Differential diagnosis app in small animal veterinary medicine (available soon)
Hi vet!
Reverse sneezing is a loud inspiratory sound that occurs without warning, usually secondary to nasopharyngeal irritation.
It can be repeated and last several minutes. The owner might think that the animal is suffocating.
Reverse sneezing is ommon in dogs, less common in cats.
Hi vet !
Bile acids are a major constituent of bile, they are synthesized in the liver from cholesterol, and are conjugated, predominantly with taurine, before biliary secretion as salts, they aid in digestion and absorption of dietary fat.
Bile acids are stored in the gallbladder and released following feeding. Enterohepatic circulation recycles bile acids released into the portal circulation: only a small amount appearing in the systemic circulation of healthy animals.
Serum bile acids concentration can be abnormal if hepatic function is sub-optimal, if there is a portosystemic shunt or if biliary obstruction occurs. Increases in serum bile acids are not specific for certain disease types.
Serum bile acids are usually evaluated in paired samples: fasting and 2 hours postprandial (bile acid stimulation test). This improves the sensibility of the test.
It must be noted that in cholestasis, fasting serum bile acids (FSBA) concentrations can be high and often do not increase much postprandially, whereas some patients with Portosystemic shunt have normal FSBA and massively abnormal postprandial serum bile acids (PPSBA) concentrations.
Reference interval (varies between authors): fasting bile acids normally < 5 μmol/L; fasting BAs > 15 μmol/L and/or postprandial BAs > 30 μmol/L are abnormal.
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Hi vet! Peripheral edema is a common clinical presentation. Do you remenber the ddx ?
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In dogs and cats with diabetic ketoacidosis (DKA), increased potassium loss in urine is observed, often leading to hypokalemia.
Furthermore, during therapy for DKA the serum potassium concentration decreases because of rehydration (dilution), insulin-mediated cellular uptake of potassium (with glucose), continued urinary losses, and correction of acidemia (translocation of potassium into the intracellular fluid compartment). That's why severe hypokalemia is the most common complication that develops during the initial 24 hours of treatment of DKA.
On the contrary, hypoadrenocorticism, Acute oliguric-anuric kidney disease and urethral obstruction lead to impaired potassium excretion in the urine, potentially creating hyperkalemia.
Alopecia can be focal or multifocal. Focal alopecia is usually limited to one area or spot on the body. Multifocal implies that more than one area of the body is affected. Multifocal alopecia can be symmetrical (present on both sides and in a similar location) or asymmetrical (not in a uniform pattern and not located in a similar location on both sides).
The causes of alopecia can be quite different between dogs and cats. Below is the differential diagnosis of canine alopecia.
Alopecia may be a primary or secondary lesion.
Hi vet! Polyuria and polyipsia are common complaints in small animal practice. Do you know all possible causes?
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However ALP should never be considered a sceening test for HAC. There is no correlation between ALP activity and HAC severity, response to therapy, or
prognosis.
Almost all ALP in dogs with HAC is a steroid-induced hepatic isoenzyme (SALP), an isoenzyme response unique to dogs.
Other relatively common laboratory abnormalities observed in dogs with HAC include :
- increased Alanine aminotransferase (ALT) activity (mild increase)
- increases in cholesterol
and triglyceride concentrations
( >50% of dogs with HAC)
- mild hyperglycemia (usually without glucosuria)
- Low Blood Urea Nitrogen (due to diuresis, 30 to 50% of dogs with HAC)
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Total T4 (TT4) is considered a highly specific diagnostic test for hyperthyroidism. Its sensitivity is acceptable although not extremely high (approximately 90%): the diagnosis of hyperthyroidism should not be excluded on the basis of one “normal” serum TT4 test result, especially in a cat with appropriate, albeit often mild, clinical signs and a palpable mass in the neck.
A stepwise approach is recommended: serum total T4 concentrations should be assessed first in cats suspected of hyperthyroidism. If values are found within the mid to high end of the reference interval, consideration should be given to measurement of the corresponding free T4 concentration. If it is elevated, hyperthyroidism is confirmed.
Hi vet !
Neutropenia is generally a result of:
• Overwhelming demand and increased migration from
circulation to tissues
• Decreased survival of cells
• Reduced or ineffective granulopoiesis.
There is also a fourth, less
common, type of neutropenia caused by shift from the circulating to marginating pool due to increased expression
of adhesion molecules on the neutrophil surface (this may be observed in the first minutes to hours of endotoxic or anaphylactic shock)
Lymphopenia is a common finding, do you know the causes?
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Erythrocytosis (also named polycythemia) is defined as an increase in the circulating red blood cell (RBC) mass and is manifested hematologically as an increase in the packed cell volume (PCV) above the reference interval (37-55% for dogs and 27-46% for cats).
Erythrocytosis may be either relative or absolute. Relative erythrocytosis may occur due to decreased plasma volume or erythrocyte redistribution. Absolute erythrocytosis is caused by an actual increase in the red cell mass and may be primary or secondary.
