RETROSPECTIVE STUDY ON BODY SURFACE ABSCESSES IN FARM ANIMALS

The aim of the present study is to determine the predilection seats of body surface abscesses in some farm animals, their relations to the way of entrance of infection as well as the methods of surgical treatment, fate and complications. The present study was carried out on a total number of 790 animals (buffaloes = 131, cattle = 240, sheep = 230, goats = 81, donkeys = 64, horses = 17 and camels = 27) suffering from presence of abscesses at different localities on the body surface. All cases were recorded during field trips to villages of 27 provinces allover Egypt from 2003 – 2018. Diagnosis was established depending on case history, clinical signs and exploratory puncture. Surgical treatment was performed either by incision of the abscess wall and evacuation of the contents or by total excision. Results indicated that abscesses were detected at the parotid region in 129 animals (16.33%), mandibular region in 120 animals (15.19%), sub-conjunctival in 36 animals (4.56%), cheek region in 33 animals (4.18%), ear region in 10 animals (1.27%), neck region in 47 animals (5.95%), thoracic limbs in 72 animals (9.11%), thoracic wall behind the elbow in 34 animals (4.30%), abdominal wall in 60 animals (7.59%), umbilical region in 68 animals (8.61%), gluteal region in 45 animals (5.70%), pelvic limbs in 102 animals (12.91%), tail region in 16 animals (2.03%) and vulvar lips in 5 animals (0.63%). The results also revealed that the ways of entrance of infection include; breach on the surface of the skin, migrating foreign bodies from the lumen of the digestive tract, iatrogenic by using non-sterilized needle for intramuscular injection, punctured wounds by infected foreign bodies and blood and lymph borne infection. Solitary abscesses were recorded in 682 animals (86.33%) while multiple abscesses were diagnosed in 108 animals (13.67%). Surgical treatment was performed by incision and evacuation of abscesses in 686 animals (86.84%) and by total excision in 104 animals (13.16%). Considering the fate of cases after surgical treatment; 589 animals (74.56%) recovered after the first surgical interference, 66 animals (8.35%) recovered after the second surgical interference after management of complications, 43 animals (5.44%) were culling either by slaughtering or euthanasia and 92 animals (11.65%) the fate was not recorded postoperatively.


INTRODUCTION
Abscess is the most common swelling observed on the skin surface of animal body. It is a collection of pus that hollow out a cavity in the tissues by destroying and expanding them. The invading micro-organisms gain entrance into the animal body through a breach in the skin or mucous membrane or transmitted passively into tissues incorporated with infected foreign bodies. Many infectious diseases are characterized by formation of either superficial abscesses underneath the skin or deep abscesses inside tissues and body organs. Bus is the end result of a war established between the invading pyogenic microorganisms and living tissues and cells. It is consisting of a dead and living polymorph nuclear leucocytes, cellular debris, pyogenic microorganisms, lymph and serum (Fubini et al., 2004;Abouelnasr et al., 2016;Sadan et al., 2019 andMisk et al., 2019).
The aim of the present study is to determine the predilection seats of body surface abscesses in some farm animals, their potential causes as well as the methods of surgical treatment, fate and complications after treatment.

MATERIALS AND METHODS
The present study was carried out on a total number of 790 animals suffering from presence of abscesses on body surface. All cases were recorded and managed during field trips to villages of 27 provinces allover Egypt during the period from 2003 to 2018. Diagnosis was established depending mainly on case history and clinical presentation of cases. Exploratory puncture was performed for confirmation of diagnosis. The surgical treatment was adopted by either performing a surgical incision through the abscess wall and evacuation of the contents or by total excision of abscesses. The follow up period was extended up to two months. The Predilection seats of abscesses were registered in all examined animals which include; buffaloes (n = 131), cattle (n = 240), sheep (n = 230), goats (n = 81), donkeys (n = 64), horses (n = 17), and camels (n = 27). The suspected way of infection was recorded according to the case history, clinical signs and findings during surgery.
The criteria for selecting and analyzing data were; frequency of occurrence of abscesses in animal species, predilection seats of abscesses, potential causes, surgical treatment options either by evacuation of abscesses contents after incision or by en bloc excision of the abscesses, recorded complications and finally, the fate after treatment.

1-
The number of affected animals and the predilection seats of body surface abscesses were summarized in table 1 and Figs 1 and 2.

