Peritonitis in Canine
Andy Pachikerl, Ph.D
Peritonitis is the inflammation of the peritoneum, which is a silk-like membrane that lines the inner abdominal wall of mammalian bodies and covers the organs within the abdomen, and it is usually due to a bacterial or fungal infection. Peritonitis typically results in rupture (perforation) in the abdomen or causes other medical conditions. In canine or dogs this condition is not that different compared to other mammals, which is the peritoneum of the abdominal cavity, becomes inflamed. In canines, this normally occurs because of an injury by physical trauma, disease, a stomach ulcer, or other problems (Latimer, et al., 2019).
The most common cause of peritonitis in canine is actually bacterial infection that moves to the abdomen from an external wound or from perforation of an internal organ. An affected dog may seem to be well, then suddenly become ill. The condition is usually painful, and most dogs will show signs of discomfort when they are been touched on the abdomen (Kine, et al., 2019).
Classification and Etiology
Peritonitis in dogs are classified in various ways, but there are two main methods of identification are (1) localized or diffuse and (2) primary, secondary, or tertiary. Localized septic peritonitis occurs when a small amount of contamination, whether bacterial or fungal is confined. The contamination usually originates from an intraabdominal organ due to secondary surgery or an underlying disease process, such as gastrointestinal (GI) perforation due to a foreign body. Diffuse peritonitis arises from either a larger amount of contamination or a failure to control localized septic peritonitis.
Primary septic peritonitis is spontaneous, and it is the infection of the peritoneal cavity with no specific intraperitoneal source of infection detected during surgery or necropsy. This type of peritonitis is more common in cats rather than dogs, with 14% of cats with septic peritonitis having primary septic peritonitis in one study (Costello, et al., 2004; Odonez & Puyana, 2006; Culp, et al., 2009). Primary septic peritonitis is usually monomicrobial, whereas secondary septic peritonitis is often polymicrobial (Mueller, et al., 2001). In one study (Mueller, et al., 2001), bacteria cultured from patients with primary peritonitis were gram positive in 80% of dogs and in 60% of cats. It is postulated that primary septic peritonitis may result from hematogenous or lymphogenous bacterial spread, transmural bacterial migration from the GI tract, or bacterial spread from the oviducts (Culp, et al., 2009; Enberg, et al., 2006).
Secondary septic peritonitis is a consequence of an underlying primary disease process and is the most common cause of septic peritonitis in dogs and cats (Mueller, et al., 2001). There are many possible causes of secondary septic peritonitis in animals; the most common are loss of integrity of the GI tract (53% to 75% of cases), foreign-body penetration, perforating ulcers (Figure 1) and surgical wound dehiscence (Mueller, et al., 2001; Costello, et al., 2004).
It is the upmost recommendation that canines showing peritonitis signs should seek medical help from a veterinarian for a proper diagnosis and treatment, as it can be a life-threatening condition.
Figure 1: Septic peritonitis secondary to jejunal rupture from a perforating ulcer (arrow).
Symptoms of Peritonitis in Dogs
In most cases, the symptoms of peritonitis in canines are easy to recognize. A dog may seem fine, then suddenly become very ill the following day. They will almost certainly show signs of pain when their abdomen is been touched (DeClue, et al., 2011).
Canine that has been injured or wounded seemed fine but suddenly develop the following symptoms the next day then one may consider seeking a veterinarian right away.
- Fever: – normal body temperature in canine ranges from 99.5 – 102.5 ° F, whereas a body temperature of at least 103.5 ° F (39.7 ° C) can be considered as fever.
- Black stools
- Abdominal pain
- Taking unusual positions to relieve pain
- Low blood pressure
- Increased heart rate
- Increased respiration rate
- Low body temperature
- Pale gums
- Jaundice: – Jaundice in canines refers to a build-up of yellow pigment in the blood and tissue, which causes a yellow discoloration in the skin, gums, and eyes.
- Swelling in the abdomen
- Ascites: – Ascites in canines is an abnormal build-up of fluid in the abdomen. It is also called abdominal effusion.
- Arrhythmia: – Arrhythmia in canines is an abnormality in the rhythm of the heart, which can include the speed, strength, or regularity of heart beats.
There are cases when peritonitis could become severely complicated by gut microbiota of the dog. These can lead to changes in the dog’s micro flora forever. Such a case is shown as follow.
