- Infections of the genital organs in rams
|Last update: April 4, 2012 03:20:41 PM|
INFECTIONS OF THE GENITAL ORGANS IN RAMS
E. M. VAN TONDER
Since the confirmation of Brucella ovis infection in this country in 1958, the condition known as "epididymitis" or inflamation of the epididymis and its clinical manifestations became known to the majority of small stock owners and most people concerned with the small stock industry. Terms and expressions like epididymitis, ram disease, scrotal abscesses, testicular abscessation, infertility and infectious infertility have become very familiar and in common usage. Unfortunately, however, these terms are all regarded as synonymous denoting any clinical of palpable aberration from the normal scrotum and contents no matter what the actual causes for such aberrations are. It will also appear as if quite a percentage of stock owners are not conversant with the fact that different causes could be involved in testicular abnormalities and furthermore that epididymitis itself could be caused by different infective agents.
In the present survey on the incidence of epididymitis caused by a particular organism it became evident that a large number of farmers do not differentiate and as a matter of fact regard Brucella ovis and Corynebacterium pseudotuberculosis (Preisz Nocard organism) as one and the same organism and responsible for all testicular abnormalities. On these particular farms as well as other farms, a great deal of ignorance exists as regards the correct use and purpose of the different vaccines. We do find for instance that on certain properties Rev. I vaccine (against Brucella ovis) is used with the object of combating scrotal and other abscesses due to Coryne bacterium pseudotuberculosis while on other farms again, Coryne bacterium vaccination is practised in order to control and eliminate epididymitis caused by Brucella ovis or tit new organism called Actinobacillus seminis. This incorrect and indiscriminate use of the different vaccines is mainly due to ignorance as regards the specific conditions of the genital organs and their specific causes and is directly responsible for complaints of ineffective vaccines or the persistence of particular conditions despite the use of vaccines.
The information obtained from this particular survey has revealed another disappointing and alarming state of affairs. Despite the availability of this highly efficient vaccine at a minimal cost, an astonishingly large number of Merino stud farms were encountered, where Rev. I vaccination is not practised at all while an additional number of breeders used the vaccine when it was introduced but discontinued this practice after one or more years. In the former cases where vaccination is not practised the owners invariably considered their farms as free from infection while in the second instance the breeders discontinued vaccination under the impression that the infection was successfully controlled. Clinical examinations and blood tests confirmed the presence of Brucella ovis infections on the majority of these farms. Although regular elimination of rams with lesions considered to be due to non-specific causes, effected some control on the incidence and spread of infection on some of these properties, it did not eliminate the infection and regular ram losses.
Another aspect which has also come to light from the relevant information is the age at which regular vaccinations are carried out. Although it is recommended that ram lambs should be vaccinated at weaning age to ensure that these animals are free from infection at the time of inoculation, too many breeders are inclined to postpone this procedure for any length of time up to the four tooth stage. It should be noted that the vaccine can be effectively applied to animals of older age on the condition that they are free of infection at the time of application and the best way of ensuring this is to do them at the recommended age before they are exposed to infection.
In order to elucidate the problem of scrotal and testicular lesions due to the different infections, it is deemed necessary to give a brief description of the normal scrotum and its contents.
The testicle is an oval glandular structure consisting of numerous microscopic tubular glands responsible for the production of sperm cells. The tubules of these glands unite to form a network in the central cord of connective tissue called the mediastinum of the testis. From this network a number of ducts ascend to the upper end of the testis, pierce the wall and unite to form a single duct or tube.
This tube which is of considerable length is coiled upon itself and forms the structure known as the epididymis. The epididymis starts from the upper third of the front side of the testes, curves over the upper end and extends along the back side towards the lower end of the testis. The epididymis is divided into a head (the upper end), a body, (the part leading downwards) and the tail or lower end. At the tail of the epididymis the tube straightens out to form the vas deferens (semen tube) which ascends along the inside of the testis, is included in the spermatic cord and enters the abdomen in the region of the groin. Both the testis and epididymis are covered with a thin moist membrane closely attached to their surfaces.
The two testes and epididymi are situated in the scrotum which is divided into two separate parts by a layer of tissue directly underlying the skin, so that each testis occupies its own cavity. These cavities are lined with a smooth and moist membrane called the tunica vaginalis.
Having dealt with the particular organs, a few specific conditions and the terms used to describe them, can now be explained.
Epididymitis describes an inflammatory condition of the epididymis and it can be acute or chronic and is usually of a purulent nature. Likewise the term orchitis is used to indicate an inflammatory process of the testicle itself, which could also be acute or chronic. When both these structures are involved the condition is known as epididymo-orchitis. An abscess is a localised purulent inflammation of any tissue characterised by cavity formation and the collection of pus in that particular cavity. Apart from the rest of the body, abscesses can therefore be found anywhere on the scrotum, usually situated between the skins and underlying tissues, or in the epididymis and the testes. Sometimes a collection of pus is also found in the scrotal cavity surrounding the testicle.
