Screening for Hidden Diseases Prior to Breeding: Blood and Urine Analysis
by Nancy McDonald, RN
Prior to breeding, the breeder must consider the health and well being of not only the bitch but also the future get as well. Blood and urine analysis, two standard, economical tests can be preformed in advance of a breeding on both the sire and dam, indicating the health of the sire and dam and the future genetic health of the get. In the light of today’s economics, breeding a litter of Bichons is an economic investment. The cost of stud fees and vet fees continue to increase. Whelping and raising a litter of pups by a bitch whose health is compromised could jeopardize not only the pups she produces but also her future breeding potential. A bitch may not tolerate whelping and lactating if she is unhealthy, and a dog or a bitch may have decreased fertility if hidden health conditions exist. Blood and urine analysis can be used to screen breeding pairs for internal organ function alerting the breeder to a potential health problem or an inherited genetic disease. Many health conditions can remain hidden, with no apparent symptoms, until the dog is stressed or older in age, such as endocrine diseases (Cushings, Addisons, diabetes, hypothroid), bladder stones, liver or pancreas disease, kidney disease, cancer, bleeding disorders, anemia and infections.
A complete blood analysis involves the assessment of cellular components (solids) and serum (liquids). The solids are red blood cells, white blood cells, and platelets. Red blood cells (RBC) are manufactured in the bone marrow. Their function, made possible by the hemoglobin they contain, carry oxygen from the lungs to every cell in the body. Anemia, too few RBCs, is caused by failure of bone marrow to produce adequate numbers of RBCs. Bone marrow failure is a common complication caused by many chronic disease processes such as liver dysfunction, cancer, and advanced renal failure.
White blood cells (WBC) fight infections by attacking them directly and by producing antibodies to neutralize them. WBCs are produced in the bone marrow except for one, a lymphocyte, produced in the lymph nodes. During severe infections, such as pyometra or hepatitis, the number of WBCs in the blood will rise. However, in an overwhelming infection, as with parvoviral infection, WBCs are used up faster than they can be produced resulting in an excessively low count.
Platelets, also known as thrombocytes, are produced in the bone marrow and play a critical roll in blood clotting. Immune-mediated thrombocytopenia is a disease where the immune system attacks and destroys platelets, causing their numbers to drop to a dangerously low level that can cause hemorrhaging.
When the cells, (RBCs, WBCs, and platelets), are removed from the blood, a fluid remains, called serum. Serum contains electrolytes, minerals, enzymes, and toxic waste products. The analysis of these factors is called blood chemistries.
Glucose is one of the factors measured in a blood chemistry test. A high glucose level can indicate diabetes. Low glucose levels can be a complicating factor in dogs with severe infections or pancreatic cancer. Another factor, blood urea nitrogen (BUN) and creatinine, are waste products of protein metabolism. The kidneys are responsible for removing them from the bloodstream. In kidney failure, they both rise. Other enzymes, amylase and lipase, detected in the blood stream may be indicative of an inflamed pancreas. Liver enzymes, (known by their acronyms –ALT, AST, ALP, and GGT), rise with liver inflammation, indicating, among other things, hepatitis, liver shunt, or Cushing’s disease. In advanced liver disease, bilirubin, the by-product of the breakdown of red blood cells, rises. The bilirubin also rises in dogs with immune-mediated hemolytic anemia.
The primary proteins that are analyzed in blood are albumin and globulin. Albumin is produced in the liver. Albumin levels fall when liver function is compromised, or in a malnourished dog, or heavy parasite load, or inflammatory bowel disease or kidney inflammation. Globulins are antibodies that fight infections and rise with long-standing infections and with a certain cancer, myeloma.
The most commonly measured electrolytes and minerals in the blood are sodium, potassium, calcium, and phosphorus. Lactating bitches can have low levels of calcium. A high calcium level could indicate the presence of a malignant cancer. Abnormal sodium and potassium could indicate Addison’s disease. A rise in phosphorus signals loss of kidney function. A low thyroid hormone level suggests hypothyroidism or a range of illnesses that suppress the activity of the thyroid gland.
The primary role of the kidneys is to clear toxic waste products from the bloodstream and to help maintain fluid balance. Changes in the urine can be indicative of changes in the blood. Logically, both tests, a blood analysis and urinalysis, are performed when evaluating the health of breeding pairs.
A midstream urine sample (collecting the urine after the dogs starts the stream) can be collected in a clean container at home. Though making a “free catch” is easy in a male dog, it can be challenging in a low-squatting bitch. A soup ladle or a small, flat pie plate may be needed to collect a sample from a bitch as she squats to urinate. Also, a veterinarian can catheterize a dog’s urethra or collect it by cystocentesis, a process by which a needle is inserted through the belly wall directly into the bladder. The cystocentesis method is ideal if a sterile sample is going to be sent to the laboratory for a bacterial culture.
A urinalysis evaluates the physical properties, chemical properties and microscopic properties of the urine. Physical properties of urine are the color, appearance, specific gravity and acidity. Normal color of urine is tinted with yellow. Other color may indicate blood in the urine or infection. Be aware that food consumed may change urine color. The appearance of urine should be clear or slightly hazy. Cloudiness may indicate the presence of white blood cells, bacteria, crystals or mucus. Specific gravity is the density of the urine (pure water is 1.000). Normal SG of a dog contains salts that raise the SG to over 1.030. In kidneys unable to concentrate urine and hormone imbalances such as Cushings, the specific gravity is less than 1.012. The pH, balance between acidic and alkaline properties, of a dog is between 6 and 7. Bacteria in the bladder or kidneys often cause the pH to rise above 7.
Chemical properties (using a dipstick) can indicate a higher amount of protein than the normal trace amount. Levels rise with infection and fever. Glucose can indicate diabetes. Ketones, too, are seen in diabetes and malnutrition. A small amount of bilirubin, the byproduct of the breakdown of red blood cells by the liver, is normal, but if the level is high, the liver function needs to be checked. Blood in the urine, in most cases, is due to bleeding in the urinary tract and often indicates bladder stones. Other hemoglobin in the urine could result from hemolytic anemia or a urinary tract tumor.
Once urine is centrifuged, the fluid portion is discarded and the material that sinks to the bottom of the tube is analyzed under a microscope and is termed cytology. Red cells confirm the presence of blood. Red and white cells in urine sediment indicate an inflammation in the urinary tract. The presence of bacteria in the urine suggests infection. However, unless the urine was collected by cystocentesis, it may be a contaminant. Crystals in the sediment commonly form when the urine pH rises (when bacteria are multiplying in the urine). Crystals may also suggest the presence of stones in the bladder.
Because an abnormal blood test or urinalysis may be indicative of problems needing further exploration, getting them well in advance of breeding is advised. These standard tests performed in the vet’s office could well benefit the next generation of Bichons.
Laboratory Tests: Implications for Nurses by Dr. Mikel A. Rothenberg, 1998.
“Blood Tests May be the Window to Your Dog’s Health” by Jeff Grognet DVM, AKC Gazette, November 2004.
“Urine Interpretation: What Do Those Test Results Really Tell You and Your Vet?” by Jeff Grognet DVM, AKC Gazette, October 2004