14 minute read
Pulmonary toxoplasmosis in a puppy
from VetScript May 2020
by VetScript
Geoff Orbell, Veterinary Clinical Director at Gribbles Veterinary Laboratories Palmerston North, tracks the source of Toxoplasma gondii infection in a puppy.
of the clinical signs, the puppy was euthanased and a postmortem examination was performed.
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The most significant findings on gross postmortem examination were the lungs, which were diffusely firm, rubbery and discoloured and partially sank in formalin. Histologically there was a severe interstitial pneumonia with marked Type 2 pneumocyte hyperplasia. Multifocally septa were disrupted by necrosis associated with a low number of protozoal tachyzoites (Figure 1). PCR (polymerase chain reaction) of the fixed tissue identified Toxoplasma gondii. No other tissues were submitted for histology.
Toxoplasma gondii is an apicomplexan, intracellular, protozoal parasite
A 10-WEEK-OLD HEADING Dog puppy presented to a veterinary clinic moribund with severe respiratory distress. Three days previously the puppy had stopped eating, and a day later had developed laboured breathing. The puppy had been born on farm and two litter mates were clinically normal. The puppies were being fed a commercial diet as well as raw mutton.
Clinically, differential diagnoses included hypoxia due to severe
FIGURE 1:Lung (400x magnification). Necrosis of alveolar septa with haemorrhage, fibrin, degenerate neutrophils and karyorrhectic debris with intralesional protozoal zoites (arrow).
haemolytic anaemia, streptococcal pneumonia, aspiration pneumonia, pneumonia secondary to kennelcough complex and a toxic insult of some description. Due to the severity for which the definitive host is the domestic cat and other felids. All other mammalian species, as well as cats, serve as intermediate hosts. Intermediate hosts are infected by ingestion of oocysts from feline faeces, consumption of tissue containing infective cysts containing bradyzoites or congenital infection. In domestic cats and other felids, consumption of infected prey is most commonly believed to be the cause.
Following ingestion of oocysts or tissue cysts, asexual and sexual reproduction occurs in the feline intestine, resulting in oocyst shedding.
Only asexual reproduction occurs in intermediate hosts with no oocyst production. Oocyst shedding is highest in young kittens, immunosuppressed or retroviral infected adult cats and those infected by ingestion of infected intermediate host tissue.
Clinical toxoplasmosis in dogs is rare and is most commonly seen in immunosuppressed dogs or those with concurrent disease. Most commonly it presents as neuromuscular disease similar to Neospora caninum infection, which is more common in dogs but can also affect horses and ruminants. Less commonly, it presents as respiratory disease, which is more often seen in cats with congenital or systemic infection. In the current case, there would likely have been other organs infected but these were not submitted for histology.
This puppy could have been infected by eating raw meat or ingesting oocysts. On further questioning the owner said the meat the puppy was fed had been frozen at -18° Celsius for more than 24 hours, which should have been enough to kill encysted toxoplasmosis bradyzoites.
The owner also reported they had two healthy adult cats, but in the previous two weeks had noticed a stray kitten around the puppy’s kennel. In this case the wild kitten would have been the most likely source of Toxoplasma gondii infection for the affected puppy.
FURTHER READING:
Calero-Bernal R, Gennari SM. Clinical toxoplasmosis in dogs and cats: An update. Frontiers in Veterinary Science 6, 54, 2019
Pepper A, Mansfield C, Stent A, Johnstone T. Toxoplasmosis as a cause of life-threatening respiratory distress in a dog receiving immunosuppressive therapy. Clinical Case Reports 7, 942–8, 2019
Shapiro K, Bahia-Oliveira L, Dixon B, Dumètre A, de Wit LA, VanWormer
E, Villena I. Environmental transmission of Toxoplasma gondii: Oocysts in water, soil and food. Food and Waterborne Parasitology 15, 2019. https://doi. org/10.1016/j.fawpar.2019.e00049
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APPs’ role in diagnosing and monitoring tissue injuries
Sandra Forsyth, Clinical Pathologist at SVS Laboratories, discusses the place of acute phase proteins (APPs) in evaluating cats and dogs with inflammatory disease.
