Hello VETAHEADER!

It’s that time again for our monthly newsletter. Today, let’s talk about guinea pigs and rabbits!

First, we have a 2023 paper on Abdominal ultrasound features and reference values in healthy guinea pigs (Cavia porcellus). The goal of this study was to determine the ultrasonographic features and reference values of the abdominal anatomy in guinea pigs. A complete abdominal ultrasonographic examination was performed in 20 adults and 20 juvenile guinea pigs. The thickness of the wall of the gallbladder, stomach, duodenum, caecum, colon and urinary bladder (UB) was measured. Also, the adrenal glands (AGs) (width of the cranial and caudal poles, length), kidneys (length, width, height), ovaries (length, width), testes (length, width), uterus (width) and seminal glands (width) and the thickness of the spleen and pancreas were measured. All the measurements were compared between age groups and sexes.

Here’s what they found:

Contradictory to popular belief that abdominal ultrasound is not useful in high gut fermenters (because of GI gas), the liver, gallbladder, gastrointestinal tract, pancreas, spleen, kidneys, UB, AGs and great vessels were clearly visualized in all the guinea pigs. Interestingly, while no significant statistical differences were observed between male and female guinea pigs, there were notable variations in the size of certain organs – namely, the kidneys, adrenal glands, pancreas, spleen, and reproductive organs – across different age groups. However, they found no significant differences in the wall thickness of the digestive system, gallbladder, and urinary bladder among the age groups. For all the measurements and amazing pictures of the ultrasounds, take a look at the paper, it is worth it!

Take home:

Abdominal ultrasound is possible and effective in guinea pigs. This is a great paper to keep as a guide with detailed descriptions of the modality in Guinea pigs. One thing that stuck in my mind: look for the spleen, we can actually find it!

Second, let’s talk about a 2023 paper on effects of human observer presence on pain assessment using facial expressions in rabbits. This study was very interesting because it made me think and question my ability to evaluate pain in rabbits. On this study they aimed to evaluate the effect of a human observer on the rabbit Grimace scale (RbtGS) scores for pain. They recorded 28 rabbits before and after they underwent orthopedic surgery. They examined them 24 hours before surgery (as a baseline), then 1 hour post-surgery, 3 hours after receiving pain medication, and finally, 24 hours post-surgery.

And here’s the twist – videos were assessed twice in random order by 3 different evaluators who were blind to the collection time and the presence or absence of an observer.

The findings?

Well, it turns out the pain scores increased after surgery, but decreased by the 24-hour mark. However, when an observer was present, those scores were lower than they should’ve have been (meaning they looked less painful than they actually were) and higher when they should’ve been lower (they looked painful when they were not, just because someone was watching). But hey, at least the evaluators seemed to agree with each other most of the time, so that’s something! In the end, it seems those rabbit grimace scores are a useful tool for assessing post-surgery pain, but having a human observer can skew the results a bit.

Take home:

Facial grimace scale detected postoperative pain in rabbits undergoing orthopedic surgery. However, the presence of an observer led to lower scores during periods of intense pain and higher scores when pain was minimal, suggesting that remote assessments may be more reliable.

I hope these are useful!

Let us know which one was your favorite!

As always, I will see you next month.