Surgical sterilization is the most performed procedure in veterinary medicine. Traditional sterilization techniques involve removal of the gonads, which eliminates hormonal secretions in addition to reproductive potential. The most common procedures performed to accomplish this in females include ovariohysterectomy (OVH) and ovariectomy (OVE). Each of these procedures has associated risks and complications.

An OVH involves removal of the ovarian and uterine tissues, whereas an OVE involves the removal of ovarian tissue only. Both procedures significantly decrease the risk of uterine and mammary cancer, significantly decrease the risk of pyometra development, and effectively prevent unwanted pregnancy. From a technical standpoint, an OVE is less invasive, requires a smaller surgical incision, is less time consuming, and causes less tissue trauma. Potential advantages of this procedure include improved visualization of the ovarian pedicle, decreased risk of hemorrhage, shorter surgery time, and improved patient recovery.

 Theoretically an OVE is safer and less technically demanding; however, the veterinary literature has not shown a difference in short- or long-term outcomes when compared to OVH.

The major benefit of an OVH is the ability to remove the uterine tissue along with the ovaries. Therefore, when uterine pathology is present, including congenital uterine abnormalities, pyometra, mucometra, cystic endometrial hyperplasia, uterine torsion, uterine prolapse, uterine rupture, and/or uterine neoplasia, an OVH is preferred over an OVE.

In the past decade, there has been an increased interest in minimally invasive surgery using laparoscopic techniques from veterinarians and pet owners. The benefits of laparoscopic approaches have been well established and include decreased surgical and anesthetic times, improved visualization of abdominal organs, a reduction in postoperative pain, decreased surgical stress, and a decreased incidence of wound healing complications.

 Typically, an OVE is the most performed surgical technique when laparoscopy is desired; however, an OVH may still be performed using minimally invasive techniques.

A laparoscopic approach typically utilizes 1 to 3 portals to gain access to the abdominal cavity. The abdominal cavity is insufflated with gas, typically carbon dioxide, for improved visualization. Hemostasis is generally achieved with bipolar vessel sealing devices. If an OVH is to be performed, a laparoscopic-assisted approach is used, meaning one of the portal incisions is extended to facilitate removal of the uterine tissue. This results in longer incisions compared with a laparoscopic OVE and may decrease the traditional benefits of a laparoscopic procedure.

Potential complications of laparoscopic procedures include subcutaneous accumulation of carbon dioxide, omental herniation, seroma formation, and/or splenic, ovarian pedicle, or uterine hemorrhage.

 In some cases, conversion to an open abdominal approach is required if visualization is impaired or hemorrhage cannot be controlled. Complication rates are similar between laparoscopic OVE and laparoscopic-assisted OVH procedures; however, laparoscopic OVE has been associated with shorter surgical times, which may decrease overall complication rates.

 Although there are many potential benefits to laparoscopy, the technique is often more costly, requiring advanced training and specialized equipment.

OVE and OVH carry similar intraoperative risks including hemorrhage, inadvertent ureteral ligation, and incomplete removal of ovarian tissue. As discussed, there is the potential for less tissue trauma when performing an OVE because the uterine tissues are minimally manipulated. The more cranial location of the incision also improves visualization of the ovary, potentially decreasing the risk of postoperative ovarian remnant syndrome.

Potential long-term risks of spaying are well established and include urinary incontinence, decreased metabolism, and/or a predisposition to various joint conditions such as hip dysplasia, elbow dysplasia, and/or cruciate ligament disease. The incidence of these complications is likely equal for OVH and OVE procedures; however, existing literature is lacking. Early spaying at less than 6 months of age may be associated with an increased incidence of urinary incontinence and joint disorders.

 Additionally, heavier dogs with a projected adult weight of more than 25 kg may be at a higher risk of developing urinary incontinence if spayed earlier in their first year of life.

 There is a significant amount of breed variation for the development of orthopedic disease and urinary incontinence at different ages.

 The decision to delay performing a spay must be weighed against the increased likelihood of developing mammary cancer with consecutive heat cycles.

A common misconception is that performing an OVE increases the risk of developing a pyometra compared with an OVH as the uterine tissues remain present. Although the exact pathophysiology of pyometra formation is not completely understood, progesterone is known to play a key role. By removing the ovarian tissue, the source of endogenous progesterone is eliminated; therefore, a pyometra should not occur. One study evaluated 141 ovariectomized dogs over the course of 6 to 11 years and none developed a pyometra.

 It is important to note that a pyometra can still develop in an ovariectomized dog if there is exposure to exogenous estrogens, which is commonly found in topical hormonal replacement therapies used by menopausal women. Likewise, pyometras can occur in a similar manner in an ovariohysterectomized dog if all uterine tissue is not removed, which is uncommonly achieved in OVH procedures.

