New tool to aid worm control

  

A free online tool to help horse owners evaluate the risk of worm infection has been launched. 

 

This simple, user-friendly resource, titled ‘What’s Your Worm Risk?’, has been developed by Austin Davis Biologics in collaboration with equine industry.

 

Anthelmintic resistance poses a significant threat to equine health and welfare, with cases now reported in all common horse worms. Effective worm control begins with assessing a horse’s risk of infection, providing essential information for decisions regarding management, testing, and treatment.

 

The tool uses widely accepted principles of equine worm control to classify each horse's risk of infection as low, moderate, or high, based on details provided by the owner. It also accounts for the potential impact of grazing companions, where applicable.

 

Jacqui Matthews, a specialist in parasitology and director of veterinary science at Austin Davis Biologics, explains: “The tool is designed to support horse owners in assessing their horse’s risk of infection, helping them make informed decisions about testing and treatment.”

 

To reduce the risk of wormer resistance, experts recommend combining excellent pasture management—reducing worm transmission from paddocks—with regular testing to guide treatment decisions.

• Faecal worm egg count (FEC) tests provide an insight into worm egg shedding levels in manure.
• Antibody tests reveal the horse’s exposure to worm infections.

 

This approach minimizes the need for blanket wormer treatments, which are known to promote resistance and reduce the effectiveness of essential drugs.

 

The ‘What’s Your Worm Risk?’ tool has been optimised for use on smartphones, laptops, and desktop computers and is tailored specifically to UK conditions.

 

By integrating testing and evidence-based treatments into worm control plans, horse owners can protect their animals while reducing the risk of drug resistance in the equine population.

 

For more details, see: 

 

https://www.whatsyourwormrisk.com

Chicory: a natural anthelmintic?

(C) Malsa et al CC BY-NC-ND 4.0

Recent research in France suggests that chicory shows promise as a natural anthelmintic for horses.

 

Cyathostomes (small redworms) are the most common gastrointestinal parasites in horses and are now the leading cause of parasite-related equine diseases. The larval stages of these worms can damage the large intestinal wall, leading to diarrhoea, colic, and loss of condition.

 

These parasites are also important because they are the most likely to develop resistance to the anthelmintics used to control them. Consequently, there is a shift away from regular deworming to reduce the development of anthelmintic resistance. Limiting unnecessary anthelmintic use is also important due to its environmental impact, particularly on insects that feed on horse manure.

 

Chicory (Cichorium intybus), a common forage plant, has been studied for its potential anthelmintic (anti-parasitic) properties, particularly in ruminants. Research has shown that certain compounds in chicory, such as sesquiterpene lactones, may have effects against gastrointestinal parasites.

 

Joshua Malsa and colleagues investigated the effect of horses grazing pasture containing a high proportion of chicory on faecal worm egg production and larval development. The research is reported in the International Journal for Parasitology: Drugs and Drug Resistance.

 

Twenty naturally infected 2-year-old saddle horses were used in the study. All horses were born and raised on the premises where the study took place and were naturally exposed to the same parasite populations. They had not been dewormed for 264 days before the onset of the trial. The last treatment given had been moxidectin.

 

 The horses were divided into two groups, each of ten horses, and were grazed either a field of chicory or a control field of mixed pasture

 

The researchers found a significant reduction in FEC after 16 days of grazing on chicory. By the end of the study grazing on chicory had an efficacy slightly lower than that of pyrantel treatment (85.5% vs 99.3% FECR for chicory and pyrantel respectively). 

 

The chicory diet also reduced the development of eggs into third-stage larvae in faeces and affected the diversity of the cyathostomin community.

 

They conclude: “Our study demonstrated the efficacy of grazing chicory (cv. Puna II) to reduce cyathostomins egg excretion and larval development in horses. The magnitude of this effect was almost as high as expected from synthetic drugs, although we identified differential sensitivity between species.”

 

Integrating chicory into a broader parasite management plan could be beneficial, especially in reducing reliance on chemical dewormers and combating drug resistance.

 

 However, while it might complement conventional parasite control methods, it should not yet be considered a replacement for standard anthelmintics without further research.

