HBIO PhD Day 2025 Abstract Book

Presence of tick-borne encephalitis virus and rustrela virus in encephalitic dogs from Sweden - Emma Thilén

Supervisory group: Cecilia Ley (HBIO), Mikael Berg (HBIO), Karolina Engdahl (KV), Sylwia Libard (Uppsala Universitet), Dennis Rubbenstroth (Friedrich-Loeffler-Institut), Kaspar Matiasek (Ludwig-Maximilians-Universität), Nils Fall (KV), Erika Karlstam (SVA)

Dogs suffering from inflammatory diseases in the central nervous system (CNS) often develop severe neurological impairment and may ultimately die. Viral infections typically cause non-suppurative inflammation of the brain (i.e. encephalitis); however, in the majority of postmortem examined cases from Sweden, no aetiological agent has been identified. Two important viruses to consider in Swedish dogs are tick-borne encephalitis virus (TBEV) and rustrela virus (RusV). TBEV is endemic in parts of Sweden and has previously been reported in one Swedish dog with histologically confirmed encephalitis. RusV has previously been associated with encephalitis in various mammal species, in Sweden and other countries, although so far not in dogs. In this ongoing study, we aimed to investigate TBEV and RusV as potential causes to non-suppurative encephalitis of undetermined aetiology in Swedish dogs.

Formalin-fixed and paraffin-embedded (FFPE) brain tissue from 79 dogs with microscopically confirmed non-suppurative encephalitis, and from 10 dogs with other or no lesions of the CNS, were screened for presence of TBEV and RusV RNA using reverse transcription quantitative polymerase chain reaction (RT-qPCR). In selected RusV positive cases, presence of RusV RNA was also investigated using in situ hybridization (ISH).

Of the encephalitic dogs, 16% (13/79) tested positive for TBEV RNA (cycle threshold values between 25.8-35.2), and 8% (6/79) tested positive for RusV RNA (cycle threshold values between 29.8-35.2). None of the samples from dogs with other or no CNS lesions showed positive results. In four selected RusV positive cases, presence of RusV RNA was confirmed using ISH.

In conclusion, preliminary results recognize TBEV as an important cause of encephalitis in Swedish dogs. This emphasizes the importance of taking precautionary measures against ticks to minimize the risk of virus transmission. The results also indicate that RusV can infect dogs, and we suggest RusV as a causative agent of canine encephalitis. Future investigations to confirm the positive RT-qPCR results for both TBEV and RusV will be performed.

A pilot study of physical activity and sleep in dogs and dog owners in a joint outdoor exercise program - Klara Smedberg

Supervisory group: E. Roman (HBIO), A. Bergh (KV), J. Söder (KV), S. Spörndly-Nees (Uppsala Universitet), J.W. Eriksson (Uppsala Universitet)

Physical activity (PA) and sleep is crucial for health and wellbeing in both dogs and humans. PA levels in humans are alarmingly low and increasing levels of canine overweight suggest a corresponding lack of PA in companion dogs. As dogs and owners often have a shared lifestyle, One Health-approaches to increase physical activity in both parties are advocated. The aim of the study was to evaluate the effects of a joint outdoor exercise program for dogs and dog owners with focus on activity levels, sleep and body measurements. Dogs with at least three days of valid data (n = 15) and owners with at least four days (n = 15) were included. Daytime was defined as 07.00–22.59 and nighttime as 23.00–06.59. PA was expressed as counts per minute (cpm) and classified as “sedentary” (dogs and owners), “light to moderate PA” (dogs), “light PA” (owners), “moderate PA” (owners) and “vigorous PA” (dogs and owners). Sleep in owners was detected with the Tudor-Locke algorithm and a ≤150 cpm cut-off was used to define sleep-like behaviour in dogs. Body condition score (BCS, scale 1–9) and body mass index (BMI) were evaluated before and after the intervention. Paired t-tests and Wilcoxon matched-pairs signed rank test were used for pre–post comparisons. High levels of sedentary behaviour were registered in both dogs and owners, however with a significant decrease of 12 minutes per day in dogs and 41 minutes in owners (P = 0.02 resp. 0.01). There were no changes in light and/or moderate PA in either dogs or owners (P > 0.05). Vigorous PA in dogs did not change and amounted to approximately 27 minutes per day. In owners, vigorous PA increased significantly (P = 0.04) from 15 to 20 minutes per day. Dogs spent approximately 90% of the nighttime period in sleep-like behaviour and owners had a sleep efficiency of approximately 90%, with no pre–post changes. Results suggest that this joint exercise program may be suitable for decreasing daytime sedentary levels in dogs and owners and increasing vigorous PA in owners. Jogging with their owner was however not enough to increase PA levels in dogs. Nighttime data suggest good sleep in both species, both before and during the program. Future studies with control groups and long-term follow-ups are needed to confirm these findings, and to further explore the importance of the human-dog bond for healthy physical activity habits in both species.

