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CLINICAL FEATURE
Staying alert to lumpy skin disease
Australia’s animal health system relies on veterinarians reporting any suspicion of an emergency animal disease. Lumpy skin disease has never occurred in Australia, but it is an emerging threat as it continues its spread through Asia and most recently into Indonesia and Singapore. Lumpy skin disease is caused by a virus from the Poxviridae family. It is a serious disease that primarily affects cattle and water buffalo, although it has also been seen in other bovids and giraffes. There is no reliable evidence that the virus causes disease in humans. It is vital that veterinarians stay alert to this disease so that early detection of an outbreak can be made. The disease would have significant and far-reaching impacts should there be an incursion in Australia. There is currently no vaccine available for use in Australia.
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Infection with lumpy skin disease virus typically causes painful characteristic skin nodules which cover the body of the animal. Cattle with lumpy skin disease may show firm, raised nodules up to 50mm in diameter which develop on the skin around the head, neck, genitals and limbs. Scabs develop in the centre of the nodules. When the scabs fall off, large holes are left which may become infected. The limbs, brisket and genitals can become swollen. The virus can persist in scabs for up to four months after the animal is infected and can persist in the environment for extended periods. Other disease symptoms include fever, watery eyes, loss of appetite, and a reluctance to move. There may also be a marked reduction in milk yield, damaged hides, and abortion in pregnant animals. While some infected animals may not show signs of disease, it can kill some animals.
The disease is highly infectious and is primarily spread through biting insects such as flies and mosquitoes, and also ticks. The movement of infected animals is another cause of spread, enabling new populations of biting insects to become mechanical vectors of the disease. The disease can also be spread by fomites such as contaminated equipment (for example, used vaccine or antibiotic needles) and in some cases, directly from animal to animal. The Emergency Animal Diseases Field Guide for Veterinarians (Department of Agriculture & CSIRO 2019)1 has more specific information about lumpy skin disease, including differential diagnoses, and is free to download.
Lumpy skin disease is a nationally notifiable disease; veterinarians should be aware of what the disease looks like and report any suspected cases of the disease immediately to the Emergency Animal Disease Watch Hotline on 1800675888. This number will connect you with your state or territory’s department of primary industries or agriculture.
Further information about lumpy skin disease can also be found on the department’s lumpy skin disease webpage (Department of Agriculture 4 March 2022)2 .
References
1. Department of Agriculture & CSIRO 2019, Emergency animal diseases: A field guide for Australian veterinarians, Canberra, available at www.outbreak.gov.au/for-vets-and-scientists/ emergency-animal-diseases-guide 2. Department of Agriculture, Water and the Environment, 4 March 2022, ‘Lumpy skin disease’, Canberra, available at https://www.awe.gov.au/ biosecurity-trade/pests-diseasesweeds/animal/ lumpy-skin-disease accessed 5 April 2022. ■ KALLY GROSS
Cows infected with lumpy skin disease virus.
Pictures Michel Bellaiche, Kimron Veterinary Institute
Penny Linnett BSc (Zool Hons) BVSc MPhil MANZCVS
Penny has worked extensively in private mixed practice, and in animal biosecurity and welfare for both government and not-for-profit organisations. She manages a 212 hectare Dorper sheep breeding property in NSW, and is co-Director ofYour Hobby Farm Success, helping hobby farmers enjoy their lifestyle, and reap the benefitsof having healthy and happy animals.
Rectal prolapse – a brief review
Summary
Rectal prolapse occurs in many species and may be caused by persistent tenesmus associated with enteritis, intestinal parasites, rectal disorders, and other underlying conditions. Diagnosis is made based on seeing a cylindrical tissue-mass protruding from the anus – either temporary or more permanent. Treatments include lavage of the protruding tissue, reduction, and placement of a temporary purse-string suture to prevent relapse. Use of local and epidural anaesthesia can help reduce straining and aid in reduction of the prolapse. Arectal prolapse can be lifethreatening as much of the large intestinal tract can prolapse.
Introduction
Rectal prolapse is characterised by the protrusion of one or more layers of the rectum through the anus. It may be ‘partial’ (also known as ‘incomplete’ and ‘rectal eversion’) or ‘complete’. In a partial prolapse, only the rectal mucosa protrudes through the anus; there may be a small portion of the rectal mucosa that is visible during defaecation but recedes afterwards. In a complete prolapse, there is a double layer evagination of the rectum, sometimes including the anorectal junction through the anal canal, and the tissue mass does not recede back through the anus.