 

 

For more details, see:

 

Joshua Malsa, Leslie Boudesocque-Delaye, Laurence Wimel, Juliette Auclair-Ronzaud, Bertrand Dumont, Núria Mach, Fabrice Reigner, Fabrice Guégnard, Angélique Chereau, Delphine Serreau, Isabelle Théry-Koné, Guillaume Sallé, Géraldine Fleurance,

Chicory (Cichorium intybus) reduces cyathostomin egg excretion and larval development in grazing horses.

International Journal for Parasitology: Drugs and Drug Resistance, (2024) Vol 24,100523

 

https://doi.org/10.1016/j.ijpddr.2024.100523

New internal parasite guidelines from AAEP

The American Association of Equine Practitioners (AAEP) has issued revised Internal Parasite Control Guidelines to help minimise the risk of parasitic disease and maintain the effectiveness of current drugs for as long as possible by delaying further development of anthelmintic resistance.

The guidelines, originally created in 2013 and last revised in 2019, account for recent advances in knowledge concerning increased anthelmintic resistance and optimisation of parasite control management practices. They also address common misconceptions and offer parasite control program recommendations for senior horses (over 15 years old), mature horses (between 5 and 15 years old), and young horses (under 5 years old).

The guidelines were reviewed and updated by the AAEP Internal Parasite Control Guidelines Task Force, chaired by Dr. Nielsen and comprised of 10 AAEP members predominantly board certified in veterinary internal medicine, veterinary parasitology and/or veterinary microbiology. 

“We have seen dramatic development in the field of equine parasite control over the past 10 years, since we first launched these guidelines, and we work hard to keep our recommendations up to date,” said Martin Nielsen, DVM, PhD, DVSc, DAVCM, DEVPC, Schlaikjer Professor of Equine Infectious Diseases at the University of Kentucky.

Important conclusions to be drawn from the revised guidelines are to:

• Perform fecal egg count reduction tests annually to ensure that you are using effective dewormers in every herd or barn.
• Recognize that no anthelmintic will eliminate all parasitic stages from a horse.
• Continue using fecal egg counts once or twice per year to stratify horses into low, medium and high shedders to reduce pasture contamination.
• Deworm all horses at a baseline rate and target selected horses more often based on fecal egg counts.
• Not use fecal egg counts to diagnose disease in horses as there is no correlation between fecal egg counts and disease-causing parasite life stages.
• Discontinue deworming all horses with fixed intervals year-round and stop blindly rotating anthelmintic classes.

View the guidelines at https://aaep.org/resource/internal-parasite-control-guidelines.

You can access the entire guidelines document by clicking the Download Resource button.

Effect of diet on strongyle infection and gut microbiome

Recent research from France suggests that the first step in controlling intestinal worm infections inanimals should be providing them with diets that maintain a healthy gut ecosystem. 

Horses’ intestines can harbour many different worms, some of which can cause severe disease. It's concerning that some of these worms are becoming resistant to deworming medications. This resistance has emerged through factors such as incorrect dosing or frequent use of the same medications.

 

It's clear that we need to adopt a more sustainable approach to managing equine  intestinal parasites.

 

To address this challenge, scientists are exploring different methods, including dietary changes. These diets might enhance the body's defences, regulate gut bacteria, or directly combat parasites. For example, certain foods containing plant compounds might hinder worm reproduction in the body.

 

A study by Noémie Laroche and colleagues, at Lab to Field, Dijon, and the University of Bourgogne Franche-Comté, investigated how diet affects strongyle infection in horses, focusing on immune-mediated, microbiota-mediated, or direct deworming mechanisms. The work is reported in PLos ONE.

 

They studied twelve adult French Trotter geldings naturally infected with strongyles. These horses were divided into two groups and fed either a high-fibre or high-starch diet, along with supplements containing polyphenol-rich pellets from dehydrated sainfoin or control pellets made from sunflower and hay.

 

The study revealed that horses on a high-starch diet had higher strongyle egg excretion compared to those on a high-fibre diet. However, adding sainfoin to the high-starch diet reduced egg excretion. What’s more, sainfoin supplementation decreased larval motility, regardless of the diet.

 

Moreover, the high-starch diet was associated with lower faecal bacterial diversity, changes in faecal microbiota structure, lower faecal pH, reduced blood acetate levels, and lower haematocrit compared to the high-fibre diet.

 

Overall, these findings suggest that dietary changes can be an alternative strategy for managing helminth infections. 

 

The study highlights the importance of considering broader ecological mechanisms in parasite management strategies. The researchers emphasize that eradicating helminth infections entirely is unrealistic and could have negative effects. 