Assessing owner ratings of dog pain sensitivity and their association with everyday dog behavior through questionnaires in Labrador retrievers - Felicia Palm

Supervisory group: Eva Sandberg (HBIO), Anna Bergh (KV), Eva Kosek (Uppsala Universitet), Kenth Svartberg (HBIO), Erika Roman (HBIO), Katja Höglund (HBIO), Katja Nilsson (HBIO)

The overall aim of my PhD project is to explore how the personalities of both dogs and owners impact pain and stress sensitivity and expression in three dog breeds by examining correlations between physiology and behavior. In this study we aimed to explore how different questionnaire-based measures capture owners’ perceptions of their dogs’ pain sensitivity, and whether these perceptions correlate with the owners’ assessment of the dogs’ everyday behavior. Questionnaire data was collected from 979 owners of Labrador Retrievers. The questionnaire contained several sections, including demographic questions, the Canine Behavioral Assessment and Research Questionnaire (C-BARQ), and 12 items assessing how painful owners believed different situations would be for their dog (rated from 0 to 5). Owners also rated their dog’s general pain sensitivity (GPS) on a scale from 0 to 4. C-BARQ subscale scores, as well as an average pain sensitivity score (APSS) based on owner ratings of their dog's pain in the different situations, were calculated. The pain scenario questions showed an acceptable internal consistency (Cronbach’s alpha = 0.85, average inter-item correlation = 0.31). Preliminary results using Spearman's rank-order correlations showed a significant correlation between APSS and GPS of 0.40 (p < 0.001). Both the APSS and GPS were also correlated with the C-BARQ subscale ‘Touch Sensitivity’ (rs = 0.21 and rs = 0.18, respectively, p < 0.001 for both). Of the other C-BARQ subscales, the APSS score was most strongly correlated with ‘Excitability’ (rs = 0.20, p < 0.001), ‘Non-Social Fear’ (rs = 0.16, p < 0.001), and ‘Dog-Directed Fear or Aggression’ (rs = 0.14, p < 0.001). No significant differences between male and female dogs in either APSS or GPS were detected using Mann-Whitney U tests. These preliminary results suggest that owners’ perceptions of their dogs’ pain sensitivity were relatively consistent across different measures in the questionnaire and correlated with some behaviors in other situations. However, the relatively low correlations with C-BARQ subscales also indicate that pain sensitivity may be somewhat independent from other dog personality factors. These correlations and their connection to other characteristics in dogs and their owners will be explored further in a larger sample.

Serglycin expression in canine mammary tumors - Sofia Tengstrand

Supervisory group: Magnus Åbrink (HBIO), Karin Vargmar (HBIO), Anna-Karin Olsson (Uppsala University), Gunnar Nilsson (Karolinska Institutet)

Serglycin is a proteoglycan expressed by a diversity of cell types in the body, but it has generated most attention as a proteoglycan of hematopoietic cells and especially mast cells. It is often classified as an intracellular proteoglycan, but it can also be secreted. In hematopoietic cells serglycin is involved in regulating the granular storage and secretion of serglycin-dependent mediators. Once secreted, some of these mediators remain associated to serglycin and can thus be protected from degradation or aided in the transportation to target sites.

Serglycin has also started to gain attention regarding its role in cancer, where overexpression of serglycin correlates with a poorer prognosis in several different human cancer types. A high serglycin expression have been connected to a more aggressive phenotype of neoplastic cells and serglycin is involved in epithelial to mesenchymal transition and metastasis, to mention a few examples. However, in a few recent studies a completely opposite picture is seen, where instead low serglycin levels correlate to a poor prognosis and that the serglycin expression decreases as cancer progresses.