There is no current consensus among veterinary surgeons on the preferred sterilization procedure in dogs. Both OVE and OVH are appropriate spay techniques for apparently healthy females. If uterine pathology is present, an OVH should be performed. Given the lack of advantages to removing the uterus in clinically normal dogs and the potential advantages of an OVE as discussed, OVE procedures may be more readily performed in the future.

, is a 2021 graduate of St. George’s University School of Veterinary Medicine in Grenada, West Indies, and received clinical training at the University of Florida in Gainesville. His internships include Auburn University in Alabama, mentored by Katelyn Hlusko, DVM DACVS-SA.

1. Charlesworth TM, Sanchez FT. A comparison of the rates of postoperative complications between dogs undergoing laparoscopic and open ovariectomy. 

. 2019;60(4):218-222. doi:10.1111/jsap.12993

2. DeTora M, McCarthy RJ. Ovariohysterectomy versus ovariectomy for elective sterilization of female dogs and cats: is removal of the uterus necessary? 

. 2011;239(11):1409-1412. doi:10.2460/javma.239.11.1409

3. Davidson EB, Moll HD, Payton ME. Comparison of laparoscopic ovariohysterectomy and ovariohysterectomy in dogs. 

. 2004;33(1): 62-69. doi:10.1111/j.1532-950x.2004.04003.x

4. Hancock RB, Lanz OI, Waldron DR, Duncan RB, Broadstone RV, Hendrix PK. Comparison of postoperative pain after ovariohysterectomy by harmonic scalpel-assisted laparoscopy compared with median celiotomy and ligation in dogs. 

. 2005;34(3):273-282. doi:10.1111/j.1532-950x.2005.00041.x

5. Devitt CM, Cox RE, Hailey JJ. Duration, complications, stress, and pain of open ovariohysterectomy versus a simple method of laparoscopic-assisted ovariohysterectomy in dogs. 

. 2005;227(6):921-927. doi:10.2460/javma.2005.227.921

eterinary Surgery: Small Animal. Elsevier; 2018.

7. Corriveau KM, Giuffrida MA, Mayhew PD, Runge JJ. Outcome of laparoscopic ovariectomy and laparoscopic-assisted ovariohysterectomy in dogs: 278 cases (2003-2013). 

. 2017;251(4):443-450. doi:10.2460/javma.251.4.443

8. Pegram C, Brodbelt DC, Church DB, et al. Associations between neutering and early-onset urinary incontinence in UK bitches under primary veterinary care. 

. 2019;60(12):723-733. doi:10.1111/jsap.13072

9. Byron JK, Taylor KH, Phillips GS, Stahl MS. Urethral sphincter mechanism incompetence in 163 neutered female dogs: diagnosis, treatment, and relationship of weight and age at neuter to development of disease. 

. 2017;31(2):442-448. doi:10.1111/jvim.14678

10. Hart BL, Hart LA, Thigpen AP, Willits NH. Assisting decision-making on age of neutering for 35 breeds of dogs: associated joint disorders, cancers, and urinary incontinence. 

. 2020;7:388. doi:10.3389/fvets.2020.00388

11. Okkens AC, Kooistra HS, Nickel RF. Comparison of long-term effects of ovariectomy versus ovariohysterectomy in bitches. 

12. Ivaldi F, Ogdon C, Khan FA. A rare case of vulvar discharge associated with exogenous oestrogen exposure in a spayed Weimaraner bitch. 

. 2022;8(5):1872-1876. doi:10.1002/vms3.860

Articles

An overview of ovariohysterectomy and ovariectomy procedures

Female sterilization procedures

The new Veterinary Trauma Readiness and Operational Medicine Agility (Vet-TROMA) program was announced today, in honor of K9 Veterans Day. A partnership of BluePearl, the US Army Office of the Surgeon General and US Army Veterinary Corps, the program is a first-of-its-kind veterinary military-civilian partnership.

BluePearl, a member of the Mars Veterinary Health family of businesses, provides specialty and emergency veterinary care training to US Army veterinarians to enhance their abilities to treat Military Working Dogs (MWDs) combat casualties. The US Army Veterinary Corps provides medical and surgical care to more than 1600 active duty MWDs that deploy and can be injured like human military personnel. Vet-TROMA is an additional training experience available for US Army veterinary personnel to prepare them to provide lifesaving care to MWD’s at their time of greatest need.

Vet-TROMA is currently offered at 2 BluePearl hospitals near US Army facilities in Lakewood, Washington, and Cary, North Carolina, with plans to expand to additional BluePearl locations. US Army veterinarians complete 67-hours of didactic distance learning followed by an intensive 3-week clinical rotation at the BluePearl sites.

“US Army veterinary teams are often faced with trauma situations in which split-second, life-or-death decisions must be made,” said Richard Stone, DVM, chief medical officer at BluePearl, in a company release. “The advanced training offered through Vet-TROMA helps create more skilled and confident veterinarians—qualities that are necessary to care for canines in combat. We are already seeing the program’s impact in the field, and we look forward to growing this partnership and giving more options for US Army veterinarians to feel confident caring for Military Working Dogs injured in combat.”