 

They write: “… pursuing a goal of eradicating helminth infection (zero infection) is not only illusionary but also likely to produce more negative effects than benefits. Mammals have coevolved with helminths during millions of years, and in most cases, the infection does not produce severe symptoms.’

 

“We therefore suggest that a safer strategy to control helminth infection would be to improve host tolerance to the infection rather than pursuing a hopeless, environmentally toxic, strategy of drug-based eradication.”

 

For more details, see:

 

Laroche N, Grimm P, Julliand S, Sorci G (2024) 

Diet modulates strongyle infection and microbiota in the large intestine of horses. PLoS ONE 19(4): e0301920. 

https://doi.org/10.1371/journal.pone.0301920

Effect of anthelmintics on the gut microbiome

 While anthelmintic treatments are invaluable for controlling parasitic worm infections, new research shows they can also have unintended consequences on the gut microbiota. 

Michel Boisseau and colleagues conducted a study to explore how helminths, particularly cyathostomins, interact with the gut microbiota in their host animals. 

 

The research team observed naturally infected ponies to track changes in this relationship over time, both before and after treating them with pyrantel. (Pyrantel targets adult cyathostomins without affecting larval stages in the gut wall.) 

 

They also looked at how the ponies' blood gene expression responded to the anthelmintic treatment. Their work is reported in iScience.

 

The study involved 40 naturally infected Welsh pony mares, divided into four groups based on their worm burden and whether they received pyrantel treatment. 

 

Among the high shedding ponies, the researchers identified 14 species of cyathostomins, the most abundant of which was Cylicocyclus nassatus. They found that ponies with high cyathostomin egg counts had a richer and more dynamic gut microbiota. The presence of butyrate-producing Clostridia seemed to play an important role in maintaining stability within the ecosystem, while also bolstering host tolerance towards cyathostomin infections. Genes involved in B-cell activation and IgA synthesis were upregulated in high shedding ponies.

 

The administration of anthelmintic treatment induced a dramatic shift in the gut environment and microbial community dynamics, with the population being less stable. These changes were still present 7 days after treatment, and to a lesser extent after 15days. Anthelmintic treatment only had a limited effect on the host blood gene expression.

 

The researchers conclude: “These observations highlight how anthelmintic treatments alter the triangular relationship of parasite, host, and gut microbiota and open new perspectives for adding nutritional intervention to current parasite management strategies.”

 

 

For more details, see:

 

Michel Boisseau, Sophie Dhorne-Pollet, David Bars-Cortina, Élise Courtot, Delphine Serreau, Gwenolah Annonay, Jérôme Lluch, Amandine Gesbert, Fabrice Reigner, Guillaume Sallé, Núria Mach,

Species interactions, stability, and resilience of the gut microbiota - Helminth assemblage in horses,

iScience, Vol 26, 2, (2023), 106044.

 

https://doi.org/10.1016/j.isci.2023.106044

 

Careful use of anthelminitcs can help limit resistance

 Recent research suggests that employing selective treatment regimens can significantly reduce the
development of anthelmintic resistance. This is particularly relevant in the context of parasites such as the cyathostomins (small redworms), which are among the most common internal parasites of horses. These parasites have developed resistance to various deworming drugs over the years due to their widespread and indiscriminate use.

In Sweden, a country known for its controlled approach to anthelmintic use, a study was conducted to investigate the presence of resistance to ivermectin, a commonly used deworming medication. The research found no evidence of resistance to ivermectin in cyathostomes in Sweden.

 

ML resistance has been observed in cyathostomins worldwide. However, the current situation in Sweden is unclear. Routine anthelmintic treatment of horses without prior diagnostic tests is rare in Sweden, since anthelmintic drugs were restricted to being available on prescription only in 2007. What effect would this have had on the development of ML resistance in the country?

 

To assess the effectiveness of deworming treatments, two common tests are used: the faecal egg count reduction test (FECRT) and the egg reappearance period (ERP) after treatment. FECRT evaluates whether a dewormer successfully reduces the number of internal parasite eggs in the horse's faeces. Samples are taken before treatment and around 10 to 14 days after deworming, and the two egg counts are compared. A high reduction percentage indicates that the dewormer is effective, while a low reduction percentage suggests potential resistance.

