aproach to disease managment Flashcards
resourses for intoxication cases
Veterinary Poison Information Service (VPIS)
BSAVA/VPIS guide to common canine and feline poisons.
Ingredient lists/data sheets
Phone triage for toxcity case
Information to acquire:
Signalment- size??
Suspected toxicant, timing of ingestion/exposure, suspected dose.
Likely time of arrival.
Instructions for owner:
Prevent further exposure- dont let animal lick toxins off coat
Bring any packaging of the suspected toxicant.
Preparation by the team:
Set up necessary medication, supportive care etc.
Contact VPIS if required
Decontamination for intoication
Topical-
Rinse eyes with tap water or sterile water
Wash skin/coat with a mild detergent
Emesis-
General rule: Sooner = better.
Solid toxins (grapes/raisins, chewing gum, chocolate) stay in the stomach longer than liquids (ethylene glycol) and powders (lily pollen).
Emesis contraindications:
Non-toxic/very low toxicity substance or dose.
Patients that have already vomited
Caustic/corrosive agent
Volatile agent e.g. petroleum products
High risk of aspiration - megaoesophagus, comatose ect
Respiratory distress
Severe acid-base or electrolyte derangements
agents for inducing emisis in toxicity cases
Inducing emesis:
Apomorphine – licensed for dogs
No licensed options for cats – xylazine preferred.
Soda crystals – care
Examine the vomitus to check the toxin has been expelled
Gastric lavage may be considered where emesis is contraindicated
activated charcoal for decontamination
Adsorbant – bind to toxins to prevent absorption
Alcohol and xylitol do not bind to activated charcoal
Repeated doses recommended
Feed as a slurry with food if possible
May affect the efficacy of orally administered medications – give drugs parenterally while giving charcoal if possible.
emergency stabalisation for toxicity
Primarily of the neurological, cardiovascular, and respiratory system.
See specific lectures for more details.
General advice:
Control seizures- rectal diaxopam
Provide oxygen
Get an IV line
baseline tests for toxicity
Haematology and biochemistry-
Often normal, especially in acute, asymptomatic cases.
Most useful for monitoring and symptomatic cases.
Urinalysis-
Especially useful for suspected ethylene glycol toxicity to look for calcium oxalate crystals.
Coagulation profiles-
Where anticoagulant rodenticide intoxication is suspected
Toxic metabolites:
It is possible to check stomach contents and blood/urine samples for a great number of toxins
Mostly used for forensic work (e.g. wildlife crime) and in zoos and other very valuable animals.
supportive care for toxicity
Intravenous fluid therapy-
Replace fluid loses e.g. from vomiting
Maintain renal perfusion and diuresis
Analgesia-
Opioids preferred over NSAIDs in most cases
Antiemetics-
Maropitant and ondansetron preferred options
Gastroprotectants-
H2 blockers- ranitidine, famotidine
Proton pump inhibitors - omeprazole
Sucralfate
Common Intoxications
Alliums
Anti-parasiticides
Avocado
Chocolate
Ethylene glycol
Grapes/raisins
Herbicides and fertilisers
Lilies
Metaldehyde
NSAIDs
Rodenticides
Teflon
Xylitol
Alliums as intoxicants
The allium family includes onions, garlic, and leeks as well as ornamental varieties.
Cats more sensitive than dogs (5 g/kg for cats; 15 to 30 g/kg for dogs).
Toxicology: Contain organosulphoxides -> organic sulphur compounds -> oxidative damage to erythrocytes -> Heinz body anaemia.
Clinical effects: Inappetence, vomiting, diarrhoea, Heinz body anaemia, methaemoglobinaemia and/or jaundice.
Treatment:
Decontamination (if possible)
Fluid therapy
Symptomatic and supportive care.
Prognosis: Favourable
Anti-parasiticides for toxicities- Pyrethroids:
Cats and snakes
Toxicity: Prevents closure of voltage-dependent sodium channels in nerve membranes, -> repetitive membrane depolarization.
Cats: Vomiting, hypersalivation, ataxia, dilated pupils, tachycardia, hyperexcitability, hyperaesthesia, hyperthermia, tachypnoea, twitching, convulsions and respiratory distress.
Reptiles: Loss of coordination, loss of righting response, sensitivity to bright light, and muscle spasms and panic.
treatment-
Active cooling
Lipid infusion
Decontamination
Seizure control – (diazepam, midazolam, pentobarbital, phenobarbital, propofol, or levetiracetam).
Fluid and nutritional support
prognosis- gaurded to poor
Anti-parasiticides for toxicities- Fipronil
frontline
Rabbits
Toxicity: Blocks GABA receptors in the CNS -> prevention of chloride ion uptake -> excessive CNS stimulation.
