bellino C, D'Angelo A. Open-label clinical trial of rectally administered levetiracetam as supplemental treatment in dogs with cluster seizures. Journal of veterinary internal medicine. 2019 Jul;33(4):1714-8. https://academic.oup.com/jvim/article-pdf/33/4/1714/66656348/jvim15541.pdf
5. Idowu O, Heading K. Hypoglycemia in dogs: Causes, management, and diagnosis. The Canadian Veterinary Journal. 2018 Jun;59(6):642. https://pmc.ncbi.nlm.nih.gov/articles/PMC5949948/pdf/cvj_06_642.pdf