 

As internal parasites develop resistance to dewormers, the egg reappearance period (ERP) shortens, meaning that eggs reappear in the faeces more quickly after treatment.

 

A study led by Ylva Hedberg Alm and her colleagues aimed to assess FECRTs and ERPs following ivermectin (IVM) treatment in Swedish horses. Sixteen equestrian establishments, each with at least six horses excreting a minimum of 150 eggs per gram of faeces (EPG) during screening, were included in the study. FECRTs and ERPs were evaluated in faecal samples before and after IVM treatment (200 µg/kg) and for eight weeks afterward.

 

The questionnaire responses revealed that 69% of establishments administered anthelmintic treatments based on faecal diagnostics. All establishments achieved a high FECRT, exceeding 99.0%, and ERPs ranged from six to over eight weeks. Notably, younger horses were found to excrete cyathostomin eggs earlier after treatment than older horses.

 

The researchers also observed that riding schools, stud farms, and those not segregating summer and winter paddocks had shorter egg reappearance periods.

 

In conclusion, this study in Swedish equestrian facilities employing selective anthelmintic treatment revealed that the establishments maintained longer ERPs and showed no confirmed resistance to ivermectin. These findings support the use of selective deworming strategies as a means of reducing the risk of anthelmintic resistance in horses. The full report is available in Veterinary Parasitology.

 

For more details, see:

 

Retained efficacy of ivermectin against cyathostomins in Swedish horse establishments practicing selective anthelmintic treatment

Ylva Hedberg Alm, Eva Osterman Lind, Frida Martin, Rebecca Lindfors, Nina Roepstorff, Ulf Hedenström, Isabelle Fredriksson, Peter Halvarsson, Eva Tydén

Veterinary Parasitology (2023) Vol 322, 110007

 

https://doi.org/10.1016/j.vetpar.2023.110007

Ivermectin resistance in small redworms

 In a recent study conducted in Brazil, it was discovered that there is widespread resistance to ivermectin among cyathostomins (small redworms) in most of the properties evaluated. This finding is concerning, as it has been increasingly recognised that important equine worms are developing resistance to commonly used anthelmintics.

The severity of this issue is underscored by the fact that resistance to all currently available classes of anthelmintics has been reported not only in cyathostomins but also in ascarids (large roundworms). Compounding the problem is the lack of new drugs on the horizon to combat this resistance.

 

Brazil is home to one of the largest horse populations globally, estimated to range from 5 to 6 million. In light of this, Giordani Mascoli de Favare and colleagues undertook a year-long research study in the western region of São Paulo state. The study aimed to assess the effectiveness of ivermectin as an anthelmintic in naturally infected horses on 12 breeding farms, involving a total of 123 horses.

 

To evaluate resistance in cyathostomins, the standard faecal egg count reduction (FECR) test was employed. If the FECR does not show a reduction of 95% or more after treatment with a macrocyclic lactone like ivermectin, it is indicative of resistance. Prior to the study, the horses had not received any anthelmintic treatment for at least 60 days. Each horse was orally administered the recommended dose of ivermectin paste based on its weight. Faecal samples were collected at the beginning of the treatment and 14 days later.

 

The results of the study revealed that in five of the properties, the FECR was below 90%, indicating significant cyathostomin resistance to ivermectin. Additionally, three properties showed a FECR between 90% and 95%, further indicating the presence of resistance. Only on four of the twelve properties did the faecal egg count reduction exceed 95%.

 

The authors of the study explain that in Brazil, the control of equine gastrointestinal parasites typically involves treating the entire herd without prior diagnosis and regularly rotating anthelmintic drugs. However, these findings highlight the urgent need for alternative strategies and interventions to effectively manage anthelmintic resistance in horses.

For more details, see:

Anthelmintic resistance of horse strongyle nematodes to ivermectin in São Paulo state, Brazil

Giordani Mascoli de Favare , Isabela de Almeida Cipriano, Tábata Alves do Carmo,  Mateus Oliveira Mena,   Gabriel Jabismar Guelpa, Alessandro Francisco Talamini do Amarante,  Ricardo Velludo Gomes de Soutello

Veterinary Parasitology: Regional Studies and Reports

Vet Parasitol Reg Stud Reports. (2023) Jun;41:100864.

 https://doi.org/10.1016/j.vprsr.2023.100864

Signs of moxidectin resistance

 Experts have been warning for some time of the danger of ending up with no effective
anthelmintics (dewormers). 

