Click here to close window and return to previous page

Other 2004 Projects Involving
Havemeyer Equine Behavior Laboratory
 


Variation in plasma ACTH concentration and dexamethasone suppression test
results in association with season, age and sex in healthy ponies and horses
Donaldson MT, McDonnell SM, Schanbacher BJ et al
 

The purpose of this study was to evaluate the variation in plasma ACTH concentration and dexamethasone suppression test (DST) results associated with season, age and sex in healthy, Shetland pony mares (n = 15) and pony stallions (n = 14) living under semi-feral conditions and horse mares (n = 10) living at pasture. Plasma ACTH concentrations were measured in September 2002, and in January, May and September 2003. Dexamethasone suppression tests were performed in January and September 2003. Plasma ACTH concentrations in September 2002 and September 2003 were similar and were significantly greater than in January and May (P < .001). Plasma ACTH concentration was within the reference range for 38 of 39 (97%) subjects in January, for 39 of 39 (100%) subjects in May, for 2 of 39 (5%) subjects in September 2002, and for 3 of 39 (8%) subjects in September 2003. Dexamethasone suppression tests were within the reference range in all subjects in January and were within the reference range for 29 of 39 (74%) subjects in September 2003. Plasma cortisol concentration at the end of the DST was significantly greater in September than January (P = .002). Age was positively correlated with plasma ACTH and plasma cortisol concentration at the beginning and end of the DST. Within the same season, plasma ACTH concentration in pony mares, pony stallions and horse mares was not significantly different (P > 0.05). Seasonal changes in plasma ACTH concentration and DST results should be considered when interpreting endocrine test results.
 

Accepted for publication in J Vet Intern Med 2004.


 
Seasonal and sample handling effects on measurement of plasma alpha-
melanocyte stimulating hormone in horses and ponies
 
McFarlane D, Donaldson MT, McDonnell SM, Cribb AE.
 

Objective:  To investigate the effects of sample handling, storage and collection time and season on a-melanocyte stimulating hormone (a-MSH) concentration in healthy horses and ponies
Sample population:  11 healthy, adult standardbreds and 13 healthy, semi-feral ponies
Procedure:  Plasma a-MSH was measured using radioimmunoassay
Results:  Measured a-MSH  concentrations were stable under most normal sample handling and storage conditions.  Samples left unseparated at 4 º C for 48 hours and plasma stored at 4 º C for 7 days showed a significant decrease in a- MSH concentration. There was a significantly greater plasma a-MSH concentration in September in both ponies (11-fold) and horses (2-fold) compared to spring.
Conclusions and Clinical Relevance:  Measured a-MSH concentrations were minimally affected by handling and storage conditions.  Most field-collected samples will be appropriate for analysis.  Seasonal variation occurs in plasma a- MSH concentration and must be considered when using this assay to diagnose equine pituitary pars intermedia dysfunction (PPID).


In press AJVR.


 
Injuries and blemishes in a semi-feral herd of ponies
Elkanah H Grogan BS and Sue M McDonnell PhD

Equine Behavior Lab, New Bolton Center
University of Pennsylvania School of Veterinary Medicine
 

With the goal of characterizing the type and degree of injuries and blemishes incurred by horses living under natural social conditions, all members of a semi-feral herd of ponies were inspected on four occasions over a period of 28 months.  Two occasions were during breeding/foaling season and two during non-breeding/foaling season months.  On each occasion, each animal was examined (n= 47 to 65) and all injuries or blemish marks were recorded.  Based on the types and number of injuries or blemishes, an Injury/Blemish Grade was assigned for each inspection, ranging from 1 for no blemishes to 6 for more than one open wound.  Almost all injuries and blemishes recorded were extremely mild.  Only 12 of the 213 inspections and 14 of the 838 total injuries and blemishes involved wounds affecting tissues other than hair and skin.

 

Males had significantly greater mean Injury/Blemish Grade than females (p<0.0001).  For all social categories and ages, the mean Injury/Blemish Grade was significantly greater in the breeding/foaling season months than during the non-breeding/foaling season (p<0.0001). 

 

All foals were blemish-free at the non-breeding\foaling season inspections (n=24) and relatively blemish-free (9 of 14) at the breeding/foaling season inspections. 

