Effect of PPID on egg shedding after deworming

It has been suggested that horses with hormonal disorders, such as insulin dysregulation and
Pituitary Pars Intermedia Dysfunction (PPID), may be more susceptible to worm infections. 

Horses with PPID often have a weakened immune system, which can allow worms, such as cyathostomes, to thrive more easily compared to healthy horses. These horses may also not respond as effectively to standard deworming treatments due to their altered immune function.

 

A study conducted in Australia aimed to determine whether horses with PPID had increased strongyle faecal egg counts (FEC) compared with control horses.

 

The study, led by Adelaina Horner, took place over a fourteen-week period and involved adult horses and ponies over eight years old in Victoria, Australia. All horses lived on pasture and had not been dewormed for at least three months prior to the study. A total of 45 privately owned horses and ponies met the criteria for inclusion, with 14 horses diagnosed with PPID and 31 serving as controls. PPID diagnosis was confirmed by elevated plasma ACTH concentrations (above 120 pg/mL) along with at least one clinical sign of the disorder.

 

All horses were dewormed with a standard dose of a commercially available ivermectin product. Faecal egg counts were taken before treatment and then every two weeks for 14 weeks. A FEC of 200 eggs per gram (EPG) or higher was used as the cutoff for significant worm burden.

 

The results showed that the egg reappearance period (ERP) after deworming was shorter in PPID horses, and cumulative FEC after deworming was higher in these horses. However, the researchers noted that some PPID horses consistently had no detectable eggs or low EPG (≤ 200) throughout the study, and this could not be explained by observed husbandry practices.

 

Worm eggs collected during the study were cultured in the laboratory, and examination of the larvae confirmed that all worms were cyathostomin species.

 

The researchers advise monitoring egg shedding before anthelmintic treatment in PPID horses, in line with sustainable worm management guidelines, as some PPID horses consistently showed low FEC results.

 

While hormonal disorders like PPID do not directly cause an increase in parasitic infections, they can impair the horse’s immune system and overall health, making them more vulnerable to worm infections and potentially reducing the effectiveness of treatments. Effective management of both the hormonal disorder and parasitic infections is crucial for maintaining the health of affected horses.

 

 

For more details, see: 

 

Strongyle egg shedding and egg reappearance periods in horses with pituitary pars intermedia dysfunction

Adelaina Horner, Nicholas J. Bamford, Michael J. Stear, David Piedrafita, Abdul Jabbar, Kristopher J. Hughes, Charles M. El-Hage, Sarah Preston

Veterinary Parasitology (2024) Vol 328, 110176

 

https://doi.org/10.1016/j.vetpar.2024.110176

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

Do haynets affect tooth wear in horses?

(c) Nigel Baker Dreamstime.com

Using haynets to feed horses has several benefits, including reducing hay waste and slowing down consumption. 

However, there are potential downsides, such as the risk of injury and unnatural feeding positions. When individual haynets are hung too high, horses may eat with their heads raised, which may lead to muscle discomfort and long-term problems. This position also increases the chance of inhaling dust or hay particles, which may cause respiratory issues.Do haynets also influence tooth wear.?

 

Michelle DeBoer and colleagues conducted a study to compare horse body weight and condition, hay consumption, tooth wear, and dental conditions between horses fed with or without hay nets. 

 

The work was presented at the Equine Science Society Symposium 2023, and a report is published in the Journal of Equine Veterinary Science.

 

Thirteen adult geldings were recruited for the cross-over study and divided into two groups.

 

They were housed in adjacent dry lots with access to shelter and water. Both groups were fed round hay bales in feeders, with one group of six horses receiving hay wrapped in hay nets, while the other five horses were given hay without nets.

 

The study spanned two years, with the two groups switching halfway through: the five horses that initially had their hay wrapped switched to unwrapped hay, while the six horses moved to wrapped hay.

 

The researchers tracked hay consumption and monitored dental health, including incisor length, dental abnormalities, and conditions. They also recorded horse body weight and body condition scores annually—before, during, and after the study.

 

Results showed that horses eating unwrapped hay consumed more and had higher body weight (BW) and body condition scores (BCS). No significant differences were found in incisor length, incisor bevels, or dental abnormalities.

 

The researchers concluded that hay nets do not negatively affect dental health but can reduce hay consumption and help manage horse body weight and condition.

 

 

 

For more details, see:

 

M. DeBoer, L. Keener, J. Layeux-Parks, O. Schueller, L. Johnson, K. Martinson,

Effect of hay nets on horse bodyweight, body condition score, hay usage, and dental health in mature adult horses,

Journal of Equine Veterinary Science,(2024) Vol 136,105051

 

https://doi.org/10.1016/j.jevs.2024.105051