All the available classes of anthelmintic have shown declining efficacy as worms, particularly the cyathostomins (small redworms), become resistant. Moxidectin, a more recent addition to the arsenal is particularly useful for its action against encysted larvae. Until now it has remained relatively unscathed in the battle to hold back the advance of anthelmintic resistance. 

 

However, it seems now that the doomsday scenario is getting nearer as researchers in Australia have shown signs of resistance to moxidectin and combinations of anthelmintics.

 

Ghazanfar Abbas and co-workers conducted a study to assess the efficacy of commonly used anthelmintics against cyathostomins in Australian thoroughbred horses.

They carried out drug efficacy trials on two Thoroughbred stud farms in Victoria, Australia.

Horses were treated with single and combinations of anthelmintics. The researchers used the faecal egg count reduction test (FECRT) to assess the efficacy and egg reappearance period (ERP) of the anthelmintics. 

 

After treatment with an effective anthelmintic the faecal worm egg count (FEC) would be expected to be substantially reduced a couple of weeks later. So, for moxidectin, anything less than a 95% reduction in FEC two weeks after treatment would be taken as an indication of resistance.

 

The worm egg reappearance period (ERP) is the time taken for eggs to reappear in the faeces after successful treatment. It gives an early indication of the development of resistance. 

 

The research team found resistance to various anthelmintics and anthelmintic combinations, (including oxfendazole, abermectin and an oxfendazole/pyrantel combination).  

 

Although moxidectin was highly effective in one farm, producing a 100%  reduction in egg count two weeks after treatment, it showed a shortened ERP. (5 weeks – compared with the expected ERP when the drug is effective of 10 – 12 weeks). Resistance to moxidectin was found on the second farm with reduced efficacy of 90%.

A full report is published in Parasites and Vectors.

 

The authors conclude that the study provides the first evidence of moxidectin and multidrug-resistant (abermectin and combinations of anthelmintics) in cyathostomins in Australia. They suggest the need for continuous surveillance of the efficacy of currently effective anthelmintics and large-scale investigations to assess the ERP for various anthelmintics.

 

For more details, see:

 

Cyathostomin resistance to moxidectin and combinations of anthelmintics in Australian horses

Ghazanfar Abbas, Abdul Ghafar, John Hurley, Jenni Bauquier, Anne Beasley, Edwina J. A. Wilkes, Caroline Jacobson, Charles El-Hage, Lucy Cudmore, Peter Carrigan, Brett Tennent-Brown, Charles G. Gauci, Martin K. Nielsen, Kristopher J. Hughes, Ian Beveridge & Abdul Jabbar 

Parasites & Vectors volume 14, Article number: 597 (2021)

https://doi.org/10.1186/s13071-021-05103-8

 

See also the American Association of Equine Practitioners Parasite Control Guidelines: 

 

https://aaep.org/sites/default/files/Guidelines/AAEPParasiteControlGuidelines_0.pdf

Investigating worm control measures

 Horses and foals can carry many different parasitic worms in their intestines, some of which can cause severe disease. 

 

 Over recent years it has become recognised that some of the more important worms are developing resistance to the anthelmintics (dewormers) that are used to control them.

 

The seriousness of the problem is highlighted by the fact that resistance to all currently available classes of anthelmintics has been reported in both the cyathostomins (small redworm) and ascarids (large roundworm). Furthermore, there is currently no prospect of any new drugs in the pipeline.

 

It is becoming accepted that we need to adopt a more sustainable approach to deworming.

 

In a letter to the Veterinary Record, Dr Tim Mair and colleagues announced the launch of a collaborative project (ProjectWORMS) which they hope will produce recommendations about the best and safest way to prevent serious worm infestations, whilst limiting the further development of resistance to wormers.

 

The first step is to investigate current thinking and management practices with two online questionnaires – one for horse owner/keepers and one for stud owner/managers. This information is important to be able to develop and promote new and alternative ways of controlling worms that do not add to the problem of anthelmintic resistance

 

Dave Rendle, President Elect of the British Equine Veterinary Association (BEVA) said: “BEVA are pleased to be able to support this important piece of work which will inform decision-making around anthelmintic stewardship going forward. Anthelmintic resistance presents a serious and imminent threat to the equine industry."