Captain Abbey Calvo, formally a veterinary team leader from the 218th Medical Detachment (Veterinary Service Support), was the first Veterinary Corps officer to complete a clinical rotation with BluePearl as part of the Vet-TROMA program. During the onsite immersion, Calvo saw 105 emergency cases, including a dog with a gunshot wound to the chest, acute toxicities, and patients requiring blood transfusions—all which MWD’s may experience on the battlefield.

“Military working dogs are an irreplaceable asset to our military and loyally work to protect our service members, so I need to be prepared to save them if they get injured or become ill on the battlefield,” Calvo said in the release. “The training I received from BluePearl through the Vet-TROMA program was life-changing for me and the dogs I serve, giving me additional tools, I need to ensure I am ready to assist our canine counterparts when they need me most.”

The US Army Veterinary Corps was established in 1916 to care for the large number of animals used by the US military during World War I. The Army is the only military service that delivers veterinary support within the Department of Defense to include providing veterinary medical and surgical care to working animals, decreasing the potential for transmission of diseases from animals to humans, safeguarding the food supply for service members and their families, and supporting military research and development efforts. There are currently more than 800 US Army veterinarians on active duty and in the Reserves providing care to MWDs globally.

BluePearl announces first-of-its-kind veterinary partnership with US Army. News release. Blue Pearl. March 13, 2024.

In honor of K9 Veterans Day, BluePearl announced a new program in collaboration with the US Army Office of the Surgeon General and the US Army Veterinary Corps. 

Veterinary military-civilian partnership aims to enhance lifesaving care to US Army working dogs

A companion animal therapeutics developer has published a new study with results that demonstrate the potential of an antigen-specific immunotherapy, AKS-107, to target and delete insulin-specific ß cells. The results also show the versatility of the development platform the therapy was based on.

 showed that the AKS-107 human IgG1 Fc-fusion protein safely prevented spontaneous diabetes in nonobese mice with diabetes and insulin-reactive ß cell receptor transgenic mouse strains, according to Akston Biosciences in Beverly, Massachusetts. A promising candidate for clinical development of Type 1 diabetes (T1D) prevention therapy, this protein is engineered to retain conformational insulin epitopes that bind to ß cell receptors and prevents binding to the insulin metabolic receptor, according to a news release. Additional studies have shown that AKS-107 has a protracted pharmacokinetic profile and was well-tolerated in mice and nonhuman primates.

Partnered with Dechra Pharmaceuticals PLC, Akston Biosciences is also working to commercialize canine and feline insulin therapies in its’ animal health pipeline.

These include novel therapeutic candidates AKS-321d for managing canine diabetes and AK425c for feline diabetes.

 “These insulins are able to be injected once a week,” said Todd Zion, PhD, president and CEO of Akston Biosciences, in a presentation at the 2023 Animal Health Corridor Summit in Kansas City, Missouri.

Development of both companion animal insulin therapies and AKS-107 are based on Akston Biosciences' Ambifect Fc-fusion protein platform.

 This common platform enables the company to develop therapeutic candidates that interact with parts of the immune system related to the target disease while minimizing the effects off-target.

Through this technology, Akston can reduce therapeutic development time and manufacturing costs across its pipeline, according to the company. "Akston has confirmed the versatility of the Ambifect platform across diverse treatment areas, including extended duration insulin therapies, infectious disease vaccines, and, with AKS-107, interrupting an autoimmune cascade," said Zion, in a recent news release.

 “We are now exploring its application to therapeutic vaccination, where the immune system is recruited to target proteins involved in noncommunicable diseases.”

The Ambifect Fc-fusion platform was recognized with the Most Innovative Award at the 2023 Animal Health Corridor Summit. During the summit, hosted by the KC Animal Health Corridor organization, Zion presented Akston Biosciences’ work on developing novel therapies for canine and feline diabetes that rely on monoclonal antibodies, which are also used in human medicine. He noted that the company invested in its own manufacturing facility and is leveraging technology to find cost-effective, efficient methods to address various needs in the animal health space. “We really believe that the veterinary field health field is poised to experience its’ own revolution in this area,” Zion said, at the summit.

Akston Biosciences’ AKS-107 study published in 

, displaying Ambifect Platform’s versatility. News release. Akston Biosciences. March 11, 2024. Accessed March 12, 2024. 

https://www.akstonbio.com/akston-biosciences-aks-107-study-published-in-frontiers-in-immunology-displaying-ambifect-platforms-versatility/

Alleva DG, Delpero AR, Sathiyaseelan T, etal. An antigen-specific immunotherapeutic, AKS-107, deletes insulin-specific B cells and prevents murine autoimmune diabetes. 

https://doi.org/10.3389/fimmu.2024.1367514

Long-acting Fc-fusion proteins. Akston Biosciences. Accessed March 12, 2024. 

