Ultrasound can prove to be a really important tool for hedgehog keeping and rescue, but it’s important that the correct system is chosen, and that you have support on hand during the first few months of use. We have previously discussed the best types of ultrasound equipment for hedgehogs, with our most popular choice being the ScanX with microconvex probe. In this article, we look at what the applications of ultrasound are for hedgehog rescue centres and owners.
Ultrasound for pregnancy detection
A female hedgehog can mate with several males as to increase the chances of a successful pregnancy. Pregnancy lasts for approximately 35 days, although if weather conditions are not beneficial for a litter, a mother hedgehog can send herself into a state of hibernation, putting the developing embryos on hold and thereby extending the length of pregnancy.
The average litter size is 4-5 hoglets, and while larger litters can occur, they are sadly more likely to fail to thrive. Hoglets when born will be blind, with a birth weight of approximately 25 grams (1 ounce). Hoglets will gain weight rapidly, and by 2 weeks old their eyes will open and teeth will start to appear. They may then start to forage for food with their mother and begin eating solids at 3 weeks old, before leaving the mother at 6–8 weeks old.
There is minimal scientific literature on hedgehog pregnancy scanning but, given the short gestation period, scanning from 15 days post-mating would be in line with other animals with a similar length pregnancy.
It seems likely that hedgehogs require 2-3 oestrous cycles for their uterus to ‘restart’ after hibernation, and for pregnancy to be successful. Ruth Deanesly, in her paper published in the Philosophical Transactions of the Royal Society of London in 1934, observed:
“The numbers of large corpora lutea in hedgehogs in May and June, whose uteri show no trace of recent pregnancy, make it clear that a succession of two or three pseudo-pregnancy cycles is by no means uncommon before implantation takes place.”
Why is ultrasound invaluable for hedgehog rescue centres?
When in rescue, previous history of any hedgehog may not been known, but behavioural habits and visual changes may alert you to a suspected pregnancy. Having ultrasound available means that any hedgehog can be scanned when presented to rescue.
In cases of rescue and release, knowing a pregnancy status will provide additional information enabling a successful release, as pregnant hedgehogs will require additional nutritional support and closer observation.
Is ultrasound only useful for pregnancy?
Hedgehogs can of course be affected by a range of illnesses, some of which can be detected with ultrasound, which is ideal for examining soft tissue and organs (but not bone!). Having an ultrasound scanner on hand may assist a visiting veterinarian, who can use it to perform a more thorough examination.
Cancer on ultrasound
Cancer tends to affect hedgehogs over 3 years of age. Clinical signs may not be specific, but ultrasound can be used to detect changes within the stomach, intestinal tract, or reproductive tract – specifically, hypoechoic or hyperechoic tissue and or masses.
Pyometra on ultrasound
Reproductive diseases such as pyometra can be picked up on ultrasound. Pyometra is infection within the uterus, and fluid would appear hypoechoic. Symptoms include lethargy, inappetence or discharge from the vulva. This would require veterinary treatment as a matter of urgency – depending on the severity of the disease, treatment will range from antibiotics to surgical intervention.
Ultrasound is the imaging modality of choice for identifying stones within the urinary bladder. Due to the trauma caused by the stone, the bladder walls may also be inflamed and appear thicker. Stones on ultrasound will appear as round, hyperechoic (bright white) structures, and may have acoustic shadowing below where they are so reflective they completely block the passage of ultrasound.
In hedgehogs, the most common heart disease is dilated cardiomyopathy (DCM). DCM occurs when the chambers of the heart become enlarged, and the pumping ability of the heart begins to fail (systolic dysfunction). You will see enlargement of the chambers and systolic dysfunction with ultrasound, but a detailed scan from your veterinary surgeon will be needed to obtain measurements and obtain a diagnosis.
Many of your ultrasound studies will be short and time-limited. For this reason, it’s important to save image and video files as you go along, to be reviewed after or forwarded to other members of rescue teams or a veterinary surgeon.