Scandinavian Journal of Laboratory Animal Science

NON-INVASIVE SAMPLING METHODS FOR GENOTYPING: IMPROVEMENTS TOWARDS THE 4R PRINCIPLE

Fri, 27 Mar 2026 00:00:00 +0000

Genetically modified mice are usually genotyped using invasive ear or tail biopsies. In accordance with the 4R principle (Replacement, Reduction, Refinement and Responsibility) we have developed non-invasive sampling methods to prevent stress and pain for mice. DNA could be extracted from oral swabs and hair follicles using conventional PCR and real-time PCR. Signals could be detected up to 25 days after sampling, if the swabs were shipped and stored at +4°C. In a pilot study, oral swabs, hair and biopsies were compared, showing consistent genotyping results in all three sampling methods with hair being more susceptible to contamination. Oral swab and hair follicle sampling provide an alternative that can be used for large-scale routine genotyping, especially if no invasive biopsy is allowed (e.g., animals with ear tags or toe tattoos) or no second biopsy is possible.

A Pilot study on the welfare of laboratory rabbits after urethral stricture induction by electrocauterization and open urethrotomy.

Wed, 13 May 2026 00:00:00 +0000

The study assessed the welfare of rabbits after inducing urethral stricture. This is a pilot study to assess appropriate experimental model before further experiments on the treatment of urethral stricture with artificial tissue. A review of the literature revealed that electrocauterization, also known as electrocoagulation, is the most reliable method for inducing urethral stricture in rabbits. The results were compared to the simple urethral incision, otherwise known as open urethrotomy. Unfortunately, we experienced that electrocauterization is poorly tolerated by laboratory animals. Weight loss was the most important parameter, indicated the poor health of the rabbit after surgery. In addition, we monitored other parameters such as temperature, fur quality, urination, general behavior, urine and blood samples. No major difference was found between the groups in any other parameter except for weight change. 4 weeks after the operation, the weight of the rabbits in the cauterization group had decreased by 12% compared to their initial weight. Cauterization group animals started to recover at the 5th postoperative week and returned to normal weight by the end of the 12th week. It is proven that postoperative conditions of the laboratory rabbits, like stress, discomfort during urination, pain or postoperative ileus could cause their weight loss. Open urethrotomy was tolerated better, the weight of rabbits in this group did not change notably, but urethral stricture did not develop either. In summary, we can conclude that electrocauterization is a reliable method of inducing urethral stricture, but in order to improve animal welfare, more intense analgesics and anti-inflammatory drugs should be administered. We suggest using an additional pain scale to monitor the welfare of rabbits, and continuing further experiments no earlier than 6-8 weeks after the initial urethral stricture induction, when the health of the rabbits improves.

When old is not old enough: the challenges of using aging pigs in preclinical neuro studies

Mon, 07 Sep 2026 00:00:00 +0000

Many brain disorders emerge in old age, making it essential to use aged laboratory animals to obtain reliable and translatable research outcomes. While this is feasible in rodent models, such as mice and rats, due to their short lifespan, accessing aged animals poses a significant challenge in large experimental animal models like pigs. In this study, we compared volumes of whole brains and selected brain structures from young adult Göttingen minipigs (7 months-1 year; N=4) with brains from aging minipigs (4-11 years; N=4), in addition to a single old Ossabaw pig (8 years; N=1). All nine pigs were females, and the aging pigs were the oldest we had access to. Brains were removed and stored in formalin until they were structurally scanned in a preclinical magnetic resonance imaging (MRI) scanner. The total volumes of each brain were determined, in addition to the volumes of three structures, namely the hippocampus, striatum, and amygdala (the volume of the striatum decreases with age in humans, and the same may also be true for the amygdala). The mean volume of the old Göttingen minipig brains (78,770 mm³ +/- 3,331 mm³) were 19 percent larger than for the young minipig brains (65,990 mm³ +/- 1,346 mm³) (p=0.002), while the Ossabaw pig's brain was significantly larger (85 percent, 121,767 mm³) than both the young and aging Göttingen minipig brains reflecting the bigger body size of the Ossabaw pig. The average volume fractions of the structures analyzed were slightly lower for the old minipigs compared to the young, although not significant for either the hippocampus (p=0.299), striatum (p=0.149), or amygdala (p=0.406). Qualitative MRI assessment did not reveal brain atrophy or ventricle enlargement in the old pig brains. The average volume fractions in the Ossabaw pig were comparable to those observed in the Göttingen minipigs. Even the oldest pig brains in this study showed no clear MRI-based indicators of aging-related neurodegeneration. These findings, therefore, highlight the challenges of obtaining truly aged pig brains and address a real, practical challenge for future aging research using large animal models.