This is a unusual event. I've never seen before. But maybe accidentally you have injected air the animal, and as this air is not sterile, it may have led to an inflammatory response.

Did you use flexible gave tubos or needles specific for gavage? And a important thing: have you fasted the animals at least 12 h before gavage?

The main complications of oral gavage are:

- Esophagitis (inflammation of the esophagus)

- Perforation of the esophagus or trachea

- Damage to the cardiac sphincter (upper stomach sphincter)

- Insertion of needle and solution into the lungs

- Lung perforation

- Damage to the oral cavity

- Aspiration of solution into the lungs from regurgitation

- Traumatic injuries related to improper restraint

From these complications, I believe that the most severe is the insertino of needle and solution into the lungs, that kills the animals immediataly (this occurred with me some times, when I was training in the beginning of my experiments)

If you need some help with gavage, I can send to you some texts and sites that were very helpful to me, in the beginning of my experiment when I was loosing some animals in the gavage.

Best regards,

Juliana Felix.

Air should never be introduced into a rat stomach following gavage. Rats can't burp or vomit so air can be devastating. Also, pus is a sign of damage and infection so something has been put into them by gavage that has caused this. What did you administer and how often? 

This is a unusual event. I've never seen before. But maybe accidentally you have injected air the animal, and as this air is not sterile, it may have led to an inflammatory response.

Did you use flexible gave tubos or needles specific for gavage? And a important thing: have you fasted the animals at least 12 h before gavage?

The main complications of oral gavage are:

- Esophagitis (inflammation of the esophagus)

- Perforation of the esophagus or trachea

- Damage to the cardiac sphincter (upper stomach sphincter)

- Insertion of needle and solution into the lungs

- Lung perforation

- Damage to the oral cavity

- Aspiration of solution into the lungs from regurgitation

- Traumatic injuries related to improper restraint

From these complications, I believe that the most severe is the insertino of needle and solution into the lungs, that kills the animals immediataly (this occurred with me some times, when I was training in the beginning of my experiments)

If you need some help with gavage, I can send to you some texts and sites that were very helpful to me, in the beginning of my experiment when I was loosing some animals in the gavage.

Best regards,

Juliana Felix.

Thank you Dr.Lohman, my answer to your question I give them whey protein daily for one month, but the pus was inside the muscles.

I attach the picture of the stomach and the pus.

Please tell me your opinion.

• Thank you Dr.Juliana , about fasting, I did not know about it at all besides how can I do this daily before gavage. How does this affect on the gavage success?

I would be so grateful if you send me the texts and the sites you mentioned

Perforation leading to an infection is one of the more common complications if this technique is not done carefully with good technique.  I coudn't tell from the picutre the location of the pus as it was blurry, but that is likely a perforation is the cause of the infection based on the location within the muscles.  I have seen this in mice when the tip of the gavage needle is pushed too aggressively, and it often ends up causing an infection deep within the neck muscles.

Hi Nancy,

Although esophagus rupture and aspiration are the most common complications seen in oral gavage experiments, I have observed such axillary masses in a handful of mice given daily gavages. A probable reason as pointed by Danielle could be a trauma to the pharynx leading to hematoma and/or pus collection. In my experiments though, these mice thrived fine and there were no signs of local or systemic infection.