Journal Scan: Are dogs with head trauma more likely to experience seizures?

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What they did

In an effort to assess whether dogs with head trauma have a higher incidence of seizures than the general population, researchers evaluated the medical records of dogs presenting for head trauma at a large veterinary medical center between March 1999 and September 2009. Data were also included for dogs in which epilepsy was diagnosed during the same time period.

Head trauma was defined as having evidence of skull fractures, jaw fractures, bite wounds, or soft tissue injuries to the head. Patients with altered mentation, CT or MRI evidence of hematoma, midline shift, or edema were classified as having traumatic brain injury (TBI). TBI was further classified as mild (depressed mentation, normal pupils, normal systolic pressure, or normal mentation with CT or MRI evidence of intracranial trauma), moderate TBI (depressed mentation, anisocoria or miosis or obtunded with normal pupils, anisocoria, or miosis), or severe TBI (comatose mentation or mydriasis). Patients with depressed mentation due to cardiovascular collapse were excluded.

What they found

Researchers identified 259 dogs with head trauma over the 10-year period: 63 with head injury and TBI, 169 with head injury only, and 27 with TBI only. Initial injuries and discharge status were significantly related to injury category (P < 0.001). For example, dogs discharged from the hospital were more likely (P < 0.002) to have only a head injury rather than a TBI only. Dogs with both a head injury and TBI were more likely to have longer hospital stays. Among patients with TBI, 35.6% had mild TBI, 40% had moderate TBI, and 24.4% had severe TBI, and the severity of TBI was significantly associated with survival to discharge (P = 0.017).

The incidence rate of in-hospital seizures among the study population was 3.5% (95% confidence interval [CI], 1.6% to 6.5%). This rate was 10% among patients with TBI (95% CI, 4.7% to 18.1%). The presence of TBI was significantly associated with the development of in-hospital seizures (P < 0.001), and all dogs with in-hospital seizures had moderate or severe TBI. The epilepsy rate among the general population during the study period was 1.4%.

Among the 74 owners contacted by phone after dismissal, five reported that their dogs had seizures after being discharged. One dog had seizures within one month of dismissal, three dogs had seizures more than four years after discharge, and data was unavailable for one dog.

Take-home message

Dogs with head injury, TBI, or both may be at an increased risk for the development of seizures, especially in the immediate or early posttraumatic period. The authors note that while optimal management guidelines for these patients are lacking, "the use of diazepam for active seizure control and phenobarbital for further seizure prevention" is recommended. The researchers note that later onset of seizures may also be unrelated to previous head injury and therefore prevalence of out-of-hospital seizures may be difficult to interpret.

Friedenberg SG, Butler AL, Wei L, et al. Seizures following head trauma in dogs: 259 cases (1999-2009). J Am Vet Med Assoc 2012;241(11):1479-1483.

Link to abstract: http://avmajournals.avma.org/doi/abs/10.2460/javma.241.11.1479