It will now be endeavoured to give a brief description of the specific infections of the genital organs of rams found in this country.
1. Brucella ovis
As was stated previously infection caused by this bacterial organism was confirmed in this country in 1958.
Although it is known that transmission of this infection occurs through close contact between rams, it is not exactly known how the organism gains entrance into the epididymis. It seems likely however that infection occurs through the penis and moves upwards in the urethra (urinary tube) into the vas deferens and tin ally into the epididymis. This probably takes place where rams are kept together, especially between mating seasons and where they mount each other. When an infected ram mounts another ram, the infected semen is sprayed around and especially on the bare area below the anus with the result that when healthy rams mount such a ram, the infection spreads onto the penis when contact is made with this particular area. The possibility of infection gaining entrance through the mucous membranes of the eyes, nose, etc., should also be considered
Although storms of abortion is in overseas countries, have not been reported in this country, it has been proved that this organism causes an inflammation of the vaginal canal in ewes, but that the infection is cleared at the following or second heat period following infection. The ewe then acts as an intermediate carrier or source of infection when served by infected and susceptible rams during the same or consecutive heat periods. The opinion has also been raised that the infection could be transmitted from mother to lamb) in pre-weaning stage.
This organism attacks the lining of the epididymal tube, causing an epididymitis of a progressive nature which turns into a chronic process after a variable period. During this period the entire epididymis or the head, tail or body is enlarged and palpable. In the initial stages the enlarged epididymis or part of it, will still be soft or elastic, but later on it becomes firm and hard indicating that the lesion has entered a chronic stage. Usually when the head of the epididymis is affected an elongated or egglike hardening can be felt and when the tail is affected it is round and hard like a golf ball. It should be noted however that it is very difficult to evaluate the early stages of epididymitis by palpation or clinical examination.
We often find that in these cases of epididymitis, Corynebacterium pseudotuberculosis also plays an important part as secondary invader. It will appear as if the damage to the mucous membrane of the epididymal tube, caused by Brucella ovis serves as port of entrance to the Corynebacterium organisms which; are then responsible for typical abscess-formation in the epididymis and sometimes also in the testicle. In such cases enlargement of the particular site where the abscess is located can be of considerable size and could be soft or firm, depending on the stage of the inflammatory process.
The effects of Brucella ovis infection with or without the complication of Corynebacterium infection can be described as varying degrees of infertility up to complete sterility depending upon the degree of inflammation and occlusion of the epididymal ducts, the functional state of the testes and whether one or both sides are affected. In the early cases where the epididymal duct is still patent, the animal would still be fertile, but the semen will be contaminated with the products and cells of the inflammatory process as well as organisms and their products.
The control of this particular infection can be effected on the following lines:
(a) Clinical and semen examination of all rams by a Veterinarian, and isolation and elimination of all clinically affected rams as well as those positive for Brucella ovis on semen examination. The uninfected rams should be vaccinated immediately and isolated for a period of three weeks.
(b) Where a Veterinarian is not available all rams should be palpated, infected rams eliminated and non-infected rams isolated and vaccinated. These rams should be examined regularly and those that develop clinical signs should also be eliminated. It must be remembered that where the infection is present even in the complete absence of clinical signs, vaccination would be of no avail as the vaccine is neutralised by the infection. Such rams will develop lesions as if they were not vaccinated at all.
(c) Only vaccinated rams should be introduced and preference should be given to rams inoculated at the recommended age.
(d) All stud-breeders should be urged to inoculate all ram lambs at weaning age or at the age of 2 to 4 months. It is not advisable to vaccinate lambs before the age of 2 months.
It is felt that vaccination of ram lambs is an easy task, involving minimal costs and that every stud-farmer is morally indebted to his clients to adopt this as a regular procedure. Prospective buyers should also refrain from buying rams from breeders that are reluctant or refuse to inoculate their young ram lambs. Breeders who consider their stud free of infection should nevertheless vaccinate in order to protect their sale-rams against infection later on. By doing so they will also protect their reputations and the interest of their clients. There is absolutely no ground or proof for the prejudiced belief in some of these cases that vaccination will introduce infection into these studs.
In the case of Brucella ovis infection there is only the well-known Elberg Rev. I vaccine which should be used to control the condition. It is available at three cents per dose and only one injection is necessary to protect the animal for the rest of its life. It is also strongly recommended that fresh supplies of vaccines be used and that it should be properly handled and stored before use.