Fipronil: Seizures, tremors,
anorexia, lethargy, and death
treatment-
Stasis treatment if needed
Decontamination
Seizure control – (diazepam, midazolam, pentobarbital, phenobarbital, propofol, or levetiracetam).
Fluid and nutritional support
prognosis- gaurded to poor
Anti-parasiticides for toxicities- Ivermectin
Chelonia- can use in low doses
Toxicology: Binds to GABA-gated chloride channels, -> increased chloride ion uptake -> hyperpolarization and flaccid paralysis
Flaccid paralysis and death
treatment-
respiritory support
Decontamination
Seizure control – (diazepam, midazolam, pentobarbital, phenobarbital, propofol, or levetiracetam).
Fluid and nutritional support
prognosis- gaurded to poor
Avocado as an intoxicant
Toxic compound = persin
Birds are the most commonly affected species in small animal practice.
Toxicology: Myocardial necrosis in birds and mammals; mammary necrosis and haemorrhage in mammals.
Clinical effects: GI signs (anorexia, vomiting, diarrhoea,), mastitis, cardiac insufficiency.
Treatment:
Decontamination (if possible)- gastric lavage necessary in birds and horse
Symptomatic and non-specific
Prognosis: Poor if cardiac signs have developed
Chocolate as intoxicant
Toxic compound = theobromine
Cocoa powder = highest concentration of theobromine; white chocolate contains negligible amounts.
Toxicology:
Antagonism of cellular adenosine receptors -> CNS stimulation
Inhibition of cellular calcium reuptake -> increased muscle contractility in cardiac and skeletal muscle.
Clinical effects: Vomiting
Treatment:
Decontamination
Fluid therapy
Anti-emetics e.g. maropitant
Sedation e.g benzodiazepines
Beta-blockers (e.g. atenolol, propranolol)
Prognosis: Good
Ethylene glycol as an intoxicant
Antifreeze; used in screen wash, brake fluid, fountains over winter etc.
Cats more sensitive than dogs.
Toxicology: Converted by alcohol dehydrogenase to various toxic metabolites -> renal damage and hypocalcaemia.
Clinical effects:
cannot decontaminate once symptoms show
Stage 1: Non-specific signs (vomiting, ataxia, tachycardia, weakness, PU/PD) + CNS signs in cats (convulsions, rapidly progressing to coma)
Stage 2: Cardiopulmonary signs
Stage 3: Renal signs
Clinical pathology: Metabolic acidosis, oxaluria, hyperglycaemia, hyperkalaemia and hyperphosphataemia
Treatment:
Decontamination rarely useful
Ethanol = specific antidote- competes for metabolites in liver and stops toxins being metabolised from the ethalyene glycol
Fomepizole = a competitive inhibitor of alcohol dehydrogenase
Sodium bicarbonate
Intensive fluid therapy and monitor renal enzymes
Prognosis:
Good in dogs if presented at time of ingestion, guarded to poor in all cats, and dogs once signs of renal failure have developed.
Grapes/raisins as an intoxicant
Dried fruit appears to be a greater risk than fresh fruit.
There is no apparent correlation between dose ingested and the incidence of toxicity.
Primarily canid species affected, cats tend to show GI rather than kidney signs.
Toxicology: Toxic mechanism unknown
Clinical effects: Vomiting and diarrhoea (both +/- blood), hypersalivation, ataxia, weakness, and lethargy, progressing to renal failure over 24-72 hours.
Treatment:
Decontamination (if possible)
Aggressive fluid therapy
Supportive care- very expensivve and possibly not needed! onwer needs to choose
Prognosis: Good to poor. much wosr once renal signs show
Herbicides and fertilisers as intoxicants
Herbicides:
Phenoxyacetic acid derivative herbicide – very common lawn weed killers, very acidic and volatile.
Diquat/diquat dibromide
Glyphosate
Moss killer is often iron based – treat as for iron toxicity
Most clinical signs are associated with irritation caused by the products, but renal and hepatic toxicity may occur with some products.
Fertilisers:
Most very low toxicity; clinical effects due to irritation
Clinical effects: Variable, but many are related to irritation (hypersalivation, vomiting, diarrhoea, ulceration of mucous membranes)
Treatment:
Decontamination – NOT EMESIS- topical, fairy liquid
Supportive care – fluid therapy, analgesia, GI protectants.
Feeding tube in severe cases.
Prognosis: Favourable
Lilies as an intoxicant
True lilies (Lilium spp.) and day lilies (Hemerocallis spp.) are the toxic species.
All parts of the plant are toxic.
Even very small amounts e.g. grooming pollen from fur can -> toxicity
Toxicity: Mechanism unknown, causes necrosis of renal tubular epithelial cells
Clinical effects: Vomiting, anorexia, depression, PU/PD and renal failure.