Akston Biosciences. Ambifect platform advantages. Akston Biosciences website. Accessed March 12, 2024. 

Zion T. Emerging Companies: Akston Biosciences. Presented at: 2023 Animal Health Summit; Kansas City, MO. August 28-29, 2023.

Burke J. Akston Biosciences wins innovation award at animal health summit. 

. August 31, 2023. Accessed March 12, 2024. 

https://www.dvm360.com/view/akston-biosciences-wins-innovation-award-at-animal-health-summit

The Akston Biosciences technology is used to design therapies for humans and animals with diabetes

Animal health therapeutic development platform demonstrates versatility

I was recently at a clinic giving a practice management seminar and a conversation about training and education came up. In a very confident, “as a matter of fact” tone, one of the veterinary technicians expressed frustration about career advancement because “those that are experienced prefer not to share their knowledge in an effort to maintain job security.” Has this sentiment ever been raised in your place of employment? Does it sound familiar? Believe it or not, it is quite common.

As a veterinarian who works full-time in continuing education (CE) here at 

, I believe that education is a cornerstone of our profession, and its true value is realized when it is shared rather than hoarded. Veterinary medicine is a dynamic field that constantly evolves with advancements in technology, research, and clinical practices. It is crucial for professionals in our community to actively contribute to a culture of knowledge sharing for the benefit of our patients, clients, and the overall improvement of veterinary care. Look at all the advancement in artificial intelligence, practice management software, and new ways of managing pain in our patients.

Hoarding knowledge within a team or a veterinary hospital is counterproductive and detrimental to the collective growth of the veterinary community. Employees hoard knowledge for a number of reasons. These include personal reasons like fear of competition, an attempt to keep control, or, yes, to ensure job security. I also have found it could be for their own gain like receiving praise or bonuses related to their knowledge or performance. It is something I have been hearing more as I have been chatting with practices around the country. And it truly makes me scratch my head. Collaboration and open communication foster a supportive environment where ideas can be exchanged, experiences shared, and skills enhanced. This collaborative approach not only enhances the quality of care provided but also creates a positive workplace culture, where trust and respect flourish among team members.

One of the best examples of the power of sharing knowledge is witnessed in our brand-new education program, “In the Clinic.” This is a 1-hour CE session in which an entire veterinary team is interviewed about a therapeutic topic with understanding and appreciation for their educational perspective. This innovative program was truly designed to share knowledge across the team. A recent program was on the team approach to veterinary dentistry at Heart + Paw in Lake Hopatcong, New Jersey, with Jan Bellows, DVM, DAVDC, DABVP, FAVD, as our subject matter expert. If you have not seen this webinar, I encourage all of you to view it on demand on our dvm360.com/Flex platform.

Continuing education is paramount in veterinary medicine because of the rapidly evolving nature of our field. New diagnostic tools, treatment modalities, and research findings emerge regularly. By actively participating in ongoing education, veterinarians and veterinary staff stay abreast of the latest developments, ensuring that their knowledge remains current and applicable to the ever-changing landscape of veterinary science. We welcome all of you to have a seat at the education supper table at all our Fetch veterinary conferences (new Fetch Nashville is coming up May 17 and 18, 2024). Investing in employees’ education is the single best investment one can make for the practice and patients.

Moreover, embracing CE promotes a culture of lifelong learning and professional growth. It encourages veterinary professionals to seek out new information, refine their skills, and adapt to emerging challenges. This not only benefits the individual practitioner but also elevates the overall standard of care within the veterinary community.

By withholding information, employees may inadvertently hinder the progress of the team, limit professional development opportunities, and compromise the overall standard of care. Furthermore, it can create a sense of isolation among team members, hindering the establishment of a cohesive and efficient veterinary team. No one wins, including our patients. 

The importance of education in veterinary medicine is best realized when it is shared openly among all our fellow professionals. Embracing a culture of open communication and continued learning ensures that veterinary professionals stay at the forefront of advancements, benefiting the entire veterinary community and the animals under our care. To quote Malcolm X: “Education is our passport to the future, for tomorrow belongs only to the people who prepare for it today.”

A note on the importance of training and career advancement in veterinary medicine from our chief veterinary officer, Adam Christman, DVM, MBA

Education is best when it is shared, not hoarded

Anaphylaxis is more than just an everyday allergic reaction and being prepared to recognize and treat these pets in a timely manner is crucial. Anaphylaxis is the systemic, immediate hypersensitivity reaction that is mostly caused by the Immunoglobulin E (IgE) mediated immunologic release of mediators from mast cells and basophils. The best way to differentiate an anaphylactic reaction from other simpler Type I hypersensitivity reactions is to characterize it as systemic hypersensitivity reaction involving at least 2 organ systems (dermatologic, respiratory, cardiovascular, and gastrointestinal (GI)).