2-The potential causes of abscesses in relation to different predilection seats (table 2).
The ways of entrance of infection were suspected because it is impossible to known accurately the way for infection of each case alone. Sub-conjunctival (s/c) -Entrance of infection S/C by infected foreign body.

4
Cheek region -Oral abrasions and punctures associated with dental disease or hard plant awns, etc.
-Complications of lumby skin disease. 8 Chest wall behind the elbow -Migrating foreign bodies from the reticulum. 9 Abdominal wall -Skin breach. 10 Umbilical region -Infection of the Umbilicus. 11 Pelvic limbs -Complications of Lumpy skin disease. 12 Gluteal region -Intra-muscular injection via infected needle.

3-The frequency of occurrence of solitary (S) and multiple (M) abscesses in different animal species (table 3)
Solitary abscesses were observed in a total number of 682 animals (86.33%) while animals affected by multiple abscesses were 108 (13.67%).
Recorded complications after surgical treatment (66 animals) include; recurrence of abscess at the same or another place (54 animals), sinus formation (9 animals), and ulcer formation (3 animals).
Complete recovery after the first surgical interference occurred in 74.56% of cases and after the second trail in 8.35%. A percent of 5.44% of animals were culled either by slaughtering or euthanasia and 11.65% was not recorded (Table 5).