Treatment:
Decontamination – topical, emesis and activated charcoal
Fluid therapy and close monitoring of renal function
Supportive care
Prognosis: Favourable if treatment is started before onset of renal damage
Metaldehyde as an intoxicant
Outdoor use of metaldehyde slug baits has been banned in the UK from 31 March 2022.
Toxicology: Not fully understood; possibly due to decreased inhibitory GABA concentrations.
Clinical effects: CNS signs (hyperaesthesia, muscle spasm/rigidity, tremors, twitching, convulsions), hyperthermia, tachycardia, tachypnoea or respiratory depression, and cyanosis
Treatment:
Decontamination (gastric lavage)
Diazepam to control twitching/convulsions, with escalation to full GA if required.
Active cooling
Supportive care – fluid therapy, liver support if needed.
Prognosis: Favourable if mild signs, poor once covulsions develop.
aspirin as an intoxicant
Stimulates the respiratory centre -> hyperventilation and respiratory alkalosis, ->metabolic acidosis over time.
Depression, vomiting, anorexia, hyperthermia, tachypnoea, haematemesis, melaena, abdominal tenderness and anorexia.
treatment-
Decontamination
Fluid therapy
Oxygen therapy (if required)
Antiemetics (if required)
Gastroprotectants e.g. sucralfate, ranitidine or famotidine, omeprazole
Monitor renal and hepatic enzymes, electrolytes, and acid-base changes.
paracetamol as an intoxicant
Toxic metabolite which induces cellular necrosis, methaemoglobin, and Heinz body formation.
three pathways it can be metabolised- third pathway is the toxic one, this kicks in once overdosed- cats hae limited ability to use first tow pathways so no safe dose like there is for dogs
Depression, vomiting, anorexia, hyperthermia, tachypnoea, haematemesis, melaena, abdominal tenderness and anorexia.
: Brown mucous membranes, hypothermia, and facial and paw oedema (mainly cats)
owners may be reluctant to tell about giving paracetamol- tell by clinical sigsn- face and paw oedema
treatment-
Specific antidote:
N-Acetylcysteine
Methaemoglobinaemia treatment:
Vitamin C
Methylene blue- very carcinogenic! be careful
Decontamination
Fluid therapy
Oxygen therapy (if required)
Antiemetics (if required)
Gastroprotectants e.g. sucralfate, ranitidine or famotidine, omeprazole
Monitor renal and hepatic enzymes, electrolytes, and acid-base changes.
ibupropen as an intoxicant
Non -selective COX inhibitor; toxicity due to COX-1 inhibition
Depression, vomiting, anorexia, hyperthermia, tachypnoea, haematemesis, melaena, abdominal tenderness and anorexia.
treatment-
Decontamination
Fluid therapy
Oxygen therapy (if required)
Antiemetics (if required)
Gastroprotectants e.g. sucralfate, ranitidine or famotidine, omeprazole
Monitor renal and hepatic enzymes, electrolytes, and acid-base changes.
Prostaglandin analogue (misoprotol)
Rodenticides as an intoxicant
Usually anticoagulants, occasionally vitamin D is used.
1st generation anticoagulant rodenticides are less toxic than second generation.
Toxicology:
Anticoagulants: Competitively inhibit hepatic vitamin K1 epoxide reductase -> depletion of clotting factors (II, VII, IX and X); impairment of hepatic prothrombin synthesis.
Vitamin D: Hypercalcaemia -> tissue mineralisation and renal failure
Clinical effects:
Non-specific: Lethargy, weakness, depression
Other signs will depend on the site of bleeding – petechiation, abdominal distension, cough/respiratory distress etc
Prognosis:
Favourable in mild and asymptomatic cases; poor where uncontrolled haemorrhage is present.
Treatment:
Decontamination
Anticoagulant:
Chronic/symptomatic cases = start vit K immediately.
Acute/asymptomatic cases = wait and check PT after 48-72 hours.
Severe anaemia = Blood transfusion.
Vitamin D:
Promote diuresis - fluid therapy and diuretics (e.g. furosemide)
Promote calcium excretion - bisphosphonates or calcitonin.
Polytetrafluoroethylene as an intoxicant
AKA Teflon; used in non-stick coatings, especially on cookware.
Primarily effects birds; humans can also be affected but symptoms tend to be self-resolving.
Toxicology: Overheated PTFE releases fumes which, when inhaled, -> alveolar congestion and pulmonary oedema.
Clinical effects: Respiratory distress, acute death.
Treatment:
Decontamination not possible
Supportive care only – oxygen supplementation, NSAIDs and diuretics, fluid therapy, and supplemental heat
Consider antibiosis
Prognosis: Guarded to poor
Xylitol as an intoxicant
Artificial sweetener, commonly found in chewing gum.
Toxicology: Stimulates insulin release in dogs -> severe, rapid-onset hypoglycaemia; hepatotoxic.