The overall aim of my project is to do a functional characterization of serglycin in cancer and define serglycin-dependent mechanisms that could affect cancer progression. My presentation will focus on one part of my project, where I’ve performed a more detailed investigation of the serglycin expression and distribution in canine simple mammary tumors. In total 55 tumors (34 benign and 21 malignant) from 33 patients have been analysed using qPCR and immunohistochemistry. The results revealed that the serglycin expression was significantly downregulated in grade 3 carcinomas (the most malignant tumors) in comparison to control tissue, benign tumors and grade 1 carcinomas. Immunoreactivity for serglycin protein was found in neoplastic epithelial cells, vascular endothelium and infiltrating immune cells, whereas the tumor stroma was negative. A semi-quantitative scoring of the serglycin expression in the neoplastic cells was performed where a significantly lower mean for total score (proportion of stained cells and intensity of stain) was seen in grade 2 carcinomas. The mean was also lower in grade 3 carcinomas, but this difference was not significant. Thus, when considering qPCR and IHC results, serglycin seems to have a negative relationship with malignancy grade. Further analyses regarding the impact of serglycin from infiltrating immune cells are underway.

Mitigating the risk of African swine fever transmission from food waste to pig populations - Astrid Bornfeldt Persson

Sara Tanner – MSc student
Supervisory group: Hedvig Gröndal (HBIO), Sebastian Abrahamsson (Uppsala Universitet), Erika Chenais (SVA), Elisabeth Rajala (HBIO)

Afrikan swine fever (ASF) is a lethal and contagious viral disease which affects wild boar and domestic pigs. Having been present in Europe for a long time, ASF causes major economic losses in pig farming with negative implications for global food security. The virus can be transmitted by indirect contact if wild boar feed on contaminated food waste. Thus, our project aims to contribute to the protection of Sweden’s pig populations from ASF by identifying transmission routes and critical points in the food waste management chain where wildlife may encounter food waste. A survey was distributed to Sweden’s 290 municipalities, examining problems, practices, knowledge and risk perception related to ASF and food waste. The response rate was 59% (n=161). Among the responding municipalities, 29% (n=45) reported that they have, or previously have had, problems with wild animals such as wild boar gaining access to waste. In terms of risk factors, food waste was reloaded once or more, between pickup at households and the disposal point in most municipalities. Moreover, 27% (n=38) of the respondents considered knowledge of animal diseases among municipal personnel working with food waste to be insufficient to moderate. These results underline the importance of further examining critical points in the food waste management chain in relation to ASF transmission. In-depth analysis will assess whether factors such as waste reloading and limited knowledge are associated with weak biosecurity.

Organic pig farmers’ perceptions of leg health issues and their risk factors - Lise Pinaqui

Supervisory group: Lotta Rydhmer (HBIO), Stefan Gunnarsson (THV), Katja Nilsson (HBIO), Torun Wallgren (THV)

Ensuring good leg health is a challenge faced by organic pig farmers. Previous studies have shown that organic pigs suffer from more leg problems than conventional pigs, despite using the same breeds. This creates a paradox: while organic production can enhance animal welfare with more natural living conditions, it may negatively affect their health and affective states due to poorer leg health and potential pain. As a first step towards improving the situation – the main goal of this PhD project – this study aimed to investigate farmers’ perceptions of the current magnitude of leg health issues and their potential risk factors in the organic pig herds.

An online survey was sent to all Swedish organic pig farmers (N=49), exploring their perceptions of various leg issues on their farm (e.g. lameness) and their risk factors (e.g. feed). The survey was succeeded by individual follow-up interviews (N=12). The analysis consisted of descriptive statistics for the survey, and thematic analysis for the interviews.

Results from the survey (47% response rate) showed that most of the respondents, regardless of their production type, classified the issues as “almost never” occurring. The most frequent issues seemed to be joint inflammation for piglets, and movement disorders (lameness and stiff movements) for finishers. Perceptions of severity of the problems varied, with joint inflammation being the most severe. However, the issues were in general perceived as more severe when affecting piglets than finishers (regardless of frequency). Views on risk factors also varied, but outdoor access, indoor environment, stocking density, and feed were seen as having the most effect on leg health. The analysis of the interviews enabled to refine individual perceptions of the most concerning issue(s) and clarify the effect of the most important risk factors to point out areas for improvement, as well as highlight the work performed by the farmers to limit the impact of the risk factors.
These results provide valuable insights into the perceived leg health situation of organic pigs in Sweden today. It is promising that the issues are in general almost never occurring, and that the interviewed farmers do not all perceive leg health as a challenge. The obtained knowledge will be used to further improve leg health and ultimately animal welfare in organic pig herds.