It must be noted that certain dog breeds, such as greyhounds or poodles, have PCV values above the reference interval; this also occurs in dogs that live at high altitudes.
Erythrocytosis is uncommon in dogs and rare in cats.
Both polakiuria and stanguria are common signs of lower urinary tract inflammation, infection, and/or obstruction.
These signs might be confused by owners with inappropriate elimination, tenesmus, polyuria or incontinence.
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Prolonged proestrus/estrus occurs when a bitch displays vulvar bleeding for more than 30 to 35 consecutive days, accompanied by attractiveness to males. Greater than 80% to 90% superficial cells are present on vaginal cytology. Such bi***es are variably receptive to breeding. Prolonged proestrus and/or estrus results from a persistent production of estrogens, with or without small elevations in progesterone.
Cystic ovarian follicles and
estrogen-secreting ovarian neoplasia (e.g., granulosa cell tumor, adenocarcinoma, cystadenoma) are the main causes of prolonged estrus in the bitch.
Excessive iatrogenic estrogen administration may also lead to prolonged estrus.
Observing low levels of blood urea nitrogen in our patients is not uncommon, do you know the causes?
The most common cause associated with a decrease in urea concentration is liver dysfunction, particularly cirrhosis and portosystemic shunt.
In both scenarios, the volume of the functional liver decreases and subsequently fewer hepatocytes are available to convert ammonia to urea, resulting in decreased urea concentrations.
When portosystemic shunts are successfully treated, urea usually increases.
So, when was the last time you observed reverse sneezing? what was your diagnosis?
Hi vet ! neutrophilia ddx is very extensive :)
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Hi vet ! remembering the ddx for thrombocytopenia !
when evaluating the platelet count, one should pay particular attention to lab artifacts, especially clumping (traumatic venipuncture, clots/
microclots in tube, heparinized sample).
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Other causes of increased serum bile acids include hepatic failure and cholestasis.
Hyperammonemia is another common finding in animals with portosystemic shunts.
Imaging and/or surgical explorations
are necessary to confirm the diagnosis of PSS.
Hi vet!
Polyphagia is rarely the only clinical sign of a disease. Knowing whether weight gain or loss was observed during the period the animal was polyphagic will help determine the cause.
Among the causes of polyphagia with weight GAIN, we can highlight for example:
- Hyperadrenocorticism
- Acromegaly
- Hypoglycemia
- Sudden Acquired Retinal Degeneration Syndrome (SARDS)
Hi vet ! do you know the differencials for hypocalcemia ?
Calcium serves two principal physiologic functions. First, insoluble calcium salts provide the structural characteristics that allow bones to protect internal organs and bear weight. Second, soluble calcium ions in the extracellular fluid (ECF) and cytosol are critically important for a myriad of biochemical intracellular and extracellular functions. For example, calcium is necessary for various enzymatic reactions, transport of substances across membranes and membrane stability, blood coagulation, nerve conduction, neuromuscular transmission, muscle contraction, smooth muscle tone, hormone secretion, bone formation, hepatic glycogen metabolism, cell growth, and cell division. Approximately 1% of total body calcium is contained within the ECF and soft tissue, 99% is found in bone.
The concentration of serum ionized calcium and the calcium content of skeleton is maintained within narrow limits by a complicated homeostatic system involving multiple organs (parathyroid glands, kidneys, skeleton, and gut) and several hormones (e.g., parathyroid hormone (PTH), vitamin D, and PTH-related protein (PTHrP)). The actions of PTH on bone resorption, renal calcium excretion, and metabolism of vitamin D are responsible for maintaining homeostasis. Abnormalities in any of these organs, hormones, or receptors may cause disturbances in calcium metabolism that can lead to hypercalcemia or hypocalcemia.
Hypocalcemia refers to a decrease in serum total and/or ionized calcium concentrations.
Reference intervals (for cats and dogs):
- total: 9.5-11.5 mg/dL (2.32-3.06 mmol/L)
- ionized: 1.2-1.4 mmol/L
It should be noted that clinically significant hypocalcaemia is generally not apparent until the total and ionized calcium decrease to
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Bone marrow suppresion, associated with nonregenerative anemia, is the most common clinical syndrome associated with FeLV-infection.
Regenerative anemia (indicated by increased reticulocytes and, in some cases, nucleated red blood cells) is less common in FeLV-infected cats but can happen, it is often
associated with coinfection with Mycoplasma haemofelis or Mycoplasma spp.
FeLV is also an important cause of thrombocytopenia and neutropenia in cats.
Hello vet! Check out the differentials for hyperammonemia!
Portosystemic shunt is the most common pathologic cause of hyperammonemia.
Ammonia is one of the main toxins, and the only readily measured factor, implicated in the pathogenesis of hepatic encephalopathy.
Reference intervals: less than 90-100 µg/dL (53-59 μmol/L) in dogs and cats.