Clinical effects: vomiting, tachycardia, ataxia, depression, eventually coma, convulsions and collapse; signs of liver failure and coagulopathy less common.
Treatment:
Decontamination – emesis and activated charcoal
IV dextrose CRI where hypoglycaemia is present
Liver support (SAMe, silybin)
Prognosis:
Favourable if caught early, poor where liver failure has developed.
NEOPLASIA
–> the uncontrolled, abnormal growth of cells
Benign neoplastic masses do not spread (metastasize) - Examples include lipomas and sebaceous adenomas
Malignant neoplasia frequently invade locally and metastasize “cancer” – Examples include lymphoma and carcinomas
Both benign and malignant disease are commonly seen in practice
Cancer is the cause of death in approximately 47% of dogs >10 years of age
What type of neoplasia is it? -We cannot treat it effectively if we do not know what it is
Is it benign or malignant? -Benign disease may not always need treatment
If malignant, has it spread? “Staging” - Important for prognosis and treatment
Are there any paraneoplastic effects? -High calcium with anal sac adenocarcinoma
Does the patient have co-morbidities that could impact on treatment?
Consider whole patient welfare and what is appropriate for the pet and owner
cytology for neoplasia
FINE NEEDLE ASPIRATE – For solid tumours or enlarged lymph nodes – External and internal via ultrasound guided FNA
FLUID CYTOLOGY – Abdominal & thoracic effusions, prostatic wash etc. – Make a fresh smear and put some into EDTA
(care some neoplastic effusions may not have detectable neoplastic cells on cytology)
BONE MARROW ASPIRATE –
Indications – Cytopenia - especially when multiple cell lines are affected (anaemia, thrombocytopaenia) Unexplained big increase in cell lines – lymphocytosis, neutrophilia etc. Hyperglobulinaemia (multiple myeloma)
Slides are best sent to the lab in my opinion
fine needle asprirate for neoplasia
Pros:
Simple, quick and non-invasive
Quick turnaround for results
Lower cost than surgical biopsy and histopathology
Performed awake in most cases unless:
-Fractious
-The mass in near a delicate structure
-Abdominal mass
Cons:
Smaller sample so may not be representative
Some masses such as sarcomas do not exfoliate well
Masses cannot always be graded
Contraindications:
Bleeding disorders- If no gross bleeding disordersexternal FNA is fine. For internal FNA’s check the PLT count first. (Clottingprofile if unsure)
Bladder tumours- Risk of seeding tumour cells
Immobilise the mass/or lymph node with your non dominant hand
Needleonly: -Introduce a 21 or 23g needle into the mass and move the needle back and forth several times
Suction:
-Useful for masses that do not exfoliate well
-Attach a syringe and apply suction whilst moving the needle back and forth. Release suction prior to needle removal
Attach an air-filled syringe and spray onto the slide
Make a smear
Costs: £120 FNA plus consult fee £50 (local Staffordshire practice 11/23)
Managing owner expectations -Important in all aspects of veterinary care:
Make owners aware of the cost and the benefits of the procedure
That samples may come back inconclusive or that further testing may be required
That their pet may yelp or have minor bleeding from the procedure
histopathology for neoplasia
Various methods -Incisional, excisional, pinch, Tru-Cut….
Pros:
Larger sample so increased chance of diagnosis
Architecture can be assessed, and masses graded
Provides more prognostic info
Cons:
More invasive
GA or deep sedation required
Takes more time to get results
Increased cost
Risks:
Bleeding, seeding, compromising future surgery
Contraindications:
Bleeding disorders, co-morbidities increasing the risk of GA
In practice cytology and histopathology arecomplimentary:
FNA’s are often performed first todistinguishbetweeninflammatory/hyperplastic andneoplasticlesions
Biopsy and histopathology is used if the FNA is inconclusive
Otherwise,histopathology is performed after full mass excision toconfirm the diagnosis, allow full grading and to assess surgical margins
INCISIONAL WEDGE BIOPSY-
For solid tumours and LN
Choose an appropriate location
Avoid infected, haemorrhagic or necrotic regions
Inclusion of a normalarea of tissue can beuseful,as long asthe whole biopsysite can be fully removed at follow up surgery
Be aware of local anatomy – avoid important structures!
Surgery
If subcutaneous incise overlying skin and blunt dissect down to the mass or LN
Cut a wedge out of the mass – routine closure
Place in formalin
Do not includeformalin histo samples in the same package as slides
Excisional biopsy - removing the entire mass
FNA advised first ideally. Excisional biopsy can potentially be used without FNA in:
Mammary masses
Haemorrhaging splenic masses – emergency
Deep pulmonary tumours (FNA superficial ones – syringe on!)
