Does pain affect Cushing’s test?

 

Research suggests that mild to moderate pain does not interfere with the hormone tests used to diagnose PPID.

A diagnosis of PPID (pituitary pars intermedia dysfunction, also known as Cushing’s Disease) can be supported by assessing the ACTH levels at rest and by measuring the response to a TRH (thyrotropin-releasing hormone) stimulation test.

In PPID, the over-active pituitary gland secretes higher than normal amounts of ACTH and other hormones. But pain itself may also cause increased ACTH levels.

Many horses with PPID eventually develop laminitis. Indeed, many are first suspected of having PPID when they show signs of laminitis. 

Does the pain associated with laminitis affect the value of ACTH as a diagnostic test for PPID? Heidrun Gehlen and colleagues at the Equine Clinic, and the Institute of Veterinary Epidemiology, Freie University Berlin, Germany conducted a study to investigate.

Fifteen horses being treated at the Equine Clinic for colic, laminitis or orthopaedic conditions with low to moderate intensity pain were included in the study. Horses were aged less than15 years, with no signs of PPID.

Samples were collected for basal ACTH concentrations, and a TRH-stimulation test was performed.

The intensity of pain was assessed using a composite, multifactorial pain scale. Each horse served as its own control as it was re-tested after the pain had subsided.

The researchers found no significant difference in the ACTH concentration in horses with pain and the controls, between different pain intensities or between disease groups.

They conclude that “measuring the basal ACTH concentration and performing the TRH stimulation test for the diagnosis of PPID seem to be possible in horses with a treated low to moderate pain condition.”

They suggest that “measurement of ACTH and the performance of the TRH stimulation test for PPID diagnostics can, therefore, be performed on horses in pain as long as they are not suffering from massive pain or showing a significantly disturbed general condition.”

For more details, see:

Can Endocrine Dysfunction Be Reliably Tested in Aged Horses That Are Experiencing Pain?

Heidrun Gehlen, Nina Jaburg, Roswitha Merle, and Judith Winter

Animals (Basel). (2020); 10(8): 1426.

doi:10.3390/ani10081426

Understanding ridden horse behaviour – Free webinar from World Horse Welfare

In this free webinar, Dr Sue Dyson shares some of the research that has looked at signs and behaviours horses display when they are experiencing pain, many of which can be very subtle.

She also discusses the sensitive issue of the impact of rider size on equine performance. Sue explains the influence that riders can have on their horses and what we, as owners, can do to ensure we are able to assess and recognise signs of discomfort and pain as soon as possible.

Webinar: Recognising pain in our ridden horses and the impact of rider weight - YouTube

Investigating possible melanoma therapy

 Betulinic acid shows promise as a possible topical treatment for Equine malignant melanoma (EMM) according to recent laboratory research.

Melanomas are common in grey horses affecting up to 80% of them by the time they are 15 years old. Current treatment options are limited, and often not very successful.

Lisa A. Weber, Jessica Meißner of the Foundation University of Veterinary Medicine Hannover and colleagues investigated the effects of the betulinic acid (BA) on equine melanoma cells and equine dermal fibroblasts in cell culture. They also looked at its spread through isolated equine skin.

 They found that betulinic acid inhibited cell proliferation and reduced cell viability of both equine melanoma cells and fibroblasts.  However, the results did not show a selective effect on cancer cells compared with normal cells.

In isolated skin preparations, they found that BA could penetrate the stratum corneum and spread through the epidermal and dermal layers. 

The research team conclude that “the potent percutaneous permeation of BA in normal skin together with its anticancer effects on equine melanoma cells suggest that this substance may exert antitumoral effects in vivo.”

They suggest that their findings support the use of BA in further preclinical and clinical trials for topical EMM treatment.

For more details, see:

Betulinic acid shows anticancer activity against equine melanoma cells and permeates isolated equine skin in vitro.

Lisa A. Weber, Jessica Meißner, Julien Delarocque, Jutta Kalbitz, Karsten Feige, Manfred Kietzmann, Anne Michaelis, Reinhard Paschke, Julia Michael, Barbara Pratscher, and Jessika-M. V. Cavalleri

BMC Vet Res. (2020); 16: 44.

doi: 10.1186/s12917-020-2262-5

Looking inside the horse’s gut

 A wireless endoscopy capsule can be used to inspect the inside of the horse’s gastro-intestinal tract.

The “ALICAM system” capsule is 11mm in diameter and 33mm long. It contains 4 micro-cameras, mounted at 90° to provide a 360°panoramic view. The cameras are activated by movement  (this helps prolong the battery life and so increase the length of the digestive tract that can be imaged.) When activated, the cameras record images at the rate of 20 /second and store them on the capsule’s internal memory chip.

