Dental corner: To gag or not to gag-that is the question

Many veterinary practitioners and technicians have used mouth gags in cats and dogs for years. The spring-loaded mouth gags help the veterinarian or technician hold the mouth open, allowing them to complete procedures in the oral cavity. Have you ever thought about the effects of that spring on the animal? If you have ever had dental work, you know that even holding our own mouths open for periods of time can lead to jaw tenderness and pain. The same is true in our companion animals. 

A study published in the The Veterinary Journal (2014) showed that the spring-loaded gags generate constant force that could contribute to bulging of the soft tissues between the mandible and the tympanic bulla. This force leads to the compression of the maxillary arteries as they course through the osseous structures. In cats the maxillary arteries are the main source of blood supply to the retinae and the brain. 

In this study six healthy cats were anesthetized. Comparisons where made using electroretinography (ERG) and magnetic resonance angiography (MRA). Scans were done without a gag in place, using various sized plastic mouth gags causing submaximal mouth opening and spring-loaded gags creating maximal mouth opening. No changes occurred in smaller gags. One animal had an abnormal MRA on a 42mm plastic gag. The maximal mouth opening produced altercations in the ERG waveforms consistent with circulatory compromise in one of the six cats and reductions in the signal intensity during MRA in four of the six cats. 

The reduction of the blood flow through the maxillary arteries to the retinas and brain can potentially result in temporary or permanent blindness and sometimes neurologic abnormalities. Use caution when placing a gag and minimize the duration of its use to also reduce the risk of masticatory muscle strain and injury to the temporomandibular joints. Opening the mouth wider may not be an advantage in oral surgery. As the mouth is opened wider, the tissues are stretched and become more difficult to retract to allow procedures such as dental cleanings or tooth extraction. 

So instead of reaching for that spring-loaded mouth gag, create a gentler gag by cutting the enclosed end off on a 25 gauge needle cover and place that between the maxillary and mandibular canines. 

Mary Berg BS, RVT, RLATG, VTS (dentistry) is CEO and founder of Beyond the Crown Veterinary Education in Lawrence, Kansas.