Rectal prolapse has been typed into four categories - mucosal prolapse of the rectum, complete prolapse of the rectal wall, rectal prolapse with invagination and rectal hernia.
There may be multiple contributing factors, but the basic premise is persistent tenesmus associated with anorectal, intestinal, or urogenital disease. Rectal prolapse can affect animals of any age, breed, or sex; it is most commonly seen in cattle, donkeys, pigs and sheep, and in young animals with severe diarrhea and tenesmus. Prolapses occur less often in goats than sheep.
Aetiology
There are many contributing factors including age (young animals are more susceptible; rectal prolapse affects about 2 per cent to 10 per cent of lambs from weaning to approximately 1 year of age); gender (females are thought to be over-represented); enteritis / colitis; severe / chronic diarrhea and persistent tenesmus; constipation post-gastrointestinal surgery; genetic susceptibility (not a problem in pigs); endoparasitism; pathology of the rectum (e.g. neoplasia, lacerations, foreign bodies); genitourinary pathology (e.g. urolithiasis, urethral obstruction, cystitis, prostatic disease); parturition (dystocia; very common in horses); pelvic musculature and neurological defects (e.g. perineal hernia); interference with the external anal sphincter; hormonal (in sows, prolapses occurring after oestrus may be related to sex hormone levels) and environmental.
Environmental factors are important inpigs; stalls or tethers with an excessive floor slope, and sow stalls or farrowing crates with the back retaining gate consisting of parallel bars, predispose individuals to rectal prolapse. Inpigs, rectal prolapse is a common gastrointestinal problem and is mainly due to diarrhea or weak/absent supporting tissues for the rectum within the pelvis. It is usually a sudden onset, widespread condition typically occurring in good growing pigs from 8 to 20 weeks of age; the highest incidence being described in young pigs between 6 and 16 weeks of age, varying from 0.7 per cent to 15 per cent. It israre in piglets but may be seen occasionally in sows, where the incidence varies between 0.5 per cent and 1 per cent; two-thirds of cases occur around parturition (Borobia-Belsue, 2006). In cold weather the incidence of rectal prolapse increases as pigs tend to huddle together in low temperatures, thereby increasing abdominal pressure. Also, wet conditions and slippery floors, particularly those with no bedding, increase abdominal pressure and hence the likelihood of rectal prolapses occurring. High stocking densities can prevent pigs from laying on their sides across the pen and predispose individuals to rectal prolapse.
In dogs, especially young ones, individuals with viral infections or endoparasitism are at increased risk of developing a rectal prolapse. Other predisposing factors include laxity of the anal sphincter or perianal connective tissue (perineal hernia with rectal sacculation). Rectal prolapse most commonly affects puppies under 6 months of age who have frequent bouts of severe diarrhea or strain to defecate. If left untreated, a puppy with a rectal prolapse will be unable to defecate, which will invariably lead to severe illness and eventually death.
Rectal prolapse is not common in adult horses and it is usually a sequel to excessive straining due to dystocia or other disease. However, it is common in foals in association with severe diarrhea and straining to defecate or urinate.
In cattle, rectal prolapse is an occasional occurrence and may be associated with coccidiosis (in young cattle especially), rabies (sometimes), and vaginal or uterine prolapse. Occasionally, excessive “riding” and associated traumatic injury may cause rectal prolapse in young bulls.
Insheep, rectal prolapse is common in individuals with short docked tails and especially in lambs which are fed high-concentrate rations, as occurs in feedlots. Exposure to oestrogenic pastures and oestrogenic fungal toxins may also predispose to rectal prolapse. Various clovers (e.g. lush red and white), and legumes such as alfalfa and field peas contain phytoestrogens which can cause relaxation of the anal sphincter muscles.