Infectious keratitis in horses and companion animals under Swedish conditions- Hanna Holmqvist

Supervisory group: Ingrid Hansson (HBIO, Lena Ström (KV). Katarina Nostrell (KV). Oskar Nilsson (SVA)

Infectious keratitis, i.e. inflammation and infection of the cornea, is a relatively common complication of corneal ulcers in animals, often causing severe cell infiltration and destruction of corneal tissue, corneal perforation, and loss of vision. This project aims to determine microorganisms involved in infectious keratitis in Sweden by investigating the prevalence of fungi, aerobic and anaerobic bacteria in clinical samples from horses, dogs, cats, and rabbits. Relevant pathogens will undergo antimicrobial susceptibility testing to determine their resistance patterns.
The collection of clinical samples started in June 2025, by taking cytology and bacterial swabs from patients diagnosed with corneal ulcers, with the inclusion criterion that the defect is fluorescein-positive. Animal hospitals and clinics in across various places in Sweden are participating. Each sample is cultured onto five agar plates: blood agar, lactose purple agar, fastidious anaerobic agar (FAA), hematin agar, and Sabouraud agar (SAB). Isolated bacteria are identified by MALDI-TOF. Isolates considered pathogenic are further tested for antimicrobial susceptibility by microdilution, and the minimum inhibitory concentration (MIC) is determined for relevant topical antibiotics.

Since the start of the project, 167 samples have been analysed, of which 51% (n=85) contained bacteria considered clinically relevant. To date, the most commonly identified bacteria in dog samples are Staphylococcus pseudintermedius (30%, n=15) and Streptococcus canis (33%, n=16). The predominant bacteria in the equine samples were Staphylococcus spp. (24%, n=8), Streptococcus spp. (21%, n=6), Moraxella bovoculi (14%, n=4) and Actinobacillus spp. (14%, n=4). In cat samples Staphylococcus felis (75%, n=6) was predominantly found, while in the rabbit samples, only Staphylococcus aureus was found as a pathogen.

Worm Cargo: Quantifying and Qualifying Extracellular vesicles in Parascaris larvae. - Christopher Collins

Supervisory group: Magnus Åbrink (HBIO), Eva Tydén (HBIO), Staffan Svärd (Uppsala Universitet), Susanne Nylén (Karolinska Institutet)

Parascaris is a genus of highly contagious parasitic roundworms which infect domestic horses. They consist of 2 species, Parascaris univalens and Parascaris equorum, separated only by numbers of chromosomes (one pair for the former, two for the latter) and have near universal distribution. In Sweden, Parascaris univalens is the dominant species, but for simplicities’ sake, the term Parascaris shall be used forthwith.

With such wide distribution, Parascaris infections are extremely common. Infection begins with horses ingesting eggs in contaminated food, where the eggs hatch in the small intestine. The Parascaris larvae then break through the intestinal wall and migrate first to the liver, then to the lungs, maturing for several days at each stage. Once matured, they then break through the lung-lining and are coughed and swallowed, where they moult and mature into adults within the intestinal tract. During their development, they grow from about 200μm in the larval stage to up to 50cm as adults which can lay upwards of 300,000 eggs a day. Most adult horses develop a level of immunity to the adult worms, but foals and even some yearlings can be fatally infected – typically resulting in colic.

The current treatment regime is chemotherapeutic, but resistance to our repertoire of drugs is growing rapidly. New forms of treatment are required and thus is the core of my research. Immunomodulation – the ability to modify or suppress the host’s normal immune response - is commonly seen in parasites as a defence mechanism. For Parascaris, it appears that they achieve this through the expression of extracellular vesicles (EVs), a wide class of cell-cell communication molecules. The EV content of related species has been explored but there are research gaps for both equine parasites and especially for the early larval stages. Thus, I have begun working to quantify and qualify the EV content produced by Parascaris larvae with a large number of proteins and miRNA (microRNAs) so far being identified – some of which have shown immunomodulating effects in other species. Once fully quantified and qualified, the immunomodulating EVs can be targets for future vaccines or treatments.