Anecdotally, it would seem we are seeing more severe, life-threatening anaphylactic reactions in the last 5 years, which may also be due to our improved recognition of the disease. These are often some of the most severely and acutely ill patients we see in practice, and without timely and accurate identification and intervention, mortality can be very high.

: Preformed mediators of the mast cell and basophil. (All figures courtesy of Jayme Hoffberg, DVM, DACVECC, Board Certified Criticalist) 

There are numerous causes of allergic and anaphylactic reactions including insect bites and stings, vaccines, or other drugs though many of our patients will have an unknown trigger. In this article we are going to focus on IgE mediated type I hypersensitivity. 

Our 2 main “bad boys” of anaphylaxis are the mast cell and the basophil (

). Both release histamine and mast cells will also release heparin. These 2 mediators are stored in granules preformed so there is prompt degranulation and release from the cells. This occurs when an antigen (an allergen) attaches to an IgE antibody on the surface of the cells. The release of these granules occurs within seconds to minutes. Then within 5-30 minutes there is downstream activation of the arachidonic acid cascade which releases prostaglandin, leukotrienes, and platelet activating factor. About 2-6 hours post stimulation, there is release of cytokines and chemokines such as interleukins and Tumor Necrosis Factor alpha (TNFalpha).

Histamine makes up about 70% of the weight of the basophils and mast cells so these cells pack a big punch. Histamine levels can be measured in plasma within one minute of an anaphylactic stimulus. The effects of histamine are based on the overlapping effect of the 4 histamine receptors.

 Main histamine driven effects are going to include cutaneous changes, respiratory effects, cardiovascular derangements, and GI and hepatobiliary changes. We will discuss more about the clinical presentation, but overall histamine receptor activation will cause vasodilation, increased vascular permeability, bronchoconstriction, heart rhythm disturbances (often tachycardia), and overall decrease in cardiac output driven by reduced cardiac contractility (inotropy).

The other granule mediator with early effects is heparin. Heparin will decrease clot formation but also can be a component of a hyperfibrinolytic state meaning there is an increase in clot breakdown. This means the animal can form a slower and weaker clot that is more prone to rapid breakdown and an inability to stabilize the clot.

The arachidonic acid cascade occurs after this immediate granule release when phospholipase A2 catalyzes membrane phospholipids to arachidonic acid. Arachidonic acid is then further catalyzed via COX and LOX to prostaglandins, thromboxane, and leukotrienes.

 These are responsible for additional bronchoconstriction, pulmonary and coronary vasoconstriction, and peripheral vasodilation. Slow reacting substances of anaphylaxis SRS-A) are also formed and are 1000x more potent than histamine with a longer duration of action. These cause bronchoconstriction, permeability changes, and chemotaxis. They are likely involved in the more protracted reactions.

 Cytokines and chemokines are also released. These chemotactic factors draw more immune cells to the area which causes further inflammation especially important in some of the later stage effects.

A dog’s shock organ is the GI and hepatobiliary system and this information in conjunction with the knowledge of these 2 main granules will help explain the life-threatening effects seen in canine anaphylaxis. While there is peripheral vasodilation, alternatively there is portal hypertension meaning there is an increase in the blood pressure in the portal system which is the vascular bed to the GI and hepatobiliary system. This portal hypertension occurs due to increased arterial blood flow to the portal system (hepatic arterial vasodilation) but decreased outflow of blood from the liver (increased hepatic venous outflow obstruction).

While increasing blood flow to tissues can be beneficial, when it becomes dysregulated it is detrimental to the tissues perfused causing ischemia and damage. When combined with the vascular permeability changes driven by heparin and the hypocoagulability effects from the heparin the effects are compounded.

Onset of an allergic and anaphylactic reaction are often rapid within 5 to 30 minutes with continued rapid progression. The time of onset and speed of progression are proportional to the severity of immunologic response so a bigger immune stimuli and mediator release will cause a quicker, more rapidly progressive and, therefore, more life-threatening response. There are also delayed reactions and biphasic reactions which can occur. These are often mediated by Ig other than IgE and are beyond the scope of this article, but it is important to note that there is thought that biphasic reactions may increase mortality.

Cutaneous changes such as pruritis, rhinitis, peripheral edema/erythema, facial angioedema, and urticaria are generally thought to be mediated by the H1 receptors but H2 receptors also can cause some of these skin changes which is why they are so common in allergic reactions. These cutaneous signs may be a potential precursor to more severe reactions but are also often delayed or can be completely absent in rapid anaphylaxis.

Dogs with anaphylaxis rarely present with the expected hives/cutaneous signs we would use as signs of an allergic reactions with a recent study showing 57.9% of dogs with anaphylaxis had no cutaneous signs reported.

 When these cutaneous signs occur, they may wax and wane for days.