INTRODUCTION
An acute phase reaction (APR) is a non-specific, systemic response to disturbances in homeostasis caused by infection, surgery, trauma, neoplasia or immune-mediated processes.
Inflammatory cytokines released at the site of the tissue damage initiate local vascular responses, activate inflammatory cells, stimulate the pituitary-adrenal axis and enhance the hepatic production of specific proteins called acute phase proteins (APP) that aid in the defence and healing of affected tissue.
The APR response is fast and may precede the onset of clinical signs. It is typically short in duration because it reflects an acute phase of inflammation; however, it may remain heightened in chronic conditions.
To date, most inflammatory conditions have been assessed through analyses of leukograms and fibrinogen and globulin concentrations. While these parameters are readily available and inexpensive to obtain, they respond slowly to acute inflammation. In the past two decades several APPs that change rapidly in concentration during the APR have been evaluated as markers of inflammation in various species including cats and dogs.
The leukogram In the APR, leukocytes migrate to the site of an injury under the action of cytokines and APPs, where they reduce or remove the stimulus and damaged cells, and initiate healing.
In the haemogram there may be a neutrophilia and sometimes monocytosis in mild to moderate inflammation, a left shift and toxic changes when the demand for inflammatory cells is great, and leukopenia when the demand for neutrophils is extremely high. However, in some circumstances circulating leukocyte numbers change only marginally in the face of significant inflammation, particularly early in the process or when inflammation is localised. Moreover, leukocytosis may occur with adrenaline and cortisol release, with counts occasionally reaching 30–35 x 109/L, which may cause difficulty in interpretation.
Cats in particular may show minor alterations in leukocyte and neutrophil counts in the presence of inflammation (Trumel et al., 2019). The presence of band neutrophils and toxic change are more sensitive indicators of inflammation; however, they are not useful in differentiating infectious from non-infectious causes (Segev et al., 2006).
The APP response Shortly after the onset of tissue injury, cytokines are released, enter the circulation and induce the liver to slow production of some proteins and increase the production of proteins involved in the APR. Manufacture of albumin and transferrin decreases (negative APPs) and production of C-reactive protein (CRP), serum amyloid A (SAA), alpha-1 glycoprotein, haptoglobin, ceruloplasmin and fibrinogen increases (positive APPs).
Positive APPs can be grouped into major, moderate and minor reactants based on the magnitude of change in serum concentrations following
TABLE 1: Acute phase proteins in dogs and cats
SPECIES MAJOR MODERATE MINOR
Dog
CRP SAA Ceruloplasmin Haptoglobin
Cat
A1GP SAA Haptoglobin
CRP – C-reactive protein, SAA – serum amyloid A, A1GP – alpha-1 glycoprotein Fibrinogen
Fibrinogen
stimulation (Table 1). Major APPs are low in concentration in healthy animals and increase by 100–1,000 times within 8–24 hours in the presence of acute inflammation. Moderate and minor APPs show smaller increases in concentration over a longer period of time, increasing by 50% to 10 times in one to several days. As inflammation resolves, APP concentrations decrease at a similar rate. The exception is fibrinogen, which may take a week or more to return to baseline. In general, the major APPs are most useful because there are fewer outside factors that interfere with their concentration and they increase significantly more than moderate or minor APPs, which makes interpretation more straightforward.
APR in dogs There is considerable evidence that APPs are useful for diagnosis and monitoring of inflammatory conditions caused by septic diseases and sterile inflammatory processes, including pancreatitis, immune-mediated disease and neoplasia. For example, APPs increase rapidly in dogs with pancreatitis, then fall in a five-day period as recovery occurs (Holm et al., 2004). Similarly, in post-operative patients, monitoring APP concentrations is valuable since they peak the day after surgery then decrease in dogs with uncomplicated recoveries while remaining high in those with sepsis or significant tissue necrosis (Dąbrowski et al., 2009). Monitoring APPs also has a place in managing patients with neoplasia. SAA is higher in dogs with malignant compared to benign circumanal gland tumours, and the concentration decreases with successful treatment (Lisiecka et al., 2019). It is probable that the same holds true for other tumours.