2. Actinobacillus seminis
This organism has only recently been isolated as a cause of epididymitis in rams in this country. Although it was previously described in Australia very little is known about the organism and its specific behaviour.
The different aspects of this particular infection viz. incidence, distribution, methods of transmission, effects on the different sexes and age groups etc., are now being investigated.
It will appear as if the mode of transmission, clinical symptoms and the effects on the genital organs are exactly the same as for Brucella ovis but these and other facts will be clarified by specific investigations.
From the preliminary results obtained by a specific survey being conducted at the moment, it is evident that infection due to this organism is widely distributed and of a high incidence. It also seems reasonable to accept that this condition is prevalent in this country for quite a long time and that it is as old as the condition caused by Brucella ovis. It is most likely that infection by this organism is responsible for the persistent cases and on a number of properties a high incidence of epididymitis, despite the regular use of Rev. I vaccine and elimination of clinical cases.
The elimination of rams with clinical lesions which was extensively practised when Rev. I vaccination was introduced probably effected some control on this infection, with the result that the impression was gained that epididymitis was successfully controlled. During the past few years however, this infection flared up, probably as result of a relaxation in the regular examination and elimination of clinically affected cases.
A secondary Corynebacterium infection as in the case of Brucella ovis is also often encountered. Apart from the regular elimination of clinically positive rams, there are still no means of controlling this infection.
3. Corynebacterium pseudotuberculosis
This organism is responsible for the condition known as Preisz Nocard or cheesy gland disease which is characterised by abscess-formation in the lymph glands of the body. It is also responsible for the majority of abscesses found all over the body and the scrotum and as secondary invader also in the epididymis and testes following infection by Brucella ovis or Actinobacillus seminis.
Transmission of this infection occurs through wounds caused by shearing docking, castration, tick bites, etc. Although the infection can spread from a wound and cause abscesses in other parts of the body, we usually find a localised abscess at the place of entrance or in the nearest lymph gland. Scrotal abscesses are usually found on the midline, but sometimes also at different sites on the scrotum. In the first instance ticks seem to be the major vectors since they have a predilection for this particular site, while shearing wounds and wounds caused by thorns and grass-seeds (stick-grass) located in the wool, also play an important role.
In the case of epididymal abscesses it would appear as if the damage to the lining or the epididymal tube by Brucella ovis or Actinobacillus seminis acts as the wound necessary for the entrance of Corynebacterium organisms. In these cases the infection is secondary and super-imposed on infection by the above-mentioned organisms. Good reason for this belief can be found in the fact that in a number of studs with Brucella ovis infection and epididymal abscesses where Corynebacterium pseudotuberculosis was involved, this problem was completely cleared with the use of Rev. I vaccine, although the problem of Corynebacterium abscesses elsewhere in the body continued to exist. It seems clear then that in the absence of Brucella as the primary epididymal infection, Corynebacterium could not produce epididymal abscesses since it had no wound or port of entrance.
Infection usually takes the form of typical abscesses containing greenish-yellow cheesy pus. These abscesses do rupture sometimes with extrusion of the contents, which then serves as source of infection especially in a shearing shed. In the majority of cases we find that the abscesses are well encapsulated, become firm or hard and exist in this state for the rest of the animals life.
Dis-infection and proper hygiene in the shearing shed offers the best and most practical way of controlling Preisz Nocard disease. This includes complete disinfection of the shearing shed before shearing, using a 3 to 5% Formalin solution, the provision of clean boiler suits to shearers and the shearing of young sheep first. Formalin solution should also be used in the shearing buckets and ruptured abscesses and wounds treated and disinfected with Iodine or similar preparations. Abscesses should never be opened in the shed and the contents must be buried or burnt. In case of accidental rupturing of abscesses, contaminated areas must be well cleaned and disinfected with Formalin or any other suitable disinfectant.
On farms where the condition persists despite strict hygienic measures and where a high incidence is encountered, vaccination with Corynebacterium pseudotuberculosis vaccine should be practised. Particular care should be paid to the shearing of the scrotal area in rams and the control of ticks. Wounds m this area must be treated regularly and immediately. It also seems feasible to clip the wool on the scrotal area regularly, especially where rams are put out in the veld, in order to avoid the clinging of thorns and grass-seeds.
As it seems clear that Corynebacterium pseudotuberculosis is not capable of causing epididymal abscesses by itself, but merely as a secondary complication on Brucella ovis or Actinobacillus seminis infections, it obviously follows that these primary causes should be eliminated. This can be easily effected when Brucella ovis is involved by the regular use of Rev. I vaccine but unfortunately no definite control measure or vaccine is at present available against Actinobacillus seminis infection.
Merino Breeders Journal 31 (2)