Diagnostic methods in the stallion Flashcards
What is going on with this stallion?
Why might this be important to do?
What precautions should you take?
Why might this be especially important in a gelding?
Ball of smegma
Smegma is thought to be carcinogenic. SCC develop initially around this area next urtethra due to presence of smegma material.
Smega beans found in the fossas
Can predispose to fly stike
Discuss Approach to Examining the Male?
Specific details in the stallion:
–Bacteriological screening
–Virology/vaccination for venereal pathogens
–Semen evaluation
–Ultrasonography
–Urethroscopy
–Further tests:
- ?Testicular FNA cytology (may be relevant in specific circumstances after doing more common tests)
- Cytology
Discuss Bacteriological Screening with regards to ‘low risk stallions’?
Need to do for:
‘Low Risk’ Stallion
–2 negative sets of swabs 7 days apart (from these sites: swabbing urethra, urethral fossa and the sheath)
Discuss Bacteriological Screening with regards to ‘high risk stallions’?
Need to for:
‘High Risk’ Stallion
–2 negative sets of swabs 7 days apart (from these sites: swabbing urethra, urethral fossa and the sheath)
–Plus screen 4 mares post mating
Discuss where to take swabs and considerations?
Remember:
–Swabs from urethra, urethral fossa, sheath and pre-ejaculatory fluid
–Swabs sent in Amies Medium
–Culture within 48 hours at Approved Laboratory
–Transport in charcoal based medium
What if Venereal Pathogens are Isolated?
The guidelines say?
Principle if you identify organism stop breeding, isolate and treat animal and inform other in contacts.
What if you isolate Pseudomonas aeroginosa?
Could be either veneral or environmental. Often have to work on the assumption it is veneral even though knowing in many cases this is likely to be environmental contamination.
What do you do if you isolate Pseudomonas aeroginosa?
Treatment of Venereal Pathogens
–Topical – Cleaning of the Penis
- 50% acetic acid (Pseudomonas)
- Hydrochloric acid (Pseudomonas) 10ml of 38% in 4 litres water
- Sodium hypochlorite (Klebsiella) 45ml of 5.25% in 4 litres water
How are you going to get his penis out?
Care about transmission to buckets / sponges etc
–Topical antimicrobial agents on the basis of sensitivity
- 90% Pseudomonas sensitive to polymixin
- 90% Klebsiella sensitive to neomycin
Where are you going to put these antibiotics?
–Inoculate from broth from normal stallion
- e.g. Treat for 5 days and inoculate on days 6 and 8
- Broth of material which re-establishes normal flora after antibiotic treatment
Re-test according to Guidelines
Discuss Equine Viral Arteritis (EVA)?
- Notifiable in the UK
- Can infect mares and disease mares. Proportion of stallions shed virus in their semen for a long period of time. Never sure with a stallion whether it will clear the infection or remain a persistent shedder.
What are the clinical signs of Equine Viral Arteritis (EVA)?
Clinical signs
–Malaise, predilection for mucus membranes (conjunctivitis [pink eye], cough, dyspnoea
–Diarrhoea and colic
–Urticarial rashes, oedema (scrotum, eyelids, ventral oedema)
–Abortion in mares
Discuss transmission of equine viral arteritis?
Transmission
–Droplet infection through respiratory tract
–Virus present in nasal secretion, urine, blood, faeces, semen
Course of the disease
–Symptomatic treatment and recovery over 1 month
–BUT 30% OF STALLIONS SHED VIRUS IN SEMEN FOR LIFE (virus harboured in accessory glands)
Discuss fetal abortion and equine viral arteritis?
Discuss epidemiology of equine viral arteritis?
Virus present in semen
–Infection of mares venereally
–These mares develop respiratory tract infection
–Virus is spread to other mares which if pregnant will abort
–There is no treatment for these stallions except castration
-These stallions are always seropositive
Discuss equine viral arteritis in stallions and vaccination?
- These stallions are always seropositive
- The problem is it can be difficult to differentiate serologically an infected stallion from a vaccinated stallion (have to resort to repeated semen collection and virus isolation)
–Therefore if you vaccinate a stallion it is imperative that you demonstrate he is serologically negative prior to vaccination and that the vaccination results in a positive serological response (and you document this on the vaccination certificate)
Discuss general principles of Semen Evaluation?
•General principles:
–Avoid toxic lubricants
–Avoid contamination with water
–Avoid allowing sample to become cold
–If analysis is to be delayed do not store at body temperature (allow to cool to room temperature)
What are other evaluations for semen evaluation and collection?