 

To take part in the online survey, and for more information, see:

For horse owners/keepers: https://www.surveymonkey.co.uk/r/WORMSowner

And 

For stud owners/managers: https://www.surveymonkey.co.uk/r/WORMSstud

Effect of temperature on cyathostomin larval development

The cyathostomins (small strongyles) are the most important group of intestinal parasites of the horse - both numerically, and through their ability to cause disease. Furthermore, they are becoming increasingly difficult to control as they develop resistance to the drugs used against them. 

 Infected horses pass eggs in the manure, contaminating the pasture. These eggs are not infective straight away but need time to develop into the infective third stage larvae (L3).

 

In a laboratory study, researchers investigated the effect of different temperatures on the minimum time taken by cyathostomin eggs to develop into first/second stage larvae (L1/L2), and into infective third stage larvae (L3) in horse faeces.

 

Dr Aurélie Merlin and colleagues assessed the effect of three constant temperatures (10°C, 23°C, 30°C) under laboratory conditions and one fluctuating temperature (mean: 17 ± 4 °C) under outdoor conditions.

 

Their results, published in Veterinary Parasitology: Regional Studies and Reports, show that, depending on temperature, the minimum time taken by eggs to develop into L1/L2 was between 1 and 3 days. The minimum time to develop into L3 was between 4 and 22 days. Development of the eggs to infective L3 larvae was slowest at 10°C and fastest at 30°C.

 

The researchers suggest that their findings will help improve mathematical modelling of parasitic risks in grazing horses.

 

The results support the practice of removing droppings at least twice a week, which should prevent significant contamination of the pasture.

 

 

For more details, see:

 

Effect of temperature on the development of the free-living stages of horse cyathostomins

A Merlin, N Ravinet, C Sévin , M Bernez-Romand, S Petry, M Delerue, L Briot, A Chauvin, J Tapprest, L Hébert 

Vet Parasitol Reg Stud Reports (2022) 28:100687

https://doi.org/10.1016/j.vprsr.2022.100687

Ivermectin-resistant parascaris in Poland

© Zuzana Tillerová | Dreamstime

The large roundworm (Parascaris spp) is a common parasite of foals.

Migrating larvae may cause a mild cough and nasal discharge. Adult worms live in the small intestine. A heavy infection leads to failure to thrive and may cause intestinal impaction or rupture. Deaths have been reporte

d in foals up to 4 months of age. Older foals develop immunity, and the parasite rarely causes problems in adult horses.

Ivermectin has been a popular dewormer for foals, but there have been an increasing number of reports from around the world of its lack of efficacy against Parascaris.

A recently published study, by Maria Studzińska and colleagues at the University of Life Sciences in Lublin, is the first to report ivermectin resistance in Parascaris in foals in Poland. 

A total of 225 foals, from 7 stud farms in south-eastern Poland, were treated orally with ivermectin paste. The research team collected faecal samples one day before and two weeks after deworming.

Foals with faecal worm egg counts lower than 150 eggs per gram before treatment and farms with fewer than 6 eligible foals were excluded from the statistical analysis.

The research team found that, before treatment, 40% of foals had Parascaris spp eggs in their faeces. Two weeks after ivermectin treatment, 28.4% of foals were still excreting Parascaris spp. eggs.

Faecal egg count reduction (FECR) ranged from 44% to 97%. Overall average efficacy was 49.3%.

(FECR test is the standard method of assessing resistance in small red worms (cyathostomins) but has not yet been validated for use in Parascaris. In general, for cyathostomins, if the FEC is not reduced by 95% or more after treatment with a macrocyclic lactone such as ivermectin, that is interpreted as evidence of resistance.)

The researchers found that ivermectin was least effective against Parascaris spp. infection on farms with the largest herd sizes. Reduced efficacy was more common in older foals compared with those of three months of age. In this study, ivermectin was more effective in male foals than in females

For more details, see:

A survey of ivermectin resistance in Parascaris species infected foals in south-eastern Poland

Maria Bernadeta Studzińska, Guillaume Sallé, Monika Roczeń-Karczmarz, Klaudiusz Szczepaniak, Marta Demkowska-Kutrzepa & Krzysztof Tomczuk

Acta Veterinaria Scandinavica (2020) vol 62, Article number: 28

https://doi.org/10.1186/s13028-020-00526-2