Effect of exercise and diet on the metabolomic profile of Standardbred horses - Emma Nilsson

Supervisory group: Anna Jansson (HBIO), Erika Roman (HBIO), Jan Erik Lindberg (THV)

Horses are adapted to eat a plant- or forage-based diet with a diverse microbial flora in the hindgut that effectively ferments plant-fibre into short-chain fatty acids (SCFA). Nevertheless, feeding a high amounts of starch-rich grains is common practice for performance horses. Inclusion of starch-rich cereals have been shown to affect the metabolic profile, physiological and behavioural response in horses, both at rest and during exercise.

In this PhD project metabolomic data from plasma samples and proteomic data from muscle biopsies from six horses fed two diets (forage-only (F) vs high-starch forage-concentrate (FC) diet) in a cross-over design will be analysed. Each experimental period lasted 29 days and at day 25 a standardized exercise test on a treadmill was performed where blood samples and muscle biopsies were taken before and after the test. The hypothesis is that by utilizing metabolomics and proteomics, we will find more differences between diets than previously described in the literature and that these will provide insight into effects of diet beyond energy and nutrient intake alone.

The metabolomic plasma profiles for all horses was obtained using 1H-NMR and the poster presents results from the univariate and multivariate data analyses identifying differences between diets in response to exercise. The preliminary results show several significant differences in metabolite concentrations between diets after exercise and differences in metabolites that change with exercise within diets. The Partial Least-Squares Discriminant Analysis showed clear separation between diets. We also observed a separation between the before and after exercise samples in diet FC, but this separation was not as clear in diet F. By classifying the metabolites into metabolic pathways, we found that amino acid metabolism was most affected by exercise in both diets, but with lipid metabolism more influenced in diet F and carbohydrate and energy metabolism in diet FC. These results support previous research while adding new insight into horses’ physiological adaptation to forage-only and high-starch diets, and we conclude that the diets altered the plasma metabolomic response to exercise with possible effects on performance.

Prevalence and risk of orthopedic diagnoses in Swedish Warmblood horses - Sandra Bonow

Supervisory group: Åsa Gelinder Viklund (HBIO), Susanne Eriksson (HBIO), Erling Strandberg (HBIO), Elin Hernlund (HBIO)

My PhD project is about breeding, performance, and health in the Swedish Warmblood (SWB) horse. In the first part of the project, we investigated the specialization into show jumping and dressage, and which linearly scored traits that are important for performance in these disciplines. In the second part, we investigated the prevalence and risk of orthopedic diagnoses in SWB horses, and which linearly scored traits that may influence orthopedic health.

In our recent study, insurance data for 15,619 SWB horses born between 2010 and 2020 was used. Horses were classified as jumping or dressage horses according to pedigree. The insurance data included 915 orthopedic diagnoses that were categorized into eight subgroups. The prevalence of orthopedic diagnosis in different groups of SWB horses, categorized by sex, discipline category, test status (i.e., if the horse had participated at a young horse test or not), competition status (i.e., if the horse had competed or not), was analyzed using a logistic regression with Least Squares means. Additionally, the time from birth to first orthopedic diagnosis was investigated for these groups and for three different birth cohorts (2010, 2015, and 2020) using survival analysis.

Dressage horses were at a higher risk of having orthopedic diagnoses than jumping horses (50.9% vs 43.9%, p<0.0001). Male horses were at a higher risk than females (49.7% vs 45.0%, p<0.0001), and tested horses were at a higher risk than non-tested horses (49.9% vs 44.9%, p<0.0001). No significant difference was seen between competed and non-competed horses, but the groups were predisposed to different subgroups of orthopedic diagnoses. Survival analysis showed that later cohorts were more likely to have insurance claims for orthopedic diagnoses at a younger age than earlier cohorts.
In conclusion,

Strangvac, a multicomponent vaccine registered for use in horses that protects against Streptococcus equi subspecies equi - Viktoria Langwallner

Supervisory group: Eva Tyden (HBIO), Joakim Bjerketorp (HBIO), Sara Frosth (HBIO), Angie Tegehall (HBIO), Andrew Waller (Intervacc)