DISCUSSION
Causes of abscess formation in farm animals are variable and include a breach on the surface of the skin or mucous membrane and entrance of pyogenic microorganisms through it, infected foreign bodies migrating from the lumen of digestive tract, nonsterilized needle used for intramuscular injection, punctured wounds induced by infected foreign bodies and blood and lymph-borne infection (Fubini et al., 2004;Misk et al., 2008;Misk et al., 2016 andMisk et al., 2019).
Predilection seats of abscesses in different farm animals depend mainly on the way of entrance of infection. Abscesses at the parotid and mandibular regions are due to either infected foreign body penetrating the oral mucosa and soft tissues or due to lymphatic borne infection. In the present study the most common animals affected with abscesses at the submandibular region were sheep due to caseous lymphadenitis. Transmission of caseous lymphadenitis occurs via ingestion or inhalation of infected bacteria from the environment. The organisms gain access to the body via break in the skin during shearing or dipping for external parasite. Lymph nodes at the mandibular and parotid regions as well as at the neck and hind legs often have abscesses in sheep. The abscesses are multiple and appear as firm masses that can be expressed intact by surgical excision and often has a laminar appearance when cut in cross section (Williamson et al., 2001;Misk et al., 2008 andFontasine et al., 2008).
Strangles is one of the first equine diseases described in the literatures. It is characterized by sudden onset of fever and upper respiratory catarrh, followed by acute swelling and subsequent abscess formation in the sub-maxillary, sub-mandibular and retropharyngeal lymph nodes (Reile et al., 1983;Sweeny et al., I 1987 andSweeny et al., II 1987). In the present study abscesses at the mandibular region in donkeys and horses were due to strangle infection.
Sub-conjunctival and third eyelid abscesses are usually due to penetration of the conjunctiva with infected foreign body present accidently in the conjunctival cul-de-sac. Continuous blepharospasm may force the foreign body to penetrate the palpebral or bulbar conjunctiva and inoculate infection subconjunctively with subsequent formation of abscesses (Misk et al., 1986;Lavach et al., 1990 andMisk et al., 2014). This condition was recorded frequently in buffaloes and cattle in the present study.
Cheek abscesses were also diagnosed in ruminants. Oral abrasions, openings and punctures associated with dental disease, hard plant awns, thorns, stickers or dry coarse stemmed feeds are the way for entrance of either nonspecific microorganisms inducing abscess at the cheek, mandibular space, pharynx and oral cavity or specific microorganisms as actinomyces bovis leading to actinomycosis with formation of granulomatous abscesses in the mandible, maxilla and some soft tissues.
Abscesses at the neck region especially at the base or close to the pre-scapular region are in most instances due to lymph-borne infection as the pre-scapular lymph node may be the seat of caseous lymphadenitis in most animals. Seats of abscesses in sheep and goat were the pre-scapular lymph nodes then the prefemoral lymph nodes (Abebe et al., 2015). Thoracic limbs abscesses were seen in the present study in all animals and appear to be due to lymph borne infection which may lead to caseous lymphadenitis and caseous lymphangitis.
In most instances, abscess formation adjacent to the reticulum is secondary to hardware disease. In the present study several abscesses were diagnosed in buffaloes, cattle and sheep behind the elbow at the right thoracic wall. Opening and drainage revealed presence of foreign bodies such as sewing needles and pieces of wire (Misk et al., 1981;Misk et al., 2001;Fubini et al., 2004 andSangwan et al., 2017).
Umbilical abscess or infection of any of the three components of the umbilicus (arteries, veins and urachus) may produce local infection with abscess formation. The source of infection is most commonly the external environment, coupled with failure of passive transfer. Umbilical abscesses were diagnosed in the present study mainly in buffaloes and cattle. They appear as warm, painful, non-reducible and firm or fluctuant mass. Aspiration revealed purulent material from the mass. Most of abscesses will respond to treatment by drainage and lavage of the abscess cavity (Fubini et al., 2004 andMosbah et al., 2006).
Pelvic limbs abscesses were seen frequently in the present study in cattle and sporadically in goat, sheep and buffaloes. The large number of cases recorded in cattle was due to complications of Lumpy skin disease. The latter is an infectious viral disease characterized by formation of nodules or lumps in the skin covering all parts of the body. Secondary infections sometimes occur and cause extensive suppuration and sloughing of tissues. The hind limbs show signs of inflammation and swellings at the gaskin region. The swelling was filled with pus and threads of necrotic tissues. Opening and drainage were indicated immediately for treatment of such cases (Davies, 1991;Fubini et al., 2004;Pressz et al., 2015 andTuppurainen, 2018).
Abscesses at the ventral abdominal wall, perineal region, tail and vulvar lips may be due to skin breach or penetration of infected foreign bodies through the soft thin skin at these areas. Gluteal region abscesses were recorded frequently in cattle and buffaloes. This condition appears to be due to intramuscular injection of medicaments with non-sterilized needle (Tuffyli et al., 2012;Pressz et al., 2015 andAttia et al., 2019).
Abscesses around scrotum were sporadically recorded in sheep in the present study due to faulty castration by Burdizo instrument. The most common complications after pig castration were hemorrhage, abscess, scirrhous cord, inguinal hernia and hematoma formation. Abscesses were detected in the present study after castration in the pelvic region (Szazado 1985 andSteerforth et al., 2015).
Solitary abscesses in the present study were diagnosed in 682 animals (86.33%) while multiple abscesses were detected in 108 animals (13.67%). Multiple abscesses were seen when the cause was blood or lymphborne infection as in cases of caseous lymphangitis and caseous lymphadenitis in cattle, sheep and goats.
Multiple abscesses were detected at the parotid and mandibular regions, thoracic limbs and pre-femoral lymph node, while solitary abscesses (one abscess per one animal) were detected when the cause is breach on the skin surface, penetrating foreign bodies, intramuscular injection with infected needle and migrating foreign bodies from the digestive tract (Misk et al., 1985;Misk et al., 2008 andMisk et al., 2014).
Concerning surgical treatment of abscesses, the authors of the present study suggested two approaches for correction of such cases. The first approach is the opening of the abscess after maturation and evacuation of its contents. The second is the en bloc excision of abscess. The first option is performed when the abscess has no limitations and extended under the surface of the skin as well as close to a vital structure while the second option is performed when the abscess is well circumscribed, firm and movable under the skin. Moreover, the first approach takes a long time for healing (20-30 days) and needs daily wound management for healing by second intention while the second approach needs not more than 10 days and the skin wound healed by first intention.
Around 75% of animal were recovered without any postoperative complications. 8% of animals were added to the recovery group taking in consideration some complications which may supervene during the first trial of treatment. When multiple abscesses were detected in one animal the decision of slaughtering (ruminants) or euthanasia (equine) was taken in 5.44% of affected animals. Follow up of some treated cases (11.65%) was not performed due to bad connections or carelessness of owners.
In conclusion, body surface abscess in farm animals are located at specific seats on the animal body. The location of abscesses is related to the way of infection and presented either solitary or multiple. Surgical treatment was successful in most of presented cases. Abebe, A. and Ressema, TS. (2015): Determination of corynebacterium pseudotuberculosis prevalence and antimicrobial susceptibility pattern of isolates from lemph nodes of sheep and goats at an organic export abattoir, Modjo, Ethiopia. Letters in Applied Microbiology ISSN 0266-8254. Abouelnasr, K.; El-Shafaey, E.; Mosbah, E. and El-Khodery, S. (2016): Utility of ultrasonography for diagnosis of superficial swellings in buffalo (Bubalus bubalis). Journal of