Cats will likely have more respiratory signs as the lung is their shock organ, but regardless of species, the respiratory tract is affected in anaphylactic reactions in multiple ways. This can be due to pulmonary changes caused by bronchoconstriction, vasodilation, and increased vascular permeability, which causes increased airway resistance, increased fluid leak and pulmonary edema. There can also be increased respiratory mucous production worsening airway resistance and potentially inhibiting gas exchange. Stridor or other signs of upper airway obstructive disease can also occur due to laryngeal and nasopharyngeal edema especially in patients with already compromised airway patency like brachycephalic dogs. Delayed respiratory effects can also occur due to the arachidonic acid pathway and chemokines/cytokines increasing inflammatory cell recruitment, platelet aggregation and damage to the pulmonary endothelium which can cause acute lung injury (ALI).

A recent study found 26.8% of dogs had respiratory signs with anaphylaxis, and respiratory distress was found to be associated with non-survival.

In anaphylactic reactions, the first signs are often severe GI signs. Peracute GI signs including severe vomiting and diarrhea often hemorrhagic in nature are often the presenting complaint. These GI losses will then further contribute to hypovolemic shock. Vascular permeability changes and GI barrier function damage can also allow for bacterial and cytokine translocation and SIRS/Sepsis. Furthermore, as H2 receptors mediate gastric acid secretion, there can be significant 

increases in gastric acid production which can predispose these patients to gastric and duodenal ulceration.

Anaphylaxis can affect coagulation in multiple ways with severe anaphylaxis causing a global hypocoagulable state including decreased clot formation and clot formation, increased clot breakdown, and decreased platelet count.

 The cause of this coagulaopathy is multifactorial and at this time still not fully understood, but one major cause is due to the massive release of heparin. These animals will often have a mild to severe increase in aPTT (proportionally worse than PT). In simplified terms, this is due to the abundant effect of heparin on factor X activation as part of the intrinsic pathway.

Shock occurs due to a combination of causes. One study showed cardiovascular dysfunction in 42.1% of dogs with anaphylaxis.

Hypovolemic shock occurs due to fluid losses notably in the GI tract or due to hemorrhage. Additionally, histamine can decrease cardiac contractility and cause arrhythmias thereby dropping cardiac output causing cardiogenic shock. Vasodilatory or maldistributive shock also occurs due to peripheral vasodilation. There is also metabolic shock due to the cytokine effects on cell function. These animals will often present hypotensive with other signs of severe malperfusion (dull mentation, low temperature, elevated lactate etc) but may have pink mucous membranes.

This peripheral vasodilation in shock is seen in cases of distributive shock like anaphylaxis and sepsis/SIRS as well as other conditions beyond the scope of this article. In addition to all these effects, it is important to note that histamine will also dampen the body’s response to catecholamines normally released in shock to thereby blocking the body’s ability to restore cardiac output, perfusion, and delivery of oxygen.

As there is no anaphylaxis point of care test and these dogs often do not present with telltale cutaneous signs, the necessary rapid identification can be difficult. Other non-specific signs such as rapid onset severe GI signs or shock/collapse should trigger the clinician to start looking for some markers seen in anaphylaxis. Alanine transaminase (ALT) elevation and gall bladder wall edema have been found to be markers of anaphylaxis and when combined with other findings should prompt consideration of the diagnosis.

An increase in ALT is commonly seen in anaphylaxis and often occurs very rapidly.

 ALT increases due to ischemia and hypoxia of the hepatocytes driven by alterations in blood flow as well as direct injury from cytokines to hepatocytes. ALT will generally be high in anaphylaxis with a sensitivity of 95% and specificity of 98%.

 It increases rapidly in less than 12 hours from insult, peaks usually in 1-2 days and will often return to normal in 2-3 weeks depending on the peak value.

A halo or double rim effect to the gall bladder can occur almost immediately after insult due to portal hypertension and vascular permeability changes.

 Sensitivity of this marker is 93% with a specificity of 98%.

Epinephrine is the first line treatment for anaphylaxis. It should always be the first drug reached for when all the above information triggers your suspicion of anaphylaxis.

Epinephrine is a mixed adrenergic receptor agonist. Among its effects, vasoconstriction increases blood pressure and decreases airway mucosal edema. Its positive inotropic and chronotropic effects increase cardiac output and blood pressure as well while its beta 2 effects cause bronchodilation. It will also suppress inflammatory mediator release by stabilizing the mast cell and basophil granule release and provides relief from urticaria.

Epinephrine has a short duration of effects and can cause arrhythmias, hypertension, anxiety, tremors, or pallor but side effects are generally very mild especially when given IM or as a CRI. Dose recommendation is 0.01mg/kg IM with a max dose of 0.3 mg in patients <40 kg or 0.5 mg in patients >40kg.