An 11‐year‐old intact male Poodle was brought to Oklahoma State University, Center for Veterinary Health Sciences (OSU‐CVHS), with a record of vomiting, abdominal distention, increased serum activities of alkaline phosphatase, γ‐glutamyl transferase, and hyperbilirubinemia. The dog had received amoxicillin and clindamycin (dosage and administration route unknown) prescribed by a referred veterinarian.
An abdominal ultrasonographic examination revealed a moderate amount of peritoneal fluid, widespread vascular mineralization, and a markedly thickened and irregular gallbladder wall. The abdominal fluid had a total nucleated cell count (TNCC) of 51,000/μL (CELL‐DYN 3500 analyzer; Abbott Diagnostics, Abbott Park, IL, USA), and a total protein of 5.6 g/dL via refractometry. Cytologic examination of direct smears of the abdominal fluid stained with an aqueous Romanowsky stain (Hematek 2000; Siemens Healthcare Diagnostics, Deerfield, IL, USA) demonstrated marked pyogranulomatous inflammation with abundant golden‐to‐dark green pigment, consistent with bile, present extracellularly and within macrophages. Cytologic diagnosis was bile peritonitis. No infectious organisms were identified, and successive aerobic and anaerobic bacterial cultures were negative.
The dog was intravenously dosed with ampicillin/sulbactam and enrofloxacin. Exploratory abdominal laparotomy revealed a ruptured gall bladder and a cholecystectomy and duodenotomy were performed. Following surgery, the effusion persisted, despite antimicrobial therapy, and the dog’s condition began to deteriorate. Abdominal fluid collected 6 days postsurgery had a TNCC of 96,600/μL, and a total protein of 5.3 g/dL. Cytologic examination was shown to have pyogranulomatous inflammation with several yeast organisms present extracellularly as well as within neutrophils and macrophages (Figure 2A). The basophilic organisms were round to oval, roughly 3–8 μm in diameter, and had a clear but thin circumferential halo. Few organisms showed narrow‐based budding. Rare elongated yeast organisms consistent with germ tube formation were noted phagocytized by macrophages (Figure 2B). No bacteria were seen. A second exploratory laparotomy was performed, which later showed abscess at the gallbladder fossa that was debrided and omentalized. The dog later developed anuric renal failure and was euthanized for 2 days after the second surgery. While septicemia was suspected, blood cultures were not performed, and necropsy was declined by the owner. No antifungal therapy was initiated in this dog prior to euthanasia.
Culture of the second abdominal fluid sample (sheep blood agar, MacConkey agar, and Sabouraud dextrose agar) revealed the presence of E coli and 2 morphologically distinct fungal colonies consistent with Candida spp. Colonies were identified as Candida albicans and C glabrata, respectively (MicroScan, Rapid Yeast Identification, Siemens Healthcare Diagnostics Inc., West Sacramento, CA, USA). Histopathology of the gallbladder showed severe, diffuse, chronic‐active, necrotizing suppurative cholecystitis with fibroplasia. No infectious organisms were identified in the biopsy samples using Periodic acid‐Schiff (PAS) stain or Gomori’s methamine silver (GMS).
Figure 2: Direct smears of abdominal fluid from a dog with bile peritonitis due to a gall bladder rupture (A and B) and a dog with peritonitis after enterotomy for foreign body removal (C and D); Aqueous Romanowsky stain. (A) Numerous budding yeasts within a degenerative neutrophil. (B) Yeast elongation with germ tube formation within a macrophage (arrows). (C) Elongated pseudohyphae noted as a series of conjoined yeast with obvious constrictions at septal sites. (D) True hyphae with no constrictions at septal sites. Bar = 10 μm.