Rectal prolapses are common in growing, weaned lambs and cattle from 6 months to 2 years of age and are usually secondary to other diseases or management-related circumstances. Overly fat cattle and sheep, and especially those animals in the latter stages of pregnancy, may also exhibit intermittent rectal prolapse. Also, abdominal enlargement related to excessive rumen filling or bloat may cause rectal prolapses, as can coughing during respiratory tract infections (e.g., chronic coughing). Intermittent rectal prolapse has been seen in embryo transfer cows and may be caused by obesity with excessive pelvic deposition of fat and chronic administration of estrogenic hormones.
Acommon cause of rectal prolapse in sheep is the result of ‘too short’ tail docking which compromises the innervation of the anal sphincter and perianal muscles, leading to chronically progressive rectal protrusion and ultimately, rectal prolapse.
Anderson (2009) cited a prospective study (Thomas et al 2003) where 1227 lambs at 6 locations were assigned to one of three groups – one group to have short tail dock at the level of the body,asecond group to have medium tail docking at the midpoint between the body and the attachment of the caudal tail fold to the tail skin, and athird group to receive long tail dock at the level of the attachment of the caudal tail fold to the tail skin.
Figure 1. Colin’s rectal prolapse before treatment (manual reduction under caudal epidural anaesthesia; with purse-string suture). Colin was a healthy 5-month-old pure-bred Dorper wether lamb
The incidence of rectal prolapse was reportedly 7.8 per cent of lambs with short tail docks compared to 4 per cent of lambs having medium tail docks and 1.8 per cent of lambs with long tail docks. The study also observed that lambs in feedlots had rectal prolapse more often than grazing lambs, and genetic analysis of rectal prolapse using half siblings indicated a low heritability factor (0.14). However, other factors such as increased coughing, increased body fatness, lack of exercise and diet components were not considered in the study.
While sheep of any age, breed or sex may be affected, ewe lambs that prolapse should not be retained for breeding, as they are more likely to exhibit vaginal prolapse at (or just before) lambing.
Rectal prolapses may be accompanied by intestinal intussusceptions that will likely further complicate treatment and increase mortality. Occasionally, acute rectal prolapses with evisceration will result in shock and prompt death of the animal.
Clinical signs
The primary clinical sign is an elongated, cylindrical mass protruding from the anus. The mass isusually a bright cherry-red colour initially, and it will seep red blood if the tissue has been injured or ulceration is present. With continual exposure to the environment, the mucosal surface becomes darker and congested, dry and even cracked, and possibly grossly contaminated with faeces and soil. This causes more irritation to the animal and hence, more straining. In the chronic stages, the exposed tissue mass can be necrotic.
It is important to distinguish a rectal prolapse from a prolapsed ileocolic intussusception. In small animals this is done by passing a well-lubricated probe (blunt instrument or thermometer for example) or finger between the prolapsed mass and the inner rectal wall (ie: alongside the prolapse). In a rectal prolapse, the probe cannot be inserted because of the presence of the fornix, whereas in an intussusception, the probe can be inserted cranially more than a few centimetres (i.e., 5 or 6 cm past the mass).
In the horse, systemic clinical signs include tachycardia, tachypnea, increased borborygmi, normal or increased rectal temperature, inappetance, depression, dehydration, and cardiovascular compromise.
In pigs, the size of the prolapse can varyfrom 10mm to 80mm and if small, it will often revert into the rectum spontaneously.In most cases however the prolapse remains out and becomes swollen and oedematous and subject to haemorrhage; it is often cannibalised by other pigs in the pen. If this happens, it normally results in death of the animal by septicaemia, shock, or faecal peritonitis. Affected pigs may also beanaemic, constipated, have blood in the faeces and death may occur.
Diagnosis
Diagnosis is straight forward - a tube-like mass of varying length protruding through the anal orifice is usually diagnostic. The mass can be differentiated from a prolapsed ileocolic intussusception by passing a blunt instrument or probe or finger between the prolapsed mass and the inner rectal wall. In rectal prolapse, the presence of a fornix will prevent the probe from being inserted.
A thorough physical examination should be performed. Faecal analysis (e.g., for parasite larvae/eggs), complete blood count (e.g. there may be high levels of white blood cells) and blood profile are also useful. Urinalysis (+/- culture), abdominal imaging (may demonstrate a large prostate, foreign bodies, thickening ofthe bladder walls, or kidney stones) and thoracic imaging may provide additional diagnostic causative information. In all species, identification, and elimination of the cause of the prolapse is important to prevent recurrence.