In some cases, for dog masses wherefunds are limited
60% skin masses benign in dogs vs only 20% in cats
Not appropriate for:
Masses of an unknown diagnosis
Poorly defined masses
Inflamed or oedematous masses (e.g. MCT)
Rapidly growing masses (feature of malignancy)
Ulcerated masses
HEAT DIFFUSING IMAGING for neoplasia
Cancer cells have different thermal properties than normal tissue. Heat waves (visible blue light) are sent into the mass and are read by a thermal sensor. This is thenassessed by AI and a numerical value is generated:
1 – 4 increased risk of malignancy, further testing recommended (FNA)
5 – 10 the mass appears to be benign (98% certainty)
It cannot diagnose the mass, only give an indication of benign vs malignant
Limitations:
Deep s/c masses
Large masses
Some cysts
False positives can occur in some of the above cases. Further testing would then be advised which would then identify that they areactually benign
Interesting novel, non-invasive technique. Likely further research is required
Cost:
£80/mass local Staffordshire corporate 11/23
TUMOUR STAGING – HAS IT SPREAD? TNM
T – Tumour – What is the primary tumour? - Grade?
N – Nodes – Has it spread to the local lymph node? – FNA, biopsy
M – Mets – Has it spread to distant sites? – Imaging – Thoracic radiographs and abdominal ultrasound vs CT
pulmonary mets diagnostics
Nodular interstitial pattern
Always take 3 inflated views:
R lateral
L lateral
VD or DV
THORACIC RADIOGRAPHS:
Pulmonary METS under 3 – 5mm are not visible
CT
Preferred to radiographs where possible
Able to detect pulmonary masses as small as 1 – 2mm
Even CT has limitations:
Osteosarcoma -the chestCT may benormal, but around95% of dogs havemicrometastasesat thetime of presentation
Abdominal ultrasonography for METS
Can be limited by patient size and equipment/operator- Even specialist diagnostic imagers often CT abdomens of large dogs >30kg beforeultrasound
Ultrasound cannot distinguish between benign and malignant nodules just on appearance-
The exception are targetnodules - 81% predictor of malignancy wherethere are multiple in oneorgan
FNA’s of nodules. Benign regenerative liver nodules are common in olderdogs so a dog should notbe suspected of havingMETS (and then euthanised) just off ultrasound
A liver and spleen can also have MCT METSand look normal on scan!
ONCOLOGICAL SURGERY
KNOW WHAT IT IS BEFORE YOU ATTEMPT TO REMOVE IT!-
With diagnosis and staging you can provide the owner with all the necessary information to make their decision
You do not need to know all the median survival times and treatments off the top of your head, this can be researched once a diagnosis is achieved
IS SURGERY EVEN APPROPRIATE?-
What is the prognosis with or without surgery?
What is the expected benefit?
Will surgery be curative?
What will the impact of surgery be? (to the patient and owner finances)
SURGICAL PREP-
Gentle surgical prep to reduce the risk of tumour seeding
Strict asepsis due to the higher risk of post op infections in cancer patients
SURGICAL MARGINS-
The amount of normal tissue around the tumour that is resected
Narrow surgical margins can be obtained in benign masseslimiting morbidity
If narrow margins are obtained in malignant disease, it is likely to result in treatment failure
The aim is to fully remove the tumour with appropriate margins on the first surgery to get the best chance of a cure-
Tumours are more active at their edges. Partial resection leaves the most aggressive cells behind
There will be less tissue available for closure second time round. A wider resection is also needed second time round which can compoundthe problem.
SURGICAL MARGINS for neoplasia
Narrow margins – up to 1cm – Suitable for benign masses
Wide excision- 2cm+ depending on grade, plus a fascial plane-
-Low – intermediate grade MCT -2 cm and one fascial plane (1cm for low grade)
-High grade MCT – 3 – 4 cm and one fascial plane
Radical excision – The removal of the tumour with extensive margins (includes limb amputation)
CAN YOU GET THE REQUIRED MARGINS?
Tumour location may make it difficult or impossible to get appropriate margins (for example – distal limb)
Advanced surgical skills may also be required to close deficits created by these surgeries (surgical flaps etc.)