Strangles is a contagious acute upper respiratory infection that is found in horses, that is caused by the bacteria Streptococcus equi subspecies equi (S. equi). This disease continues to have significant welfare and economic impacts. Strangvac is a recombinant protein vaccine against S. equi, developed by Intervacc. The vaccine is based on surface-localized bacterial adhesins and secreted proteins encoded by S. equi, which are then expressed as fusion proteins and purified in E. coli. These are subsequently employed as vaccine components, eliciting specific antibodies that potentially both block bacterial adhesion by binding to the adhesins and facilitate bacterial clearance by signalling immune cells. The antibody titer in vaccinated horses against the fusion proteins is high and long lasting. However, the titer against individual components of the fusion proteins is not well known. This study aims to characterize the antibody responses elicited by vaccine antigens over time and explore a potential immunological interaction between S. equi and Streptococcus equi subsp. zooepidemicus (S. zooepidemicus). Specifically, we hypothesize that exposure to S. zooepidemicus may exert a “booster effect” on immune responses against S. equi, due to it evolving from an ancestral strain of S. zooepidemicus, with which it shares >97% genome identity. To test this, eight antigens that are utilized in Strangvac will be produced and purified, and additionally a novel antigen will be designed for the specific detection of S. zooepidemicus. This will be followed by the development of enzyme-linked immunosorbent assays (ELISAs) to quantify antigen-specific antibody titers. This approach will provide insight into the immune mechanisms underlying vaccine protection and inform the rational design of improved vaccines. By advancing understanding of antigen-specific immune responses, this project contributes to the refinement of current vaccination strategies and the development of next-generation vaccines to improve equine health and reduce the global burden of strangles.

Non-linear games for two: novel analytical machinery for prediction of reproductive success and underlying sex-specific contributions. - Fotios Pappas

Supervisory group: Christos Palaiokostas (HBIO), Paul Vincent Debes (Hólar University), Martin Johnsson (HBIO)

Reproductive success in animals is influenced by complex biological factors contributed by both sexes, yet these influences are often masked when only aggregate outcomes are observed. To address this, a machine learning framework was explored in which male- and female-specific liabilities were estimated independently, and a joint prediction of fertilization success was subsequently produced through a probabilistic system designed to capture their combined influence. Simulated genomic data were used to represent varying levels of underlying determination (heritability), allowing sex-specific effects to be expressed separately. Under these conditions, clear and interpretable liability scores were recovered for each sex, while overall fertilization outcomes were predicted with accuracy proportional to the biological signal present in the data. These findings suggest that separate estimation of male and female reproductive liabilities may provide a practical means of identifying fertility challenges in breeding programs, reducing reliance on indirect or labour-intensive proxy traits.

Exposure to PFAS in humans. How to estimate tolerable levels in drinking water? -Emelie Lindfeldt

Supervisory group: Carolina Vogs (HBIO), Anders Glynn (HBIO), Gunnar Johanson (Karolinska Institutet), Irina Gyllenhammar (Livsmedelsverket)

PFAS is a large group of synthetic chemicals that are widespread in the environment, and levels can be found in almost all humans. PFAS exposure in humans is associated with adverse health effects such as effects on the immune system, blood lipids, and liver enzymes. Food and drinking water are important sources of human exposure, especially in contaminated areas. However, it is challenging to determine to what extent PFAS in drinking water or other specific food items contributes with to the overall human exposure. Toxicokinetic modelling can be used to link exposure from different sources to the internal dose in different populations. Understanding the relation between external levels, intake and internal serum levels is crucial in the health risk assessment and development of tolerable intakes of PFAS. Modelling PFAS levels in serum is of particular interest as it is non-invasive and reduces the need for costly and time-consuming biomonitoring.
My PhD project is about understanding the toxicokinetic processes of different PFAS (i.e., absorption, distribution, and elimination), to further develop a model that predicts serum levels in humans throughout life. The model will be validated using biomonitoring data from different population groups in Sweden and further applied to derive health-based maximum levels in drinking water and food items.
In my presentation, I will focus on a part of the PhD project aiming at developing a model to estimate the contribution of drinking water to total PFAS exposure. Serum PFAS concentrations will be predicted from drinking water exposure alone, and be compared with measured serum levels, reflecting the exposure from all sources, to determine the drinking water contribution.

Levels in serum and drinking water in different population groups in Sweden will be used as input data, together with parameters such as body weight, drinking water consumption, and exposure time. Similar work will be performed for fish, being another important exposure source, to further enable the work with health-based maximum levels. As a final outcome of my PhD, “a calculator tool” based on a simplified model will be developed. This tool will enable risk assessors to estimate exposure levels under various scenarios, such as exposure to PFAS-contaminated drinking water or fish, to support health risk assessments.