Arectal examination may be performed but it is important to be very careful to ensure that the animal is not in any undue stress during the procedure.
During examination of the rectal tissue mass, itmay appear swollen, and will ooze red blood if incised. The tissue, if dead, appears dark purple orblack and will ooze bluish blood if incised.
And a quick note about (the lack of) haemorrhoids in dogs. Haemorrhoids are distended blood vessels in the rectum or anal area. Haemorrhoids are swollen blood vessels that form either externally (around the anus) or internally (in the lower rectum) in the rectum or anal area. Dogs do not suffer from haemorrhoids because they do not have the added downward pressure of body and organ weight pushing on the blood vessels of the rectum and anus; this is often a contributing factor to developing haemorrhoids. By age of 50 in humans, about half of the population has experienced one or more of the classic symptoms of haemorrhoids, including rectal pain, bleeding, itching and possibly prolapse (i.e. haemorrhoids that protrude through the anal canal).
Treatment
In all animals, treatment is based on lavage of the protruding tissue, reduction, and placement of a temporarypurse-string suture. Identification and correction of the underlying cause is essential for treatment success. Laparoscopic evaluation of reduced prolapse can help assess viability of bowel and mesentery.
Treatment should be initiated promptly to reduce the possibility of further trauma, but options will depend on the stage at which the prolapse is identified, as the level of irritation and amount of prolapsed rectal tissue increases with time. Continued blood in the faeces is suggestive of tissue necrosis.
Many cases, especially those in large animals, may require immediate euthanasia on welfare grounds; also costs of treatment, ongoing care and prognosis may make treatment prohibitive.
It may be possible to provide some ‘first aid treatment’ to keep the area clean and to prevent further damage to the prolapsed tissue. For example, spraying the mass with some sterile saline contact lens solution placed into a squirt bottle, or you can make your own version of saline by mixing 1 to 2 teaspoons of table salt with about 2 cups of lukewarm water; lubricating the area with a cream, ointment, KY jelly, obstetric lube. In small animals, it may be possible to wrap the area with a towel moistened with saline solution. tissue to its proper anatomic location, or amputation if the segment is necrotic. There are three surgical techniques to treat/prevent rectal prolapse, which are placing a perianal pursestring suture; colopexy; and rectal resection. Selection of the best technique depends on whether the mass can be successfully treated (and if it is recurrent) and assessment of the viability of the prolapsed tissue.
Partial prolapses usually respond well to medical management. This includes warm saline lavage and lubrication (e.g., gel) of the prolapsed tissue before gently replacing it through the anus. Topical hypertonic sugar solution (50% dextrose or 70% mannitol) is also useful to reduce the oedema in the mucosa, as is topical glycerine, magnesium sulphate or lidocaine. Application of atopical antibiotic-steroid ointment for 7 to 10 days is recommended. To prevent a recurrence of a prolapse, a loose, anal purse-string suture should be placed and left in situ for 5 to 7 days.
Purse-string sutures are fairly quick and easy to place, and the risk of complications is minimal. It is the least invasive and least expensive technique and is usually chosen when the condition
causing the prolapse is readily treatable, and any tenesmus can be controlled.
Tenesmus (straining) can be prevented by applying a topical anaesthetic or by administering a narcotic caudal epidural injection before or after reduction. A moist diet and a faecal softener (e.g., dioctyl sodium sulfosuccinate) or enema/s are recommended postoperatively. Diarrhoea may occur post-reduction and may require appropriate supportive treatment.
Management of a complete rectal prolapse depends on tissue viability and the number of recurrences of the condition. If the rectal tissue is viable (i.e.: feels warm and has red oxygenated blood oozing from the surface) and it is the first occurrence, a simple reduction under general anaesthesia / epidural analgesia with the placement of an anal purse-string suture should be enough. The oedematous mucosa should be well lubricated and gently massaged to reduce the swelling prior to reduction. Warm isotonic solutions dilate blood vessels and allow interstitial oedema to be removed by gentle manipulation.
In order to have correct tension on the pursestring suture, it is useful to preplace the suture (at the anocutaneous line immediately cranial to the anal sac duct orifices) and then insert a well-lubricated small tube (e.g., the ‘old’ glass lavender top blood collection tube works well) and then draw the purse-string tight enough so that the rectal mucosa rests gently on the tube. The tube is then removed, and the suture can usually be left in situ for 7 to 10 days.