- Estimate penis size and chose appropriate AV (artificial vagina) and degree of filling
- Protective clothing (hard hat)
- Experienced operators
- Experienced mare in oestrus (Code of Practice) or dummy if stallion is trained
- Watch for dismounting
- May have to manipulate AV (artificial vagina)
- Keep collecting vessel directed ventrally
How can you confirm ejaculation?
On average 2 mounts required
for ejaculation and noted by:
–Flagging of the tail
–Cessation of thrusting
–Urethral pulses
–Lack of interest after dismounting
Why is there removal of Gel Fraction from sperm by filtration or suction?
–Reduces sperm motility
–Interferes with vital staining
–Makes pipetting of sperm difficult
–Reduces longevity of the sample
It is also possible to collect semen using alpha2 adrenoceptor agonists?
Causes epididymal urethral contractions.
Stallion has flaccid erection.
What is the Normal appearance of Ultrasound of the testes?
–Echogenic capsule
–Hypoechoic parenchyma
•Bright echogenic stipples
–Echogenic mediastinum testis
–Use for measurement of testicular size and volume
•Formula for the volume of an ellipse = 4/3 pi (a x b x c)
Discuss ultrasound appearance of the Accessory Glands?
Prostate Gland
- Echogenic capsule
- Hypoechoic parenchyma
Seminal Vesicles
- Hypoechoic
Bulbo-urethral glands
- Large and moderately echogenic
Discuss Urethroscopy of the stallions penis?
- Endoscopic examination of the urethral mucosa
- Sedation with alpha2 agonists + opioid
- Fibre-optic endoscope
–120cm, 9mm most commonly used
- Normal mucosa is pale pink with longitudinal folds
- Air distension may help demonstrate some lesions
- Blood in ejaculate in the stallion usually associated with a urethritis
Discuss Testicular FNA Cytology?
- Least invasive method but variable sample recovery
- Technique
–Sedation
–Skin prepared aseptically
–Deep penetration into parenchyma using 2 or 3 inch 19G needle
–Suction with 5ml syringe
–Transfer of material by squirting onto microscope slide
•Requires experienced and skilled cytologist to interpret
What are the other Cytological Methods?
Direct impression smears
–Penile tumours (although in reality most cases receive a clinical diagnosis)
Discuss azoospermia?
Discuss oligozoospermia?
Discuss teratozoospermia?
Discuss athenozoospermia?
What is the aetiology and treatment for haemospermia?
Aetiology
–Bacterial urethritis
–Accessory gland infection
–?penile laceration / tumour
Treatment
–Systemic antibiotics and NSAIDs
–Sexual rest
–Urinary acidifyers
Discuss Paraphimosis failure to retract the penis?
•Causes:
–Trauma during breeding
–Phenothiazines (as part of priapism syndrome)
- Results in marked gravity oedema to the penis and drying of the penile surface
- Once penis is swollen and weight increases if it is not pull back in sheath and stays out for few hours then oedema increases further and end up with vicious cycle of gravity oedema
Discuss Traumatic Paraphimosis?
- There is significant swelling within the preputial reflection on the penis
- There is massive swelling of the free part of the penis which with the preputial component means that the penis points backwards
- Treatment
–Critical aspect is to establish whether the horse can urinate
•Don’t catheterise it if very traumatised
–Place it into a clean box
–Consider rectal examination to see if bladder is full
Discuss treatment of Traumatic Paraphimosis?
Treatment
–If seen early try to reduce the size of the penis by using pressure bandages and massage
–If penis can be returned to sheath then keep it in place using purse-string suture
–Lifted by body band to keep it tucked up close to abdominal wall to reduce amount of swelling there
Discuss Traumatic Paraphimosis treatment further?
Treatment
–If penis cannot be returned to sheath then prevent gravity oedema by supporting the penis
•Towel under penis and tied over back, or pair of ladies tights
Chester is a 15 year old gelding
How would you manage this case?
- Consequence of poor hygiene is fly strike.
- Not cleaning the smegma adequately
Need to:
- Sedate protrude penis
- Remove the maggots
- Clean smegma from full length of penis using simple bathing
- Check urethral fossa
- Use topical Abs to control bacterial growth and heal any areas which have been munched on by maggots
- Long term care:
- Pour on insecticides/tags
- Stabling to get away from flies
- Regular cleaning of sheath