Effect-based assessment of the quality and potential presence of hazardous chemical pollutants in drinking and potable water in Mexico City - Aline Colonnello Montero

Supervisory group: Johan Lundqvist (HBIO), Geeta Mandava (HBIO)

With the increase of urbanization, the water sources used to produce drinking water are polluted with chemical mixtures. Effect-based methods (EBMs) are bioanalytical tools detecting bioactivity of chemical mixtures on different toxicological endpoints. EBMs have become increasingly important for water quality assessment and monitoring, particularly in Europe and Australia. However, there are no reports of the application of EBMs to assess the presence of potentially hazardous chemicals in water in countries such as Mexico, where although outgoing treated water meets the regulatory standards, is usually not consumed as drinking water due to perceived concerns of contamination from the distribution system, thus resorting to groundwater overexploitation to produce drinking water. The aim of this study is to use a battery of EBMs based on mammalian cells to assess the quality of drinking and tap water from Mexico City and compare the findings with bioanalytical equivalents (BEQ) from other countries, effect-based trigger (EBT) values and regulatory health guidance values for drinking water.

Our results showed that none of the samples displayed cytotoxicity, and were neither bioactive at inducing oxidative stress, genotoxicity and androgen receptor (AR) activation, which are positive indicators on the water quality. However, two tap water samples from different demarcations in Mexico City, were bioactive for aryl hydrocarbon receptor (AhR) activity (BEQ of 27 pg TCDDeq/L). AR inhibition was detected in three of the samples but only at the highest concentration (BEQ range of 106 – 141 ng OHFeq/L). Finally, estrogen receptor (ER) activity was measured in most of the samples, with the highest bioactivity detected in drinking water from a jug container (BEQ of 26 pg E2eq/L). When comparing our data with BEQ values reported from other countries, EBT values for drinking water and when possible, regulatory health guidance values, none of the bioactive samples were above EBT values and regulatory values. Moreover, our calculated BEQs were in line or below reported BEQ values for drinking water in different countries. In conclusion, the findings in this study indicate that the tested drinking and potable water sources in Mexico City surrounding states are of good quality and can be directly compared with drinking water quality standards in Uppsala Sweden.

To drink or not to drink. Evaluation of different watering strategies in cattle - Lea Managos

Supervisory group: Anna Jansson (HBIO), Sigrid Agenäs (THV), Maria Åkerlind (Växa), Per Peetz Nielsen (RISE)

Due to climate change, droughts and water scarcity may become increasingly prevalent in several parts of the world, including Sweden. Ensuring cattle's access to palatable water while reducing groundwater consumption has become more critical than ever. The PhD project aims to evaluate different watering strategies for cattle and identify alternative water resources to reduce or even eliminate the need for groundwater in the dairy and beef sectors. The project was divided into three experimental studies, focusing on both dairy and beef cattle: the effects of salt in drinking water on dairy cows (I), the effects of limited access to drinking water on dairy cows (II), and the effects of Baltic Sea water on suckler cows with calves (III). Study I included 18 high-producing dairy cows in an unbalanced Latin-square design, receiving fresh and salt (NaCl) water treatments corresponding to the salinity levels found in the Baltic Sea: CON (<1 g NaCl/Kg water), LOW (4 g NaCl/Kg water), and HIGH (8 g NaCl/Kg water). Study II included 12 high-producing dairy cows in an unbalanced crossover design, with ad libitum or restricted access to fresh water: CON (ad libitum), ONCE (access once daily for a 2-h window), TWICE (access twice daily for 2-h windows). Study III included 20 pairs of suckler cows with calves divided into BALT (access to the Baltic Sea) and CON (access to freshwater) groups. The animals were followed throughout the 4-month grazing period. In study I, no treatment effects were observed on milk yield (MY) or energy-corrected milk yield. However, water intake (WI) increased (p < 0.001) by 17.9% and 53.7% in LOW and HIGH, respectively, compared to CON. In study II, MY decreased (p < 0.001) by 3.4% and 13.1%, and WI decreased (p < 0.001) by 6.4% and 25.6% in TWICE and ONCE, respectively, compared to CON. Study III showed no treatment effect on average daily gain in calves. However, total voluntary salt block intake differed between groups: 10.5 kg in BALT and 26.75 kg in CON. The results of Studies I and III suggest potential in using Baltic Sea water as a water source for cattle without compromising the production of the animals. Study II indicates a potential to reduce WI – and thereby groundwater use – in the dairy sector; however, the milk production will be affected. These results represent an essential step towards developing more resilient and water-efficient dairy and beef production systems in Sweden.