Referral may be required
Even in referral hands margins may be impossible to achieve due to tumour size and location
This is where adjunctive treatments play a role
Chemotherapy to shrink a tumour pre surgery
General surgical principles for malignant neoplasia:
Be careful with tumour manipulation during surgery as this could seed cells – use atraumatic forceps rather than rat-tooth’s
Ligate vascular supply to the tumour as early as possible
If there are any adhesions to the tumour remove these with the mass as they could have tumour cell invasion
Remove local LN if staging has shown them to be affected or if they appear grossly abnormal during surgery. Biopsy normal appearing local LN
Lavage the op site post excision and change, drape, kit and gloves prior to closure
Adhere to normal surgical principles of closing dead space and reducing tension
Avoid chemotherapy 7 days prior to surgery and 7 days post-surgery – can affect wound healing
Approximate first opinion costs of GA, surgery, histology
£600 - 800 for an average size mass
£1000+ for more involved surgery
Cost could be reduced where needed, depending on the case,as long as the potential impacts are discussed:
No pre-GA blood – save £65
No IVFT – save £110
No histology – save £165
CHEMOTHERAPY
The use of cytotoxic drugs to kill tumour cells
Chemo drugs target rapidly dividing cells:
Tumours with a high growth rate (high grade and mitotic index)
GI tract and bone marrow- Diarrhoea and myelosuppression
The dose and frequency used aims to balance effective tumour kill whilst minimising side effects by allowing time for normal tissue to recover
Lower dosages are used in veterinary medicine compared to human oncology. We want to improve median survival times in our patients whilst limiting any negative side effects
As the main treatment for conditions such as lymphoma/leukaemia andmetastatic neoplasia
After the surgery of tumours with a high risk of metastasis- Intermediate grade MCT with a high mitotic index, high grade MCT, osteosarcoma,haemangiosarcoma
Neoadjuvant chemo to reduce a non-operable tumour into a smaller operable size
For in-operable chemo-sensitive tumours
There are published protocols for a variety of neoplasticconditions, but in an ever-evolving field it can be useful to contact an oncologist for advice
Chemopetis an oncologist led business that provides expert advice and pre prepared chemotherapeutics to first opinion practices
Cytotoxic drugs are carcinogenic, mutagenic, teratogenic, abortifacient and increase the risk of stillbirth.
At risk people should avoid administering chemotherapy and being around patients posttreatment
At risk groups:
Pregnant, lactating or people trying to conceive
Young children and elderly people
Immunocompromised people
Safe handling is essential to reduce the risk to staff and owners
Appropriate PPE:
Thicker nitrile gloves
Gown
Face shield/eye protection
Mask
Use PPE when handling patient urine, faeces, saliva or vomit.
Drug residues can be found in the urine and faeces for around 7 days
Double bag faeces
Pour water over the site of urination/defecation
CHEMOTHERAPUTICS Safety considerations
Safe administration of injectable chemotherapeutics
PPE
Low risk staff
Safe handling using a needle free closed system to reduce the risk of spillage
Appropriate disposal of materials contaminated with cytotoxic residues
miroclave extentsion set
syringe with spyros attached
CHEMOTHERAPY – PATIENT CONSIDERATIONS
Chemotherapy drugs have a narrow therapeuticindex so accurate dosing is essential:- Use mg/m^2 rather than mg/kg for most dosages (table in the back of the formulary)
Save peripheral veins for chemotherapy – take bloods from the jugular
“One-stick” technique when placing IV catheters- Avoids multiple punctures of the vein that could lead to chemo drugs leaking perivascular
Draw back to demonstrate a “blood flash”
Vincristine, vinblastine and doxo/epirubicinare vesicants – local tissue necrosis can occur if the chemo leaks outside the vein
Early signs of extravasation:
Pain, swelling and redness at the catheter site
If extravasation is suspected:
Stop the chemo
Attach a new syringe and try to aspirate as much as possible
Cold and warm compresses – contact an oncologist for specific treatments where available
iv protocall-
Pre-procedure checks – Appropriate neutrophil count - >1.5 × 10^9/L - if less, delay treatment (2 – 7 days) & reduce dosage (10 – 20%)
Maropitant
First stick catheter
Attach extension set with the clave port
Saline flush and demonstrate “blood flash”
Put on PPE
Attach the chemo syringe Spirosto the clave port
Administer the chemo at an appropriate rate
Monitor for signs of extravasation
Flush 10 – 15ml saline through to clear drug residue from the catheter lockoff and do not disconnect
Remove the IV, extension set and syringe as one and put into cytotoxic bin
Apply dressing – remove PPE and wash hands
CHEMOTHERAPY – PATIENT SIDE EFFECTS
GASTROINTESTINAL-
Diarrhoea, nausea/loss of appetite
Pre-treatment with maropitant – oral for home use
Delayed ileus with vincristine – metoclopramide and supportive treatment
MYELOSUPPRESSION-
Takes time for max suppression – monitor the neutrophilnadir(peak of suppressiom) – around 7 days (5-10)
Risk of sepsis if the neutrophil count drops <0.75 × 109/L- Prescribe prophylactic potentiated amoxicillin
Febrile neutropaeniais an emergency – isolation, IV broad spectrum AB including a fluroquinolone
STERILE HAEMORRHAGIC CYSTITIS-
Cyclophosphamide
RENAL TOXICITY-
Carboplatin and cisplatin
CARDIOTOXICITY-
Doxo/epirubicin
HEPATOTOXICITY-
Lomustine
ELECTROCHEMOTHERAPY (ECT) for neoplasia
Electrical pulses are administered to a mass after an IV or local dose of chemotherapy
The electrical pulses make the tumour cells more permeable to the chemotherapy drug allowing greater uptake and increased sensitivity to the drug- may decrease dose needed
Side effects are generally low but can include local inflammation and myelosuppression
Whilst general chemotherapy for conditions such as lymphoma can be performed in general practice ECT typically requires referral
Treatment is administered under GA/sedation and often two treatments are used two weeks apart
Indications:
Tumours that are inoperable
As part of palliative care in advanced disease
Typical tumours treated:
Carcinomas such as nasal squamous cell carcinomas in cats
Mast cell tumours
Melanomas, sarcomas
radiotherapy for neoplasia
High energy x-rays from a linear accelerator can beused to killcancer cells
Indications:
Tumours of the nasal cavity (carcinoma, lymphoma)
Brain neoplasia – Meningioma
Palliative pain relief of bone tumours such as osteosarcomas
Palliative care of inoperable tumours e.g. oral malignant melanoma that is not amenable to surgery
After the surgical removal of invasive tumours (mast cells tumours, soft tissue sarcomas) to reduce the risk of regrowth
Acute:
Inflamed skin, hair loss etc.