Images are only available for inspection once the capsule has passed through the digestive tract and has been retrieved from the manure (using radiography).

Researchers at the University of Calgary have been studying the technique.

Five adult horses with no signs or history of gastro-intestinal disease were included in the study. The researchers assessed different protocols for preparing the horses and found that the one giving most useful images was to starve the horse for 24 hours before introducing the capsule.

Satisfactory images were obtained of the pylorus, major duodenal papilla, individual villi, and ileocecal junction. Visualization of large intestinal mucosa was poor.

Among the abnormalities identified on the images were mucosal erosion, ulceration and haemorrhage, areas of thickened mucosa, and evidence of parasitism.

On average, it took 6.5 days from introduction for the capsule to be retrieved in the manure.

The researchers conclude: “this novel endoscopic capsule appears safe, practical, and non-invasive in horses; however, variability in capsule excretion time must be taken into account for clinical application.”

For more details, see:

A wireless endoscopy capsule suitable for imaging of the equine stomach and small intestine

Mei Steinmann, Rebecca J. Bezugley, Stephanie L. Bond, Jill S. Pomrantz, and Renaud Léguillette

J Vet Intern Med. (2020) 34(4): 1622–1630.

doi: 10.1111/jvim.15825

Response to changing meal times

 

How do horses react to changes in their routine? It may come as no surprise that horses notice when their meal is late.

Research by Manja Zupan and colleagues at the University of Ljubljana, Slovenia examined the effect of altering the morning feeding time on eight horses kept in individual boxes.

The study extended over ten weeks. During that time, the morning feed (normally at six o’clock) was given an hour early on Thursdays, and an hour later on Saturdays.

The researchers monitored the effect of the change on the horses’ behaviour.

They found that, when horses were fed early, they spent less time eating hay, more time resting and less often took a look toward the door.

When feeding was delayed, the horses more often performed pawing the ground, kicking, comfort behaviour (such as grooming), and looking toward the door.

They conclude “Our results indicate that deviations from the regular feeding schedule affected the behaviour of horses and compromised their temporal predictability.”

For more details, see:

The Effect of an Irregular Feeding Schedule on Equine Behavior

Manja Zupan, Ivan Štuhec, Dušanka Jordan

J Appl Anim Welf Sci (2020) ;23:156-163.

doi: 10.1080/10888705.2019.1663734

Youtube channel highlights equine behaviour

Three scientists with an interest in equine behaviour have joined forces to launch a YouTube channel called “Equine Science Talk International” dedicated to explaining the discoveries of equine research and what they mean for riders, trainers, and researchers.

Professor Konstanze Krüger of Nurtingen-Geisslingen University is Germany’s first Professor of Equine Management. Her main areas of research are the behaviour of wild living horses, and social learning and social cognition in horses.

She is joined by Dr Laureen Esch, a veterinary surgeon, whose doctoral thesis was on equine behaviour, now specialising in equine dentistry, and Dr Isabell Marr, an independent horse trainer for western riding, who qualified as a stable manager before moving on to study animal biology and biomedical sciences.

Translations are provided by Kate Farmer, a journalist, horse trainer and independent equine behaviour researcher. The videos are available in English and German.

Topics covered include: How do horses interpret the world differently on their left and right sides? Why do some horses become aggressive? The key to successful training, and the meaning of positive and negative reinforcement.

For more details, see:

https://www.youtube.com/channel/UCzNBXlzMAeu83481wEOI6Pg/      (English)

https://www.youtube.com/channel/UC0s5sXLk1W28r_Y9CLswRhw         (German)

Obesity on podcast menu

 

Nutrition, in particular the problem of obesity, is the subject of the latest episode of the Morris Animal
Foundation’s “Fresh Scoop” podcast, which is now available.

Host Dr Kelly Diehl speaks with Dr Patricia Harris who is Head of the Equine Studies Group at the Waltham Petcare Science Institute. She also is on the board of the American Academy of Veterinary Nutrition.

Dr. Harris discusses the equine obesity epidemic and the value of regularly assessing a horse’s body condition. She also offers advice for owners on how to help their horse lose weight as well as strategies to prevent obesity.

Obesity is a globally recognized welfare issue in horses, affecting about a third of the equine population. It is associated with an increased risk of health issues including laminitis and colic, and carries direct negative consequences on horses’ skeletal and immune systems.

“Fresh Scoop” is a monthly podcast from the Morris Animal Foundation aimed practicing veterinarians, veterinary technicians or students, as well as animal-loving science enthusiasts.

Episodes are available on iTunes, Spotify, Google Play Music and Stitcher, as well as the Foundation’s podcast page.

 For more details, see:

https://www.morrisanimalfoundation.org/article/episode-26-equine-nutrition-podcast