ELISA-based evaluation of digital dermatitis (DD) status at individual and herd levels - Lex Roelofs

Supervisory group: Sara Frosth (HBIO), Anna Rossander (HBIO), Joakim Bjerketorp (HBIO), Ingrid Hansson (HBIO)

Background:

Lameness is a major welfare and economic issue in cattle. Digital Dermatitis (DD) is a contagious multi-bacterial infection of the feet and one of the main causes of lameness worldwide. Although the complete ethiology is not yet understood Treponema phagedenis plays a key role in disease development. Diagnosis is currently based on visual inspection which is very labor-intensive and early cases are often missed. We have developed an enzyme-linked immuno sorbent assay (ELISA) based on three different T. phagedenis proteins (VspA, VspB and PrrA) and evaluated its potential to diagnose DD at both the individual and herd levels.

Methods:

Serum samples were collected from three DD-infected herds (DD+ cows, n=29; DD- cows, n=29) and two DD-free herds (n=20). Bulk tank milk (BTM) samples were collected from nine DD-infected and five DD-free herds. ELISAs were performed using Medisorp plates coated with a mix of the three T. phagedenis proteins. Samples were incubated, followed by addition of an HRP-conjugated anti-bovine antibody, and measured using a plate reader at OD450.

Results:

Sensitivity and specificity from serum ELISA ranged from 76-90% and 86-96% respecitively, depending on the chosen percent positive (PP) cut-off. When comparing DD+ cows to DD- cows from DD-free herds sensitivity and specificity increased to 97% and 95% (PP > 17). For BTM samples the average corrected OD450 was 2.08 for DD-infected herds and 0.47 for DD-free herds, a 4.4-fold average increase.

Conclusion:

Our ELISA shows strong potential for diagnosing DD-status at both individual and herd levels. Although only a limited number of BTM samples have been tested, the assay is now being evaluated on a larger dataset (n=600) from Swedish dairy herds.

Inbreeding and genetic diversity in Llamas, Alpacas, and Vicuñas from Bolivia: Implications for Breeding and Conservation - Pilar Román Peña

Supervisory group: Erling Strandberg (HBIO), Anna Maria Johansson (HBIO), Volga Iñiguez, Julia Barreta (IBMB-UMSA, La Paz-Bolivia)

South American camelids are crucial for Andean communities and ecosystems due to their adaptation to harsh environments. Llamas and alpacas were domesticated from their wild relatives, the guanaco and the vicuña. Vicuñas have two subspecies, northern and southern, while llamas and alpacas differ in fibre and production goals. Given their importance in Bolivia, genomic data are needed to assess genetic diversity and population differentiation, which can be achieved using SNP arrays. We genotyped 370 individuals using the multispecies Axiom Camelids Array (~50K SNPs, Affymetrix) to analyse inbreeding (runs of homozygosity, FROH, FHOM, and FIS), genetic differentiation (FST, AMOVA, and Nei distances), and migration patterns. FIS results revealed high inbreeding in llamas and vicuñas compared to alpacas and hybrids, and pairwise FST showed a closer relationship between alpacas and hybrids, consistent with introgression. Longer ROH, high FROH, and variable inbreeding among vicuña populations reflect a history shaped by bottlenecks and subsequent recovery. This bottleneck may have occurred ~50 years ago, before the initiation of regional conservation efforts. Patterns of differentiation and migration, along with the identification of three groups based on Nei’s genetic distances, suggest that subspecies assignment may not fully correspond to genetic structure. Llamas had shorter and more numerous ROH, reflecting past inbreeding. Although their population structure was weak, the presence of differentiated southern individuals suggests local selection. Regional alpaca differentiation aligns with the central population introduced in the 1980s, where drift, selection, or adaptation may explain variation. Finally, hybrids (llama × alpaca) exhibited low inbreeding values, confirming mixed origin and heterozygosity. Llama and alpaca gene flow is confirmed by some inbred hybrids, genetic closeness between llamas and alpacas, and low alpaca–hybrid differentiation, which supports the notion that hybridization is intrinsic to their domestication. Overall, genomic patterns suggest that Andean camelid diversity is the result of domestication, adaptive introgression, demographic fluctuations, and ongoing human management. These findings underscore the importance of targeted vicuña conservation, considering taxonomic units and adaptive variation.