 The dose can be repeated every 5-15 minutes as needed to help relieve signs. The author will give an immediate IM dose on suspicion for anaphylaxis. If shock or a hemoabdomen is identified, then a second IM dose is given before starting a CRI titrated to normalize blood pressure starting at 0.05 mcg/kg/min.

The author also treats other allergic reactions with epinephrine IM even if there are no “anaphylactic cues” as anecdotally it seems to help relieve hives sooner in these patients but there is currently no evidence to support this in canine patients.

Commercial epinephrine pens are usually not used as the needle is too short if a patient is obese (SQ injections are not recommended), you cannot dose <15 kg accurately, there is a short, labeled shelf life of 12-18 months, and they are very expensive.

Antihistamines are considered a second line drug in people and administration should never cause a delay of administration of epinephrine. Even though it is not a first line drug, blocking histamine is very important as part of treatment. Since there are overlapping effects from different histamine receptors consider blocking both H1 and H2 by pairing Diphenhydramine (2.2mg/kg IM, SQ, or PO every 8 hours) and famotidine (0.5-1mg/kg IM, SQ, or PO q 12 hours). We generally recommend continued antihistamine medications for 3-5 days as the lasting effects of the histamine release can cause wax and wane signs for a few days, especially the skin effects.

Glucocorticoids may have a couple purposes in allergic reactions, but their use is controversial in human medicine to treat anaphylaxis. Steroids do not generally have direct effects on the early symptoms of anaphylaxis such as dermatologic changes but their direct physiologic benefit in anaphylaxis is more directed in down regulating the late-stage response mediated by arachidonic acid and cytokines/chemokines or may help limit a biphasic reaction. The onset of action is about 4-6 hours regardless of route so again these are likely not helping as much as we may believe in the acute treatment. They can be useful in animals with upper airway swelling causing obstructive changes.

The author uses steroids in severe anaphylactic patients and simple allergic reactions in patients who are brachycephalic and have signs of upper airway obstructive disease regularly but does not use them in most other simple allergic reactions. Dosing may change based on clinical preference, but the author generally will start with a 0.1mg/kg dexamethasone dose IV, SQ, or IM then a tapering dose of prednisone depending on the clinical picture of the patient.

There are many factors that cause the potential for high mortality in anaphylactic patients if not treated correctly. The patients that have had the worst morbidity and mortality in the authors experience are those with severe hemoabdomen. Remember, these dogs have portal hypertension and this change, vascular permeability alterations, and coagulopathy will all set a perfect stage for intraabdominal bleeding.

Interestingly, not all dogs with hemoabdomen have been found to have coagulation testing abnormalities again confirming this is a multifactorial cause which can complicate treatment.

 Hemoabdomen ranging from mild to severe and rapidly fatal can occur and need to be the addressed immediately as the more an animal bleeds, the worse their coagulopathy will become further impeding our ability to treat. If there is evidence of an anaphylactic reaction and hemoabdomen, clotting times or viscoelastic testing should be evaluated but waiting on these tests may not be feasible to prevent worsening morbidity and mortality.

: Ultrasound images of hypoechoic liver masses identified on dog diagnosed with anaphylactic reaction.

Rapid administration of the above epinephrine dose should be given along with plasma transfusion starting with 20ml/kg of fresh frozen plasma should be considered. These dogs often rapidly stabilize after epinephrine and plasma, but some need a larger volume of plasma, red blood cells, platelets, or fresh whole blood transfusions and prolonged epinephrine CRI to stabilize. If blood products are not available, the IM epinephrine recommendations should be followed immediately while looking for rapid transfer to a facility with blood product availability.

: Recheck ultrasound of same dog as figure 2 one week later showing resolving masses.

It is important to note that if ultrasound is performed on these patients, mass like hematomas have been noted especially in the liver due to the intraparenchymal bleeding (

). It is a clinical judgment call based on all the information of the case that will help you determine if this is a patient with a hemoabdomen due to a primary bleeding mass that needs surgical stabilization or if this is an anaphylactic patient with hepatic hematomas who needs rapid medical stabilization. These mass like lesions, if they are hematomas, should resolve over time on recheck ultrasounds (

As the treatment of these patients is so crucial, at the authors hospital we utilize a flow chart (

) in our training to help aid diagnostics and treatment.

: Flow chart utilized at the author's hospital for treatment and diagnostic recommendations for an anaphylactic hemoabdomen.