CRP and SAA are the major APPs studied most closely in dogs, and as a result there have been several papers comparing the two. Older studies that used analysis methods different from those used currently variably found one more sensitive than the other, suggesting that both are suitable for the investigation of acute inflammation. Nonetheless, a recent study evaluating APP concentrations in 500 dogs found that SAA was better in terms of diagnostic performance than CRP (Christensen et al., 2014).
APR in cats There are fewer papers investigating the use of APPs in cats than there are investigating dogs. However, recently a group comparing the leukogram with serum APP concentrations found that fibrinogen and SAA provided greater sensitivity and specificity in identifying inflammation in this species (Trumel et al., 2019). Similar to that seen in dogs, SAA increases within 24 hours of surgery and falls over ensuing days in uncomplicated recoveries. It also increases in feline patients with acute pancreatitis and in some neoplastic conditions (Tamamoto et al., 2009).
While fibrinogen concentration increases in inflammation, it also increases in hepatic neoplasia and hepatic lipidosis (Dircks et al., 2012; Vilhena et al., 2019), although it could be argued that these conditions may have an associated inflammatory component. SAA has also been reported to increase in diseases that are not historically considered inflammatory, including hyperthyroidism, diabetes mellitus and renal failure (Trumel et al., 2019).
SUMMARY
APPs have a place in evaluations of patients with inflammatory diseases. They frequently increase before abnormalities are noted in the leukogram, and the alteration in their concentration can often provide a gauge as to the severity of the disease process.
REFERENCES: Christensen MB, Langhorn R, Goddard A, Andreasen EB, Moldal E, Tvarijonaviciute A, Kirpensteijn J, Jakobsen S, Persson F,
Kjelgaard-Hansen M. Comparison of serum amyloid A and C-reactive protein as diagnostic markers of systemic inflammation in dogs. Canadian Veterinary Journal 55, 161–8, 2014
Dąbrowski R, Kostro K, Lisiecka U, Szczubiał
M, Krakowski L. Usefulness of C-reactive protein, serum amyloid A component, and haptoglobin determinations in bitches with pyometra for monitoring early post-ovariohysterectomy complications. Theriogenology 72, 471–6, 2009
Dircks B, Nolte I, Mischke R. Haemostatic abnormalities in cats with naturally occurring liver diseases. Veterinary Journal 193, 103–8, 2012
Holm JL, Rozanski EA, Freeman LM, Webster
CRL. C-reactive protein concentrations in canine acute pancreatitis. Journal of Veterinary Emergency and Critical Care, 14, 183–6, 2004
Lisiecka U, Dudek K, Brodzki A, Kostro K, Czop
M, Brodzki P. Evaluation of serum acute phase protein concentrations in dogs with circumanal gland tumours. Journal of Comparative Pathology 171, 12–8, 2019
Segev G, Klement E, Aroch I. Toxic neutrophils in cats: Clinical and clinicopathologic features, and disease prevalence and outcome – a retrospective case control study. Journal of Veterinary Internal Medicine 20, 20–31, 2006
Tamamoto T, Ohno K, Ohmi A, Seki I,
Tsujimoto H. Time-course monitoring of serum amyloid A in a cat with pancreatitis. Veterinary Clinical Pathology 38, 83–6, 2009
Trumel C, Gaillard E, Leynaud V, Aumann M,
Braun JP. Comparison of the diagnostic accuracy of markers of the acute phase of inflammation in cats. A preliminary evaluation. Comparative Clinical Pathology 28, 505–11, 2019
Vilhena H, Tvarijonaviciute IA, Cerón JJ, Figueira AC, Miranda S, Ribeiro A, Canadas
A, Dias-Pereira P, Rubio CP, Franco L, et al. Acute phase proteins and biomarkers of oxidative status in feline spontaneous malignant mammary tumours. Veterinary Comparative Oncology 17, 394–406, 2019
THE PANDEMIC, YOUR AND YOUR EMPLOYEES’ RIGHTS AND OBLIGATIONS
What obligations do veterinary employers have to their staff? Shaun Phelan, National Manager of Business Advisory Services at MAS, explains what you need to know.
THE COVID-19 PANDEMIC has been underway for several months but it’s still a rapidly evolving beast. There’s still much we don’t know about the virus and its long-term effects on our economy and society, but it’s clear that communities need to work together to halt its spread. Businesses have a vital role in this, particularly in protecting their employees and their families.