 

The rump and the barrel areas were the most common site of injuries or blemishes, both as a percentage of the total injury count as well as a percentage of inspections involving those areas.  These findings are consistent with the seasonal and gender patterns of aggressive behavior observed in this herd.  Compared to reports of truly feral horse populations, it appears that injuries are fewer and less severe in this semi-feral herd.  In addition, there appears to be fewer leg injuries in this semi-feral herd than has been described for truly feral horse populations.

Injuries and blemishes by body area

Body Area

Percent of Total 838

Injuries/Blemishes

Percent of 213 Inspections with

Body Area Affected

Rump

39

42

Barrel

32

37

Neck

7

15

Chest

7

15

Head

6

16

Hind Legs

5

9

Muzzle

4

9

Front Legs

1

4

Ears

1

2

Eyes

< 1

< 1

 

This is a Dorothy Russell Havemeyer Foundation project.


 
Effects of intranasal treatment on behavior of horses and ponies
 
Elkanah H Grogan BS and Sue M McDonnell PhD

Equine Behavior Lab, New Bolton Center
University of Pennsylvania School of Veterinary Medicine
 

            Intranasal application of medications is becoming more common in veterinary medicine. For the horse, intranasal treatments available in recent years include vaccination against Streptococcus equi, equine influenza, and equine rhinopneumonitis-influenza. To evaluate anecdotally reported behavioral resistance to intranasal treatment and the development of head shyness and behavioral aversions as a result of intranasal treatments in horses, horses and ponies were exposed to intranasal treatments using Heska or Fort Dodge type intranasal applicators (marketed at the time of this study) or control procedure. Our objective was to evaluate behavioral compliance of horses to intranasal treatment itself, and to assess development of aversion to veterinary examination as a result of experience with intranasal applicators.

            Subjects included 37 horses and ponies including 28 light horse mares, 4 pony geldings, and 5 light horse and pony stallions. Compliance with the procedure itself, as well as with a standard physical examination pre- and post-treatment, was measured. For 22 horses receiving intranasal treatment, no problematic avoidance behavior was elicited during the intranasal treatment, and no effect on duration of or compliance with a standard physical examination including manipulation of the head, nose, and mouth was detected. Results were similar for Heska and Fort Dodge applicators, both for the treatment procedure and for compliance with the physical examination. For 3 of the 6 ponies receiving intranasal treatment, significant avoidance behavior was observed, as well as apparent adverse effects on compliance in post-treatment physical examination. Comparison of results of a subset of subjects treated with warm (n=6) and cold (n=6) applicators and contents during cold wither months suggest no difference in compliance due to this factor.

Of the 6 ponies receiving intranasal treatments, 3 exhibited significant avoidance behavior during the treatment itself, as well as mildly to moderately increased aversion to subsequent physical examination of the ears, nose, and mouth, but not to hand sweep of the body and auscultation, wiping of the eyes, or jugular stick. The technician, who treated both the horses and the ponies in this work, attributed the ponies’ greater resistance to intranasal treatment to greater likelihood of contact of the applicator with the considerably narrower and shorter nasal passage.

            While there is potential for problems with behavioral compliance with intranasal treatments and subsequent aversion to physical examination as seen here in some ponies, no problems were seen in the 22 treated horses compared to controls. Further work is needed to understand factors involved in practitioner reports of aversions developing in association with intranasal vaccination procedures.

This is a Dorothy Russell Havemeyer Foundation project. Fort Dodge and Heska kindly provided intranasal applicators. Dr. Patricia Sertich facilitated use of horses in this study. Dr. Rob Holland of Intervet offered suggestions on possible causes of behavioral resistance.


 

Color Doppler Ultrasound Evaluation of Testicular Blood Flow in Stallions
MA Pozor, Med.Vet, PhD1a and SM McDonnell, MS, PhD2

1Department of Animal Reproduction, University of Agriculture
30-059 Krakow,  POLAND and
2University of Pennsylvania School of Veterinary Medicine
New Bolton Center, Kennett Square, PA 19348, USA

aAuthor of Correspondence and Reprints
Malgorzata Pozor, Med.Vet., PhD
Current address: University of Florida, College of Veterinary Medicine,
LACS, PO Box 100136, Gainesville, FL 32610-0136, USA
 