Hi vet !
Enlarged prostate is a common finding in dogs.
It is rare in cats and has only been described in association with neoplastic lesions, bacterial prostatitis, and prostatic abscess.
For example, in severe chronic hepatopathies such as cirrhosis,
and also portosystemic shunts (PSS),
there may be marked hepatic dysfunction with no or minimal
marker enzyme release. This occurs because there is
either insufficient functional hepatic mass to synthesize
and release the enzymes (e.g. cirrhosis, PSS) or no active hepatic damage (e.g. PSS).
It should also be noted that ALT is more specific than AST for evaluating liver damage.
ALT is a leakage enzyme that is free in the cytoplasm, it is often considered “liver-specific” in the cat and dog since the highest concentrations of ALT occur in hepatocytes, however, it is also present in lesser intracellular quantities in heart, kidney, and skeletal muscle.
AST is a leakage enzyme that is found predominantly in the cytoplasm, with about 20% located within mitochondria. AST is present at highest concentrations in hepatocytes and muscle cells (both skeletal and cardiac). It is also present in brain, kidneys, small intestine, spleen, and erythrocytes. Therefore, AST is not a liver-specific enzyme.
Hi vet! Do you remember the differentials for non-regenerative anemia?
Anemia is defined as a decrease in the mass of red blood cells. In practical terms, it can be defined as a decrease in hematocrit (HcT), or as a hemoglobin concentration or red blood cell count below the reference intervals established for the species considered.
Anemia is non-regenerative or “inappropriately” regenerative when there is insufficient production of red blood cells in the bone marrow to compensate for the decrease in red blood cell mass (absence of reticulocytosis).
In non-regenerative anemia there is no increased release of reticulocytes from the bone marrow and the anemia is normocytic and normochromic, with no increase in RDW (red cell distribution width). In a blood smear, erythrocytes are uniform in size and polychromatic cells are rare (
Hi vet! Check out the differencials for chronic diarrhea 😎
Diarrhea is caused by excess f***l water. It can result from decreased intestinal absorption or increased intestinal secretion.
Small intestinal disease causes diarrhea only if the material exiting the ileum exceeds the absorptive capacity of the colon or causes colonic secretion of water. It should then be noted that many animals with sever small intestinal disease do not have diarrhea.
In contrast, large intestinal disease commonly causes diarrhea because there is nothing distal to it to absorb water.
Diarrhea not clearly improving within 14 days is considered chronic.
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ALT is more specific than AST for evaluating liver damage.
In liver disease, rises
in AST activity usually parallel ALT. Thus, an increase in AST and creatine kinase, but not ALT, probably indicates muscle damage.
ALT is a leakage enzyme that is free in the cytoplasm, it is often considered “liver-specific” in the cat and dog since the highest concentrations of ALT occur in hepatocytes, however, it is also present in lesser intracellular quantities in heart, kidney, and skeletal muscle.
AST is a leakage enzyme that is found predominantly in the cytoplasm, with about 20% located within mitochondria. AST is present at highest concentrations in hepatocytes and muscle cells (both skeletal and cardiac). It is also present in brain, kidneys, small intestine, spleen, and erythrocytes. Therefore, AST is not a liver-specific enzyme.
Hi vet ! Increased apartate aminotransferase can be observed in many conditions. Check them out.
Unlike ALT (alanine aminotransferase), AST is present in muscle cells, thus an increase in AST and creatine kinase, but not ALT, probably indicates muscle damage.
Because some of the hepatocellular AST is mitochondrial-bound rather than all free in the cytosol, some clinicians argue that release requires more severe injury, i.e. cell necrosis rather than increased cell membrane permeability. Therefore, release of AST often lags slightly behind ALT and, because its half-life is shorter, its presence probably suggests more profound or persistent injury than an increase in ALT alone. Consequently, increased serum AST may be a more specific marker of significant liver damage than ALT as it is less likely to be increased in secondary hepatopathies e.g. glucocorticoid hepatopathy.
Reference interval is variable among laboratories and dependent upon analyzers / methodologies.
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Determination of serum lipid
concentrations (cholesterol, triglycerides) should always follow a fast of at least 12 hours (in an adult animal).
Although fasting hypercholesterolemia and hypertriglyceridemia can be associated with several other disorders, their presence in a dog with appropriate clinical signs is strong evidence for hypothyroidism.
Common clinical findings observed with hypothyroidism in dogs include (but are not limited to) :
-Lethargy
-Mental dullness
-Inactivity
-Weight gain
- Weakness
-Endocrine alopecia
-Pyoderma
References :
- Nelson, R.W., Couto, C.G et al. (eds). 2019. Small animal internal medicine, sixth edition. Elsevier, chapter 52, pp 908-914.
- Nelson, R.W., Couto, C.G et al. (eds). 2019. Small animal internal medicine, sixth edition. Elsevier, chapter 48, pp 767-805.
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