Reversible
Late:
Damage to vascular and connective tissue
Cataracts, retinal issues,skin & joints etc.
Rarely neoplasia
Irreversible
CANCER TREATMENT- PAIN
The control of pain is essential in all aspects of veterinary care to ensure patient welfare
Sources of pain in oncology patients:
The cancer itself – bone neoplasia is notoriously painful
The treatment – surgery etc.
Pre-empting pain and multi-modal analgesia is essential. Chronic pain is often underestimated
Multi-modal analgesia-
NSAIDs – Ensure no contraindications and do not give to patients having corticosteroids as part of their treatment
Paracetamol – Dogs only
Gabapentin – Good for neuropathic pain
Monoclonal antibodies targeting nerve growth factor (Librela/solensia)
Amantadine – Good for pain refractory to NSAIDs but could be restricted
Ketamine – Low dose subcutaneously – monthly to weekly
Antidepressants
CANCER TREATMENT- EUTHANASIA
One of the options to alleviate pain and suffering in our patients
It must be approached with great care and empathy
In our patients it could be due to welfare of the patient and/orcost concerns
We need to be compassionate and ensure the process goes as smoothly as possible
lead with open questions. “Have you thought about euthanasia” is too direct and can be jarring
“How is Kevin getting on?”
“How are you feeling about his treatment?”
If open questions do not prompt the discussion and you are concerned about the patient’s quality of life a delicate more direct approach can be considered:
“We always have to be mindful of how happy our pets are. Are we having more bad days than good days?”
“I’m worried Kevin is not doing as well on treatment anymore. What do you think?”
Quiet private room and where possible ensure there is enough time
Ensure consent and understanding
“Put to sleep term”
Options for their pets afterwards
Signed consent form
Discuss the procedure and whether owners would like to stay
Most do but never assume
SEBACEOUS ADENOMAS
Benign
Raised pink to pigmented lobulated masses – “wart like” – “brains”
Common in middle aged to older dogs – terriers, poodles, cocker spaniels
The appearance is fairly typical but ddx can include:
Viral papilloma
Dermal MCT
Melanoma
Basal celltumour
Squamouscellcarcinoma
Melanoma
Diagnosis:
High suspicion on gross appearance – definitive by FNA/histo
Treatment:
Not required if not causing a problem – just cosmetic
Surgical excision if bothering the dog
Common neoplastic conditions of the skin
SEBACEOUS ADENOMAS
BENIGN CUTANEOUS CYSTS
HISTIOCYTOMAS
LIPOMAS
CANINE MAST CELL TUMOURS (MCT)
BENIGN CUTANEOUS CYSTS
Multiple types which can be considered under the umbrella term of cyst
Follicular cysts – Dermal raised masses filled with a thick keratinaceous material (cheese/paste like on gross FNA) – dilated hair follicles
Sebaceous cysts – look similar – develop in and around the sebaceous gland
Both can rupture generating an inflammatory response and secondary infection
Common in multiple breeds of dog including Shih Tzus, Hounds, Schnauzers and Boxers
Ddx – dermal MCT, deep pyoderma – can look similar to a ruptured cyst
Diagnosis:
Suspicion on appearance and paste like gross FNA material
Benign on heat imaging although false malignancies can occur
Definitive on FNA/histo
Treatment:
Monitor vs surgical excision
Excision recommended for cysts that are prone to rupture
HISTIOCYTOMAS
Benign small pink-red domed cutaneous mass, often found on the limbs, ears or head/neck
Common in young dogs <2 years but can be seen in middle aged dogs too
They can ulcerate -> self-trauma
Ddx
Dermal MCT, Ulceratedmelanoma, Cutaneous lymphoma
Non neoplastic lesion – inflammation, FB, insect bite
Diagnosis:
Suspicion on appearance in a young dog on the limbs
Benign reading on heat imaging
Definitive on FNA (ideal)
Treatment:
May regress spontaneously in a month or so
If not and/or bothering the dog – surgical excision is curative
LIPOMAS
LIPOMAS
Subcutaneous mass made up of fat cells, normally soft and mobile on palpation (occasionally can be found internally)
Very common in middle aged to senior dogs
Gross oily fat on slide after FNA
Ddx:
S/c MCT, soft tissue sarcoma, liposarcoma
Diagnosis:
“Targeted” FNA
Cytology will come back as “lipid”, but this could be just subcutaneous fat, so the clinician needs to ensure the FNA was directly from the mass
Treatment:
None required unless growing in an areas that could cause a problem – axillae - surgical excision
Is it appropriate to diagnose a lipoma based off the exam and demonstrating a fatty oil-like appearance on gross FNA?