As New Zealand’s veterinary practices are classified as providing essential services, they’re continuing to operate during the pandemic. This makes it all the more important that practice owners consider what they can do (and what they have to do) for their employees during this time.
If one of your employees is unwell, clearly they shouldn’t turn up at work and you should support them as they recover. But what are your legal obligations? How should sick leave be used, and what are the broader considerations when it comes to dealing with the virus?
HOW SICK LEAVE CAN BE USED
First things first. Every employee, regardless of their profession, is entitled to use their sick leave allocation if they’re ill or if their spouse or a dependant is sick and the employee has to stay home to care for them.
Legally speaking, an employee isn’t entitled to paid sick leave if they’re off work because there may be a risk of their catching the virus (there’s no actual illness). However, their employer can use their own judgement and decide to take a more generous approach.
Some employment agreements will already state that sick leave can be used for situations like this, and employers can agree to employees using their sick leave to avoid the risk of contracting COVID-19. Similarly, employers can agree to an employee using sick leave to look after people who are not dependants; however, this may not be possible for all businesses.
In general, whenever you agree to relax the rules on using sick leave, it’s a good idea to record the agreement in writing.
REQUIRING EMPLOYEES TO STAY AWAY FROM WORK
If an employee is ready, willing and able to work, you’re obliged to provide them with work. However, you may not want the employee to turn up at work if there’s a risk that they’ve been exposed to COVID-19.
In this case you’re entitled – and may be obliged under the Health and Safety at Work Act 2015 – to direct the employee to not turn up at work. If there are so many employees absent that your business can’t function safely or be viable, you may be forced into a closedown situation. The issue is then whether healthy but absent employees are entitled to be paid.
Do employers have to pay employees who are required to stay away? If you decide that an employee can’t come to work, the employee is generally entitled to be paid as long as they’re ready, willing and able to work. There are some possible exceptions to this, such as if your employment agreement includes a clause excluding payment in this situation.
Many employment agreements include ‘force majeure’ clauses, which release the employers from their contractual obligations to pay employees or provide them with work during extraordinary events. However, the threshold is high for invoking such a clause and you should seek legal advice before doing this.
What happens if an employee is compulsorily quarantined? In this situation the employee can’t be said to be ready, willing and able to work, so they’d not be entitled to be paid. However, before making this decision you should look at the feasibility of their working from home or other options for reducing personal contact. You and the employee may also agree to use sick leave or annual leave to cover the situation.
What happens if an employee needs to stay home to look after a child? Children who are sick count as dependants, so the employee would
IN SUMMARY, EMPLOYERS SHOULD:
keep up to date on the latest information on the pandemic, from trusted sources
review their obligations under the Health and Safety at Work Act
develop policies dealing with the situations discussed in this article, and provide clear guidance to practice managers and employees
discuss the evolving situation regularly with employees
document all agreements made with employees.
be entitled to use their paid sick leave until it runs out. However, if a child is well and staying at home because of a school closure, you’re not obliged to pay the employee. Of course you and the employee can agree to different arrangements, and you may choose to take a more relaxed, flexible approach than you’re legally required to.
When can an employee refuse to go to work? Under the Health and Safety at Work Act an employee can refuse to go to work if they have reasonable grounds to believe they could suffer serious harm. If they have a reasonable fear of contracting the virus at work, they may have a right to refuse to go.
Ideally, you and the employee should discuss the situation and whether there are other solutions such as working from home. You probably have no obligation to pay the employee if they refuse to turn up at work unless you’re at fault in some way.
HOW THE GOVERNMENT WILL HELP
If you would like to find out more about this package, your obligations towards your staff and what government support you might be eligible to receive, we’ve put together some general advice at
www.healthypractice.co.nz/news/ covid-19-wage-subsidy-update.
MAS staff are happy to answer any questions you have on practice issues or dilemmas. Email your questions to
business@mas.co.nz.
This article is of a general nature and is not a substitute for professional and individually tailored business or legal advice. © Medical Assurance Society New Zealand Limited 2020.
FURTHER READING:
Ministry of Health: www.health.