Abstract
        The objectives of this study were to evaluate potential use of color Doppler ultrasound to characterize blood flow to the stallion testis, and to establish reference values for Doppler measures of blood flow in the testicular artery of the stallion. Two testes from each of 52 horses were examined using a pulsed-wave color Doppler ultrasound with a sector array 5/7.5 MHz transducer with a 1 mm gate setting. Peak Systolic Velocity, End Diastolic Velocity, Resistive Index, and Pulsatility Index of the testicular artery were measured in each of two locations, the convoluted aspect (spermatic cord) and the marginal aspect of the artery (on the epididymal edge of testis).  We found that: 1) all measures were obtainable; 2) except for Pulsatility Index, the majority of the measures were higher at the cord location than at the marginal aspect of the artery (p<0.05); and 3) measures for left and right testes were similar (p > 0.10). Resulting measures from 41 of these stallions (82 testes) that appeared free of testicular pathology provide useful reference values for clinical evaluation. Evaluation of eleven cases with testicular pathology suggests further investigation of possible effects of these various conditions on testicular blood flow and testicular function.

Key Words: Stallion; Testis; Artery; Color Doppler; Equine; Pathology

ACKNOWLEDGMENTS

Funding was provided by the Polish Committee for Research Grants (5PO6D01117) and The Dorothy Russell Havemeyer Foundation. Gabriel Wojcieszek and Adam Mroz provided technical support. Sebastian Harnik, Katarzyna Polanska prepared drawings. Mr. Frank Kemme of Pie Medical Equipment B.V., Maastricht, The Netherlands, assisted with arrangements for obtaining ultrasound equipment. Mr. Nestorowicz of Faxon International, Poland, kindly provided color video printer for this study.


 
A Field Study on Ultrasonographic Assessment of Orbital Diameters in Pony Fetuses
 
Regina M. Turner, Sue M. McDonnell, Robert Foglia, and Elkanah Grogan

Section of Reproduction and the Equine Behavior Lab, New Bolton Center
University of Pennsylvania School of Veterinary Medicine
 

            Real-time, transrectal ultrasonographic measurements of the fetal orbit have been proposed as a means of predicting gestational age in pregnant horse mares.  Published studies to date have been performed predominantly on standardbred and thoroughbred mares in a controlled environment.  Our hypothesis is that similar measurements can be applied to pony mares and that measurement of fetal orbital length and width can be used to predict gestational age in pony breeds.  Additionally, we hypothesized that this method could be performed efficiently and accurately even under field conditions.  With this in mind, the specific aims of this 2 year study are to:

Year 1
1) Perform transrectal, real time ultrasonographic measurements of fetal orbital length and width in pregnant pony mares housed and examined under field conditions and to determine if this technique can be performed efficiently and accurately.
2) Determine if there is an association between fetal orbital measurements and the gestational ages of pony fetuses,

Year 2
3) Use the data acquired in year 1 in a prospective study to attempt to predict the date of parturition in pregnant pony mares.

In year 1, 20 semi-feral, pregnant pony mares were studied between December of 2003 and August of 2004.  Each mare’s reproductive tract was examined once monthly by 1 of 2 theriogenologists using transrectal palpation and ultrasonography.  At each examination, the fetal orbit was imaged, and 3 independent measures of orbital length and width were obtained.  The results were averaged.  Examinations were discontinued once the mare foaled.  Mean orbital length, width and area will be plotted against gestational age (working backward from day of foaling).

           During year 1, we were readily able to perform transrectal ultrasonographic examination of the reproductive tract of semi-feral pony mares under field conditions.  Preliminary data analysis suggests that orbital measures may be useful in predicting trimester of pregnancy, but that the standard deviation about the mean is too variable to allow accurate prediction of the exact month of gestation.   

In year 2, we will formerly test the hypothesis that these measures can be used to accurately predict gestational age by using the graphs generated in year 1 in a prospective study.  Pregnant mares will be examined monthly beginning in August, 2004 until foaling in the spring of 2005.  A blinded researcher will use the graph generated in year 1 and the monthly orbital measures obtained in year 2 to attempt to predict the month of foaling.  At the conclusion of the study, we will determine how accurate these predictions were. 

 To our knowledge, this is the first ultrasonographic study of the growth dynamics of pony fetuses.  Additionally, to our knowledge, this is the first attempt to use fetal measurements obtained in a field situation to prospectively predict parturition date in equids.