If the rectal prolapse is viable but cannot be reduced manually,or if there is a historyof
Figure2. Colin’srear end after 6 weeks
multiple recurrences, then celiotomy or celiotomy and colopexy is recommended. Colopexy is an effective prophylactic treatment in cats where purse-string management is often ineffective and the risks of suture line dehiscence or rectal stricture after amputation are high. Epidural anaesthesia is useful to prevent and reduce straining.
When the prolapsed segment is devitalised (i.e., is dark purple or black in colour and exudes dark cyanotic blood from the surface), rectal resection and anastomosis are required. Complications include suture line dehiscence and stricture formation.
If the underlying cause remains undetermined or was not eliminated, owners should be made aware of the likelihood of recurrence of the rectal prolapse. A rectal prolapse does not occur without cause. Also, any surgery site needs to be monitored for the first 5 to 7 days, as there is the possibility of splitting and reopening, especially when the animal defaecates.
Colopexy is invasive, and recurrence of the prolapse may occur if the cause of the tenesmus is not controlled. There is little additional risk tothe patient.
Rectal resection has the advantage of removing the diseased portion of the rectum and it eliminates redundant tissue, thereby decreasing the risk of the prolapse recurring. There is increased risk of more serious complications with this technique such as incontinence, formation of strictures, and wound dehiscence which may be life-threatening.
For all cases, the goal should be to eliminate any post-operative tenesmus. Local anaesthetic ointments instilled rectally, or epidural analgesia are recommended for short-term (i.e. few days) use. Faecal softeners, such as dioctyl sodium sulfosuccinate, should be given as well as antibiotics, intestinal protectants, or anticholinergics if diarrhea is present.
Prognosis depends on degree, duration, and underlying cause. It is usually good provided the underlying cause can be identified and corrected, and the prolapse is not chronic.
Large animals
In large animals, caudal epidural anaesthesia is recommended to reduce straining, facilitate reduction of the prolapse, and permit surgical manipulation. A purse-string suture should be placed to prevent recurrence of the prolapse, and it should be loose enough to leave a onefinger opening into the rectum in pigs and sheep, and appropriately larger in cattle and horses.
In horses, the preferred treatment for the most commonly seen types of rectal prolapse (rectal mucosal prolapse and prolapse of rectal mucosa and muscularis layers) is manual reduction of the prolapse (under general / epidural anaesthesia) in conjunction with physiotherapy to reduce oedema and swelling of the rectal mucosa, and supportive treatment. More severe cases (prolapse of the small colon that has undergone intussusception through the rectum and prolapse of the rectal mucosa and muscularis with concurrent intussusception of the small colon) represent a much more difficult problem and carry a guarded prognosis; exploratory laparotomy is recommended in the management of these cases. Surgical resection or euthanasia may be required. If neglected, rectal prolapse in mares can lead to prolapse of the small colon. As the blood supply to the small colon is easily disrupted, replacement of a rectal prolapse with prolapse of the small colon followed by the placement of an anal pursestring suture, has a poor prognosis. Treatment success depends on the extent of the prolapse –good in many mild cases if the underlying disease is also treated and guarded in cases where amputation of the prolapsed portion of bowel was necessary.
Generally, a rectal prolapse can be salvaged by conservative treatments unless deep necrosis or trauma to the tissue exists, or the tissue is firm, indurated and cannot be manually reduced. Amputation of the rectum should be reserved for severe cases; complete amputation has a higher incidence of rectal stricture formation, especially in horses and pigs.
Aprolapse rectal ring, syringe case, or short piece of hose/plastic tubing may be used in severe cases and as an alternative to surgical amputation in pigs and sheep. The ring (use the largest size possible) is inserted into the rectum and the prolapse is tied off close to the body with an elastrator ring or umbilical tape. The prolapsed tissue will slough in about 7 to 10 days (may be as early as 5 days). The animal should be given a faecal softener and adequate antibiotic coverage.