During an infection, Candida can readily react to the host’s immune system by undergoing phenotypic switching, which changes its morphotype from blastoconidia to a more resistant germ tube or elongated yeast, pseudohyphae, and/or hyphal forms (Figure 1). Also, macrophage ingestion of C albicans can stimulate germ tube formation/elongation aDuring an infection, Candida can readily react to the host’s immune system by undergoing phenotypic switching, which changes its morphotype from blastoconidia to a more resistant germ tube or elongated yeast, pseudohyphae, and/or hyphal forms (Figure 1). Also, macrophage ingestion of C albicans can stimulate germ tube formation/elongation and allow escape and evasion of the immune system (Raska, et al., 2007; Koh, et al., 2008). This ability to alternate between yeast and hyphal morphotypes increases Candida’s virulence and enhances its potential for tissue invasion (Raska, et al., 2007; Koh, et al., 2008). An exception is C glabrata, which appears to only exhibit the yeast pattern in vivo (Fidel, et al., 1999) and allow escape and evasion of the immune system (Raska, et al., 2007; Koh, et al., 2008). This ability to alternate between yeast and hyphal morphotypes increases Candida’s virulence and enhances its potential for tissue invasion (Raska, et al., 2007; Koh, et al., 2008). An exception is C glabrata, which appears to only exhibit the yeast pattern in vivo (Fidel, et al., 1999).
Causes of Peritonitis in Dogs
In canines, there are a couple of possibilities that may bring about peritonitis. As mentioned earlier, bacterial infection being the most common cause that moves to the abdomen from an external wound or perforated organ. However, there are other factors that my contribute to peritonitis in canines as well and they are listed below (Lerman, et al., 2019; Kine, et al., 2019; Rossmeissl, et al., 2011).
- Intestinal or stomach tumour that ruptures the bowel
- Stomach or intestinal ulcer, which can be caused by anti-inflammatory medications
- Liver abscess
- Pancreatic inflammation
- Ruptured gallbladder or bile duct
- Ruptured bladder
- Perforated colon
- Ruptured uterus
- Ruptured appendix
- Liver, heart, or kidney disease
- Chemical contamination
- Prostate cysts
- Wound or injury to the abdomen
Treatments for Peritonitis in Dogs
Treatment for peritonitis in canines may just starts right away with hospitalization to prevent the condition becoming severe. The vet may give the dog intravenous fluids, and if the dog needs nutritional support, the vet required to use a feeding tube to direct nutrients into the digestive tract or administer feedings via injection.
Depending on the severity and cause of the condition, the vet may need to perform surgery. This is especially true in cases where a bacterial infection or chemical contamination is the cause of the peritonitis.
Surgery for these conditions involves flushing the abdomen with saline. However, many dogs don’t recover from this kind of peritonitis, as it is quite life-threatening.
Affected canines will likely be recommended for special diet and this will help with the body’s essential fluid retention. Vets often prescribe a low-sodium diet, especially for dogs who have heart disease. Vets may also prescribe medications, including antibiotics or painkillers to control the pain. Additionally, dogs will need follow-up vet visits to make sure there are no recurring symptoms.
Veterinarian usually performs a thorough physical examination of the dog having abdominal pain. Additionally, veterinarian will also perform tests including a chemical blood profile, a complete blood count, a urinalysis and an electrolyte panel (Hodgson, et al., 2018). The health history of the dog must be provided as well that entails how the symptoms arises and possible incidents that might have contributed to this condition. The history provided will let the veterinarian known whether other organs are causing the condition or being affected specifically.
Even though physical examinations are important, radiograph and ultrasound imaging are equally critical for visualizing the presence of free fluid in the abdomen. Free gas in the abdomen, and an abscess should be completely check for their presence through these imaging analyses. A fluid sample taken by abdominocentesis should be done so that a sample can be stored in a vacuum blood collection tube (EDTA tube) for laboratory analysis. If fluid cannot be recovered during an abdominocentesis, a diagnostic peritoneal lavage (stomach wash) can be done (Jaffey, et al., 2018; Kim, et al., 2018).
Other than having veterinarian diagnosing the symptoms of peritonitis, there is another way of diagnosing as well. With the aid of rapid test kits, e.g. Peritonitis Detection Kit developed by Bioguard ®. The concept is simple with this detection kit. Peritonitis Detection Kit is made by acetic acid for distinguishing between exudates due to peritonitis and effusions caused by other diseases from feline specimen. It has an assay time of 3 – 5 minutes.
In Peritonitis Detection Kit, the test tube is filled with distilled water and acetic acid. One drop of the sample to be tested is added to this mixture. If the drop dissipates, the test is negative, indicating a transudate. If the drop precipitates, the test is positive, indicating an exudate. By this means, the device can easily indicate the peritonitis in the sample.
Figure 3: Test Principle
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