No – some neoplasia such as MCT can appear fatty
Yes & no – Where funds are limited, or surgery would never be considered
As long as the limitations are discussed with the owners and documented in the clinical notes
CANINE MAST CELL TUMOURS (MCT)
Mast cells have an important role in inflammatory, immune and allergic reactions
They are present in most tissues in the body and malignant transformation leads to MCTs
7 – 21% of call canine skin tumours
Majority are dermal but they can be subcutaneous
Predisposition:
Any breed but particularlyBulldogs, Staffordshire bull terriers, Boston terriers, Boxers, Pugs, Beagles, Lab/Golden Retrievers, Dachshunds, Shar-peis, Rhodesian Ridgebacks, Weimeraner
Pugs are prone to getting multiple low grade MCT
Shar-peis tend to get high grade metastatic disease
Appearance - Variable – why FNA is so important
Approx 2/3rds of masses may show benign behaviour and present as a slow growing cutaneous lesion
Subcutaneous masses are often less aggressive and may appear like lipomas – FNA’s are very important
Masses can be inflamed from histamine release and can wax and wane in size (vomiting, diarrhoea/melaena)
Rapid growth and mass ulceration can be seen in high grade MCT
MCT diagnosis
FNA -fine basophilic cytoplasmic granules
The Camus grading system and 2022 Paes adaptation were developed to try and give an indication of grade based off cytology
The study showed a high correlation between cytological and histopath grade so it can give a good initial indication
Cytology can overestimate the grade compared to histo
MCT Grading from Histopathology:
Currently only apply to cutaneous MCT’s not s/c ones although dogs with s/c MCT’s tend to have a longer survival time
Various grading systems -Patnaik orKuipel
Grade correlates to prognosis
OTHER PROGNOSTIC INDICATORS-
Size and growth rate – High growth is a sign of malignancy, larger MCTs are harder to remove
Appearance – Inflammation, ulceration and pruritus = poorer prognosis
Systemic signs – vomiting and melaena = poorer prognosis
Breed- pug low grade, sharpei high grade
Location – In some but not all studies, preputial, muzzle, nail bed, perineal and those in mucocutaneous areas = a poorer prognosis
Grade is the most important prognostic indicator
The histology report will come back with the grade and the option of further testing - proliferation markers. These can provide more prognostic information
Ki67 – identifies the growth fraction (activelydividing cells)
AgNOR– identifies the generation time (speed ofcell cycle progression
They can cost an extra £300 odd to test
SHOULD WE TAKE AN INCISIONAL BIOPSY AFTER FNA OF EVERY MCT TO ALLOW FULL GRADING?
Historically yes – before the cytological grading system was developed this was the only way to establish the MCT grade to then know what surgical margins to take
Today with a good cytological grading system we often decide on appropriate staging and treatment based off the FNA grade and other prognostic indicators
Patnaik Grading
CANINE MCT - GRADING
Grade 1 (low grade, well differentiated)– no mitotic figures
Grade 2 (Intermediate)
0 – 2 mitotic figures per hpf, some pleomorphic cells- variation in size
Areas of oedema and necrosis
Infiltration of lower dermis/subcutaneoustissue
Grade 3 (high grade, poorly differentiated)- multiple abnomal cells
3 – 6 mitotic figures per hpf, sheets of pleomorphic cells
Odema/necrosis/haemorrhage and ulceration is common,
Infiltration of lower dermis/subcutanous tissue
KuipelGrading
Low grade
High grade-
7 or more mitotic figures
Generally low mitotic index and well differentiated = lower grade and better prognosis
High mitotic index (>5) and poorly differentiated = higher grade and worse prognosis