In pigs, rectal prolapses need to be recognised early and the animal removed from the pen. The simplest treatment is to replace the prolapse and insert a purse-string or mattress suture. If the prolapse has been badly torn, it should still
be replaced, and the pig moved to a separate pen and treated with a long-acting antibiotics. The damaged tissues may become scarred in a proportion of cases, with constriction leading to rectal strictures. The incidence of this can be reduced by replacing the prolapse and suturing. Postoperative antibiotics and faecal softener are recommended.
In 2008, the Pipestone Veterinary Clinic published a technique for the early treatment of rectal prolapse in sheep. Briefly,the technique involves the injection of a substance such as oxytetracycline or iodine along the rectal wall (use a maximum of 4 ml and a 2-inch 18-gauge needle inserted full length, 1 ml per site, and the needle should stay parallel to the rectum and should not penetrate the rectal wall); injecting at 3(female) or 4 (male) sites around the anus. It is recommended that ewe lambs be injected at the 12, 3 and 9 o’clock positions and male lambs at the 12, 3, 6 and 9 o’clock positions. Injecting ewe lambs at 6 o’clock can form adhesions between the rectum and the reproductive tract. This may be combined with a purse string suture; daily administration of a mild laxative and suitable antibiotic coverage are required.
For more severe cases, a prolapse rectal ring (or short piece of hose) can be used for repair. The ring is placed in the rectum and umbilical tape (or elastrator band) is placed around the protruding rectal tissue. The prolapsed tissue will slough in about 7 to 10 days. And daily administration of a faecal softener and antibiotic coverage is recommended.
Prevention
As rectal prolapse is, generally speaking for most species, an uncommon disorder, it is difficult to prevent. Good management practices such as keeping animals healthy (regular parasite control, vaccination, good feed with attention to concentrate rations and water availability), not breeding from affected individuals, and seeking veterinary assistance for coughing / diarrhoea / constipation / dystocia will help reduce the possibility of rectal prolapse occurring.
The incidence of rectal prolapses can be reduced, or even prevented, with good management practices. Given the possible causative factors, probably the most important step is selecting the correct/best genetics. Rectal prolapse is closely associated with oestrogen and therefore, incidences of rectal prolapse are rarely observed in rams, for example.
In breeding programs, ideally, ewe lambs that have prolapsed should not be used and rams that have prolapsed themselves or that sire a high percentage (greater than 10) of prolapsing offspring should not be used either. A more conservative approach for the young ewes could be limiting access to high quality supplementary feeding from weaning to 10 months of age; these animals only receiving natural pasture and moderate to low quality roughage. Black-headed lambs are thought to be more susceptible to developing rectal prolapse so judicious weightmanagement is recommended for owners of these breeds.
Fat ewe lambs are more prone to prolapsing than ram or wether lambs as they have more fat in the pelvic region. And this means that even more pressure is placed on the rectum when the animal coughs. Ewe lambs should be monitored as part of a good management program so that the body condition score does not exceed much more than a 3 – and ewe lambs that have prolapsed should not (ideally) be kept as replacements.
Tail dock length is important as is maintaining lambs in good, but not fat, condition score. Chronic coughing is a primary cause of rectal prolapse in lambs raised on drypasture and this is especially the case during drought conditions. Arectal prolapse as a result of coughing will usually worsen if not treated. Infectious agents, dusty feeds and internal parasites are well known causes.
Selected references
1. Anderson DE (2009) Rectal Prolapse in Food Animal Practice. https://doi.org/10.1016/ B978-141603591-6.10032-6 2. Brister J (2020) Rectal Prolapse in Dogs and Cats. https://veterinarypartner.vin.com/default. aspx?pid=19239&catId=102903&id=9761112 3. Gallagher A (2020) MSD Manual – Rectal prolapse in animals. https://www.msdvetmanual.com/ digestive-system/diseases-of-the-rectum-andanus 4.Gillette J (2021) Rectal Prolapse in Dogs. https://www.petmd.com/dog/conditions/diges tive/c_multi_rectal_prolapse 5.ScienceDirect Topics – Rectum Prolapse: an overview. https://www.sciencedirect.com/ topics/immunology-and-microbiology/rectumprolapse 6. Schoenian S (2006) Rectal prolapse. https://www.sheepandgoat.com/rectalpro 7. Thomas DL (2003) Length of docked tail and the incidence of rectal prolapse in lambs http://www.ncbi.nlm.nih.gov/pubmed/14601875