General care for shock for these patients is instituted including fluid therapy, epinephrine CRI as needed, or dobutamine if there is continued hypotension and evidence of poor inotropy. Monitoring and correction of cardiac arrhythmias may be necessary. GI support is also important such as supported enteral nutrition via a nasogastric tube. Monitoring of organ function, hematologic variables, and other hemodynamics will vary based on the case presentation.

 is Head of Emergency and Critical Care at Thrive Pet Healthcare Specialists in Hoffman Estates, a suburb of Chicago. She earned her Bachelor of Science degree and then her Doctor of Veterinary Medicine with high honors from the University of Illinois. She went on to complete a three-year residency in emergency and critical care at the Veterinary Teaching Hospital of Michigan State University before becoming an assistant clinical professor at the University of Wisconsin. Hoffberg has spent the last 10 years developing emergency and critical care departments and house officer training programs at multiple large private specialty hospitals. She finds excitement watching the quality of medicine and job satisfaction improve across an entire team when training and education is prioritized. Clinically, Hoffberg’s main interests are in extracorporeal therapies, polytrauma, and hematologic and coagulopathic conditions. Hoffberg is also a published author and co-author of multiple veterinary journals and publications.

Lieberman P, Nicklas RA, Oppenheimer J, et al. The diagnosis and management of anaphylaxis practice parameter: 2010 update [published correction appears in J Allergy Clin Immunol. 2010 Dec;126(6):1104]. 

. 2010;126(3):477-80.e842. doi:10.1016/j.jaci.2010.06.022

Shmuel DL, Cortes Y. Anaphylaxis in dogs and cats. 

. 2013;23(4):377-394. doi:10.1111/vec.12066

Smith MR, Wurlod VA, Liu CC. Evaluation of hemostatic derangements associated with canine anaphylaxis and the relationship to syndrome severity. 

 2023;33(6):648-655. doi:10.1111/vec.13345

Fosset FTJ, Lucas BEG, Wolsic CL, Billhymer AC, Lavergne SN. Retrospective evaluation of hypersensitivity reactions and anaphylaxis in dogs (2003-2014): 86 cases. 

. 2023;33(5):577-586. doi:10.1111/vec.13319

Quantz JE, Miles MS, Reed AL, White GA. Elevation of alanine transaminase and gallbladder wall abnormalities as biomarkers of anaphylaxis in canine hypersensitivity patients. 

. 2009;19(6):536-544. doi:10.1111/j.1476-4431.2009.00474.x

Shaker MS, Wallace DV, Golden DBK, et al. Anaphylaxis-a 2020 practice parameter update, systematic review, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) analysis. 

. 2020;145(4):1082-1123. doi:10.1016/j.jaci.2020.01.017

Hnatusko AL, Gicking JC, Lisciandro GR. Anaphylaxis-related hemoperitoneum in 11 dogs. 

. 2021;31(1):80-85. doi:10.1111/vec.13017

Summers AM, Culler C, Cooper E. Spontaneous abdominal effusion in dogs with presumed anaphylaxis. 

. 2021;31(4):483-489. doi:10.1111/vec.13070

Identifying culprits of this allergic reaction to help veterinary teams save their patients’ lives

Navigating canine anaphylaxis 

The World Veterinary Association (WVA) announced that this year’s World Veterinary Day will celebrate veterinarians as essential workers in their communities. The official theme, “Veterinarians are essential health workers” honors veterinarians and all do to keep their communities safe and protected.

“This dimension of the veterinarians’ work often remains invisible to the society but protecting and improving the health of people and their communities is an essential part of the vet profession,” the WVA shared in an organizational release.

 “All graduated veterinarians have undergone comprehensive medical training, and regardless of their professional area of practice, are responsible, for promoting public health and food safety and security.”

In 2000, the WVA created World Veterinary Day to celebrate the veterinary profession and it takes place each year on the last Saturday of April. Each year, the WVA and the Health for Animals, a global health care industry association, present the World Veterinary Day Award.

 The award is presented to whomever is promoting the theme to the highest degree. The winning campaigns can be campaigns local to communities, educational seminars, new research, media campaigns, and more. If selected, the winner will receive $5,000.

For example, on 2021, the American Veterinary Medical Association (AVMA) won the award for the theme “Veterinarian response to the COVID-19 Crisis resource center. The AVMA kept the center up to date throughout the COVID-19 pandemic to make sure veterinarians across the world had access to these resources to better serve their communities. The resource center included scientific summaries, short videos, risk assessments summaries, online tools, blogs, and other resources.

World Veterinary Day - World Veterinary Association. World Veterinary Association. Published March 18, 2022. https://worldvet.org/activities/world-veterinary-day/

World Veterinary Day celebrates veterinarians as essential health workers. News release. American Veterinary Medical Association. March 11, 2024. Accessed March 11, 2024. https://www.avma.org/news/world-veterinary-day-celebrates-veterinarians-essential-health-workers

AVMA wins World Veterinary Day Award 2021 recognizing the veterinary response to the COVID-19 crisis. News release. American Veterinary Medical Association. July 30, 2021. Accessed March 11, 2024. https://www.avma.org/news/press-releases/avma-wins-world-veterinary-day-award-2021-recognizing-veterinary-response-covid#:~:text=%E2%80%9CIn%20the%20U.S.%2C%20the%20work,2021%20World%20Veterinary%20Day%20Award.

The 2024 World Veterinary Day theme honors veterinarians as essential workers 